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Chronic pulmonary disease continues to be a major cause of morbidity and mortality in individuals living with the human immunodeficiency virus, even with optimal HIV control. And this is independent, as seen in many studies, of age, smoking, and pulmonary infections.
Both chronic pulmonary obstructive disease (COPD) and lung cancer occur more frequently in people living with HIV than in the general population, and at earlier ages, and with worse outcomes. The risk for emphysema and interstitial lung abnormalities also appears to be higher, research has shown. And asthma has also recently emerged as another important lung disease in people with HIV (PWH).
“There is evidence that the severity of immunocompromise associated with HIV infection is linked with chronic lung diseases. People who have a lower CD4 cell count or a higher viral load do have an increased risk of COPD and emphysema as well as potentially lung cancer. ,” said Kristina Crothers, MD, professor in the division of pulmonary, critical care, and sleep medicine at the University of Washington, Seattle.
Research has evolved from a focus on the epidemiology of HIV-related chronic lung diseases to a current emphasis on “trying to understand further the mechanisms [behind the heightened risk] through more benchwork and corollary translational studies, and then to the next level of trying to understand what this means for how we should manage people with HIV who have chronic lung diseases,” Dr. Crothers said. “Should management be tailored for people with HIV infection?”
Impairments in immune pathways, local and systemic inflammation, oxidative stress, dysbiosis, and accelerated cellular senescence are among potential mechanisms, but until ongoing mechanistic research yields more answers, pulmonologists should simply – but importantly – be aware of the increased risk and have a low threshold for investigating respiratory symptoms, she and other experts said in interviews. Referral of eligible patients for lung cancer screening is also a priority, as is smoking cessation, they said.
Notably, while spirometry has been the most commonly studied lung function measure in PWH, another noninvasive measure, diffusing capacity for carbon monoxide (DLCO), has garnered attention in the past decade and thus far appears to be the more frequent lung function abnormality.
In an analysis published in 2020 from the longitudinal Multicenter AIDS Cohort Study (MACS) – a study of a subcohort of 591 men with HIV and 476 without HIV – those with HIV were found to have a 1.6-fold increased risk of mild DLCO impairment (< 80% of predicted normal) and a 3-fold higher risk of more severe DLCO impairment (< 60% of predicted normal). There was no significant difference in spirometry findings by HIV status.
Such findings on DLCO are worthy of consideration in clinical practice, even in the absence of HIV-specific screening guidelines for noncommunicable lung diseases, Dr. Crothers said. “In thinking about screening and diagnosing chronic lung diseases in these patients, I’d not only consider spirometry, but also diffusing capacity” when possible, she said. Impaired DLCO is seen with emphysema and pulmonary vascular diseases like pulmonary hypertension and also interstitial lung diseases.
Key chronic lung diseases
Ken M. Kunisaki, MD, MS, associate professor of medicine at the University of Minnesota, Minneapolis, and the first author of the MACS analysis of lung function – one of the most recent and largest reports of DLCO impairment – points out that studies of chest computed tomography (CT) have also documented higher rates of emphysema and interstitial lung abnormalities.
A chest CT analysis from a cohort in Denmark (the Copenhagen Comorbidity in HIV Infection [COCOMO] cohort) found interstitial lung abnormalities in 10.9% of more than 700 PWH which represented a 1.8-fold increased risk compared to HIV-negative controls. And a study from an Italian sample of never-smoking PWH and controls reported emphysema in 18% and 4%, respectively. These studies, which did not measure DLCO, are among those discussed in a 2021 review by Dr. Kunisaki of advances in HIV-associated chronic lung disease research.
COPD is the best studied and most commonly encountered chronic lung disease in PWH. “Particularly for COPD, what’s both interesting and unfortunate is that we haven’t really seen any changes in the epidemiology with ART (antiretroviral therapy) – we’re still seeing the same findings, like the association of HIV with worse COPD at younger ages,” said Alison Morris, MD, MS, professor of medicine, immunology, and clinical and translational research at the University of Pittsburgh. “It doesn’t seem to have improved.”
Its prevalence has varied widely from cohort to cohort, from as low as 3% (similar to the general population) to over 40%, Dr. Kunisaki said, emphasizing that many studies, including studies showing higher rates, have controlled for current and past smoking. In evaluating patients with low or no smoking burden, “don’t discount respiratory symptoms as possibly reflecting underlying lung disease because COPD can develop with low to no smoking history in those with HIV,” he advised.
A better understanding of how a chronic viral infection like HIV leads to heightened COPD risk will not only help those with HIV, he notes, but also people without HIV who have COPD but have never smoked – a woefully underappreciated and understudied population. Ongoing research, he said, “should help us understand COPD pathogenesis generally.”
Research on asthma is relatively limited thus far, but it does appear that PWH may be more prone to developing severe asthma, just as with COPD, said Dr. Kunisaki, also a staff physician at the Minneapolis Veterans Administration Health Care System. Research has shown, for instance, that people with HIV more frequently needed aggressive respiratory support when hospitalized for asthma exacerbations.
It’s unclear how much of this potentially increased severity is attributable to the biology of HIV’s impact on the body and how much relates to social factors like disparities in income and access to care, Dr. Kunisaki said, noting that the same questions apply to the more frequent COPD exacerbations documented in PWH.
Dr. Crothers points out that, while most studies do not suggest a difference in the incidence of asthma in PWH, “there is some data from researchers looking at asthma profiles [suggesting] that the biomarkers associated with asthma may be different in people with and without HIV,” signaling potentially different molecular or biologic underpinnings of the disease.
Incidence rates of lung cancer in PWH, meanwhile, have declined over the last 2 decades, but lung cancer remains the leading cause of cancer-related mortality in PWH and occurs at a rate that is 2-2.5 times higher than that of individuals not infected with HIV, according to
Janice Leung, MD, of the division of respiratory medicine at the University of British Columbia and the Centre for Heart Lung Innovation at St. Paul’s Hospital in Vancouver.
Patients with HIV have “worse outcomes overall and a higher risk of mortality, even when presenting at the same stage,” said Dr. Leung, who reviewed trends in COPD and lung cancer in a recently published opinion piece.
Potential drivers
A bird’s eye view of potential – and likely interrelated – mechanisms for chronic lung disease includes chronic immune activation that impairs innate and adaptive immune pathways; chronic inflammation systemically and in the lung despite viral suppression; persistence of the virus in latent reservoirs in the lung, particularly in alveolar macrophages and T cells; HIV-related proteins contributing to oxidative stress; accelerated cellular aging; dysbiosis; and ongoing injury from inhaled toxins.
All are described in the literature and are being further explored. “It’s likely that multiple pathways are playing a role,” said Dr. Crothers, “and it could be that the balance of one to another leads to different manifestations of disease.”
Biomarkers that have been elevated and associated with different features of chronic lung disease – such as airflow obstruction, low DLCO, and emphysema – include markers of inflammation (e.g., C-reactive protein, interleukin-6), monocyte activation (e.g., soluble CD14), and markers of endothelial dysfunction, she noted in a 2021 commentary marking 40 years since the first reported cases of acquired immunodeficiency syndrome.
In her laboratory, Dr. Leung is using new epigenetic markers to look at the pathogenesis of accelerated aging in the lung. By profiling bronchial epithelial brushings for DNA methylation and gene expression, they have found that “people living with both HIV and COPD have the fastest epigenetic age acceleration in their airway epithelium,” she said. The findings “suggest that the HIV lung is aging faster.”
They reported their findings in 2022, describing methylation disruptions along age-related pathways such as cellular senescence, longevity regulation, and insulin signaling.
Dr. Leung and her team have also studied the lung microbiome and found lower microbial diversity in the airway epithelium in patients with HIV than those without, especially in those with HIV and COPD. The National Institutes of Health–sponsored Lung HIV Microbiome Project found that changes in the lung microbiome are most pronounced in patients who haven’t yet initiated ART, but research in her lab suggests ongoing suppression of microbial diversity even after ART, she said.
Dr. Morris is particularly interested in the oral microbiome, having found through her research that changes in the oral microbiome in PWH were more related to impaired lung function than alterations in the lung and gut microbiome. “That may be in part because of the way we measure things,” she said. “But we also think that the oral microbiome probably seeds the lung [through micro-aspiration].” A study published in 2020 from the Pittsburgh site of the MACS described alterations in oral microbial communities in PWH with abnormal lung function.
Preliminary research suggests that improved dental cleaning and periodontal work in PWH and COPD may influence the severity of COPD, she noted.
“We don’t see as much of a signal with the gut microbiome [and HIV status or lung function], though there could still be ways in which gut microbiome influences the lung,” through systemic inflammation, the release of metabolites into the bloodstream, or microbial translocation, for instance, she said.
The potential role of translocation of members of the microbiome, in fact, is an area of active research for Dr. Morris. Members of the microbiome – viruses and fungi in addition to bacteria – “can get into the bloodstream from the mouth, from the lung, from the gut, to stimulate inflammation and worsen lung disease,” she said.
Key questions in an evolving research landscape
Dr. Kunisaki looks forward to research providing a more longitudinal look at lung function decline– a move beyond a dominance of cross-sectional studies – as well as research that is more comprehensive, with simultaneous collection of various functional measures (eg., DLCO with chest imaging and fractional excretion of nitric oxide (FENO – a standardized breath measure of Th2 airway inflammation).
The several-year-old NIH-supported MACS/WIHS (Women’s Interagency HIV Study) Combined Cohort study, in which Dr. Kunisaki and Dr. Morris participate, aims in part to identity biomarkers of increased risk for chronic lung disease and other chronic disorders and to develop strategies for more effective interventions and treatments.
Researchers will also share biospecimens, “which will allow more mechanistic work,” Dr. Kunisaki noted. (The combined cohort study includes participants from the earlier, separate MACS and WIHS studies.)
Questions about treatment strategies include the risks versus benefits of inhaled corticosteroids, which may increase an already elevated risk of respiratory infections like bacterial pneumonia in PWH, Dr. Kunisaki said.
[An aside: Inhaled corticosteroids also have well-described interactions with ART regimens that contain CYP3A4 inhibitors (e.g., ritonavir and cobicistat) that can lead to hypercortisolism. In patients who require both types of drugs, he said, beclomethasone has the least interactions and is the preferred inhaled corticosteroid.]
For Dr. Crothers, unanswered critical questions include – as she wrote in her 2021 commentary – the question of how guidelines for the management of COPD and asthma should be adapted for PWH. Is COPD in PWH more or less responsive to inhaled corticosteroids, for instance? And are antifibrotic treatments for interstitial lung disease and immunotherapies for asthma or lung cancer similarly effective, and are there any increased risks for harms in people with HIV?
There’s also the question of whether PWH should be screened for lung cancer earlier and with a lower smoking exposure than is advised under current guidelines for the general population, she said in the interview. “And should the approach to shared decision-making be modified for people with HIV?” she said. “We’re doing some work on these questions” right now.
None of the researchers interviewed reported any conflicts of interest relevant to the story. Dr. Kunisaki reported that he has no relevant disclosures, and said that his comments are his personal views and not official views of the U.S. Government, Department of Veterans Affairs, the Minneapolis VA, or the University of Minnesota.
Chronic pulmonary disease continues to be a major cause of morbidity and mortality in individuals living with the human immunodeficiency virus, even with optimal HIV control. And this is independent, as seen in many studies, of age, smoking, and pulmonary infections.
Both chronic pulmonary obstructive disease (COPD) and lung cancer occur more frequently in people living with HIV than in the general population, and at earlier ages, and with worse outcomes. The risk for emphysema and interstitial lung abnormalities also appears to be higher, research has shown. And asthma has also recently emerged as another important lung disease in people with HIV (PWH).
“There is evidence that the severity of immunocompromise associated with HIV infection is linked with chronic lung diseases. People who have a lower CD4 cell count or a higher viral load do have an increased risk of COPD and emphysema as well as potentially lung cancer. ,” said Kristina Crothers, MD, professor in the division of pulmonary, critical care, and sleep medicine at the University of Washington, Seattle.
Research has evolved from a focus on the epidemiology of HIV-related chronic lung diseases to a current emphasis on “trying to understand further the mechanisms [behind the heightened risk] through more benchwork and corollary translational studies, and then to the next level of trying to understand what this means for how we should manage people with HIV who have chronic lung diseases,” Dr. Crothers said. “Should management be tailored for people with HIV infection?”
Impairments in immune pathways, local and systemic inflammation, oxidative stress, dysbiosis, and accelerated cellular senescence are among potential mechanisms, but until ongoing mechanistic research yields more answers, pulmonologists should simply – but importantly – be aware of the increased risk and have a low threshold for investigating respiratory symptoms, she and other experts said in interviews. Referral of eligible patients for lung cancer screening is also a priority, as is smoking cessation, they said.
Notably, while spirometry has been the most commonly studied lung function measure in PWH, another noninvasive measure, diffusing capacity for carbon monoxide (DLCO), has garnered attention in the past decade and thus far appears to be the more frequent lung function abnormality.
In an analysis published in 2020 from the longitudinal Multicenter AIDS Cohort Study (MACS) – a study of a subcohort of 591 men with HIV and 476 without HIV – those with HIV were found to have a 1.6-fold increased risk of mild DLCO impairment (< 80% of predicted normal) and a 3-fold higher risk of more severe DLCO impairment (< 60% of predicted normal). There was no significant difference in spirometry findings by HIV status.
Such findings on DLCO are worthy of consideration in clinical practice, even in the absence of HIV-specific screening guidelines for noncommunicable lung diseases, Dr. Crothers said. “In thinking about screening and diagnosing chronic lung diseases in these patients, I’d not only consider spirometry, but also diffusing capacity” when possible, she said. Impaired DLCO is seen with emphysema and pulmonary vascular diseases like pulmonary hypertension and also interstitial lung diseases.
Key chronic lung diseases
Ken M. Kunisaki, MD, MS, associate professor of medicine at the University of Minnesota, Minneapolis, and the first author of the MACS analysis of lung function – one of the most recent and largest reports of DLCO impairment – points out that studies of chest computed tomography (CT) have also documented higher rates of emphysema and interstitial lung abnormalities.
A chest CT analysis from a cohort in Denmark (the Copenhagen Comorbidity in HIV Infection [COCOMO] cohort) found interstitial lung abnormalities in 10.9% of more than 700 PWH which represented a 1.8-fold increased risk compared to HIV-negative controls. And a study from an Italian sample of never-smoking PWH and controls reported emphysema in 18% and 4%, respectively. These studies, which did not measure DLCO, are among those discussed in a 2021 review by Dr. Kunisaki of advances in HIV-associated chronic lung disease research.
COPD is the best studied and most commonly encountered chronic lung disease in PWH. “Particularly for COPD, what’s both interesting and unfortunate is that we haven’t really seen any changes in the epidemiology with ART (antiretroviral therapy) – we’re still seeing the same findings, like the association of HIV with worse COPD at younger ages,” said Alison Morris, MD, MS, professor of medicine, immunology, and clinical and translational research at the University of Pittsburgh. “It doesn’t seem to have improved.”
Its prevalence has varied widely from cohort to cohort, from as low as 3% (similar to the general population) to over 40%, Dr. Kunisaki said, emphasizing that many studies, including studies showing higher rates, have controlled for current and past smoking. In evaluating patients with low or no smoking burden, “don’t discount respiratory symptoms as possibly reflecting underlying lung disease because COPD can develop with low to no smoking history in those with HIV,” he advised.
A better understanding of how a chronic viral infection like HIV leads to heightened COPD risk will not only help those with HIV, he notes, but also people without HIV who have COPD but have never smoked – a woefully underappreciated and understudied population. Ongoing research, he said, “should help us understand COPD pathogenesis generally.”
Research on asthma is relatively limited thus far, but it does appear that PWH may be more prone to developing severe asthma, just as with COPD, said Dr. Kunisaki, also a staff physician at the Minneapolis Veterans Administration Health Care System. Research has shown, for instance, that people with HIV more frequently needed aggressive respiratory support when hospitalized for asthma exacerbations.
It’s unclear how much of this potentially increased severity is attributable to the biology of HIV’s impact on the body and how much relates to social factors like disparities in income and access to care, Dr. Kunisaki said, noting that the same questions apply to the more frequent COPD exacerbations documented in PWH.
Dr. Crothers points out that, while most studies do not suggest a difference in the incidence of asthma in PWH, “there is some data from researchers looking at asthma profiles [suggesting] that the biomarkers associated with asthma may be different in people with and without HIV,” signaling potentially different molecular or biologic underpinnings of the disease.
Incidence rates of lung cancer in PWH, meanwhile, have declined over the last 2 decades, but lung cancer remains the leading cause of cancer-related mortality in PWH and occurs at a rate that is 2-2.5 times higher than that of individuals not infected with HIV, according to
Janice Leung, MD, of the division of respiratory medicine at the University of British Columbia and the Centre for Heart Lung Innovation at St. Paul’s Hospital in Vancouver.
Patients with HIV have “worse outcomes overall and a higher risk of mortality, even when presenting at the same stage,” said Dr. Leung, who reviewed trends in COPD and lung cancer in a recently published opinion piece.
Potential drivers
A bird’s eye view of potential – and likely interrelated – mechanisms for chronic lung disease includes chronic immune activation that impairs innate and adaptive immune pathways; chronic inflammation systemically and in the lung despite viral suppression; persistence of the virus in latent reservoirs in the lung, particularly in alveolar macrophages and T cells; HIV-related proteins contributing to oxidative stress; accelerated cellular aging; dysbiosis; and ongoing injury from inhaled toxins.
All are described in the literature and are being further explored. “It’s likely that multiple pathways are playing a role,” said Dr. Crothers, “and it could be that the balance of one to another leads to different manifestations of disease.”
Biomarkers that have been elevated and associated with different features of chronic lung disease – such as airflow obstruction, low DLCO, and emphysema – include markers of inflammation (e.g., C-reactive protein, interleukin-6), monocyte activation (e.g., soluble CD14), and markers of endothelial dysfunction, she noted in a 2021 commentary marking 40 years since the first reported cases of acquired immunodeficiency syndrome.
In her laboratory, Dr. Leung is using new epigenetic markers to look at the pathogenesis of accelerated aging in the lung. By profiling bronchial epithelial brushings for DNA methylation and gene expression, they have found that “people living with both HIV and COPD have the fastest epigenetic age acceleration in their airway epithelium,” she said. The findings “suggest that the HIV lung is aging faster.”
They reported their findings in 2022, describing methylation disruptions along age-related pathways such as cellular senescence, longevity regulation, and insulin signaling.
Dr. Leung and her team have also studied the lung microbiome and found lower microbial diversity in the airway epithelium in patients with HIV than those without, especially in those with HIV and COPD. The National Institutes of Health–sponsored Lung HIV Microbiome Project found that changes in the lung microbiome are most pronounced in patients who haven’t yet initiated ART, but research in her lab suggests ongoing suppression of microbial diversity even after ART, she said.
Dr. Morris is particularly interested in the oral microbiome, having found through her research that changes in the oral microbiome in PWH were more related to impaired lung function than alterations in the lung and gut microbiome. “That may be in part because of the way we measure things,” she said. “But we also think that the oral microbiome probably seeds the lung [through micro-aspiration].” A study published in 2020 from the Pittsburgh site of the MACS described alterations in oral microbial communities in PWH with abnormal lung function.
Preliminary research suggests that improved dental cleaning and periodontal work in PWH and COPD may influence the severity of COPD, she noted.
“We don’t see as much of a signal with the gut microbiome [and HIV status or lung function], though there could still be ways in which gut microbiome influences the lung,” through systemic inflammation, the release of metabolites into the bloodstream, or microbial translocation, for instance, she said.
The potential role of translocation of members of the microbiome, in fact, is an area of active research for Dr. Morris. Members of the microbiome – viruses and fungi in addition to bacteria – “can get into the bloodstream from the mouth, from the lung, from the gut, to stimulate inflammation and worsen lung disease,” she said.
Key questions in an evolving research landscape
Dr. Kunisaki looks forward to research providing a more longitudinal look at lung function decline– a move beyond a dominance of cross-sectional studies – as well as research that is more comprehensive, with simultaneous collection of various functional measures (eg., DLCO with chest imaging and fractional excretion of nitric oxide (FENO – a standardized breath measure of Th2 airway inflammation).
The several-year-old NIH-supported MACS/WIHS (Women’s Interagency HIV Study) Combined Cohort study, in which Dr. Kunisaki and Dr. Morris participate, aims in part to identity biomarkers of increased risk for chronic lung disease and other chronic disorders and to develop strategies for more effective interventions and treatments.
Researchers will also share biospecimens, “which will allow more mechanistic work,” Dr. Kunisaki noted. (The combined cohort study includes participants from the earlier, separate MACS and WIHS studies.)
Questions about treatment strategies include the risks versus benefits of inhaled corticosteroids, which may increase an already elevated risk of respiratory infections like bacterial pneumonia in PWH, Dr. Kunisaki said.
[An aside: Inhaled corticosteroids also have well-described interactions with ART regimens that contain CYP3A4 inhibitors (e.g., ritonavir and cobicistat) that can lead to hypercortisolism. In patients who require both types of drugs, he said, beclomethasone has the least interactions and is the preferred inhaled corticosteroid.]
For Dr. Crothers, unanswered critical questions include – as she wrote in her 2021 commentary – the question of how guidelines for the management of COPD and asthma should be adapted for PWH. Is COPD in PWH more or less responsive to inhaled corticosteroids, for instance? And are antifibrotic treatments for interstitial lung disease and immunotherapies for asthma or lung cancer similarly effective, and are there any increased risks for harms in people with HIV?
There’s also the question of whether PWH should be screened for lung cancer earlier and with a lower smoking exposure than is advised under current guidelines for the general population, she said in the interview. “And should the approach to shared decision-making be modified for people with HIV?” she said. “We’re doing some work on these questions” right now.
None of the researchers interviewed reported any conflicts of interest relevant to the story. Dr. Kunisaki reported that he has no relevant disclosures, and said that his comments are his personal views and not official views of the U.S. Government, Department of Veterans Affairs, the Minneapolis VA, or the University of Minnesota.
Chronic pulmonary disease continues to be a major cause of morbidity and mortality in individuals living with the human immunodeficiency virus, even with optimal HIV control. And this is independent, as seen in many studies, of age, smoking, and pulmonary infections.
Both chronic pulmonary obstructive disease (COPD) and lung cancer occur more frequently in people living with HIV than in the general population, and at earlier ages, and with worse outcomes. The risk for emphysema and interstitial lung abnormalities also appears to be higher, research has shown. And asthma has also recently emerged as another important lung disease in people with HIV (PWH).
“There is evidence that the severity of immunocompromise associated with HIV infection is linked with chronic lung diseases. People who have a lower CD4 cell count or a higher viral load do have an increased risk of COPD and emphysema as well as potentially lung cancer. ,” said Kristina Crothers, MD, professor in the division of pulmonary, critical care, and sleep medicine at the University of Washington, Seattle.
Research has evolved from a focus on the epidemiology of HIV-related chronic lung diseases to a current emphasis on “trying to understand further the mechanisms [behind the heightened risk] through more benchwork and corollary translational studies, and then to the next level of trying to understand what this means for how we should manage people with HIV who have chronic lung diseases,” Dr. Crothers said. “Should management be tailored for people with HIV infection?”
Impairments in immune pathways, local and systemic inflammation, oxidative stress, dysbiosis, and accelerated cellular senescence are among potential mechanisms, but until ongoing mechanistic research yields more answers, pulmonologists should simply – but importantly – be aware of the increased risk and have a low threshold for investigating respiratory symptoms, she and other experts said in interviews. Referral of eligible patients for lung cancer screening is also a priority, as is smoking cessation, they said.
Notably, while spirometry has been the most commonly studied lung function measure in PWH, another noninvasive measure, diffusing capacity for carbon monoxide (DLCO), has garnered attention in the past decade and thus far appears to be the more frequent lung function abnormality.
In an analysis published in 2020 from the longitudinal Multicenter AIDS Cohort Study (MACS) – a study of a subcohort of 591 men with HIV and 476 without HIV – those with HIV were found to have a 1.6-fold increased risk of mild DLCO impairment (< 80% of predicted normal) and a 3-fold higher risk of more severe DLCO impairment (< 60% of predicted normal). There was no significant difference in spirometry findings by HIV status.
Such findings on DLCO are worthy of consideration in clinical practice, even in the absence of HIV-specific screening guidelines for noncommunicable lung diseases, Dr. Crothers said. “In thinking about screening and diagnosing chronic lung diseases in these patients, I’d not only consider spirometry, but also diffusing capacity” when possible, she said. Impaired DLCO is seen with emphysema and pulmonary vascular diseases like pulmonary hypertension and also interstitial lung diseases.
Key chronic lung diseases
Ken M. Kunisaki, MD, MS, associate professor of medicine at the University of Minnesota, Minneapolis, and the first author of the MACS analysis of lung function – one of the most recent and largest reports of DLCO impairment – points out that studies of chest computed tomography (CT) have also documented higher rates of emphysema and interstitial lung abnormalities.
A chest CT analysis from a cohort in Denmark (the Copenhagen Comorbidity in HIV Infection [COCOMO] cohort) found interstitial lung abnormalities in 10.9% of more than 700 PWH which represented a 1.8-fold increased risk compared to HIV-negative controls. And a study from an Italian sample of never-smoking PWH and controls reported emphysema in 18% and 4%, respectively. These studies, which did not measure DLCO, are among those discussed in a 2021 review by Dr. Kunisaki of advances in HIV-associated chronic lung disease research.
COPD is the best studied and most commonly encountered chronic lung disease in PWH. “Particularly for COPD, what’s both interesting and unfortunate is that we haven’t really seen any changes in the epidemiology with ART (antiretroviral therapy) – we’re still seeing the same findings, like the association of HIV with worse COPD at younger ages,” said Alison Morris, MD, MS, professor of medicine, immunology, and clinical and translational research at the University of Pittsburgh. “It doesn’t seem to have improved.”
Its prevalence has varied widely from cohort to cohort, from as low as 3% (similar to the general population) to over 40%, Dr. Kunisaki said, emphasizing that many studies, including studies showing higher rates, have controlled for current and past smoking. In evaluating patients with low or no smoking burden, “don’t discount respiratory symptoms as possibly reflecting underlying lung disease because COPD can develop with low to no smoking history in those with HIV,” he advised.
A better understanding of how a chronic viral infection like HIV leads to heightened COPD risk will not only help those with HIV, he notes, but also people without HIV who have COPD but have never smoked – a woefully underappreciated and understudied population. Ongoing research, he said, “should help us understand COPD pathogenesis generally.”
Research on asthma is relatively limited thus far, but it does appear that PWH may be more prone to developing severe asthma, just as with COPD, said Dr. Kunisaki, also a staff physician at the Minneapolis Veterans Administration Health Care System. Research has shown, for instance, that people with HIV more frequently needed aggressive respiratory support when hospitalized for asthma exacerbations.
It’s unclear how much of this potentially increased severity is attributable to the biology of HIV’s impact on the body and how much relates to social factors like disparities in income and access to care, Dr. Kunisaki said, noting that the same questions apply to the more frequent COPD exacerbations documented in PWH.
Dr. Crothers points out that, while most studies do not suggest a difference in the incidence of asthma in PWH, “there is some data from researchers looking at asthma profiles [suggesting] that the biomarkers associated with asthma may be different in people with and without HIV,” signaling potentially different molecular or biologic underpinnings of the disease.
Incidence rates of lung cancer in PWH, meanwhile, have declined over the last 2 decades, but lung cancer remains the leading cause of cancer-related mortality in PWH and occurs at a rate that is 2-2.5 times higher than that of individuals not infected with HIV, according to
Janice Leung, MD, of the division of respiratory medicine at the University of British Columbia and the Centre for Heart Lung Innovation at St. Paul’s Hospital in Vancouver.
Patients with HIV have “worse outcomes overall and a higher risk of mortality, even when presenting at the same stage,” said Dr. Leung, who reviewed trends in COPD and lung cancer in a recently published opinion piece.
Potential drivers
A bird’s eye view of potential – and likely interrelated – mechanisms for chronic lung disease includes chronic immune activation that impairs innate and adaptive immune pathways; chronic inflammation systemically and in the lung despite viral suppression; persistence of the virus in latent reservoirs in the lung, particularly in alveolar macrophages and T cells; HIV-related proteins contributing to oxidative stress; accelerated cellular aging; dysbiosis; and ongoing injury from inhaled toxins.
All are described in the literature and are being further explored. “It’s likely that multiple pathways are playing a role,” said Dr. Crothers, “and it could be that the balance of one to another leads to different manifestations of disease.”
Biomarkers that have been elevated and associated with different features of chronic lung disease – such as airflow obstruction, low DLCO, and emphysema – include markers of inflammation (e.g., C-reactive protein, interleukin-6), monocyte activation (e.g., soluble CD14), and markers of endothelial dysfunction, she noted in a 2021 commentary marking 40 years since the first reported cases of acquired immunodeficiency syndrome.
In her laboratory, Dr. Leung is using new epigenetic markers to look at the pathogenesis of accelerated aging in the lung. By profiling bronchial epithelial brushings for DNA methylation and gene expression, they have found that “people living with both HIV and COPD have the fastest epigenetic age acceleration in their airway epithelium,” she said. The findings “suggest that the HIV lung is aging faster.”
They reported their findings in 2022, describing methylation disruptions along age-related pathways such as cellular senescence, longevity regulation, and insulin signaling.
Dr. Leung and her team have also studied the lung microbiome and found lower microbial diversity in the airway epithelium in patients with HIV than those without, especially in those with HIV and COPD. The National Institutes of Health–sponsored Lung HIV Microbiome Project found that changes in the lung microbiome are most pronounced in patients who haven’t yet initiated ART, but research in her lab suggests ongoing suppression of microbial diversity even after ART, she said.
Dr. Morris is particularly interested in the oral microbiome, having found through her research that changes in the oral microbiome in PWH were more related to impaired lung function than alterations in the lung and gut microbiome. “That may be in part because of the way we measure things,” she said. “But we also think that the oral microbiome probably seeds the lung [through micro-aspiration].” A study published in 2020 from the Pittsburgh site of the MACS described alterations in oral microbial communities in PWH with abnormal lung function.
Preliminary research suggests that improved dental cleaning and periodontal work in PWH and COPD may influence the severity of COPD, she noted.
“We don’t see as much of a signal with the gut microbiome [and HIV status or lung function], though there could still be ways in which gut microbiome influences the lung,” through systemic inflammation, the release of metabolites into the bloodstream, or microbial translocation, for instance, she said.
The potential role of translocation of members of the microbiome, in fact, is an area of active research for Dr. Morris. Members of the microbiome – viruses and fungi in addition to bacteria – “can get into the bloodstream from the mouth, from the lung, from the gut, to stimulate inflammation and worsen lung disease,” she said.
Key questions in an evolving research landscape
Dr. Kunisaki looks forward to research providing a more longitudinal look at lung function decline– a move beyond a dominance of cross-sectional studies – as well as research that is more comprehensive, with simultaneous collection of various functional measures (eg., DLCO with chest imaging and fractional excretion of nitric oxide (FENO – a standardized breath measure of Th2 airway inflammation).
The several-year-old NIH-supported MACS/WIHS (Women’s Interagency HIV Study) Combined Cohort study, in which Dr. Kunisaki and Dr. Morris participate, aims in part to identity biomarkers of increased risk for chronic lung disease and other chronic disorders and to develop strategies for more effective interventions and treatments.
Researchers will also share biospecimens, “which will allow more mechanistic work,” Dr. Kunisaki noted. (The combined cohort study includes participants from the earlier, separate MACS and WIHS studies.)
Questions about treatment strategies include the risks versus benefits of inhaled corticosteroids, which may increase an already elevated risk of respiratory infections like bacterial pneumonia in PWH, Dr. Kunisaki said.
[An aside: Inhaled corticosteroids also have well-described interactions with ART regimens that contain CYP3A4 inhibitors (e.g., ritonavir and cobicistat) that can lead to hypercortisolism. In patients who require both types of drugs, he said, beclomethasone has the least interactions and is the preferred inhaled corticosteroid.]
For Dr. Crothers, unanswered critical questions include – as she wrote in her 2021 commentary – the question of how guidelines for the management of COPD and asthma should be adapted for PWH. Is COPD in PWH more or less responsive to inhaled corticosteroids, for instance? And are antifibrotic treatments for interstitial lung disease and immunotherapies for asthma or lung cancer similarly effective, and are there any increased risks for harms in people with HIV?
There’s also the question of whether PWH should be screened for lung cancer earlier and with a lower smoking exposure than is advised under current guidelines for the general population, she said in the interview. “And should the approach to shared decision-making be modified for people with HIV?” she said. “We’re doing some work on these questions” right now.
None of the researchers interviewed reported any conflicts of interest relevant to the story. Dr. Kunisaki reported that he has no relevant disclosures, and said that his comments are his personal views and not official views of the U.S. Government, Department of Veterans Affairs, the Minneapolis VA, or the University of Minnesota.