Stefan Bornstein, MD, PhD, professor, made it clear during a press conference at the 67th Congress of the German Society of Endocrinology (DGE) that there is more than one interaction between them. Nowadays, one can almost speak of an “endocrine virology and even of the virome as an additional, hormonally metabolically active gland,” said Dr. Bornstein, who will receive the Berthold Medal from the DGE in 2024.
Many questions remain unanswered: “We need a better understanding of the interaction of hormone systems with infectious agents — from basics to therapeutic applications,” emphasized the director of the Medical Clinic and Polyclinic III and the Center for Internal Medicine at the Carl Gustav Carus University Hospital, Dresden, Germany.
If infectious diseases could trigger diabetes and other metabolic diseases, this means that “through vaccination programs, we may be able to prevent the occurrence of common metabolic diseases such as diabetes,” said Dr. Bornstein. He highlighted that many people who experienced severe COVID-19 during the pandemic, or died from it, exhibited diabetes or a pre-metabolic syndrome.
“SARS-CoV-2 has utilized an endocrine signaling pathway to invade our cells and cause damage in the organ systems and inflammation,” said Dr. Bornstein. Conversely, it is now known that infections with coronaviruses or other infectious agents like influenza can significantly worsen metabolic status, diabetes, and other endocrine diseases.
SARS-CoV-2 Infects the Beta Cells
Data from the COVID-19 pandemic showed that the likelihood of developing type 1 diabetes significantly increases with a SARS-CoV-2 infection. Researchers led by Dr. Bornstein demonstrated in 2021 that SARS-CoV-2 can infect the insulin-producing cells of the organ. They examined pancreatic tissue from 20 patients who died from COVID-19 using immunofluorescence, immunohistochemistry, RNA in situ hybridization, and electron microscopy.
They found viral SARS-CoV-2 infiltration of the beta cells in all patients. In 11 patients with COVID-19, the expression of ACE2, TMPRSS, and other receptors and factors like DPP4, HMBG1, and NRP1 that can facilitate virus entry was examined. They found that even in the absence of manifest newly onset diabetes, necroptotic cell death, immune cell infiltration, and SARS-CoV-2 infection of the pancreas beta cells can contribute to varying degrees of metabolic disturbance in patients with COVID-19.
In a report published in October 2020, Tim Hollstein, MD, from the Institute for Diabetology and Clinical Metabolic Research at UKSH in Kiel, Germany, and colleagues described the case of a 19-year-old man who developed symptoms of insulin-dependent diabetes after a SARS-CoV-2 infection, without the presence of autoantibodies typical for type 1 diabetes.
The man presented to the emergency department with diabetic ketoacidosis, a C-peptide level of 0.62 µg/L, a blood glucose concentration of 30.6 mmol/L (552 mg/dL), and an A1c level of 16.8%. The patient’s history revealed a probable SARS-CoV-2 infection 5-7 weeks before admission, based on a positive antibody test against SARS-CoV-2.
Some Viruses Produce Insulin-Like Proteins
Recent studies have shown that some viruses can produce insulin-like proteins or hormones that interfere with the metabolism of the affected organism, reported Dr. Bornstein. In addition to metabolic regulation, these “viral hormones” also seem to influence cell turnover and cell death.
Dr. Bornstein pointed out that antiviral medications can delay the onset of type 1 diabetes by preserving the function of insulin-producing beta cells. It has also been shown that conventional medications used to treat hormonal disorders can reduce the susceptibility of the organism to infections — such as antidiabetic preparations like DPP-4 inhibitors or metformin.
In a review published in 2023, Nikolaos Perakakis, MD, professor, research group leader at the Paul Langerhans Institute Dresden, Dresden, Germany, Dr. Bornstein, and colleagues discussed scientific evidence for a close mutual dependence between various virus infections and metabolic diseases. They discussed how viruses can lead to the development or progression of metabolic diseases and vice versa and how metabolic diseases can increase the severity of a virus infection.
Viruses Favor Metabolic Diseases...
Viruses can favor metabolic diseases by, for example, influencing the regulation of cell survival and specific signaling pathways relevant for cell death, proliferation, or dedifferentiation in important endocrine and metabolic organs. Viruses are also capable of controlling cellular glucose metabolism by modulating glucose transporters, altering glucose uptake, regulating signaling pathways, and stimulating glycolysis in infected cells.
Due to the destruction of beta cells, enteroviruses, but also the mumps virus, parainfluenza virus, or human herpes virus 6, are associated with the development of diabetes. The timing of infection often precedes or coincides with the peak of development of islet autoantibodies. The fact that only a small proportion of patients actually develop type 1 diabetes suggests that genetic background, and likely the timing of infection, play an important role.
...And Metabolic Diseases Influence the Course of Infection
Infection with hepatitis C virus (HCV), on the other hand, is associated with an increased risk for type 2 diabetes, with the risk being higher for older individuals with a family history of diabetes. The negative effects of HCV on glucose balance are mainly attributed to increased insulin resistance in the liver. HCV reduces hepatic glucose uptake by downregulating the expression of glucose transporters and additionally impairs insulin signal transduction by inhibiting the PI3K/Akt signaling pathway.
People with obesity, diabetes, or insulin resistance show significant changes in the innate and adaptive functions of the immune system. Regarding the innate immune system, impaired chemotaxis and phagocytosis of neutrophils have been observed in patients with type 2 diabetes.
In the case of obesity, the number of natural killer T cells in adipose tissue decreases, whereas B cells accumulate in adipose tissue and secrete more proinflammatory cytokines. Longitudinal multiomics analyses of various biopsies from individuals with insulin resistance showed a delayed immune response to respiratory virus infections compared with individuals with normal insulin sensitivity.
This story was translated from Medscape Germany using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article appeared on Medscape.com.