Andrew Pachner, MD

Andrew R. Pachner, MD is the Murray B. Bornstein professor of neurology at Geisel School of Medicine at Dartmouth and director of the Multiple Sclerosis Center at Dartmouth-Hitchcock Medical Center. We spoke to Dr. Pachner about his research into the molecular processes of multiple sclerosis (MS) and the potential impact on patient management.

What do we know about the molecular processes behind relapsing-remitting and progressive MS?

DR. PACHNER:  The progress--in terms of molecules--has not been rapid in the field of MS. The only molecular biomarker we use in practice is oligoclonal bands or other measures of immunoglobulin production in the nervous system, and that biomarker was described in 1942. So, it has been a long time since we have seen a relevant molecule that we can use clinically.

But there has been a lot of progress in the general field of neuroinflammation. MS is one of a large number of diseases that results in neuroinflammation and demyelination.

One thing we have learned over time is that there are many different subtypes of MS. They probably have some shared molecular processes, but they also are likely to have divergent molecular processes.

Over the past 5 to 10 years, researchers have been interested in trying to dissect some of the molecular aspects of MS to identify biomarkers that can, in turn, differentiate subtypes of MS. This will help to identify different ways of treating MS that are optimal for individual patients. It is clear that each patient is quite different and unlikely to be standardized in the way they respond to treatment.

The degree to which relapsing-remitting and progressive MS are differentiated on the molecular level is dependent on how much influence there is of the immune system in the periphery. When MS first starts in a patient, the brain has either no or a very primitive immune system, and then over time it changes, and it becomes much more immune-oriented and populated by immune cells and molecules. So, there’s a trend over time of the central nervous system becoming increasingly populated by immune cells and able to make immune molecules.

What has your recent research on murine models representing these disease patterns shown?

DR. PACHNER:  Even though in humans there is a continuum from relapsing remitting to progressive, it is not like they are completely separate. Frequently in the middle of relapsing-remitting disease there is some progression over time.

In mouse models, we like things to be very clear and separate. We try to make things as simple as possible because of the complexity of the nervous and immune systems.

The simple model for the relapsing-remitting disease is experimental autoimmune encephalomyelitis (EAE), the most commonly studied model of neuroinflammation.

For the progressive form of MS, we use the Theiler’s virus model, which is a type of virus called the picornavirus that is injected into the brain of mice resulting in a slowly progressive, chronic viral infection that looks very much like progressive MS.

In EAE, the disease is induced by presenting an antigen to the peripheral immune system, allowing cells from the peripheral immune system to enter into the central nervous system. It is a manifestation of inflammation and the immune response is in the periphery. In the Theiler’s model, it is a localized process within the central nervous system because the virus is injected directly into the brain.

We found that in EAE the pattern is very much dominated by what happens in the periphery and the injury is very transient. There are cells that enter the nervous system that cause inflammation and damage, but there are also processes that downregulate those cells and processes and eventually the animal improves--similar to an MS attack.

By contrast, in the Theiler’s model there is progressive injury that is dominated by two molecular processes in the central nervous system that we do not see in relapsing-remitting MS or in EAE, and that is the activation of Type 1 interferons and also a very pronounced immunoglobulin production along with all the molecules that help support plasma cells making immunoglobulin.

These are two different animal models that provide us insight into how the central nervous system can be injured in the course of neuroinflammation and they look to be very different in how they manifest themselves, both in the periphery and in the central nervous system.

How may these new findings impact the future management and treatment of MS?

DR. PACHNER:  When I see a patient with MS, I tell them that we absolutely need to focus on your own disease and how it responds, rather than taking too much guidance from MS as a whole. Because each patient with MS is different.

One of the things that we have tried to do is to identify molecular markers that might help us in management and treatment. As an example, we have learned that some patients who present with their first episode of MS do very poorly. These patients have many more attacks and/or have very aggressive progression in terms of their disability so that they potentially could be in a wheelchair within a few years. Other patients have what we call a benign variant MS. These patients may have an initial episode that is not that different than the other patient, but this type of patient may not have anything else for the rest of their life.

We would like to have some differentiation of those two types of patients. In the first example you can try to be very aggressive and minimize the neuroinflammation with powerful immune-suppressing drugs that have a high risk of causing side effects, such as cancer or opportunistic infections, but on the other hand may have a high benefit in preventing future inflammatory events and progressive injury. But that would not be the correct treatment choice for the second patient example.

It would be nice to tailor treatment to a predictive biomarker. That is something we have been working very hard on. Based on some of the animal models, we have identified a molecular signature of inflammatory MS that is very predictive of future events and we are hoping that that will help us differentiate patients. In other words, not just treat every MS patient the same, but identify whether they need a very powerful immunosuppressant drug, or a mildly immunosuppressant drug, or no treatment at all.

If you have a patient who has one attack and never has any other problem with their MS, then they do not need to be on any treatment. Unfortunately, we do not have predictive value at this point for any molecule or any other attribute of the patient at this point in time. We are trying to remedy that.

That is one very practical aspect of our work in trying to understand the biology of the disease better--identifying molecules that are associated with future damage and inflammation and using those in a predictive manner in patients to guide treatment.

Another important aspect is the attempt to understand the biology of neuroinflammation and how it causes both demyelination and progressive injury to neurons.

References:

Pachner AR, DiSano K, Royce DB, Gilli F. Clinical utility of a molecular signature in inflammatory demyelinating diseases. Neurol Neuroimmunol Neuroinflamm.2019;6(1):e520.

Andrew R. Pachner, MD is the Murray B. Bornstein professor of neurology at Geisel School of Medicine at Dartmouth and director of the Multiple Sclerosis Center at Dartmouth-Hitchcock Medical Center. We spoke to Dr. Pachner about his research into the molecular processes of multiple sclerosis (MS) and the potential impact on patient management.

What do we know about the molecular processes behind relapsing-remitting and progressive MS?

DR. PACHNER:  The progress--in terms of molecules--has not been rapid in the field of MS. The only molecular biomarker we use in practice is oligoclonal bands or other measures of immunoglobulin production in the nervous system, and that biomarker was described in 1942. So, it has been a long time since we have seen a relevant molecule that we can use clinically.

But there has been a lot of progress in the general field of neuroinflammation. MS is one of a large number of diseases that results in neuroinflammation and demyelination.

One thing we have learned over time is that there are many different subtypes of MS. They probably have some shared molecular processes, but they also are likely to have divergent molecular processes.

Over the past 5 to 10 years, researchers have been interested in trying to dissect some of the molecular aspects of MS to identify biomarkers that can, in turn, differentiate subtypes of MS. This will help to identify different ways of treating MS that are optimal for individual patients. It is clear that each patient is quite different and unlikely to be standardized in the way they respond to treatment.

The degree to which relapsing-remitting and progressive MS are differentiated on the molecular level is dependent on how much influence there is of the immune system in the periphery. When MS first starts in a patient, the brain has either no or a very primitive immune system, and then over time it changes, and it becomes much more immune-oriented and populated by immune cells and molecules. So, there’s a trend over time of the central nervous system becoming increasingly populated by immune cells and able to make immune molecules.

What has your recent research on murine models representing these disease patterns shown?

DR. PACHNER:  Even though in humans there is a continuum from relapsing remitting to progressive, it is not like they are completely separate. Frequently in the middle of relapsing-remitting disease there is some progression over time.

In mouse models, we like things to be very clear and separate. We try to make things as simple as possible because of the complexity of the nervous and immune systems.

The simple model for the relapsing-remitting disease is experimental autoimmune encephalomyelitis (EAE), the most commonly studied model of neuroinflammation.

For the progressive form of MS, we use the Theiler’s virus model, which is a type of virus called the picornavirus that is injected into the brain of mice resulting in a slowly progressive, chronic viral infection that looks very much like progressive MS.

In EAE, the disease is induced by presenting an antigen to the peripheral immune system, allowing cells from the peripheral immune system to enter into the central nervous system. It is a manifestation of inflammation and the immune response is in the periphery. In the Theiler’s model, it is a localized process within the central nervous system because the virus is injected directly into the brain.

We found that in EAE the pattern is very much dominated by what happens in the periphery and the injury is very transient. There are cells that enter the nervous system that cause inflammation and damage, but there are also processes that downregulate those cells and processes and eventually the animal improves--similar to an MS attack.

By contrast, in the Theiler’s model there is progressive injury that is dominated by two molecular processes in the central nervous system that we do not see in relapsing-remitting MS or in EAE, and that is the activation of Type 1 interferons and also a very pronounced immunoglobulin production along with all the molecules that help support plasma cells making immunoglobulin.

These are two different animal models that provide us insight into how the central nervous system can be injured in the course of neuroinflammation and they look to be very different in how they manifest themselves, both in the periphery and in the central nervous system.

How may these new findings impact the future management and treatment of MS?

DR. PACHNER:  When I see a patient with MS, I tell them that we absolutely need to focus on your own disease and how it responds, rather than taking too much guidance from MS as a whole. Because each patient with MS is different.

One of the things that we have tried to do is to identify molecular markers that might help us in management and treatment. As an example, we have learned that some patients who present with their first episode of MS do very poorly. These patients have many more attacks and/or have very aggressive progression in terms of their disability so that they potentially could be in a wheelchair within a few years. Other patients have what we call a benign variant MS. These patients may have an initial episode that is not that different than the other patient, but this type of patient may not have anything else for the rest of their life.

We would like to have some differentiation of those two types of patients. In the first example you can try to be very aggressive and minimize the neuroinflammation with powerful immune-suppressing drugs that have a high risk of causing side effects, such as cancer or opportunistic infections, but on the other hand may have a high benefit in preventing future inflammatory events and progressive injury. But that would not be the correct treatment choice for the second patient example.

It would be nice to tailor treatment to a predictive biomarker. That is something we have been working very hard on. Based on some of the animal models, we have identified a molecular signature of inflammatory MS that is very predictive of future events and we are hoping that that will help us differentiate patients. In other words, not just treat every MS patient the same, but identify whether they need a very powerful immunosuppressant drug, or a mildly immunosuppressant drug, or no treatment at all.

If you have a patient who has one attack and never has any other problem with their MS, then they do not need to be on any treatment. Unfortunately, we do not have predictive value at this point for any molecule or any other attribute of the patient at this point in time. We are trying to remedy that.

That is one very practical aspect of our work in trying to understand the biology of the disease better--identifying molecules that are associated with future damage and inflammation and using those in a predictive manner in patients to guide treatment.

Another important aspect is the attempt to understand the biology of neuroinflammation and how it causes both demyelination and progressive injury to neurons.

References:

Pachner AR, DiSano K, Royce DB, Gilli F. Clinical utility of a molecular signature in inflammatory demyelinating diseases. Neurol Neuroimmunol Neuroinflamm.2019;6(1):e520.

Andrew R. Pachner, MD is the Murray B. Bornstein professor of neurology at Geisel School of Medicine at Dartmouth and director of the Multiple Sclerosis Center at Dartmouth-Hitchcock Medical Center. We spoke to Dr. Pachner about his research into the molecular processes of multiple sclerosis (MS) and the potential impact on patient management.

What do we know about the molecular processes behind relapsing-remitting and progressive MS?

DR. PACHNER:  The progress--in terms of molecules--has not been rapid in the field of MS. The only molecular biomarker we use in practice is oligoclonal bands or other measures of immunoglobulin production in the nervous system, and that biomarker was described in 1942. So, it has been a long time since we have seen a relevant molecule that we can use clinically.

But there has been a lot of progress in the general field of neuroinflammation. MS is one of a large number of diseases that results in neuroinflammation and demyelination.

One thing we have learned over time is that there are many different subtypes of MS. They probably have some shared molecular processes, but they also are likely to have divergent molecular processes.

Over the past 5 to 10 years, researchers have been interested in trying to dissect some of the molecular aspects of MS to identify biomarkers that can, in turn, differentiate subtypes of MS. This will help to identify different ways of treating MS that are optimal for individual patients. It is clear that each patient is quite different and unlikely to be standardized in the way they respond to treatment.

The degree to which relapsing-remitting and progressive MS are differentiated on the molecular level is dependent on how much influence there is of the immune system in the periphery. When MS first starts in a patient, the brain has either no or a very primitive immune system, and then over time it changes, and it becomes much more immune-oriented and populated by immune cells and molecules. So, there’s a trend over time of the central nervous system becoming increasingly populated by immune cells and able to make immune molecules.

What has your recent research on murine models representing these disease patterns shown?

DR. PACHNER:  Even though in humans there is a continuum from relapsing remitting to progressive, it is not like they are completely separate. Frequently in the middle of relapsing-remitting disease there is some progression over time.

In mouse models, we like things to be very clear and separate. We try to make things as simple as possible because of the complexity of the nervous and immune systems.

The simple model for the relapsing-remitting disease is experimental autoimmune encephalomyelitis (EAE), the most commonly studied model of neuroinflammation.

For the progressive form of MS, we use the Theiler’s virus model, which is a type of virus called the picornavirus that is injected into the brain of mice resulting in a slowly progressive, chronic viral infection that looks very much like progressive MS.

In EAE, the disease is induced by presenting an antigen to the peripheral immune system, allowing cells from the peripheral immune system to enter into the central nervous system. It is a manifestation of inflammation and the immune response is in the periphery. In the Theiler’s model, it is a localized process within the central nervous system because the virus is injected directly into the brain.

We found that in EAE the pattern is very much dominated by what happens in the periphery and the injury is very transient. There are cells that enter the nervous system that cause inflammation and damage, but there are also processes that downregulate those cells and processes and eventually the animal improves--similar to an MS attack.

By contrast, in the Theiler’s model there is progressive injury that is dominated by two molecular processes in the central nervous system that we do not see in relapsing-remitting MS or in EAE, and that is the activation of Type 1 interferons and also a very pronounced immunoglobulin production along with all the molecules that help support plasma cells making immunoglobulin.

These are two different animal models that provide us insight into how the central nervous system can be injured in the course of neuroinflammation and they look to be very different in how they manifest themselves, both in the periphery and in the central nervous system.

How may these new findings impact the future management and treatment of MS?

DR. PACHNER:  When I see a patient with MS, I tell them that we absolutely need to focus on your own disease and how it responds, rather than taking too much guidance from MS as a whole. Because each patient with MS is different.

One of the things that we have tried to do is to identify molecular markers that might help us in management and treatment. As an example, we have learned that some patients who present with their first episode of MS do very poorly. These patients have many more attacks and/or have very aggressive progression in terms of their disability so that they potentially could be in a wheelchair within a few years. Other patients have what we call a benign variant MS. These patients may have an initial episode that is not that different than the other patient, but this type of patient may not have anything else for the rest of their life.

We would like to have some differentiation of those two types of patients. In the first example you can try to be very aggressive and minimize the neuroinflammation with powerful immune-suppressing drugs that have a high risk of causing side effects, such as cancer or opportunistic infections, but on the other hand may have a high benefit in preventing future inflammatory events and progressive injury. But that would not be the correct treatment choice for the second patient example.

It would be nice to tailor treatment to a predictive biomarker. That is something we have been working very hard on. Based on some of the animal models, we have identified a molecular signature of inflammatory MS that is very predictive of future events and we are hoping that that will help us differentiate patients. In other words, not just treat every MS patient the same, but identify whether they need a very powerful immunosuppressant drug, or a mildly immunosuppressant drug, or no treatment at all.

If you have a patient who has one attack and never has any other problem with their MS, then they do not need to be on any treatment. Unfortunately, we do not have predictive value at this point for any molecule or any other attribute of the patient at this point in time. We are trying to remedy that.

That is one very practical aspect of our work in trying to understand the biology of the disease better--identifying molecules that are associated with future damage and inflammation and using those in a predictive manner in patients to guide treatment.

Another important aspect is the attempt to understand the biology of neuroinflammation and how it causes both demyelination and progressive injury to neurons.

References:

Pachner AR, DiSano K, Royce DB, Gilli F. Clinical utility of a molecular signature in inflammatory demyelinating diseases. Neurol Neuroimmunol Neuroinflamm.2019;6(1):e520.