Sam Horng, MD, PhD

Sam Horng, MD, PhD, came to The Corinne Goldsmith Dickinson Center for Multiple Sclerosis in 2015 on a three-year combined clinical and research fellowship after completing his neurology residency at the Icahn School of Medicine at Mount Sinai. His work exemplifies the Center’s expanding expertise and reach beyond the borders of multiple sclerosis into other related autoimmune disorders that similarly affect neurological function and quality of life.

“People with autoimmune diseases tend to have a higher risk of developing another autoimmune syndrome,” says Dr. Horng, whose training in MS management led him to also explore other autoimmune conditions affecting the brain and spinal cord. “With multiple sclerosis we see higher proportions of individuals with other autoimmune conditions. Even our treatments can sometimes induce autoimmune attack on the joints or the gastrointestinal tract.”

He adds, “Autoimmunity generally is not well understood. We still do not fully understand what the precipitating event for many autoimmune diseases is.”

After joining the faculty in 2018, Dr. Horng explored these questions while leading a basic science lab for six years. His laboratory studied how structures of the blood-brain barrier control inflammation.

Expanding the purview of the Center to encompass not only multiple sclerosis but also other autoimmune brain conditions and overlap syndromes with rheumatology has been a rewarding aspect of his work and has enabled the Center’s scope to grow.

Dr. Horng also continues to serve as a co-investigator in clinical trials at the Center, which says has been involved in essentially all clinical trials of newly approved MS medications over the past 15 years.

“The Center is an engine for testing new therapies. It’s a place where people are moving the field forward,” he says.

“We discovered that interactions between resident blood brain barrier cells called astrocytes and immune cells infiltrating the brain could change the pattern of autoimmune disease,” he says.

What mechanisms trigger relapsing MS, and what drives disease progression, are questions that continue to challenge the field.

“Different cell systems are contributing to the immune system to fight infection, but in autoimmune diseases there are various ways in which these defensive cells are not functioning as well as they normally would,” he says.

In multiple sclerosis, certain cells mistakenly cross the blood-brain barrier and launch an inflammatory attack on the central nervous system.

“I explain to patients that it’s like the military. You have different regiments, divisions of the immune system that do varied things to fight off infection,” he says. But instead of an army, navy, and air force, T-cells, B-cells, and macrophages are collaborating to battle the disease.

In recent years, our understanding of how these different cell types contribute to MS has been refined, according to Dr. Horng. For many years MS was thought to be driven by T-cells. Over the last two decades, the focus has shifted to B-cells as a central player because B-cell depletion therapy was discovered to have powerful suppressive benefits against the frequency of MS attacks and the slope of MS progression.

“We don’t really understand why, but one clue is that the Epstein-Barr virus is highly associated with MS, and B-cells are the reservoirs in which Epstein-Barr stays latent in our bodies,” he says. Lupus is another autoimmune disease that has a strong connection with the Epstein-Barr virus.

Other advancements in understanding MS progression include single cell sequencing and genetics screening that have identified a correlation between MS progression and dysfunction of microglia, a specialized immune surveillance cell type in the brain that may also be more broadly implicated in other central nervous system disorders, including neurodegenerative disease.

Another area that interests Dr. Horng is the interplay between rheumatologic diseases, which are systemic autoimmune conditions involving other body organs, and the overlap of these syndromes with those that affect the brain and spinal cord.

“This is the frontier of our field,” he says. “Autoimmune neurologists have a lot to learn from rheumatologists because there are likely to be common mechanisms driving diseases across our specialties.”

In 2024, Dr. Horng shifted his focus from research at the bench to full-time clinical care at the bedside and now sees a wide range of autoimmune brain conditions in addition to MS.

“I’m taking a lot of the ‘mystery cases’ and seeing MS Center patients with complex syndromes,” he says. “It’s exciting to see these mysteries unfold as we’re learning more about MS and other related diseases.”

A lot of these patients have ailments that may mimic MS, including neuromyelitis optica, myelin oligodendrocyte glycoprotein-associated demyelinating disease, neurosarcoidosis, and other autoantibody-driven inflammatory diseases of the brain and spinal cord.

“Everyone who goes into neurology is fascinated by the black box that is the brain. It is the material substrate for where our identity, our perceptions, our experiences lie,” Dr. Horng says.

By Kenneth Bandler, a multiple sclerosis patient, advocate, and member of The Corinne Goldsmith Dickinson Center for Multiple Sclerosis Advisory Board.

Event speakers and members of the Clinically Based Nurse Scientist Summit Planning Committee (from left to right): Reynaldo Rivera, DNP, RN, NEA-BC, FAAN, FAONL, Director, Nursing Research and Innovation, NewYork-Presbyterian; Deborah Stamps, EdD, MBA, MS, RN, GNP, NE-BC, CDE, FADLN, FAAN, Founder and Chief Executive Officer, Deborah Stamps Consulting, LLC; Allison Andreno Norful, PhD, MPhil, MSN, BSN, ANP-BC, FAAN, Assistant Professor, Columbia University School of Nursing; Bernice Coleman, PhD, ACNP-BC, FAHA, FAAN, Director, Nursing Research, Cedars Sinai; Rose Sherman, EdD, RN, NEA-BC, FAAN, Emeritus Professor, Florida Atlantic University College of Nursing; Esther Chipps, PhD, RN, NEA-BC, FAONL, Clinical Nurse Scientist, The Ohio State University Wexner Medical Center; Perry Gee, PhD, RN, NEA-BC, FAAN, Director of Nursing Research and Evidence-Based Practice, Intermountain Healthcare; Kimberly Souffront, PhD, RN, FNP-BC, FAAN, Associate Director, Center for Nursing Research and Innovation; and Bevin Cohen, PhD, MPH, MS, RN, FAAN, Director, Center for Nursing Research and Innovation.

The landscape of research conducted by nurses is evolving, and Mount Sinai’s Center for Nursing Research and Innovation (CNRI) is leading the charge. In June 2025, the Health System hosted the nation’s first conference on the role of the clinically based nurse scientist—a growing workforce of researchers who investigate nursing practice questions with direct impact on health care systems and patient care.

Clinically based nurse scientists are nurses with PhDs and advanced research training who work inside health care delivery settings. Their roles span designing and leading large-scale clinical trials and health services research, securing funding for research and training from organizations such as the National Institutes of Health, and partnering with the clinical nursing workforce to translate research into practice and investigate timely research questions that arise from patient care.

“Schools of nursing have long been the center of robust programs of research,” says Bevin Cohen, PhD, MPH, MS, RN, FAAN, Director of the CNRI. “But today, more health systems are exploring the benefits of having nurse scientists on staff to better connect research with practice.”

There is also growing interest in clinically based roles among nurse scientists themselves, many of whom wish to remain close to patients and conduct research with immediate impact.

Mount Sinai Health System has been at the forefront of this important movement, as evidenced by the CNRI itself.

The Center is a hub at the intersection of academia and clinical practice that supports and advances nursing research throughout the Health System. Through a comprehensive offering of programs and resources, the Center serves two primary communities: nurse scientists with advanced training who lead their own panels of research, and clinical nurses who are embarking on research, quality improvement, and evidence-based practice projects.

“The clinical setting is not a space where many nurse scientists have traditionally worked,” Dr. Cohen says. “We have an unprecedented opportunity to conduct research that improves clinical nursing practice at scale, but we also need to build the infrastructure and collaborative networks to facilitate this important work.”

Across the United States, many clinically based nurse scientists have sought collaboration with colleagues in similar roles to share strategies, successes, and challenges on developing research programs within their own hospital systems.

“Until recently, we have had little opportunity to formally connect and collaborate across institutions,” says Dr. Cohen. “Over the past few years, local research interest groups have formed, along with a wonderful virtual collaborative network. Simultaneously, we began dreaming of a national summit where we could all meet in person.”

With input from fellow nurse scientists at Mount Sinai and an expert committee with representatives from across the country, Dr. Cohen wrote a grant proposal to do just that.

The Agency for Healthcare Research and Quality (AHRQ) awarded funding to support the three-day Clinically Based Nurse Scientist Summit hosted by Mount Sinai in June 2025, which was attended by more than 100 nurse scientists and leaders from around the country. The event brought together expert presenters and panelists, featured discussions and breakout sessions, and created opportunities for networking and collaborative forums.

“From the outset, our goal was to accelerate the scale, scope, speed, and rigor of research conducted by clinically based nurse scientists,” says Dr. Cohen. “To do this, we needed to understand both the challenges and successes of the role and focus on ways to maximize its potential.”

A major outcome of the summit will be the development of a five-year strategic framework for how the role can contribute to the AHRQ mission of enhancing the quality, safety, accessibility, affordability, and equity of health care in the United States.

Another significant outcome to emerge from the summit is an energized and engaged national community of clinically based nurse scientists who are sharing resources in partnership with similarly aligned groups.

In addition, eleven active workgroups formed by summit participants are conducting research and developing foundational manuscripts about the role of clinically based nurse scientists.

“By coming together as a nationwide community, clinically based nurse scientists are growing networks and infrastructure to support faster, larger, and more impactful research to advance nursing practice and improve patient outcomes,” says Dr. Cohen. Mount Sinai is proud to play a lead role in shaping this important work.