Jeff Fischer
President & Co-Founder, Longhorn Vaccines & Diagnostics | Chronic Inflammation & Longevity
Jeff Fischer is the president and co-founder of Longhorn Vaccines & Diagnostics, a commercial diagnostics company that is also developing monoclonal antibodies for the prevention of disease. Its lead candidate is an anti-peptidoglycan antibody aimed at a key driver of chronic inflammation linked to metabolic and neurodegenerative disease.
Fischer came to the field through family. His father, a pediatric infectious-disease specialist, made discoveries in preventing bacterial infections in premature infants, including early work on a respiratory-syncytial-virus antibody, and asked Fischer to help build a company around the science. A former US Marine Corps infantry officer, Fischer went to business school and has spent his career building biotechnology ventures since.
Fischer appeared on Open Door Salon alongside Steve Butts, chief executive of Arrivo BioVentures, for a conversation on longevity and sex-based medicine. His company’s thesis is that components of the body’s trillions of bacteria leak into the bloodstream through weakened gut junctions and switch on the immune system, leaving the body in a state of chronic inflammation that damages organs and shortens healthspan.
Rather than block the immune system the way most biologics do, Fischer argued, the better approach is to remove the upstream trigger of that inflammation. He framed the stakes in terms of access: the question, he said, is whether longevity will be “for a few or for a lot,” and his interest is in interventions that can extend healthy life for the masses rather than only those who can afford expensive cell and gene therapies.
Frequently Asked Questions About Jeff Fischer
What is Jeff Fischer an expert in?
Jeff Fischer is an expert in building biotechnology ventures in diagnostics and monoclonal antibodies, with a focus on chronic inflammation as a driver of metabolic and neurodegenerative disease and on extending healthspan.
Who is Jeff Fischer?
Jeff Fischer is the president and co-founder of Longhorn Vaccines & Diagnostics, a commercial diagnostics company also developing monoclonal antibodies for the prevention of disease. A former US Marine Corps infantry officer, he came to the field through his father, a pediatric infectious-disease specialist, and has spent his career building biotechnology ventures. He appeared on Open Door Salon, the life sciences podcast hosted by Lori Ellis.
How does Jeff Fischer think about chronic inflammation and longevity?
Jeff Fischer's thesis is that components of the body's bacteria leak into the bloodstream through weakened gut junctions and switch on the immune system, leaving the body in a state of chronic inflammation that damages organs and shortens healthspan. Rather than block the immune system the way most biologics do, he argues the better approach is to remove the upstream trigger, and he frames the stakes in terms of access, asking whether longevity will be “for a few or for a lot.”
On Open Door Salon
“Why Men and Women Age Differently — And Why Investors Don't Get It”
Jeff Fischer & Steve Butts · March 18, 2026
Episode page & show notes on Open Door Salon
In this episode
- The gut-leak theory of chronic inflammation
- Remove the trigger, don't block the immune system
- Why dropping estrogen opens the gut's junctions
- "Leaky gut": from dismissed to mainstream
- Longevity for the few, or longevity for the many?
- A father's RSV-antibody discovery, and a family calling
- How GLP-1s may be healing the gut
- Sharing healthspan gains across the masses
Topics
Watch on Open Door Salon
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