by Daniel Brouse
July 29, 2025
Multiple Sclerosis (MS) is a devastating autoimmune disorder in which the immune system mistakenly targets the protective myelin sheath that insulates nerve fibers, impairing communication between the brain and body. With a history of MS in my family, I've long explored whether its roots are hereditary, environmental, or microbial. Recent research reveals that the gut microbiome may hold the key--not only to MS, but to a broader understanding of chronic illness, infectious disease, and even climate-driven health threats.
A groundbreaking study by researchers at Ludwig Maximilian University of Munich (LMU) has made visible what many have long suspected: auto-aggressive T cells--central agents in MS--are activated in a specific region of the gut. Critically, this activation is microbiome-dependent.
A rare twin study involving 81 genetically identical pairs--where only one sibling developed MS--identified Eisenbergiella tayi and Lachnoclostridium as microbial suspects. These species reside in the small intestine and belong to the Lachnospiraceae family, normally thought to aid digestion. But under low-fiber diets, these bacteria switch to digesting the gut’s protective mucus layer--weakening the intestinal barrier and triggering immune surveillance systems.
This shift primes the immune system to attack, a process potentially intensified by E. tayi's metabolic byproducts: ethanol and succinate, known stimulants of Th17 immune cells. Th17 overactivation is a known mechanism in MS, where misdirected immune responses degrade neural insulation.
This microbial mechanism isn't unique to MS. It echoes findings from studies on COVID-19, where disruptions in gut flora are tied directly to disease severity. In the study "Gut microbiota composition reflects disease severity and dysfunctional immune responses in patients with COVID-19," researchers found:
COVID-19 patients exhibited dramatically altered gut microbiomes compared to non-COVID individuals.
These disruptions correlated with disease severity, higher inflammatory cytokines, and markers such as C-reactive protein and liver enzymes.
Even after the acute phase, dysbiosis persisted--possibly contributing to long-COVID symptoms.
Though SARS-CoV-2 infects the respiratory system, the gut's immune role appears central to disease trajectory. Associations between microbial composition and immune signaling point to the gut as a regulator of inflammation--whether in neurodegeneration or viral response.
What links MS, COVID-19, and climate change? The answer lies in systemic feedback loops--interconnected cycles that amplify disruption once they begin.
As rising global temperatures destabilize natural systems, they trigger multiple health-related feedback loops. These loops are not isolated or linear; instead, they feed into one another, accelerating deterioration of immune function, environmental integrity, and human health. The breakdown of one system--for example, air quality--exacerbates others, such as susceptibility to infection or chronic illness.
The relationship between air pollution and COVID-19 is a textbook example of a compounding health feedback loop:
Long-term exposure to polluted air weakens immune systems and causes chronic respiratory and cardiovascular disease.
Infection with COVID-19 hits this vulnerable population harder, increasing hospitalizations and death rates.
Survivors often face long-COVID complications, further compromised by ongoing pollution exposure.
This cycle continues, draining resilience and pushing individuals toward chronic illness or early death.
This isn't hypothetical. It's observable now, and it’s worsening.
These feedback loops don’t stop at the individual. They strain health systems, drain economic productivity, and destabilize entire populations. Hospitals flooded with heatstroke patients or long-COVID sufferers are not just medical crises--they are system-level tipping points. Workforce depletion, skyrocketing healthcare costs, and shortened life expectancy are cascading consequences.
And there are generational echoes. Chronic stress and inflammation--driven by microbial imbalance and environmental toxins--can trigger epigenetic changes that increase disease susceptibility in offspring. This sets in motion a transgenerational health spiral that compounds the crisis.
The climate crisis is a public health emergency. Its intersections with microbial dysbiosis, pollution, and immune dysfunction form a web of reinforcing threats that erode life expectancy and societal resilience.
To break these cycles, we must:
Reduce greenhouse gas emissions to mitigate extreme heat and its biological stressors.
Regulate air and water pollutants that impair immune function and gut health.
Support microbiome research and gut-health interventions that could prevent or treat autoimmune and infectious diseases.
Build resilient, climate-adaptive healthcare systems capable of withstanding compounding pressures.
Understanding the gut as a frontline in the battle for human health gives us a new lens--one that reveals not only the root causes of illness, but the urgent need for holistic, systems-level interventions. The time to act is now.
Climate-Driven Health Collapse: The Compounding Feedback Loops of Disease, Pollution, and Extreme Weather Brouse (2025)