Complex I inhibitors promote tissue regeneration in RA and fibrosis, offering a new therapeutic path for healthy aging and resilience.
A study published this week in The Journal of Pharmacology and Experimental Therapeutics highlights an unusual – and potentially far-reaching – therapeutic strategy: repairing tissue damage in chronic inflammatory and degenerative diseases via mitochondrial Complex I inhibition. The research, conducted by Istesso, a UK-based biotech focused on tissue repair, suggests its novel compounds may restore damaged tissue by prompting the body’s own regenerative systems into action – not by suppressing inflammation, but by enhancing resilience at the cellular level.
This development could represent an incremental step toward rethinking how chronic diseases, particularly those associated with aging, such as rheumatoid arthritis (RA), pulmonary fibrosis, osteoporosis and sarcopenia, are managed – not purely as conditions to be suppressed, but as manifestations of impaired repair that might be restored. The early data come from a combination of preclinical studies and ongoing clinical trials with Istesso’s investigational oral drug, Leramistat, a first-in-class Complex I inhibitor that appears to activate mitochondrial signaling pathways involved in repair and recovery [1].
Longevity.Technology: There’s something quietly radical about a drug that doesn’t aim to suppress, block or mute biological processes – but rather encourages them to do better. Istesso’s approach to tissue repair – not through brute-force immunosuppression or anti-inflammatory sleight of hand, but by gently nudging mitochondria to reinstate the body’s own repair mechanisms – feels less like high drama and more like an elegant correction of a faltering system. The mitochondrion has long been blamed as a culprit in aging, its dysfunction synonymous with fatigue and decline – yet here it is, being repurposed as a therapeutic lever.
Interestingly, by modulating Complex I, Istesso seems to be exploiting a metabolic choke point to restore balance without tipping the whole cellular edifice into crisis – a biochemical middle path. What’s more, the early human data hints not just at disease modification in rheumatoid arthritis, but at genuine structural improvement – an increasingly rare ambition in a pharmaceutical landscape content with symptom management. That this repair signal also corresponds with markers of inflammaging and biological resilience only adds to its longevity chops – particularly if the data hold up in more advanced trials. Of course, the proof of the pudding is always in the patient outcomes – but the idea that oral small molecules could elicit tissue restoration across age-linked conditions like sarcopenia, osteoporosis and fibrosis is as welcome as it is ambitious. Repair over suppression isn’t just neat – it might, in time, prove necessary. After all, fixing the roof is better than mopping the floor.
Harnessing mitochondrial biology for repair
Mitochondria have long held center stage in the biology of aging – both as a source of cellular energy and as a key node in the inflammatory and metabolic signaling that governs resilience and decline. Leramistat, Istesso’s lead compound, selectively inhibits mitochondrial Complex I, a mechanism that, perhaps counterintuitively, appears to promote the recruitment of progenitor cells and restoration of damaged tissues [1].
“This is the first time adaptive tissue repair has been demonstrated with oral agents in these settings,” said Dr Lisa Patel, Istesso’s CEO and lead study author. “We are very excited to be pioneering this game-changing new field, offering a novel path to stopping, or even reversing, progressive tissue decline.”
Preclinical models showed improvements in both inflammatory and fibrotic conditions – including arthritis and lung scarring – while early human data suggest Leramistat may improve bone erosion and fatigue scores in RA patients, alongside positive changes in inflammatory and metabolic biomarkers such as CRP, GDF15 and FGF21 [1]. These findings suggest the potential for broader application in diseases of aging where repair fails to keep pace with damage – particularly those involving structural tissue loss.
A broader strategy for healthy aging
Chronic inflammation and tissue degradation are central to many conditions of aging – not just autoimmune diseases like RA, but also muscle and bone wasting, organ fibrosis and, potentially, neurodegeneration. While most therapies aim to block the drivers of disease, few actively engage the biology of repair – an omission that may limit their ability to change long-term outcomes. The notion that mitochondrial modulation could not only reduce damage but restore structure raises the possibility of addressing aging at its physiological roots.
“Tissue damage is a universal feature of aging and chronic disease,” notes the study. The fact that Leramistat appears to operate without serious adverse events or overt immunosuppression also strengthens its potential role as a longer-term intervention in degenerative conditions. Indeed, the compound has already been granted both Fast Track and Orphan Drug status by the FDA for idiopathic pulmonary fibrosis, indicating a potential regulatory path forward.
“This work opens a new chapter in mitochondrial pharmacology,” commented Professor Sir Keith Peters, Regius Professor of Physic Emeritus and a non-executive board director at Istesso.
Science meets strategy
While much of aging research has focused on delaying decline, the capacity to reverse or repair damage may be more clinically meaningful – particularly as populations age and health systems strain under the burden of chronic, slow-burning disease. If Leramistat or its pipeline successors can prove their worth in broader cohorts, the implications could stretch beyond rheumatology – touching on geroscience, sarcopenia treatment, and the pharmacological restoration of resilience.
Recalibrating the clock
Much remains to be seen – not least in the forthcoming publication of clinical trial results – but Istesso’s strategy, blending metabolic insight with tissue engineering ambitions, taps into a current of longevity science that is gaining momentum: that aging is, in part, the erosion of repair. Rekindling that repair, not with cells or implants or gene edits, but with an oral drug that leverages the body’s own systems, might just offer a more sustainable path to healthier, longer lives.
[1] https://jpet.aspetjournals.org/article/S0022-3565(25)39874-5/fulltext
