Introduction
The phenomenon of inflammaging—a chronic, low-grade inflammation associated with aging—is increasingly recognized as a critical driver of age-related diseases, such as Alzheimer’s disease (AD) and type 2 diabetes mellitus (T2DM). Typically, this sterile inflammation arises through mechanisms involving endogenous nucleic acid species and activation of inflammasomes, the multi-protein complexes central to innate immunity. Recently, nucleoside reverse transcriptase inhibitors (NRTIs), well-established antiviral agents against HIV and hepatitis B virus (HBV), have attracted interest for their potential to modulate inflammaging. This article critically reviews emerging epidemiological and mechanistic evidence supporting the repurposing of NRTIs as therapeutic agents to counteract inflammaging and reduce the incidence or progression of major age-related diseases.
Background: Clinical Context and Disease Burden
Age-related diseases including AD and T2DM represent substantial and growing public health challenges globally. Inflammation is a key pathogenic factor in these conditions, contributing to tissue damage and metabolic dysregulation. Chronic exposure to endogenous retroelements, including long interspersed nuclear elements (LINEs), short interspersed nuclear elements (SINEs), and human endogenous retroviruses (HERVs), increases with aging and promotes sterile inflammation via nucleic acid sensing pathways and inflammasome activation. Current anti-inflammatory treatments for these conditions have limited efficacy and often target downstream pathways. Hence, novel upstream interventions that can modulate fundamental drivers of inflammaging are highly desirable.
Study Design and Evidence Sources
The evidence reviewed is drawn principally from epidemiological cohort studies analyzing incidence rates of age-related diseases among populations treated with NRTIs compared to other antiretroviral classes, alongside mechanistic studies exploring NRTI actions on endogenous retroelement activity and inflammasomes. While randomized controlled trials specifically repurposing NRTIs for aging-related inflammation remain scarce, observational data coupled with preclinical mechanistic insights provide a compelling rationale for further clinical investigations.
Key Findings
Anti-Inflammatory Effects of NRTIs
NRTIs inhibit the reverse transcriptase enzyme, not only in viral pathogens but also reverse transcriptase activities associated with endogenous retroelements. By blocking the formation of RNA:DNA hybrids and other immunostimulatory nucleic acid species, NRTIs mitigate activation of innate immune sensors such as the NLRP3 inflammasome. This results in reduced secretion of proinflammatory cytokines like IL-1 and IL-18, which are implicated in tissue inflammation and systemic immune activation seen in aging.
Epidemiological Evidence Linking NRTIs to Reduced Age-Related Disease Incidence
Recent large-scale epidemiological analyses demonstrate significantly lower incidence rates of Alzheimer’s disease and type 2 diabetes among patients on long-term NRTI therapy for HIV or HBV. Such effects were not observed in patients receiving other antiretroviral drug classes, suggesting a unique protective role attributable to reverse transcriptase inhibition. These observational findings align with preclinical data suggesting that endogenous retroelement activity contributes to pathological inflammation driving neurodegeneration and metabolic dysfunction.
Safety and Mitochondrial Toxicity Considerations
A historic concern regarding NRTIs has been mitochondrial toxicity, contributing to adverse effects that limited the clinical use of older agents. However, contemporary NRTIs possess improved safety profiles with markedly reduced mitochondrial toxicity. This favorable safety evolution supports renewed interest in repurposing these agents for chronic age-related conditions, especially given the low to moderate dosing requirements anticipated in such indications.
Expert Commentary and Mechanistic Insights
The inhibition of endogenous retroelement reverse transcription provides a novel biological mechanism by which NRTIs may attenuate inflammaging, distinct from their antiviral effects. By preventing the generation of nucleic acid ligands that activate inflammasomes and other nucleic acid sensors, NRTIs interfere with sterile inflammation at a proximal trigger level. This intervention may subsequently delay or reduce progression of neurodegenerative and metabolic age-related diseases.
While promising, current evidence is primarily associative and mechanistic. Prospective, randomized clinical trials are essential to confirm the protective effects of NRTIs in non-infectious aging contexts and to elucidate the optimal compounds and dosing regimens that balance efficacy with safety. Furthermore, development of novel NRTI analogs tailored to minimize side effects while maximizing anti-inflammaging properties represents an attractive research avenue.
Conclusion
Nucleoside reverse transcriptase inhibitors represent an innovative and potentially transformative therapeutic approach to mitigate inflammaging and its contribution to age-related diseases such as Alzheimer’s disease and type 2 diabetes. Epidemiological data demonstrate an association between chronic NRTI use and reduced incidence of these diseases, supported by mechanistic insights into their inhibition of endogenous retroelement activity and inflammasome activation. Although safety concerns related to mitochondrial toxicity were noteworthy with first-generation NRTIs, newer agents render this class viable for repurposing in the aging population. Future clinical trials and drug development efforts are warranted to fully harness NRTIs’ anti-inflammaging potential and address the unmet medical needs posed by age-related chronic diseases.
Funding and Clinical Trials
No specific funding or clinical trial registrations are reported in the current literature regarding NRTIs repurposing for inflammaging. However, emerging interest calls for coordinated research initiatives to rigorously evaluate their clinical benefits in aging-associated disease prevention.
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