Autophagy inducer rapamycin treatment reduces IFN-I-mediated Inflammation and improves anti-HIV-1 T cell response in vivo

Rapamycin and Starvation Mitigate Indomethacin-Induced Intestinal Damage through Preservation of Lysosomal Vacuolar ATPase Integrity

Nonsteroidal anti-inflammatory drugs (NSAIDs) possess anti-inflammatory, antipyretic, and analgesic properties and are among the most commonly used drugs. Although the cause of NSAID-induced gastric ulcers is well understood, the mechanism behind small intestinal ulcers remains elusive. In this study, we examined the mechanism through which indomethacin (IM), a prominent NSAID, induces small intestinal ulcers, both in vitro and in vivo. In IEC6 cells, a small intestinal epithelial cell line, IM treatment elevated levels of LC3-II and p62. These expression levels remained unaltered after treatment with chloroquine or bafilomycin, which are vacuolar ATPase (V-ATPase) inhibitors. IM treatment reduced the activity of cathepsin B, a lysosomal protein hydrolytic enzyme, and increased the lysosomal pH. There was a notable increase in subcellular colocalization of LC3 with Lamp2, a lysosome marker, post IM treatment. The increased lysosomal pH and decreased cathepsin B activity were reversed by pretreatment with rapamycin (Rapa) or glucose starvation, both of which stabilize V-ATPase assembly. To validate the in vitro findings in vivo, we established an IM-induced small intestine ulcer mouse model. In this model, we observed multiple ulcerations and heightened inflammation following IM administration. However, pretreatment with Rapa or fasting, which stabilize V-ATPase assembly, mitigated the IM-induced small intestinal ulcers in mice. Coimmunoprecipitation studies demonstrated that IM binds to V-ATPase in vitro and in vivo. These findings suggest that IM induces small intestinal injury through lysosomal dysfunction, likely due to the disassembly of lysosomal V-ATPase caused by direct binding. Moreover, Rapa or starvation can prevent this injury by stabilizing the assembly. SIGNIFICANCE STATEMENT: This study elucidates the largely unknown mechanisms behind small intestinal ulceration induced by indomethacin and reveals the involvement of lysosomal dysfunction via vacuolar ATPase disassembly. The significance lies in identifying potential preventative interventions, such as rapamycin treatment or glucose starvation, offering pivotal insights that extend beyond nonsteroidal anti-inflammatory drugs-induced ulcers to broader gastrointestinal pathologies and treatments, thereby providing a foundation for novel therapeutic strategies aimed at a wide array of gastrointestinal disorders.

Examining Chronic Inflammation, Immune Metabolism, and T Cell Dysfunction in HIV Infection

Chronic Human Immunodeficiency Virus (HIV) infection remains a significant challenge to global public health. Despite advances in antiretroviral therapy (ART), which has transformed HIV infection from a fatal disease into a manageable chronic condition, a definitive cure remains elusive. One of the key features of HIV infection is chronic immune activation and inflammation, which are strongly associated with, and predictive of, HIV disease progression, even in patients successfully treated with suppressive ART. Chronic inflammation is characterized by persistent inflammation, immune cell metabolic dysregulation, and cellular exhaustion and dysfunction. This review aims to summarize current knowledge of the interplay between chronic inflammation, immune metabolism, and T cell dysfunction in HIV infection, and also discusses the use of humanized mice models to study HIV immune pathogenesis and develop novel therapeutic strategies.

The role of autophagy in insulin resistance and glucolipid metabolism and potential use of autophagy modulating natural products in the treatment of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a severe, long-term condition characterised by disruptions in glucolipid and energy metabolism. Autophagy, a fundamental cellular process, serves as a guardian of cellular health by recycling and renewing cellular components. To gain a comprehensive understanding of the vital role that autophagy plays in T2DM, we conducted an extensive search for high-quality publications across databases such as Web of Science, PubMed, Google Scholar, and SciFinder and used keywords like 'autophagy', 'insulin resistance', and 'type 2 diabetes mellitus', both individually and in combinations. A large body of evidence underscores the significance of activating autophagy in alleviating T2DM symptoms. An enhanced autophagic activity, either by activating the adenosine monophosphate-activated protein kinase and sirtuin-1 signalling pathways or inhibiting the mechanistic target of rapamycin complex 1 signalling pathway, can effectively improve insulin resistance and balance glucolipid metabolism in key tissues like the hypothalamus, skeletal muscle, liver, and adipose tissue. Furthermore, autophagy can increase β-cell mass and functionality in the pancreas. This review provides a narrative summary of autophagy regulation with an emphasis on the intricate connection between autophagy and T2DM symptoms. It also discusses the therapeutic potentials of natural products with autophagy activation properties for the treatment of T2DM conditions. Our findings suggest that autophagy activation represents an innovative approach of treating T2DM.

Autophagy of umbilical cord mesenchymal stem cells induced by rapamycin conduces to pro-angiogenic function of the conditioned medium

Angiogenesis is critical for wound healing and tissue repair. Umbilical cord mesenchymal stem cells (UCMSCs)-conditioned medium has certain actions to promote angiogenesis, and is expected for wound healing and tissue repair. However, recent studies showed that the pro-angiogenic efficacy of unprocessed MSCs-conditioned medium is low, and insufficient for tissue repair. Autophagy is a process for protein recycling and a contributor for cell exocrine, which may enhance pro-angiogenic efficacy of the conditioned medium by stimulating cytokine release from UCMSCs. Therefore, in this study we attempted to obtain enhanced autophagy in UCMSCs using different concentrations of rapamycin and compared pro-angiogenic functions of the conditioned media. The in vitro data showed that although 100 nM-10 μM rapamycin all could induce autophagy in UCMSCs, 100 nM was the best dose to optimize the angiogenic effect of the conditioned medium. The in vivo data also showed that pro-angiogenic effect of the optimized conditioned medium was more obvious than that of the control conditioned medium (0 nM group) in the injected matrigel plaques. Further, the expressions of VEGF, FGF-2, MMP-9, PDGF-α and PDGF-β were markedly increased in UCMSCs treated with 100 nM rapamycin. In conclusion, appropriately enhancing autophagy of UCMSC can improve pro-angiogenic efficacy of the conditioned medium, which may optimize therapeutic applications of UCMSCs-conditioned medium in wound healing and tissue repair.

Effect of rapamycin on Cryptococcus neoformans: cellular organization, biophysics and virulence factors

Background: Cryptococcus neoformans is an opportunistic fungal pathogen that causes infections mainly in immunosuppressed individuals, such as transplant recipients. Aims: This study investigated the effects of rapamycin, an immunosuppressant drug, on the cellular organization, biophysical characteristics, and main virulence factors of C. neoformans. Methods: Morphological, structural, physicochemical and biophysical analyses of cells and secreted polysaccharides of the reference H99 C. neoformans strain were investigated under the effect of subinhibitory concentrations of rapamycin. Results: Rapamycin at a minimum inhibitory concentration of 2.5 μM reduced C. neoformans cell viability by 53%, decreased capsule, increased cell size, chitin and lipid body formation, and changed peptidase and urease activity. Conclusion: Further studies are needed to assess how rapamycin affects the virulence factors and pathogenicity of C. neoformans.

Targeting autophagy to treat HIV immune dysfunction

Chronic immune activation and inflammation are hallmarks of Human Immunodeficiency Virus-1 (HIV-1) pathogenesis. Therefore, approaches to safely reduce systematic inflammation are essential to improve immune responses and thus slow or prevent HIV progression. Autophagy is a cellular mechanism for the disposal of damaged organelles and elimination of intracellular pathogens. It is not only vital for energy homeostasis, but also plays a critical role in regulating immunity. However, how it regulates inflammation and antiviral T cell responses during HIV infection is unclear. Our study demonstrated that impairment of autophagy leads to spontaneous type I-Interferons (IFN-I) signaling, while autophagy induction reduces IFN-I signaling in macrophages. Importantly, we demonstrated that in vivo treatment of autophagy inducer rapamycin in chronically HIV infected humanized mice decreased chronic IFN-I signaling, improved exhausted anti-viral T cell function, and reduced viral loads. Taken together, our study supports the therapeutic potential of rapamycin and potentially other autophagy inducers in alleviating HIV-1 immunopathogenesis and improving anti-viral T cell responses.

Harnessing Autophagy to Overcome Antigen-Specific T-Cell Dysfunction: Implication for People Living with HIV-1

Like other chronic viral infections, HIV-1 persistence inhibits the development of antigen-specific memory T-cells, resulting in the exhaustion of the immune response and chronic inflammation. Autophagy is a major lysosome-dependent mechanism of intracellular large-target degradation such as lipid and protein aggregates, damaged organelles, and intracellular pathogens. Although it is known that autophagy may target HIV-1 for elimination, knowledge of its function as a metabolic contributor in such viral infection is only in its infancy. Recent data show that elite controllers (EC), who are HIV-1-infected subjects with natural and long-term antigen (Ag)-specific T-cell protection against the virus, are characterized by distinct metabolic autophagy-dependent features in their T-cells compared to other people living with HIV-1 (PLWH). Despite durable viral control with antiretroviral therapy (ART), HIV-1-specific immune dysfunction does not normalize in non-controller PLWH. Therefore, the hypothesis of inducing autophagy to strengthen their Ag-specific T-cell immunity against HIV-1 starts to be an enticing concept. The aim of this review is to critically analyze promises and potential limitations of pharmacological and dietary interventions to activate autophagy in an attempt to rescue Ag-specific T-cell protection among PLWH.