The antiretroviral drug emtricitabine increases kynurenine: tryptophan ratio, aryl hydrocarbon receptor activation, and cellular senescence in female mice.

With obesity on the rise among people living with HIV (PLWH), there is growing concern that weight gain may result as an undesired effect of antiretroviral therapy (ART). This analysis sought to assess the association between ART regimens and changes in body mass index (BMI) among ART-experienced, virologically suppressed PLWH. ART-experienced, virologically suppressed PLWH ≥18 years of age in the Observational Pharmacoepidemiology Research and Analysis (OPERA) cohort were included for analysis if prescribed a new regimen containing one of the following core agents: dolutegravir (DTG), elvitegravir/cobicistat (EVG/c), raltegravir (RAL), rilpivirine (RPV), or boosted darunavir (bDRV), for the first time between August 1, 2013 and December 31, 2017. Multivariable linear regression was used to assess the association between regimen and mean changes in BMI at 6, 12, and 24 months after switch. In unadjusted analyses, BMI increases ranged from 0.30 kg/m2 (bDRV) to 0.83 kg/m2 (RPV) at 24 months following switch, but gains were observed with every regimen. In adjusted analyses, compared to DTG, only bDRV was associated with a smaller increase in BMI at all time points, while EVG/c and RAL were associated with smaller increases in BMI at 6 months only. Overall, results were consistent in analyses stratified by baseline BMI category. BMI increases were relatively small but followed an upward trend over time in this cohort of treatment-experienced, suppressed PLWH. Gains were attenuated with a longer period of follow-up. BMI gains did not differ by regimens, except for bDRV regimens, which were consistently associated with smaller BMI increases than DTG.

Integrase strand transfer inhibitor (INSTI)-based antiretroviral therapy (ART) might be associated with weight gain. The impact of different types of INSTIs has not been determined, particularly in combination with tenofovir disproxil fumarate (TDF) or tenofovir alafenamide fumarate (TAF). We conducted a retrospective cohort study using real-world data from people living with HIV (PLWH) aged ≥18 years who newly started ART between 2019 and May 2023 in Shenzhen, China. We performed linear mixed models to assess whether BMI changes of PLWH differed significantly over time across ART classes, among INSTIs, and between TAF- and TDF-containing regimens. 5,102 PLWH who newly started ART (4,771 [93.5%] men; median age 31 [IQR 26-40]) were included in the study. Significant differences in BMI changes were observed among the treatment groups. Compared to PLWH who contemporaneously used nonnucleoside reverse transcriptase inhibitor (NNRTI)-based regimens, people who used INSTI-based regimens 0-0.5 years after ART initiation experienced 1.27 greater BMI gain (95% CI 1.14 to 1.50), 0.5-1.5 years after ART initiation 0.18 greater BMI gain (95% CI 0.03 to 0.33). Compared to PLWH who newly started TDF+lamivudine [3TC]+DTG, TAF/emtricitabine [FTC]/EVG/c and TAF/FTC/BIC, those who used 3TC/DTG experienced greater BMI increases after ART initiation. Compared to people who contemporaneously used TAF-containing regimens, people who used TDF-containing regiments 0.5-1.5 years after ART initiation experienced 1.07 less BMI gain (-1.34 to -0.79). Compared with NNRTIs, INSTIs were associated with an increase in BMI. The increase in BMI associated with 3TC/DTG is particularly prominent. Additionally, TDF showed potential weight-neutral or weight-suppressive effects.

Functional coupling between inositol (1,4,5)-trisphosphate receptor (IP(3)R) and ryanodine receptor (RyR) represents a critical component of intracellular Ca(2+) signaling in many excitable cells; however, the role of this mechanism in skeletal muscle remains elusive. In skeletal muscle, RyR-mediated Ca(2+) sparks are suppressed in resting conditions, whereas application of transient osmotic stress can trigger activation of Ca(2+) sparks that are restricted to the periphery of the fiber. Here we show that onset of these spatially confined Ca(2+) sparks involves interaction between activation of IP(3)R and RyR near the sarcolemmal membrane. Pharmacological prevention of IP(3) production or inhibition of IP(3)R channel activity abolishes stress-induced Ca(2+) sparks in skeletal muscle. Although genetic ablation of the type 2 IP(3)R does not appear to affect Ca(2+) sparks in skeletal muscle, specific silencing of the type 1 IP(3)R leads to ablation of stress-induced Ca(2+) sparks. Our data indicate that membrane-delimited signaling involving cross-talk between IP(3)R1 and RyR1 contributes to Ca(2+) spark activation in skeletal muscle.

Advances and challenges in antiretroviral therapy for acquired immunodeficiency syndrome.

IntroductionData on renal impairment in sub-Saharan Africa (SSA) remains scarce, determination of renal function is not part of routine assessments. We evaluated renal function and blood pressure in a cohort of people living with HIV (PLWH) on antiretroviral treatment (ART) in the Renal Care Zambia project (ReCaZa).MethodsUsing routine data from an HIV outpatient clinic from 2011–2013, we retrospectively estimated the glomerular filtration rate (eGFR, CKD-Epi formula) of PLWH on ART in Lusaka, Zambia. Data were included if adults had had at least one serum creatinine recorded and had been on ART for a minimum of three months. We investigated the differences in eGFR between ART subgroups with and without tenofovir disproxil fumarate (TDF), and applied multivariable linear models to associate ART and eGFR, adjusted for eGFR before ART initiation.Results and discussionAmong 1118 PLWH (63,3% female, mean age 41.8 years, 83% ever on TDF; median duration 1461 [range 98 to 4342] days) on ART, 28.3% had an eGFR <90 ml/min, and 5.5% <60 ml/min at their last measurement. Information on other conditions associated with renal impairment was not systematically documented. Fourteen per cent of the PLWH who later switched to TDF-free ART had an initial eGFR lower 60ml/min. Nineteen percent had first-time hypertensive readings at their last visit. The multivariable models suggest that physicians acted according to guidelines and replaced TDF-containing ART if patients developed moderate/severe renal impairment.ConclusionsAssessment of renal function in SSA remains a challenge. The vast majority of PLWH benefit from long-term ART, including improved renal function. However, approximately 5% of PLWH on ART may have clinically relevant decreased eGFR, and 27% hypertension. While a routine renal assessment might not be feasible, strategies to identify patients at risk are warranted. Targeted monitoring prior and during ART is recommended, however, should not delay ART access.

It has been proven that intra-articular injection of mesenchymal stromal cells (MSCs) can alleviate cartilage damage in osteoarthritis (OA) by differentiating into chondrocytes and protecting inherent cartilage. However, the mechanism by which the OA articular microenvironment affects MSCs' therapeutic efficiency is yet to be fully elucidated. The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor involved in various cellular processes, such as osteogenesis and immune regulation. Tryptophan (Trp) metabolites, most of which are endogenous ligand for AHR, are abnormally increased in synovial fluid (SF) of OA and rheumatoid arthritis (RA) patients. In this study, the effects of kynurenine (KYN), one of the most important metabolites of Trp, were evaluated on the chondrogenic and chondroprotective effects of human umbilical cord-derived mesenchymal stromal cells (hUC-MSCs). hUC-MSCs were cultured in conditioned medium containing different proportions of OA/RA SF, or stimulated with KYN directly, and then, AHR activation, proliferation, and chondrogenesis of hUC-MSCs were measured. Moreover, the chondroprotective efficiency of short hairpin-AHR-UC-MSC (shAHR-UC-MSC) was determined in a rat surgical OA model (right hind joint). OA SF could activate AHR signaling in hUC-MSCs in a concentration-dependent manner and inhibit the chondrogenic differentiation and proliferation ability of hUC-MSCs. Similar results were observed in hUC-MSCs stimulated with KYN in vitro. Notably, shAHR-UC-MSC exhibited superior therapeutic efficiency in OA rat upon intra-articular injection. Taken together, this study indicates that OA articular microenvironment is not conducive to the therapeutic effect of hUC-MSCs, which is related to the activation of the AHR pathway by tryptophan metabolites, and thus impairs the chondrogenic and chondroprotective effects of hUC-MSCs. AHR might be a promising modification target for further improving the therapeutic efficacy of hUC-MSCs on treatment of cartilage-related diseases such as OA.

Factors Associated With Coronavirus Disease 2019 Morbidity in a Cohort of People Living With Human Immunodeficiency Virus.

What Might Surviving Coronavirus Disease 2019 Look Like for People Living with HIV?

PIN85 - TENOFOVIR ALAFENAMIDE’S IMPACT ON COMORBIDITIES AMONG PEOPLE LIVING WITH HIV IN PORTUGAL: A SIMULATION STUDY

ABSTRACTIntestinal microbiota-mediated aryl hydrocarbon receptor (AhR) activation plays an important role in host–microbiota interactions and disease development. However, whether AhR activation mediates infection-induced inflammation in remote organs is not clear. The purpose of this study is to assess the effects and underlying mechanism of AhR activation and gut microbiota-mediated dietary tryptophan (Trp) metabolism on infection-induced inflammation using an Escherichia coli (E. coli)-induced endometritis model in mice. We found that AhR activation by 6-formylindolo (3,2-b) carbazole (Ficz), which is an AhR agonist derived from the photooxidation of Trp, alleviated E. coli-induced endometritis by repairing barrier function and inhibiting inflammatory responses, while inhibition of AhR by CH223191, which is a synthetic AhR antagonist, aggravated E. coli-induced endometritis. Gut dysbiosis damaged AhR activation and exacerbated E. coli-induced endometritis in mice, which responded to the reduced abundance of AhR ligand producers, such as Lactobacillus spp. Supplementation with dietary Trp ameliorated E. coli-induced endometritis in a microbiota-dependent manner, which was associated with the production of AhR ligands. Administration of AhR ligands, including indole and indole aldehyde, but not indole-3-propionic acid, rescued the protective effect of Trp on E. coli-induced endometritis in dysbiotic mice. Moreover, consumption of Lactobacillus reuteri (L. reuteri) containing AhR ligand-producing capability also alleviated E. coli-induced endometritis in mice in an AhR-dependent manner. Our results demonstrate that microbiota-mediated AhR activation is a key factor in fighting pathogen-caused inflammation, which leads to a potential strategy to regulate the gut microbiota and metabolism by dietary Trp or probiotics for the intervention of infectious diseases and reproductive health.IMPORTANCE Infection-induced endometritis is a common and frequently occurring disease in humans and animals. Accumulating evidence suggests an important role of the gut microbiota in the development of infection-induced inflammation. Whether and how gut microbiota-mediated AhR activation regulates the pathogenesis of pathogen-induced endometritis remains unknown. The current study found that AhR activation ameliorated E. coli-induced endometritis, and inhibition of AhR produced negative results. Gut dysbiosis reduced the abundance of AhR ligand producers including Lactobacillus spp., damaged AhR activation, and exacerbated E. coli-induced endometritis. Supplementation with dietary Trp, AhR ligands, and L. reuteri containing AhR ligand-producing capability alleviated E. coli-induced endometritis in mice. Our results suggest an important role of microbiota-mediated AhR activation in the pathogenesis of endometritis and provide potential strategies for the intervention of infectious diseases and reproductive health by regulating the gut microbiota and metabolism.

3-Hydroxypropionaldehyde modulates tryptophan metabolism to activate AhR signaling and alleviate ethanol-induced liver injury.

Musculoskeletal frailty, often associated with aging, is frequently observed in patients living with HIV on long term anti-retroviral therapy (ART) and linked to poor health outcomes from accelerated disease progression to increased mortality. Mechanisms underlying this frailty phenotype are poorly understood but may involve disease progression as well as ARTs themselves. One possible mediator is activation of the aryl hydrocarbon receptor (AhR). NF-κB, activated by HIV infection, is an upstream regulator of AhR which induces the enzyme IDO-1 to produce the endogenous AhR ligand kynurenine. However, connections between ART, HIV, and AhR in musculoskeletal frailty had not been previously explored. In preliminary studies we tested the effects of tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) ARTs in a mouse myoblast cell line (C2C12). FTC, but not TDF, increased transcriptional activity of AhR, expression of AhR and its target gene CYP1A1, and increased cellular indicators of senescence. FTC also impaired myoblast differentiation as confirmed morphologically by microscopy. Next, we tested the effects of FTC and another ART agent, tenofovir alafenamide (TAF, a prodrug of TDF) in primary human mesenchymal stem cells and myoblasts, showing increased expression of AhR, AhR target genes, and increased senescence in both cell populations. Moreover, FTC and TAF decreased expression of myoblast differentiation markers (MYOG and MYOD). While further research is needed to elucidate the underlying mechanisms of interactions between ART, HIV, and AhR signaling, these studies raise the possibility that targeting AhR may serve as a novel therapeutic approach for improving musculoskeletal function in this setting.

HIV-associated morbidity and death have been decreased by antiretroviral therapy (ART), however age-related musculoskeletal frailty is exacerbated in people living with HIV (PLWH) and those on ART, contributing to poor healthspan. However, the combined effects of aging, HIV, and ART in musculoskeletal tissues have not been thoroughly studied. Here we investigated the effects of Emtricitabine (FTC), an FDA approved ART, or its vehicle (VEH) on skeletal muscle DNA methylation patterns in a female HIV transgenic mouse model (Tg26). Comparing the impact of HIV phenotypes in the absence of ART (i.e., WT+VEH vs. Tg26+VEH), 303 CpGs were significantly hypermethylated (methDiff≥0.1) whereas 273 were hypermethylated when comparing the same groups in the presence of ART (i.e., WT+FTC vs. Tg26+FTC). Mechanistically, the effects of FTC with TDF (Tenofovir, another ART) and TAF (Tenofovir alafenamide, a prodrug of TDF) as a combination ART (cART) were tested in primary human muscle cells. The cART treatment induced cellular senescence, (senescence-associated β-galactosidase staining) and qPCR suggested downregulated expression of genes involved in myoblast differentiation. These findings suggest that ART may have deleterious consequences on muscle function and may contribute to epigenetic changes in DNA methylation and cellular senescence, exacerbating muscle wasting and dysfunction in patients with HIV receiving ART treatments. Further research is needed to elucidate the mechanisms that drive muscle cell damage in PLWH on long-term cART and to understand contributions of altered DNA methylation to these processes. These insights could inform potential epigenetic-targeted therapeutic approaches for mitigation of musculoskeletal decline in PLWH on ART.

Aryl hydrocarbon receptor (AhR) is a critical player in the crosstalk between the gut microbiota and its host. However, factors regulating AhR within the gut, which is a complex metabolomic environment, are poorly understood. This study investigates the effect of a combination of metabolites on the activation mechanism of AhR. AhR activity was evaluated using both a luciferase reporter system and mRNA levels of AhR target genes on human cell lines and human colonic explants. AhR activation was studied by radioligand-binding assay, nuclear translocation of AhR by immuofluorescence and protein co-immunoprecipitation of AhR with ARNT. Indirect activation of AhR was evaluated using several tests and inhibitors. The promoter of the target gene CYP1A1 was studied both by chromatin immunoprecipitation and by using an histone deacetylase HDAC inhibitor (iHDAC). Short-chain fatty acids, and butyrate in particular, enhance AhR activity mediated by endogenous tryptophan metabolites without binding to the receptor. This effect was confirmed in human intestinal explants and did not rely on activation of receptors targeted by SCFAs, inhibition of AhR degradation or clearance of its ligands. Butyrate acted directly on AhR target gene promoter to reshape chromatin through iHDAC activity. Our findings revealed that butyrate is not an AhR ligand but acts as iHDAC leading to an increase recruitment of AhR to the target gene promoter in the presence of tryptophan-derived AhR agonists. These data contribute to a novel understanding of the complex regulation of AhR activation by gut microbiota-derived metabolites.

Screening a mouse liver gene expression compendium identifies modulators of the aryl hydrocarbon receptor (AhR).