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BACKGROUND: Sarcopenia is a progressive and systemic skeletal muscle disorder associated with an increased risk of hospitalization and adverse effects on survival. This study aims to investigate the prevalence and related risk factors of sarcopenia in people living with HIV using the revised European Working Group on Sarcopenia in Older People (EWGSOP2) definition. METHODS: This cross-sectional study comprising 379 patients with confirmed HIV infection evaluated the appendicular skeletal muscle mass by employing the bioelectrical impedance analysis method. Muscle strength and functional mobility were analyzed using the five-time sit-to-stand test and the timed "Up and Go" test. RESULTS: The prevalence rates of pre-sarcopenia and sarcopenia among people living with HIV were 3.4 % and 2.1 % according to the revised EWGSOP2 definition. Advanced age (Odds Ratio 1.07, p = .03), lower body mass index (Odds Ratio 0.79, p = .012) and CD4+ T-cell count below 500/µl (Odds Ratio 2.22, p = .007) were identified as significant factors associated with sarcopenia. Sarcopenia was also identified as a significant correlate of frailty (p < .001). CONCLUSION: This is the first study examining the prevalence of sarcopenia in people living with HIV according to the revised EWGSOP2 clinical algorithm. Advanced age, lower body mass index and a poor immune status are determined as promoting factors of sarcopenia. Sarcopenia significantly correlates with frailty. Standardized clinical algorithms are essential for reliable sarcopenia diagnosis in people living with HIV in order to promote intervention strategies and to prevent adverse health outcomes.
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Cross-reactive cellular and humoral immunity can substantially contribute to antiviral defense against SARS-CoV-2 variants of concern (VOC). While the adult SARS-CoV-2 cellular and humoral immunity and its cross-recognition potential against VOC is broadly analyzed, similar data regarding the pediatric population are missing. In this study, we perform an analysis of the humoral and cellular SARS-CoV-2 response immune of 32 convalescent COVID-19 children (children), 27 convalescent vaccinated adults(C + V+) and 7 unvaccinated convalescent adults (C + V-). Similarly to adults, a significant reduction of cross-reactive neutralizing capacity against delta and omicron VOC was observed 6 months after SARS-CoV-2 infection. While SAR-CoV-2 neutralizing capacity was comparable among children and C + V- against all VOC, children demonstrated as expected an inferior humoral response when compared to C + V+. Nevertheless, children generated SARS-CoV-2 reactive T cells with broad cross-recognition potential. When compared to V + C+, children presented even comparable frequencies of WT-reactive CD4 + and CD8 + T cells with high avidity and functionality. Taking into consideration the limitations of study - unknown disease onset for 53% of the asymptomatic pediatric subjects, serological detection of SARS-CoV-2 infection-, our results suggest that following SARS-CoV-2 infection children generate a humoral SARS-CoV-2 response with neutralizing potential comparable to unvaccinated COVID-19 convalescent adults as well a sustained SARS-CoV-2 cellular response cross-reactive to VOC.
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COVID-19 , SARS-CoV-2 , Adulto , Niño , Adolescente , Humanos , Inmunidad Celular , Linfocitos T CD8-positivos , Inmunidad Humoral , Anticuerpos Antivirales , Anticuerpos NeutralizantesRESUMEN
The role of adaptive SARS-CoV-2 specific immunity in post-acute sequelae of COVID-19 (PASC) is not well explored, although a growing population of convalescent COVID-19 patients with manifestation of PASC is observed. We analyzed the SARS-CoV-2-specific immune response, via pseudovirus neutralizing assay and multiparametric flow cytometry in 40 post-acute sequelae of COVID-19 patients with non-specific PASC manifestation and 15 COVID-19 convalescent healthy donors. Although frequencies of SARS-CoV-2-reactive CD4+ T cells were similar between the studied cohorts, a stronger SARS-CoV-2 reactive CD8+ T cell response, characterized by IFNγ production and predominant TEMRA phenotype but low functional TCR avidity was detected in PASC patients compared to controls. Of interest, high avidity SARS-CoV-2-reactive CD4+ and CD8+ T cells were comparable between the groups demonstrating sufficient cellular antiviral response in PASC. In line with the cellular immunity, neutralizing capacity in PASC patients was not inferior compared to controls. In conclusion, our data suggest that PASC may be driven by an inflammatory response triggered by an expanded population of low avidity SARS-CoV-2 reactive pro-inflammatory CD8+ T cells. These pro-inflammatory T cells with TEMRA phenotype are known to be activated by a low or even without TCR stimulation and lead to a tissue damage. Further studies including animal models are required for a better understanding of underlying immunopathogensis. Summary: A CD8+ driven persistent inflammatory response triggered by SARS-CoV-2 may be responsible for the observed sequelae in PASC patients.
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Emerging variants of concern (VOC) raise obstacles in shaping vaccination strategies and ending the pandemic. Vaccinated SARS-CoV-2 convalescence shapes the current immune dynamics. We analyzed the SARS-CoV-2 VOC-specific cellular and humoral response of 57 adults: 42 convalescent mRNA vaccinated patients (C+V+), 8 uninfected mRNA vaccinated (C-V+) and 7 unvaccinated convalescent individuals (C+V-). While C+V+ demonstrated a superior humoral SARS-CoV-2 response against all analyzed VOC (alpha, delta, omicron) compared to C-V+ and C+V-, SARS-CoV-2 reactive CD4+ and CD8+ T cells, which can cross-recognize the alpha, delta and omicron VOC after infection and/or vaccination were observed in all there groups without significant differences between the groups. We observed a preserved cross-reactive C+V+ and C-V+ T cell memory. An inferior humoral response but preserved cross-reactive T cell memory in C+V- compared to C+V+ was observed, as well as an inferior humoral response but preserved cross-reactive T cell memory in C+V- compared to C-V+. Adaptive immunity generated after SARS-CoV-2 infection and vaccination leads to superior humoral immune response against VOC compared to isolated infection or vaccination. Despite the apparent loss of neutralization potential caused by viral evolution, a preserved SARS-CoV-2 reactive T cell response with a robust potential for cross-recognition of the alpha, delta and omicron VOC was detected in all studied cohorts. Our results may have implications on current vaccination strategies.
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COVID-19 , Inmunidad Humoral , Adulto , Humanos , SARS-CoV-2 , Convalecencia , COVID-19/prevención & control , Anticuerpos Antivirales , Vacunación , ARN MensajeroRESUMEN
ATP-driven bacterial AAA+ proteases have been recognized as drug targets. They possess an AAA+ protein (e.g., ClpC), which threads substrate proteins into an associated peptidase (e.g., ClpP). ATPase activity and substrate selection of AAA+ proteins are regulated by adapter proteins that bind to regulatory domains, such as the N-terminal domain (NTD). The antibacterial peptide Cyclomarin A (CymA) kills Mycobacterium tuberculosis cells by binding to the NTD of ClpC. How CymA affects ClpC function is unknown. Here, we reveal the mechanism of CymA-induced toxicity. We engineered a CymA-sensitized ClpC chimera and show that CymA activates ATPase and proteolytic activities. CymA mimics adapter binding and enables autonomous protein degradation by ClpC/ClpP with relaxed substrate selectivity. We reconstitute CymA toxicity in E. coli cells expressing engineered ClpC and ClpP, demonstrating that gain of uncontrolled proteolytic activity causes cell death. This validates drug-induced overriding of AAA+ protease activity control as effective antibacterial strategy.
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ATPasas Asociadas con Actividades Celulares Diversas/antagonistas & inhibidores , Antibacterianos/farmacología , Escherichia coli/química , Oligopéptidos/farmacología , ATPasas Asociadas con Actividades Celulares Diversas/genética , ATPasas Asociadas con Actividades Celulares Diversas/metabolismo , Antibacterianos/química , Antibacterianos/aislamiento & purificación , Escherichia coli/citología , Modelos Moleculares , Conformación Molecular , Mycobacterium tuberculosis/efectos de los fármacos , Mycobacterium tuberculosis/enzimología , Oligopéptidos/química , Oligopéptidos/aislamiento & purificaciónRESUMEN
AAA+ disaggregases solubilize aggregated proteins and confer heat tolerance to cells. Their disaggregation activities crucially depend on partner proteins, which target the AAA+ disaggregases to protein aggregates while concurrently stimulating their ATPase activities. Here, we report on two potent ClpG disaggregase homologs acquired through horizontal gene transfer by the species Pseudomonas aeruginosa and subsequently abundant P. aeruginosa clone C. ClpG exhibits high, stand-alone disaggregation potential without involving any partner cooperation. Specific molecular features, including high basal ATPase activity, a unique aggregate binding domain, and almost exclusive expression in stationary phase distinguish ClpG from other AAA+ disaggregases. Consequently, ClpG largely contributes to heat tolerance of P. aeruginosa primarily in stationary phase and boosts heat resistance 100-fold when expressed in Escherichia coli This qualifies ClpG as a potential persistence and virulence factor in P. aeruginosa.
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Adaptación Fisiológica , Proteínas Bacterianas/metabolismo , Calor , Pseudomonas aeruginosa/enzimología , Proteínas Bacterianas/genética , Regulación Bacteriana de la Expresión Génica , Regulación Enzimológica de la Expresión Génica , Transferencia de Gen Horizontal , Filogenia , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/metabolismoRESUMEN
Ring-forming AAA+ chaperones exert ATP-fueled substrate unfolding by threading through a central pore. This activity is potentially harmful requiring mechanisms for tight repression and substrate-specific activation. The AAA+ chaperone ClpC with the peptidase ClpP forms a bacterial protease essential to virulence and stress resistance. The adaptor MecA activates ClpC by targeting substrates and stimulating ClpC ATPase activity. We show how ClpC is repressed in its ground state by determining ClpC cryo-EM structures with and without MecA. ClpC forms large two-helical assemblies that associate via head-to-head contacts between coiled-coil middle domains (MDs). MecA converts this resting state to an active planar ring structure by binding to MD interaction sites. Loss of ClpC repression in MD mutants causes constitutive activation and severe cellular toxicity. These findings unravel an unexpected regulatory concept executed by coiled-coil MDs to tightly control AAA+ chaperone activity.