Biology subjects

Alvarez, R. A.

Publications and source records attributed to Alvarez, R. A..

5 recordsLinked to original sources

bioRxiv2024

Longitudinal transcriptional changes reveal genes from the natural killer cell-mediated cytotoxicity pathway as critical players underlying COVID-19 progression

Patients present a wide range of clinical severities in response SARS-CoV-2 infection, but the underlying molecular and cellular reasons why clinical outcomes vary so greatly within the population remains unknown. Here, we report that negative clinical outcomes in severely ill patients were associated with divergent RNA transcriptome profiles in peripheral immune cells compared with mild cases during the first weeks after disease onset. Protein-protein interaction analysis indicated that early-responding cytotoxic NK cells were associated with an effective clearance of the virus and a less severe outcome. This innate immune response was associated with the activation of select cytokine-cytokine receptor pathways and robust Th1/Th2 cell differentiation profiles. In contrast, severely ill patients exhibited a dysregulation between innate and adaptive responses affiliated with divergent Th1/Th2 profiles and negative outcomes. This knowledge forms the basis of clinical triage that may be used to preemptively detect high-risk patients before life-threatening outcomes ensue. Highlights- Mild COVID-19 patients displayed an early transcriptional commitment with NK cell function, whereas severe patients do so with neutrophil function. - The identified co-expressed genes give insights into a coordinated transcriptional program of NK cell cytotoxic activity being associated with mild patients. - Key checkpoints of NK cell cytotoxicity that were enriched in mild patients include: KLRD1, CD247, and IFNG. - The early innate immune response related to NK cells connects with the Th1/Th2 adaptive immune responses, supporting their relevance in COVID-19 progression.

immunology↗

bioRxiv2021

Humoral immune responses against seasonal coronaviruses predict efficiency of SARS-CoV-2 spike targeting, FcγR activation, and corresponding COVID-19 disease severity

Despite SARS-CoV-2 being a "novel" coronavirus, several studies suggest that detection of anti-spike IgG early in infection may be attributable to the amplification of humoral memory responses against seasonal hCoVs in severe COVID-19 patients. In this study, we examined this concept by characterizing anti-spike IgG from a cohort of non-hospitalized convalescent individuals with a spectrum of COVID-19 severity. We observed that anti-spike IgG levels positively correlated with disease severity, higher IgG cross-reactivity against betacoronaviruses (SARS-CoV-1 and OC43), and higher levels of proinflammatory Fc gamma receptor 2a and 3a (Fc{gamma}R2a & Fc{gamma}R3a) activation. In examining the levels of IgG targeting betacoronavirus conserved and immunodominant epitopes versus disease severity, we observed a positive correlation with the levels of IgG targeting the conserved S2FP region, and an inverse correlation with two conserved epitopes around the heptad repeat (HR) 2 region. In comparing the levels of IgG targeting non-conserved epitopes, we observed that only one of three non-conserved immunodominant epitopes correlated with disease severity. Notably, the levels of IgG targeting the receptor binding domain (RBD) were inversely correlated with severity. Importantly, targeting of the RBD and HR2 regions have both been shown to mediate SARS-CoV-2 neutralization. These findings show that, aside from antibody (Ab) targeting of the RBD region, humoral memory responses against seasonal betacoronaviruses are potentially an important factor in dictating COVID-19 severity, with anti-HR2-dominant Ab profiles representing protective memory responses, while an anti-S2FP dominant Ab profiles indicate deleterious recall responses. Though these profiles are masked in whole antigen profiling, these analyses suggest that distinct Ab memory responses are detectable with epitope targeting analysis. These findings have important implications for predicting severity of SARS-CoV-2 infections (primary and reinfections), and may predict vaccine efficacy in subpopulations with different dominant antibody epitope profiles.

microbiology↗

bioRxiv2021

Non-neutralizing antibodies targeting the immunogenic regions of HIV-1 envelope reduce mucosal infection and virus burden in humanized mice

Antibodies are principal immune components elicited by vaccines to induce protection from microbial pathogens. In the Thai RV144 HIV-1 vaccine trial, vaccine efficacy was 31% and the sole primary correlate of reduced risk was shown to be vigorous antibody response targeting the V1V2 region of HIV-1 envelope. Antibodies against V3 also were inversely correlated with infection risk in subsets of vaccinees. Antibodies recognizing these regions, however, do not exhibit potent neutralizing activity. Therefore, we examined the antiviral potential of poorly neutralizing monoclonal antibodies (mAbs) against immunodominant V1V2 and V3 sites by passive administration of human mAbs to humanized mice engrafted with CD34+ hematopoietic stem cells, followed by mucosal challenge with an HIV-1 infectious molecular clone (IMC) expressing the envelope of a tier 2 resistant HIV-1 strain. Treatment with anti-V1V2 mAb 2158 or anti-V3 mAb 2219 did not prevent infection, but both reduced the virus burden, and V3 mAb 2219 displayed a superior potency compared to V1V2 mAb 2158. While these mAbs had no or weak neutralizing activity and elicited undetectable levels of antibody-dependent cellular cytotoxicity (ADCC), V3 mAb 2219 displayed a greater capacity to bind virus- and cell-associated HIV-1 envelope and to mediate antibody-dependent cellular phagocytosis (ADCP) and C1q complement binding as compared to V1V2 mAb 2158. Mutations in the Fc region of 2219 abolished these effector activities and abrogated virus control in humanized mice. These results demonstrate the importance of Fc functions other than ADCC for antibodies without potent neutralizing activity.

immunology↗

bioRxiv2021

Soluble guanylate cyclase stimulation mitigates skeletal and cardiac muscle dysfunction in a mdx model of Duchenne muscular dystrophy

The impairment of neuronal nitric oxide synthase (nNOS) signaling contributes to disease pathology in the muscle wasting disorder Duchenne muscular dystrophy (DMD). nNOS signal propagation occurs through nitric oxide sensitive soluble guanylate cyclase (sGC), a critical source of cyclic guanosine monophosphate (cGMP) in muscle. Although both nNOS and sGC activity are impaired in DMD patients, little is known about sGC as a therapeutic target. In this study, we tested the hypothesis that stimulating sGC activity with the allosteric agonist BAY41-8543 mitigates striated muscle pathology in the mdx4cv mouse model of DMD. In contrast to DMD patients, mdx mice exhibited greater basal sGC activity than wild type controls with preservation of cGMP levels due partly to upregulation of sGC in some muscles. Stimulating sGC activity in mdx mice with BAY41-8543 substantially reduced skeletal muscle damage, macrophage densities and inflammation and significantly increased resistance to contraction-induced fatigue. BAY41-8543 also enhanced in vivo diaphragm function while reducing breathing irregularities suggesting improved respiratory function. BAY41-8543 attenuated cardiac hypertrophic remodeling, fibrosis and diastolic dysfunction including left atrium enlargement in aged mdx mice. Overall, sGC stimulation significantly mitigated skeletal and cardio-respiratory dysfunction in mdx4cv mice. Importantly, this study provides compelling pre-clinical evidence supporting sGC as a novel target in DMD and the repurposing of FDA-approved sGC stimulators, such as riociguat and veraciguat, as a novel therapeutic approach for DMD.

physiology↗

bioRxiv2019

P2X1 selective antagonists block HIV-1 infection through inhibition of envelope conformation-dependent fusion

Purinergic receptors detect extracellular ATP and promote inflammatory processes. Emerging literature has demonstrated that inhibition of these proinflammatory receptors can block HIV-1 productive infection. The specificity of receptor type and mechanism of interaction has not yet been determined. Here we characterize the inhibitory activity of P2X1 receptor antagonists, NF279 and NF449 in cell lines, primary cells, and in a variety of envelope clades. NF279 and NF449 blocked productive infection at the level of viral membrane fusion with a range of inhibitory activities against different HIV-1 envelopes. A mutant virus carrying a truncation deletion of the C-terminal tail of HIV-1 envelope (Env) glycoprotein 41 (gp41) showed reduced sensitivity to P2X1 antagonists, indicating that the sensitivity of inhibition by these molecules is modulated by Env conformation. By contrast, a P2X7 antagonist, A438079, had limited effect on productive infection and fusion. Inhibition with NF449 interfered with the ability of the V1V2 targeted broadly neutralizing antibody PG9 to block productive infection, suggesting that these drugs may antagonize HIV-1 Env at gp120 V1V2 to block viral membrane fusion. Our observations indicate that P2X1 antagonism can inhibit HIV-1 replication at the level of viral membrane fusion through interaction with Env. Future studies will probe the nature of these compounds in inhibiting HIV-1 fusion and in development of a different class of small molecules to block HIV-1 entry.\n\nIMPORTANCEWhile effective treatment can lower the severe morbidity and mortality associated with HIV-1 infection, patients infected with HIV-1 suffer from significantly higher rates of non-communicable comorbidities associated with chronic inflammation. Emerging literature suggests a key role for P2X1 receptors in mediating this chronic inflammation but the mechanism is still unknown. Here, we demonstrate that HIV-1 infection is reduced by P2X1 receptor antagonism. This inhibition is mediated by interference with HIV-1 Env and can impact a variety of viral clades. These observations highlight the importance of P2X1 antagonists as potential novel therapeutics that could serve to block a variety of different viral clades with additional benefits for their anti-inflammatory properties.

microbiology↗