Biology subjects

Nerurkar, V. R.

Publications and source records attributed to Nerurkar, V. R..

6 recordsLinked to original sources

bioRxiv2023

SARS-CoV-2 infection leads to sustained testicular injury and functional impairments in K18 hACE2 mice

Compromised male reproductive health is one of the symptoms of long COVID with a decrease in male fertility markers including testosterone levels and sperm count for months in recovering patients. However, the long-term impact of SARS-CoV-2 infection on testicular injury and underlying mechanisms remains unknown. We previously demonstrated a disrupted tissue architecture with no evidence of virus replication in the testis during the acute stage of the disease in K18-hACE2 mice. Here, we systematically delineate the consequences of SARS-CoV-2 infection on the testis injury and function both during the acute stage of the disease and up to 4 weeks after infection in survivor K18-hACE2 mice. The gross morphological defects included sloughing of healthy spermatids and spermatocytes into the lumen, lack of lumen, and increase in apoptotic cells that sustained for at least 2 weeks after infection. Testis injury correlated with systemic and testicular inflammation, and infiltration of immune cells in the interstitial space and seminiferous tubules. Transcriptomic analysis identified dysregulation of key pathways of testicular immune homeostasis, spermatogenesis, and cell death at the symptomatic and short-term recovery stages. Further, a significant reduction in testosterone levels was associated with transient reduction in sperm count and mouse fertility. Most of the testicular impairments except testosterone levels were resolved within 4 weeks, which is almost one spermatogenesis cycle in mice. These findings provide much-needed mechanistic insights beyond our current understanding of testicular pathogenesis, suggesting that recovering COVID-19 patients should be closely monitored to rescue the pathophysiological effects on male reproductive health.

microbiology↗

bioRxiv2023

Single-cell RNA sequencing reveals characteristics of myeloid cells in pulmonary post-acute sequelae of SARS-CoV-2

BackgroundAlthough our understanding of the immunopathology and subsequent risk and severity of COVID-19 disease is evolving, a detailed account of immune responses that contribute to the long-term consequences of pulmonary complication in COVID-19 infection remain unclear. Few studies have detailed the immune and cytokine profiles associated with post-acute sequalae of SARS-CoV-2 infection with persistent pulmonary symptoms (PPASC). However, the dysregulation of the immune system that drives pulmonary sequelae in COVID-19 survivors and PASC sufferers remains largely unknown. ResultsTo characterize the immunological features of pulmonary PASC (PPASC), we performed droplet-based single-cell RNA sequencing to study the transcriptomic profiles of peripheral blood mononuclear cells (PBMCs) from participants naive to SARS-CoV-2 (Control) and infected with SARS-CoV-2 with chronic pulmonary symptoms (PPASC). We analyzed more than 34,139 PBMCs by integrating our dataset with previously reported control datasets (GSM4509024) cell distribution. In total, 11 distinct cell populations were identified based on the expression of canonical markers. The proportion of myeloid-lineage cells ([MLCs]; CD14+/CD16+monocytes and dendritic cells) was increased in PPASC compared to controls. MLCs from PPASC displayed up-regulation of genes associated with pulmonary symptoms/fibrosis, while glycolysis metabolism-related genes were downregulated. Similarly, pathway analysis showed that fibrosis- related (VEGF, WNT, and SMAD) and cell death pathways were up-regulated, but immune pathways were down-regulated in PPASC. In PPASC, we observed interactive VEGF ligand- receptor pairs among MLCs, and network modules in CD14+ (cluster 4) and CD16+ (Cluster 5) monocytes displayed a significant enrichment for biological pathways linked to adverse COVID- 19 outcomes, fibrosis, and angiogenesis. Further analysis revealed a distinct metabolic alteration in MLCs with a down-regulation of glycolysis/gluconeogenesis in PPASC compared to SARS- CoV-2 naive samples. ConclusionThis study offers valuable insights into the immune response and cellular landscape in PPASC. The presence of elevated MLC levels and their corresponding gene signatures associated with fibrosis, immune response suppression, and altered metabolic states suggests their potential role as a driver of PPASC.

microbiology↗

bioRxiv2022

Phenotypic alteration of low-density granulocytes in people with pulmonary post-acute sequalae of SARS-CoV-2 infection

Low-density granulocytes (LDGs) are a distinct subset of neutrophils whose increased abundance is associated with the severity of COVID-19. However, the long-term effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on LDG levels and phenotypic alteration remain unexplored. Using participants naive to SARS-CoV-2 (NP), infected with SARS-CoV-2 with no residual symptoms (NRS), and infected with SARS-CoV-2 with chronic pulmonary symptoms (PPASC), we compared LDG levels and their phenotype by measuring the expression of markers for activation, maturation, and neutrophil extracellular trap (NET) formation using flow cytometry. The number of LDGs was significantly elevated in PPASC compared to NP. Individuals infected with SARS-CoV-2 (NRS and PPASC) demonstrated increased CD10+ and CD16HI subset counts of LDGs compared to NP group. Further characterization of LDGs demonstrated that LDGs from PPASC displayed higher NET forming ability and aggregation with platelets compared to LDGs from NP and NRS. Our data demonstrates that mature neutrophils with a heightened activation phenotype remain in circulation long after initial SARS-CoV-2 infection. Persistent elevation of markers for neutrophil activation and NET formation on LDGs, as well as an enhanced proclivity for platelet-neutrophil aggregation (PNA) formation in individuals with PPASC may be associated with the development of long-term pulmonary sequelae.

immunology↗

bioRxiv2022

In vitro evidence against productive SARS-CoV-2 infection of human testicular cells: Bystander effects of infection mediate testicular injury.

The hallmark of severe COVID-19 involves systemic cytokine storm and multi-organ failure including testicular injury and germ cell depletion. The ACE2 receptor is also expressed in the resident testicular cells however, SARS-CoV-2 infection and mechanisms of testicular injury are not fully understood. The testicular injury can likely result either from direct virus infection of resident cells or by exposure to systemic inflammatory mediators or virus antigens. We here characterized SARS-CoV-2 infection in different human testicular 2D and 3D models including primary Sertoli cells, Leydig cells, mixed seminiferous tubule cells (STC), and 3D human testicular organoids (HTO). Data shows that SARS-CoV-2 does not establish a productive infection in any testicular cell types. However, exposure of STC and HTO to inflammatory supernatant from infected airway epithelial cells and COVID-19 plasma depicted a significant decrease in cell viability and death of undifferentiated spermatogonia. Further, exposure to only SARS-CoV-2 envelope protein, but not Spike or nucleocapsid proteins led to cytopathic effects on testicular cells that was dependent on the TLR2 receptor. A similar trend was observed in the K18h-ACE2 mouse model which revealed gross pathology in the absence of virus replication in the testis. Collectively, data strongly indicates that the testicular injury is not due to direct infection of SARS-CoV-2 but more likely an indirect effect of exposure to systemic inflammation or SARS-CoV-2 antigens. Data also provide novel insights into the mechanism of testicular injury and could explain the clinical manifestation of testicular symptoms associated with severe COVID-19.

microbiology↗

bioRxiv2021

Algorithm for the Quantitation of Variants of Concern for Rationally Designed Vaccines Based on the Isolation of SARS-CoV-2 Hawaii Lineage B.1.243

SARS-CoV-2 worldwide emergence and evolution has resulted in variants containing mutations resulting in immune evasive epitopes that decrease vaccine efficacy. We acquired clinical samples, analyzed SARS-CoV-2 genomes, used the most worldwide emerged spike mutations from Variants of Concern/Interest, and developed an algorithm for monitoring the SARS-CoV-2 vaccine platform. The algorithm partitions logarithmic-transformed prevalence data monthly and Pearsons correlation determines exponential emergence. The SARS-CoV-2 genome evaluation indicated 49 mutations. Nine of the ten most worldwide prevalent (>70%) spike protein changes have r-values >0.9. The tenth, D614G, has a prevalence >99% and r-value of 0.67. The resulting algorithm is based on the patterns these ten substitutions elucidated. The strong positive correlation of the emerged spike protein changes and algorithmic predictive value can be harnessed in designing vaccines with relevant immunogenic epitopes. SARS-CoV-2 is predicted to remain endemic and continues to evolve, so must SARS-CoV-2 monitoring and next-generation vaccine design.

molecular biology↗

bioRxiv2021

Genetic Characteristics and Phylogeny of 969-bp S Gene Sequence of SARS-CoV-2 from Hawaii Reveals the Worldwide Emerging P681H Mutation

COVID-19 pandemic has ravaged the world, caused over 1.8 million deaths in the first year, and severely affected the global economy. Hawaii is not spared from the transmission of SARS-CoV-2 in the local population, including high infection rates in racial and ethnic minorities. Early in the pandemic, we described in this journal various technologies used for the detection of SARS-CoV-2. Herein we characterize a 969-bp SARS-CoV-2 segment of the S gene downstream of the receptor-binding domain. At the John A. Burns School of Medicine Biocontainment Facility, RNA was extracted from an oropharyngeal swab and a nasal swab from two patients from Hawaii who were infected with the SARS-CoV-2 in August 2020. Following PCR, the two viral strains were sequenced using Sanger sequencing, and phylogenetic trees were generated using MEGAX. Phylogenetic tree results indicate that the virus has been introduced to Hawaii from multiple sources. Further, we decoded 13 single nucleotide polymorphisms across 13 unique SARS-CoV-2 genomes within this region of the S gene, with one non-synonymous mutation (P681H) found in the two Hawaii strains. The P681H mutation has unique and emerging characteristics with a significant exponential increase in worldwide frequency when compared to the plateauing of the now universal D614G mutation. The P681H mutation is also characteristic of the new SARS-CoV-2 variants from the United Kingdom and Nigeria. Additionally, several mutations resulting in cysteine residues were detected, potentially resulting in disruption of the disulfide bridges in and around the receptor-binding domain. Targeted sequence characterization is warranted to determine the origin of multiple introductions of SARS-CoV-2 circulating in Hawaii.

evolutionary biology↗