Biology subjects

Levit, R. D.

Publications and source records attributed to Levit, R. D..

3 recordsLinked to original sources

bioRxiv2021

TREM2+ and interstitial macrophages orchestrate airway inflammation in SARS-CoV-2 infection in rhesus macaques

The COVID-19 pandemic remains a global health crisis, yet, the immunopathological mechanisms driving the development of severe disease remain poorly defined. Here, we utilize a rhesus macaque (RM) model of SARS-CoV-2 infection to delineate perturbations in the innate immune system during acute infection using an integrated systems analysis. We found that SARS-CoV-2 initiated a rapid infiltration (two days post infection) of plasmacytoid dendritic cells into the lower airway, commensurate with IFNA production, natural killer cell activation, and induction of interferon-stimulated genes. At this early interval, we also observed a significant increase of blood CD14-CD16+ monocytes. To dissect the contribution of lung myeloid subsets to airway inflammation, we generated a novel compendium of RM-specific lung macrophage gene expression using a combination of sc-RNA-Seq data and bulk RNA-Seq of purified populations under steady state conditions. Using these tools, we generated a longitudinal sc-RNA-seq dataset of airway cells in SARS-CoV-2-infected RMs. We identified that SARS-CoV-2 infection elicited a rapid recruitment of two subsets of macrophages into the airway: a C206+MRC1-population resembling murine interstitial macrophages, and a TREM2+ population consistent with CCR2+ infiltrating monocytes, into the alveolar space. These subsets were the predominant source of inflammatory cytokines, accounting for ~75% of IL6 and TNF production, and >90% of IL10 production, whereas the contribution of CD206+MRC+ alveolar macrophages was significantly lower. Treatment of SARS-CoV-2 infected RMs with baricitinib (Olumiant(R)), a novel JAK1/2 inhibitor that recently received Emergency Use Authorization for the treatment of hospitalized COVID-19 patients, was remarkably effective in eliminating the influx of infiltrating, non-alveolar macrophages in the alveolar space, with a concomitant reduction of inflammatory cytokines. This study has delineated the major subsets of lung macrophages driving inflammatory and anti-inflammatory cytokine production within the alveolar space during SARS-CoV-2 infection. One sentence summaryMulti-omic analyses of hyperacute SARS-CoV-2 infection in rhesus macaques identified two population of infiltrating macrophages, as the primary orchestrators of inflammation in the lower airway that can be successfully treated with baricitinib

microbiology↗

bioRxiv2020

Baricitinib treatment resolves lower airway inflammation and neutrophil recruitment in SARS-CoV-2-infected rhesus macaques

Effective therapeutics aimed at mitigating COVID-19 symptoms are urgently needed. SARS-CoV-2 induced hypercytokinemia and systemic inflammation are associated with disease severity. Baricitinib, a clinically approved JAK1/2 inhibitor with potent anti-inflammatory properties is currently being investigated in COVID-19 human clinical trials. Recent reports suggest that baricitinib may also have antiviral activity in limiting viral endocytosis. Here, we investigated the immunologic and virologic efficacy of baricitinib in a rhesus macaque model of SARS-CoV-2 infection. Viral shedding measured from nasal and throat swabs, bronchoalveolar lavages and tissues was not reduced with baricitinib. Type I IFN antiviral responses and SARS-CoV-2 specific T cell responses remained similar between the two groups. Importantly, however, animals treated with baricitinib showed reduced immune activation, decreased infiltration of neutrophils into the lung, reduced NETosis activity, and more limited lung pathology. Moreover, baricitinib treated animals had a rapid and remarkably potent suppression of alveolar macrophage derived production of cytokines and chemokines responsible for inflammation and neutrophil recruitment. These data support a beneficial role for, and elucidate the immunological mechanisms underlying, the use of baricitinib as a frontline treatment for severe inflammation induced by SARS-CoV-2 infection.

immunology↗

bioRxiv2020

Biomaterial encapsulation of human mesenchymal stromal cells modulates paracrine signaling response and enhances efficacy for treatment of established osteoarthritis

Mesenchymal stromal cells (MSCs) have shown promise as a treatment for osteoarthritis (OA); however, effective translation has been limited by numerous factors ranging from high variability and heterogeneity of hMSCs, to suboptimal delivery strategies, to poor understanding of critical quality and potency attributes. The objective of the current study was to assess the effects of biomaterial encapsulation in alginate microcapsules on human MSC (hMSC) secretion of immunomodulatory cytokines in an OA microenvironment and therapeutic efficacy in treating established OA. Lewis rats underwent Medial Meniscal Transection (MMT) surgery to induce OA. Three weeks post-surgery, after OA was established, rats received intra-articular injections of either encapsulated hMSCs or controls (saline, empty capsules, or non-encapsulated hMSCs). Six weeks post-surgery, microstructural changes in the knee joint were quantified using contrast enhanced microCT. Encapsulated hMSCs attenuated progression of OA including articular cartilage degeneration (swelling and cartilage loss) and subchondral bone remodeling (thickening and hardening). A multiplexed immunoassay panel (41 cytokines) was used to profile the in vitro secretome of encapsulated and non-encapsulated hMSCs in response to IL-1{square}, a key cytokine involved in OA. Non-encapsulated hMSCs showed an indiscriminate increase in all cytokines in response to IL-1{square} while encapsulated hMSCs showed a highly targeted secretory response with increased expression of some pro-inflammatory (IL-1{beta}, IL-6, IL-7, IL-8), anti-inflammatory (IL-1RA), and chemotactic (G-CSF, MDC, IP10) cytokines. These data show that biomaterial encapsulation using alginate microcapsules can modulate hMSC paracrine signaling in response to OA cytokines and enhance the therapeutic efficacy of the hMSCs in treating established OA.

bioengineering↗