Mesenchymal stem cell derived exosomes mitigate COVID-19 cytokine storm via Annexin A1 and TGF-β mediated MAPK pathway inhibition

Abstract

Background Severe COVID-19 is marked by a dysregulated inflammatory response, known as a cytokine storm, resulting in acute respiratory distress syndrome (ARDS) and multiple organ failure. Mesenchymal stem cell-derived exosomes (MSC-Exos) have demonstrated potential as immunomodulatory agents. This work investigates the possibility of MSC-Exos to mitigate excessive inflammation in COVID-19 by targeting the mitogen-activated protein kinase (MAPK) signalling pathway. Methodology We integrated molecular docking analysis between TGF-β and Annexin A1 as exosomal proteins and key component proteins of the MAPK pathway (p38, ERK1/2, JNK1). The in-silico results were then validated in vivo using a Syrian hamster model of SARS-CoV-2 infection. Quantitative PCR (qPCR), western blotting, and histological examination were employed to evaluate the effects of MSC-Exos therapy on MAPK pathway activation, cytokine production, and lung tissue pathology. Results The in-silico study revealed extensive hydrogen bonding and hydrophobic interactions at the protein–protein interfaces between exosomal proteins and MAPK components. These interactions suggest that exosomal proteins may modulate MAPK signaling pathways. In vivo, MSC-Exos administration led to marked downregulation of pivotal genes in the MAPK signaling pathway (MEKK1, MEKK2, MEKK3), diminished phosphorylation of JNK1, p38, and ERK1/2, and lowered production of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α). Histopathological examination demonstrated ameliorated lung tissue structure, characterized by diminished alveolar wall thickness and decreased immune cell infiltration.

1. Introduction

The COVID-19 pandemic, induced by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has created an extraordinary worldwide health emergency [1]. Although vaccination initiatives have demonstrated substantial efficacy in mitigating severe illness, the rapid emergence of viral variants capable of evading neutralizing antibodies underscores the need for alternative and adjunctive therapeutic strategies [2]. Severe COVID-19 is now recognized as the consequence of a multifactorial pathogenic process in which an exaggerated inflammatory response (cytokine storm) represents one prominent component alongside endothelial dysfunction, coagulopathy, and metabolic dysregulation, collectively contributing to acute respiratory distress syndrome (ARDS), multiorgan injury, and death [3].

One of the central signaling networks governing host responses to viral infection is the mitogen-activated protein kinase (MAPK) pathway, which encompasses the ERK1/2, p38, and JNK branches [4]. This pathway integrates multiple extracellular stress and immune signals and plays a pivotal role in regulating cytokine production, apoptosis, and immune cell activation [4, 5]. In the context of SARS-CoV-2 infection, aberrant activation of MAPK signaling, particularly through the p38 MAPK, ERK1/2, and JNK branches [6, 7]. However, accumulating evidence indicates that MAPK signaling is not unidirectionally pro-inflammatory; rather, its functional output is highly context, cell type, and time-dependent. In myeloid and other innate immune cells, ERK1/2 activation downstream of pattern‑recognition and cytokine receptors clearly promotes the production of classical pro‑inflammatory mediators, including TNF, IL‑1β, IL‑6 and IL‑12, and is frequently upregulated in chronically inflamed tissues [8]. At the same time, the ERK1/2 module can support anti-inflammatory or pro-resolving programs, for example by enhancing IL-10 expression, restraining excessive IL-12 production, and modulating T-cell differentiation in a way that limits sustained Th1-skewed responses. In non‑immune compartments, ERK1/2 signaling has likewise been implicated in cytoprotection and limitation of tissue damage, as shown in experimental models of acute myocardial injury and other inflammatory settings.