494 IgG-mediated mast cell dysregulation drives chronic pain in post-acute sequelae of SARS-CoV-2 (PASC)

Objectives/Goals: PASC affects 6%#_msocom_1 of individuals recovering from SARS-CoV-2 infection. The primary objective of this study was to explore the underlying neuroimmune changes which are responsible for the chronic widespread pain and fatigue that these patients often experience. #_msoanchor_1 Methods/Study Population: We recruited eight post-acute sequelae of SARS-CoV-2 (PASC) patients from the PASC and physical medicine and rehabilitation clinics. Patients were included if they had daily, chronic pain, rated at least 5/10 intensity on the numeric rating scale. Patients were excluded if they had pre-existing pain or autoimmune conditions. Healthy age-matched controls were also recruited. We obtained blood samples from both groups of patients and purified IgG from the plasma. The IgG was reconstituted and transferred to 48 mice via intraperitoneal injection. After IgG transfer, we completed behavioral, flow cytometry, immunofluorescence, and degranulation assays to quantify the effects of the IgG on the animal’s behavior and mast cell activity. Results/Anticipated Results: IgG from PASC patients selectively binds mast cells and induces greater mast cell activation and degranulation than IgG from healthy control patients (p<0.001). This increase in mast cell activation is dependent on mas-related G-protein coupled receptor member X2 signaling. Transferring IgG from PASC patients to mice produces increased sensitivity to cold (p<0.001) in the animals and also decreases their locomotor activity (p<0.01). IgG from healthy patients did not induce any changes cold sensitivity in the animals, nor did it affect their locomotor activity (p<0.001). Lastly, transferring IgG from PASC patients to mice increases the mast cell population in the animals’ hindpaws (p<0.05). #_msocom_2 Discussion/Significance of Impact: This work elucidates a pathophysiological mechanism involved in the development of PASC-associated chronic pain. It also provides insights that may be useful in understanding the pain that is often associated with other autoimmune conditions.