The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in the human host can lead to various clinical manifestations, from symptomless carriers to mild to moderate to severe/critical illness. Therefore, the clinical classification of SARS-CoV-2 disease, based on severity, is a reliable way to predict disease states in SARS-CoV-2 infection. Recent studies on genomics, transcriptomics, epigenomics, and immunogenomics, along with spatial analysis of immune cells have delineated and defined the categorization of these disease groups using these high throughout technologies. These technologies hold the promise of providing not only a detailed but a holistic view of SARS-CoV-2-led pathogenesis. The main genomic, cellular, and immunologic features of each disease category, and what separates them spatially and molecularly are discussed in this brief review to provide a foundational spatial understanding of SARS-CoV-2 immunopathogenesis.

Immune responses are orchestrated by controlling the initiation, magnitude, and duration of various signaling pathways. Adaptor proteins act as positive or negative regulators by targeting critical molecules of signaling cascades. Signal-transducing adaptor protein-2 (STAP-2) contains typical features of adaptor proteins, like a pleckstrin homology (PH) domain in the N-terminal region and a Src homology 2 (SH2) domain in the central region. STAP-2 binds to a variety of signaling or transcriptional molecules to control multiple steps of inflammatory/immune responses. STAP-2 enhances T-cell receptor (TCR)-mediated signaling via the association with TCR-proximal CD3ζ immunoreceptor tyrosine-based activation motifs (ITAMs) and lymphocyte-specific protein tyrosine kinase (Lck). STAP-2 decreases adherence of T-cells to fibronectin (FN) through an association with focal adhesion kinase (Fak) and Casitas B-lineage Lymphoma (c-Cbl), and increases chemotaxis of T-cells toward stromal cell-derived factor-1α (SDF-1α) through interactions with Vav1 and Ras-related C3 botulinum toxin substrate 1 (Rac1). STAP-2 positively regulates activation-induced cell deathrough the association with Fas and caspase-8. This review describes the current knowledge of the roles of STAP-2 in T-cell-dependent immune responses and the possible clinical utility of STAP-2-targeting therapies.

Psoriasis is a skin disease characterized by scaly erythema, parakeratosis, and epidermal hyperplasia. Application of imiquimod (IMQ), a ligand for Toll-like receptor 7, produces a mouse model for psoriasis. IMQ application induces scaling, erythema, and thickness in skin lesions, and the symptoms are milder in interleukin-23 p19 (Il23p19)-deficient and Il17a-deficient mice than in wild-type mice; this suggests that the interleukin-23 (IL-23)/T helper 17 (Th17) axis and Th17 cell-secreting cytokines play essential roles in the IMQ-induced psoriasis model. It is notable that a genome-wide association study identified the human tyrosine kinase 2 (TYK2) gene within the psoriasis susceptibility locus. After IMQ application, mice lacking Tyk2, a mouse homologue of the human TYK2 gene, exhibited significantly lower symptom scores of psoriasis and diminished inflammatory cell infiltration in the skin lesions. Tyk2-deficient mice also failed to increase CD4⁺IL-17⁺ or CD4⁺ interferon-γ⁺ (IFN-γ⁺) T cells in the draining lymph nodes or to produce Th17 cell-related cytokines after IMQ application. Furthermore, Tyk2 deficiency led to diminished skin inflammation induced by IL-23 and IL-22 injections. These results indicate that Tyk2-mediated signals in mice contribute to multiple steps of immune and inflammatory responses during the development of psoriasis; therefore, TYK2 targeting may be a promising strategy to treat patients with psoriasis. Recent clinical trials have shown that TYK2 inhibitors have a high overall response rate with good tolerability in the management of psoriasis. This review describes the fundamental mechanisms of Tyk2 inhibition in immune/inflammatory diseases.