Diagnostic Value of Natural Killer Cells, CD56+ CD16+ Natural Killer Cells, NLRP3, and Lactate Dehydrogenase in Severe/Critical COVID-19: A Prospective Longitudinal Study According to the Severe/Critical COVID-19 Definitions

Innate immunity, as the first line of defense of our immune system, plays a crucial role in defending against SARS-CoV-2 infection and also its immunopathogenesis. We aim to investigate the immune status of natural killer (NK) cells, natural killer T (NKT) cells, and NLRP3 gene expression in COVID-19 patient blood samples. The immunophenotype of NK cell subsets and NKT cells was detected by flow cytometry and the expression of NLRP3 gene assessed by reverse transcriptase real-time polymerase chain reaction in 44 COVID-19 patients and 20 healthy individuals. The percentage of most of NK cell subpopulation and NKT cells was significantly decreased in COVID-19 patients. The percentage of CD56dim CD16- NK cell subsets, and NLRP3 gene expression increased. The percentage of total NK cells, CD56+ CD16+ NK cells, and NLRP3 gene expression had acceptable sensitivity and specificity for assisting diagnosis of severe/critical COVID-19. O₂ saturation% and lactate dehydrogenase levels showed valuable diagnostic value to identify critical cases. The declined NK and NKT cells in COVID-19 patients and enhanced NLRP3 gene expression were associated with disease severity. Total NK cells, CD56+ CD16+ NK cells, and NLRP3 gene expression might be used as meaningful indicators for assisting diagnosis of severe/critical COVID-19.

COVID-19 and the potential of Janus family kinase (JAK) pathway inhibition: A novel treatment strategy

Recent evidence proposed that the severity of the coronavirus disease 2019 (COVID-19) in patients is a consequence of cytokine storm, characterized by increased IL-1β, IL-6, IL-18, TNF-α, and IFN-γ. Hence, managing the cytokine storm by drugs has been suggested for the treatment of patients with severe COVID-19. Several of the proinflammatory cytokines involved in the pathogenesis of COVID-19 infection recruit a distinct intracellular signaling pathway mediated by JAKs. Consequently, JAK inhibitors, including baricitinib, pacritinib, ruxolitinib, and tofacitinib, may represent an effective therapeutic strategy for controlling the JAK to treat COVID-19. This study indicates the mechanism of cytokine storm and JAK/STAT pathway in COVID-19 as well as the medications used for JAK/STAT inhibitors.

The Role of Distinct Subsets of Macrophages in the Pathogenesis of MS and the Impact of Different Therapeutic Agents on These Populations

Multiple sclerosis (MS) is a demyelinating inflammatory disorder of the central nervous system (CNS). Besides the vital role of T cells, other immune cells, including B cells, innate immune cells, and macrophages (MФs), also play a critical role in MS pathogenesis. Tissue-resident MФs in the brain’s parenchyma, known as microglia and monocyte-derived MФs, enter into the CNS following alterations in CNS homeostasis that induce inflammatory responses in MS. Although the neuroprotective and anti-inflammatory actions of monocyte-derived MФs and resident MФs are required to maintain CNS tolerance, they can release inflammatory cytokines and reactivate primed T cells during neuroinflammation. In the CNS of MS patients, elevated myeloid cells and activated MФs have been found and associated with demyelination and axonal loss. Thus, according to the role of MФs in neuroinflammation, they have attracted attention as a therapeutic target. Also, due to their different origin, location, and turnover, other strategies may require to target the various myeloid cell populations. Here we review the role of distinct subsets of MФs in the pathogenesis of MS and different therapeutic agents that target these cells.

Immunological and Clinical Aspects of Immune Responses to SARS-CoV-2

The Coronavirus Disease 2019 (COVID-19) caused by a coronavirus named SARS-CoV-2 from the family Coronaviridae, was first reported in December 2019 in China. The disease have mild or severe symptoms such as fever, chills, cough, shortness of breath, body aches, and gastrointestinal symptoms, followed by severe inflammation, cytokine storm, acute respiratory distress syndrome, and dysfunction of other organs. In this narrative review study, the search was conducted on related studies published during January- October 2020 in Google Scholar, PubMed, Embase, and Scopus databases using the keywords Covid-19, Immunology, and Immunopathogenesis. Among abundant and mostly repetitive information, the immunological aspects were selected. The SARS-CoV-2 can enter the cell by binding to the Angiotensin-Converting Enzyme 2 (ACE2) receptor and Trans-Membrane Protease Serine 2 (TMPRSS2) on the surface of lung epithelial cells. The main pathogenic mechanism of infection with SARS-CoV-2 is the stimulation of inflammatory response followed by damage to the alveoli of lung tissue. In uncontrolled immune responses, the infiltration of macrophages, monocytes, neutrophils, and inflammatory T cells into the alveoli increases which leads to tissue damage in the lungs and other organs by overproduction of inflammatory cytokines such as Interleukin 6 (IL-6), Tumor Necrosis Factor alpha (TNF-α), Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF), Interleukin 6 (IL-8), Interferon gamma (IFNγ), etc. The Natural Killer (NK) and T cell dysfunction, lymphopenia, and infection of immune cells such as monocytes with ADE mechanism are factors causing the body’s failure in resistance to SARS-CoV-2 virus. Diagnosis of COVID-19 is based on the clinical symptoms and the results of molecular tests (e.g. Polymerase Chain Reaction test), or computerized tomography scan followed by serological tests and measuring biochemical factors in the blood (e.g. lymphocyte count, C-reactive protein, dimerized plasmin fragment D, etc.). Due to the association of the severity of COVID-19 with the uncontrolled immune response of the host, targeting any of the immunopathological pathways to inhibit inflammatory responses can be considered as potential therapeutic goals. The use of immune system regulators such as chloroquine, corticosteroids, inflammatory cytokine blockers such as anti-IL-6, anti-IL-1, and cell therapy at the right time have an enhanced effect on the recovery of the disease or inhibit the disease progression.