Various substances in the blood plasma serve as prognostic indicators of the progression of COVID-19. Consequently, multi-omics studies, such as proteomic and metabolomics, are ongoing to identify accurate biomarkers. Cytokines and chemokines, which are crucial components of immune and inflammatory responses, play pivotal roles in the transition from mild to severe illness. To determine the relationship between plasma cytokines and the progression of COVID-19, we used four study cohorts to perform a systematic study of cytokine levels in patients with different disease stages. We observed differential cytokine expression between patients with persistent-mild disease and patients with mild-to-severe transformation. For instance, IL-4 and IL-17 levels significantly increased in patients with mild-to-severe transformation, indicating differences within the mild disease group. Subsequently, we analysed the changes in cytokine and chemokine expression in the plasma of patients undergoing two opposing processes: the transition from mild to severe illness and the transition from severe to mild illness. We identified several factors, such as reduced expression of IL-16 and IL-18 during the severe phase of the disease and up-regulated expression of IL-10, IP-10, and SCGF-β during the same period, indicative of the deterioration or improvement of patients’ conditions. These factors obtained from fine-tuned research cohorts could provide auxiliary indications for changes in the condition of COVID-19 patients.

The coronavirus disease 19 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become the worst public health crisis in a century. However, knowledge about the dynamics of antibody responses in patients with COVID-19 is still poorly understood. In this study, we performed a serological study with serum specimens collected at the acute and the convalescent phases from 104 patients with severe COVID-19 who were part of the first wave of COVID-19 cases in Wuhan, China. Our findings revealed that neutralizing antibodies to SARS-CoV-2 are persistent for at least 6 months in patients with severe COVID-19, despite that IgG levels against the receptor binding domain (RBD) and nucleocapsid protein (N) IgG declined from the acute to the convalescent phase. Moreover, we demonstrate that the level of RBD-IgG is capable of correlating with SARS-CoV-2–neutralizing activities in COVID-19 serum. In summary, our findings identify the magnitude, functionality, and longevity of antibody responses in patients with COVID-19, which sheds light on the humoral immune response to COVID-19 and would be beneficial for developing vaccines.

Sepsis-induced acute kidney injury (SI-AKI) is the most common organ dysfunction of sepsis, characterized with prolonged hospitalization periods and significantly elevated mortality rates. Piplartine (PLG), an alkaloid extracted from Piper longum within the Piperaceae family, has exhibited diverse pharmacological activities, including anti-inflammatory, anti-atherosclerotic, and anti-tumor effects. Herein, we investigated whether the PLG could reverse SI-AKI and explore its possible anti-inflammatory mechanisms. We constructed an SI-AKI model using cecal ligation and puncture (CLP) and systematically evaluated the protective effect of PLG administered by gavage in the SI-AKI mice. Subsequently, we performed proteomic sequencing of the kidney and integrated data from the GeneCards and SwissTargetPrediction databases to identify potential targets and mechanisms. Immunofluorescence and western blotting were used to examine the expression of relevant targets and pathways in vivo and in vitro. The influence of PLG on the predicted target and pathway was verified using an agonist of the target protein and a series of biochemical experiments. PLG exhibited significant efficacy against pathological damage, neutrophil and macrophage infiltration, and macrophage pyroptosis in kidneys at 30 mg/kg. An integrated analysis of proteomic data identified the translocator protein (TSPO) as a potential target for the renoprotective effects of PLG. Moreover, a TSPO agonist (RO5-4864) prominently reversed the protective effect of PLG in SI-AKI mice, as manifested by a deterioration in renal function, histopathological lesions and macrophage pyroptosis in the kidneys. Our results suggest that PLG may ameliorate SI-AKI, potentially through partial inhibition of the TSPO-macrophage pyroptosis pathway.

Summary: Background: Lymphopenia is a typical symptom in the COVID-19 patients. While millions of patients are clinical recovered, little is known about the immune status of lymphocytes in these individuals. Methods: A clinical recovered cohort (CR) of 55 COVID-19 individuals (discharged from hospital 4 to 11 weeks), and 55 age and sex matched healthy donors cohort (HD) were recruited. Detailed analysis on phenotype of the lymphocytes in peripheral blood mononuclear cells (PBMCs) was performed by flow cytometry. Findings: Compared with cohort HD, the CD8 ⁺ T cells in cohort CR had higher Teff and Tem, but lower Tc1 (IFN-γ ⁺ ), Tc2 (IL-4 ⁺ ) and Tc17 (IL-17A ⁺ ) frequencies. The CD4 ⁺ T cells of CR had decreased frequency, especially on the Tcm subset. Moreover, CD4 ⁺ T cells of CR expressed lower PD-1 and had lower frequencies of Th1 (IFN-γ ⁺ ), Th2 (IL-4 ⁺ ), Th17 (IL-17A ⁺ ) as well as circulating Tfh (CXCR5 ⁺ PD-1 ⁺ ). Accordingly, isotype-switched memory B cell (IgM ^- CD20 ^hi ) in CR had significantly lower proportion in B cells, though level of activation marker CD71 elevated. For CD3 ^- HLA-DR ^lo lymphocytes of CR, besides levels of IFN-γ, Granzyme B and T-bet were lower, the correlation between T-bet and IFN-γ became irrelevant. In addition, taken into account of discharged days, all the lowered function associated phenotypes showed no recovery tendency within whole observation period. Interpretation: The CR COVID-19 individuals still showed remarkable phenotypic alterations in lymphocytes after clinical recovery 4 to 11 weeks. This suggests SARS-CoV-2 infection imprints profoundly on lymphocytes and results in long-lasting potential dysfunctions. Funding: Kunming Science and Technology Department (2020-1-N-037)

Protein phosphorylation is one of the most common and important post-translational modifications and is involved in many biological processes, including DNA damage repair, transcriptional regulation, signal transduction, and apoptosis regulation. The use of antibodies targeting phosphorylated protein is a convenient method to detect protein phosphorylation. Therefore, high-quality antibodies are essential, and uniform and effective standards are urgently needed to evaluate the quality of these phosphorylation-specific antibodies. In this study, we established a simple, broad-spectrum system for the preparation of phosphorylation-positive samples. The positive samples for evaluation of phosphorylation-specific antibodies were then validated in cells from different species and tissues, and also been proven effectively in western blot, enzyme-linked immunosorbent assays, LC-MS/MS and immunofluorescence analysis. Overall, our findings established a novel approach for evaluation of the quality of phosphorylation-specific antibodies and may have applications in various biomedical fields.