Regulatory T-cells are central hubs for age-, sex- and severity-associated cellular networks during COVID-19

Using single-cell proteomics by mass cytometry, we investigate changes to a broad selection of over 10,000,000 immune cells in a cohort of moderate, severe, and critical Japanese COVID-19 patients and healthy controls with a particular focus on regulatory T-cells (Tregs). We find significant disruption within all compartments of the immune system and the emergence of atypical CTLA-4high CD4 T-cells and proliferating HLA-DRlowCD38high Tregs associated with critical patients. We also observed disrupted regulation of humoral immunity in COVID-19, with a loss of circulating T follicular regulatory T cells (Tfr) and altered T follicular helper (Tfh)/Tfr and plasma cell/Tfr ratios, all of which are significantly lower in male patients. Shifting ratios of CXCR4 and CXCR5 expression in B-cells provides further evidence of an autoimmune phenotype and dysregulated humoral immunity. These results suggest that Tregs are central to the changing cellular networks of a wide range of cells in COVID-19 and that sex specific differences to the balance of Tfr, Tfh and plasma cells may have important implications for the specificity of the humoral immune response to SARS-CoV-2.

Failure of Fecal Microbiota Transplantation in a Three-Year-Old Child with Severe Refractory Ulcerative Colitis / 대한소아소화기영양학회지

Fecal microbiota transplantation (FMT) is a treatment designed to correct gut dysbiosis by administration of feces from a healthy volunteer. It is still unclear whether FMT for children with ulcerative colitis (UC) is effective or hazardous. Here we describe a young patient to have received FMT for UC. A three-year-old girl was admitted to our hospital with severe active UC, and treated with aminosalicylates and various immunosuppressive drugs. As remission was not achieved, we decided to try FMT before colectomy. We administered donor fecal material a total of six times by retention enema (×2) and via a nasoduodenal tube (×4) within 10 days. The patient developed abdominal pain and pyrexia after each FMT session. Analyses revealed the transferred donor fecal microbiota had not been retained by the patient, who ultimately underwent colectomy. The severity of the UC and/or timing of FMT may have partly accounted for the poor outcome.