Human intestinal tissue-resident memory T cells comprise transcriptionally and functionally distinct subsets

Tissue-resident memory T (T_RM) cells provide key adaptive immune responses in infection, cancer, and autoimmunity. However, transcriptional heterogeneity of human intestinal T_RM cells remains undefined. Here, we investigate transcriptional and functional heterogeneity of human T_RM cells through study of donor-derived T_RM cells from intestinal transplant recipients. Single-cell transcriptional profiling identifies two transcriptional states of CD8+ T_RM cells, delineated by ITGAE and ITGB2 expression. We define a transcriptional signature discriminating these populations, including differential expression of cytotoxicity- and residency-associated genes. Flow cytometry of recipient-derived cells infiltrating the graft, and lymphocytes from healthy gut, confirm these CD8+ T_RM phenotypes. CD8+ CD69+CD103+ T_RM cells produce interleukin-2 (IL-2) and demonstrate greater polyfunctional cytokine production, whereas β2-integrin+CD69+CD103− T_RM cells have higher granzyme expression. Analysis of intestinal CD4+ T cells identifies several parallels, including a β2-integrin+ population. Together, these results describe the transcriptional, phenotypic, and functional heterogeneity of human intestinal CD4+ and CD8+ T_RM cells

The effects of hyperoxic and hypercarbic gases on tumour blood flow

Carbogen (95% O2 and 5% CO2) has been used in preference to 100% oxygen (O2) as a radiosensitizer, because it is believed that CO2 blocks O2-induced vasoconstriction. However, recent work suggests that both normal and tumour arterioles of dorsal flap window chambers exhibit the opposite: no vasoconstriction vs constriction for O2 vs carbogen breathing respectively. We hypothesized that CO2 content might cause vasoconstriction and investigated the effects of three O2–CO2 breathing mixtures on tumour arteriolar diameter (TAD) and blood flow (TBF). Fischer 344 rats with R3230Ac tumours transplanted into window chambers breathed either 1%, 5%, or 10% CO2 + O2. Intravital microscopy and laser Doppler flowmetry were used to measure TAD and TBF respectively. Animals breathing 1% CO2 had increased mean arterial pressure (MAP), no change in heart rate (HR), transient reduction in TAD and no change in TBF. Rats breathing 5% CO2 (carbogen) had transiently increased MAP, decreased HR, reduced TAD and a sustained 25% TBF decrease. Animals exposed to 10% CO2 experienced a transient decrease in MAP, no HR change, reduced TAD and a 30–40% transient TBF decrease. The effects on MAP, HR, TAD and TBF were not CO2 dose-dependent, suggesting that complex physiologic mechanisms are involved. Nevertheless, when ≥ 5% CO2 was breathed, there was clear vasoconstriction and TBF reduction in this model. This suggests that the effects of hypercarbic gases on TBF are site-dependent and that use of carbogen as a radiosensitizer may be counterproductive in certain situations

Complications of Pediatric Renal Transplantation

The major advance allowing prolonged graft survival has been the use of immunosuppressive drugs that downregulate the immune response. The immunosuppression that is used varies among centers and evolves with the development of new medications