T cells are an important part of the adaptive immune system and play critical roles in the elimination of various pathogens. T cells could differentiate into distinct cellular subsets under different extracellular signals and then play different roles in maintaining host homeostasis and defense. The mechanistic target of rapamycin (mTOR) is a conserved intracellular serine/threonine kinase which belongs to the phosphoinositide 3‐kinase‐ (PI3K‐) related kinase family. The mTOR signaling pathway is closely involved in a variety of cell biological processes, including cell growth and cell metabolism, by senses and integrates various environmental cues. Recent studies showed that mTOR including mTORC1 and mTORC2 is closely involved in the development of T cell subpopulations such as Th1, Th2, Th9, Th17, follicular helper T cells (Tfh), and Treg cells through distinctive pathways. We herein mainly focused on the recent progress in understanding the roles of mTOR in regulating the development and differentiation of CD4 ⁺ T cell subsets.

Cancer risks in recipients of renal transplants: a meta-analysis of cohort studies Cancer risks in recipients of renal transplants: a meta-analysis of cohort studies

Improved survival following organ transplantation has brought to the forefront some long-term complications, among which osteoporosis and associated fractures are the major ones that adversely affect the quality of life in recipients. The pathogenesis of osteoporosis in transplant recipients is complex and multifactorial which may be related to increased bone resorption, decreased bone formation, or both. Studies have shown that the preexisting underlying metabolic bone disorders and the use of immunosuppressive agents are the major risk factors for osteoporosis and fractures after organ transplantation. And rapid bone loss usually occurs in the first 6–12 months with a significant increase in fracture risk. This paper will provide an updated review on the possible pathogenesis of posttransplant osteoporosis and fractures, the natural history, and the current prevention and treatment strategies concerning different types of organ transplantation.

Since December 2019, the ongoing coronavirus disease 2019 (COVID-19) pandemic has significantly affected solid organ transplantation (SOT) worldwide and has become a threat to the lives of SOT recipients. Here, we have reviewed, condensed, and organized the available information on COVID-19 to provide recommendations to transplant healthcare workers. Our review of reported cases shows that the symptoms of SOT patients with COVID-19 are similar to those of the normal population, but their severity and outcomes are worse. Thus far, there is no evidence that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) directly causes permanent damage to kidney, liver, or heart allografts.

Neutrophils, which are traditionally regarded as a hallmark of inflammation, are also a member of the intratumoral immune cells. The roles of neutrophils in cancer development are diverse and undefined. So far, they are known to be involved in tumor initiation and tumor cell proliferation and metastasis. They show heterogeneity in both phenotypes and functions during early versus late stage of cancer development. Because they are also associated with the clinical outcomes of various types of solid tumors, cancer treatments that target neutrophils might be highly effective. In this review, we briefly cover the latest findings on the multiple roles of neutrophils in cancer development and point out the future directions as well.