Reversal of senescent phenotypes in human T cells

Age-related declines in immune function result in enhanced susceptibility to infection and decreased vaccine efficacy. While aged immune cells exhibit signs of cellular senescence, such as a reduced proliferative capacity, many maintain effector function. In this episode, Sian Henson discusses the characterization of a subset of human effector memory CD8+ T cells that reexpress the naïve T cell marker CD45RA (EMRA cells). Despite their senescent-like state, EMRA cells exhibited potent cytotoxic activity, the energy for which was generated by anaerobic glycolysis. Inhibition of p38 MAPK signaling in EMSA cells reversed senescent phenotypes and increased autophagy. These results indicate that some aspects of CD8+ T cell senescence may be reversible.

Autophagy defends β cells from amyloid accumulation

β cell dysfunction is a hallmark of type 2 diabetes (T2D) and is associated with extracellular accumulation of amyloid plaques comprised of islet amyloid polypeptide (IAPP). Human IAPP is potentially toxic and has been shown to accumulate within β cells of T2D patients and in transgenic rodent models. In this episode, Safia Costes and colleagues examine the role of autophagy in the degradation of human IAPP in murine models. Human IAPP aggregated within p62-positive inclusions in transgenic animals, with no apparent loss of β cell function or mass; however, human IAPP-expressing mice with a β cell-specific autophagy defect developed overt diabetes due β cell death. These results indicate that autophagy is protective against IAPP-induced toxicity in β cells and suggest the autophagy pathway as a potential theraputic target for treatment and/or prevention of T2D.

Evaluation of kisspeptin-54 for egg maturation

In virto fertilization (IVF) has helped millions of couples have children. While considered relatively safe, there are risks associated with this procedure. Among the more serious complications is the development of ovarian hyperstimulation syndrome (OHSS), which in extreme cases can be fatal. OHSS results from excessive stimulation of the luteinizing hormone (LH) receptor by human chorionic gonadotropin (hCG), which is commonly used as part of the IVF cycle to promote egg maturation. In this episode, Waljit Dhillo discusses the results from a small clinical trial that evaluated use of the fertility hormone kisspeptin-54 for egg maturation in IVF. Dhillo and colleagues report that kisspeptin-54 treatment resulted in mature eggs that were successfully fertilized and transferred, with pregnancy in 23% of patients.

Unraveling profibrotic pathways in the kidney

Fibrosis is a hallmark of chronic kidney disease that is characterized by accumulation of extracellular matrix and an influx of immune cells. Autophosphorylation of serine residues within the type II TGF-β receptor (TβRII) following activation by TGF-β induces a SMAD-dependent profibrotic signaling cascade; however, there are multiple tyrosine residues within the cytoplasmic tail of TβRII that have potential to regulate this pathway. In this episode, Ambra Pozzi reveals that phosphorylation of tyrosine residues in the cytoplasmic tail of TβRII does influence the fibrotic signaling cascade. Specifically, Pozzi and colleagues determined that integrin α1β1 recruits the phosphatase TCPTP to TβRII, subsequently dephosphorylating tyrosine residues within the TβRII cytoplasmic tail. Furthermore, mice lacking α1β1 integrin exhibited enhanced phosphorylation of TβRII due to decreased recruitment of TCPTP, resulting in severe fibrosis following kidney injury.

MicroRNA-regulated network promotes pulmonary hypertension

Pulmonary hypertension is a complex disease that affects multiple vascular cell types, and mircoRNAs (miRNAs) have been implicated in the pathogenesis of this condition. In this episode, Stephen Chan discusses how his group used network theory to identify miRNA-130/301 as a regulator of a system of miRNAs that promote the development of pulmonary hypertension. Furthermore, inhibition of miR130/301 prevented the development on pulmonary hypertension in a hypoxic murine model. The results of this study support the use of network analysis for identifying complex miRNA-regulated pathways involved in disease manifestations.