Gastrointestinal mucosal biopsies in Parkinson's disease: beyond alpha-synuclein detection.

Alpha-synuclein deposits, the pathological hallmarks of Parkinson's disease, are consistently found in the gastrointestinal tract of parkinsonian subjects. These observations have raised the potential that endoscopically obtainable mucosal biopsies can aid to a molecular diagnosis of the disease. The possible usefulness of mucosal biopsies is, however, not limited to the detection of alpha-synuclein, but also extends to other essential aspects underlying pathophysiological mechanisms of gastrointestinal manifestations in Parkinson's disease. The aim of the current review is to provide an appraisal of the existing studies showing that gastrointestinal biopsies can be used for the analysis of enteric neuronal and glial cell morphology, intestinal epithelial barrier function, and gastrointestinal inflammation in Parkinson's disease. A perspective on the generation of organoids with GI biopsies and the potential use of single-cell and spatial transcriptomic technologies will be also addressed.

Galectin-3 expression in donor T cells reduces GvHD severity and lethality after allogeneic hematopoietic cell transplantation.

Abundant donor cytotoxic T cells that attack normal host organs remain a major problem for patients receiving allogeneic hematopoietic cell transplantation (allo-HCT). Despite an increase in our knowledge of the pathobiology of acute graft versus host disease (aGvHD), the mechanisms regulating the proliferation and function of donor T cells remain unclear. Here, we show that activated donor T cells express galectin-3 (Gal-3) after allo-HCT. In both major and minor histocompatibility-mismatched models of murine aGvHD, expression of Gal-3 is associated with decreased T cell activation and suppression of the secretion of effector cytokines, including IFN-γ and GM-CSF. Mechanistically, Gal-3 results in activation of NFAT signaling, which can induce T cell exhaustion. Gal-3 overexpression in human T cells prevents severe disease by suppressing cytotoxic T cells in xenogeneic aGvHD models. Together, these data identify the Gal-3-dependent regulatory pathway in donor T cells as a critical component of inflammation in aGvHD.

Gastrointestinal Biopsies for Evaluation of Acute Graft-Versus-Host Disease in Allogeneic Hematopoietic Stem Cell Transplant Patients.

Graft-versus-host disease (GVHD) is the major complication post hematopoeitic stem cell transplantation (HSCT) causing significant morbidity and mortality. Colonic biopsies were performed in 25 post HSCT patients presenting the diarrhea for diagnosis of acute graft versus host disease (A-GVHD). The present study was undertaken to evaluate and illustrate histomorphological features of A-GVHD in GI biopsies and to grade them. Histopathological features of gastrointestinal biopsies from 25 allogeneic HSCT patients having clinical suspicion of A-GVHD were evaluated and compared with colonic biopsies from negative controls. A-GVHD was observed in 17 cases, CMV colitis was present in 3 cases and one case had herpes simplex infection diagnosed in conjunction with serological findings. A-GVHD was graded as grade 1 and 2 in 10 cases and grade 3 and 4 in 7 cases. Apoptosis of crypt epithelial cells was the cardinal feature for diagnosis. Grade 1 and grade 2 A-GVHD cases showed crypt apoptosis in all cases as well as pericryptal apoptosis in lamina propria in many cases. Occasional crypt loss was seen in grade 2 GVHD. Inflammatory infiltrate was composed of lymphocytes and plasma cells. Neutrophils were inconspicuous. Grade 3 and grade 4 A-GVHD cases showed contiguous areas of multiple crypt loss and ulceration with inflammatory infiltrate predominantly composed of lymphocytes and plasma cells, but neutrophils were more prominent than in grade 1 and 2 A-GVHD. Apoptosis of crypt epithelial cells was present in all grade 3 &4 cases except one case. CMV cases were diagnosed by CMV inclusions and IHC stain. Several factors including drug-induced side effects and infections can cause difficulty in histologic interpretation of gastrointestinal biopsies for GVHD. Proper histomorphological interpretation of intestinal A-GVHD is critical for clinical management. A-GVHD is treated with immunosuppression which may worsen infective condition, if present.