Histopathology of non-coeliac gluten sensitivity.

Diagnosis of non-coeliac gluten sensitivity (NCGS) remains still problematic due to the subjectiveness and lack of a specific biomarker. We aimed to compare NCGS duodenal mucosae with healthy individuals and Marsh type 1 coeliac disease (CD), to determine whether NCGS has characteristic histological features. A total of 44 healthy controls, 42 NCGS, and 44 type 1 CD patients were selected according to clinical, serological, and laboratory data. Duodenal biopsies were evaluated on H&E, CD, and CD117 for villus/crypt ratio, IEL counts/100 enterocytes, uneven distribution pattern with clusters of IELs in the villous epithelium, linear distribution of T lymphocytes in the basal lamina propria, and eosinophils and mast cells in the lamina propria. IEL counts were within normal range in controls (13 ± 7.65), normal or mildly increased in NCGS (24.7 ± 10.46), and increased in CD (58.79 ± 14.97) on CD3. The presence of uneven distribution pattern of IELs in the villous epithelium was significantly higher in NCGS (90.5%), in contrast to controls (27.3%) and CD (34.1%). The presence of linear distribution of T lymphocytes in the basal lamina propria (68.2%, 76.2%, 78.1%), eosinophil counts (6.85 ± 3.42, 6.21 ± 2.8, 7.62 ± 3.89), and mast cell counts (25.1 ± 5.1, 26 ± 2.9, 30.3 ± 4.4) was similar in controls, NCGS, and CD, respectively. In conclusion, duodenal mucosae in NCGS are characterized by preserved villous architecture, normal or mildly increased IELs with clusters, and eosinophils and mast cells within normal limits. We believe uneven distribution of IELs with clusters in the villous epithelium can be used as a supportive histopathological tool for NCGS in the right clinical setting.

Role of PD-1/PD-L1-mediated tumour immune escape mechanism and microsatellite instability in the BCG failure of high-grade urothelial carcinomas.

BACKGROUND: Intravesical BCG treatment fails inexplicably in 30%-45% of patients for high-grade nonmuscle-invasive bladder cancer (NMIBC). We aimed to investigate the role of PD-1/PD-L1 interaction on BCG failure of high-grade NMIBC and to identify biomarkers for predicting BCG responsive cases. METHODS: Thirty BCG responsive and 29 nonresponsive NMIBCs were included in the study. Expressions of PDL1(SP-263), MSH2, MSH6, PMS2, and MLH1 were evaluated on pre- and post-BCG transurethral resection (TUR-B) specimens by immunohistochemistry. PD-L1(SP-263) expression was categorised as negative/low, high. DNA mismatch repair protein (MMR) expressions were classified as "reduced" if ≤30% of nuclei stained, "preserved" if >30% of nuclei stained. Microsatellite instability (MSI) testing was performed by PCR using five mononucleotide markers. RESULTS: Reduced DNA MMR protein expression was found to be significantly higher in the pretreatment biopsies of BCG-responsive group than the BCG nonresponsive tumour group (p = 0.022). PD-L1 expression did not show any significant difference between the pre- and posttreatment TUR-B specimens of the BCG nonresponsive tumour group or between the pretreatment TUR-B specimens of BCG nonresponsive and the BCG responsive groups (p = 0.508, p = 0.708, respectively). DISCUSSION: Immune escape of tumour cells by PD-1/PD-L1 interaction does not seem to have any role in BCG failure of NMIBCs. Reduced MMR expression may help to determine cases that will respond well to BCG therapy. A better antitumour activity of BCG in NMIBCs with reduced MMR expression may be related to the ongoing accumulation of cancer neoantigens in correlation with increased tumour mutation load as a result of DNA repair defects.