Characterizations of a neutralizing antibody broadly reactive to multiple gluten peptide:HLA-DQ2.5 complexes in the context of celiac disease.

In human celiac disease (CeD) HLA-DQ2.5 presents gluten peptides to antigen-specific CD4+ T cells, thereby instigating immune activation and enteropathy. Targeting HLA-DQ2.5 with neutralizing antibody for treating CeD may be plausible, yet using pan-HLA-DQ antibody risks affecting systemic immunity, while targeting selected gluten peptide:HLA-DQ2.5 complex (pHLA-DQ2.5) may be insufficient. Here we generate a TCR-like, neutralizing antibody (DONQ52) that broadly recognizes more than twenty-five distinct gluten pHLA-DQ2.5 through rabbit immunization with multi-epitope gluten pHLA-DQ2.5 and multidimensional optimization. Structural analyses show that the proline-rich and glutamine-rich motif of gluten epitopes critical for pathogenesis is flexibly recognized by multiple tyrosine residues present in the antibody paratope, implicating the mechanisms for the broad reactivity. In HLA-DQ2.5 transgenic mice, DONQ52 demonstrates favorable pharmacokinetics with high subcutaneous bioavailability, and blocks immunity to gluten while not affecting systemic immunity. Our results thus provide a rationale for clinical testing of DONQ52 in CeD.

Nucleosome Positioning and Gene Regulation of the SGLT2 Gene in the Renal Proximal Tubular Epithelial Cells.

Filtered glucose is mostly reabsorbed by sodium-glucose cotransporter 2 (SGLT2) in the proximal tubules. SGLT2 is predominantly expressed in the human kidney. However, the regulatory mechanisms for SGLT2 gene expression in the human kidney remain unclear. We in this work elucidated the transcriptional regulatory mechanisms for the SGLT2 gene by nucleosome occupancy in the SGLT2 promoter region. Expressions of SGLT2 mRNA and protein were markedly weaker in human kidney-derived HK-2 cells than the human kidney. The nucleosome occupancy level in the SGLT2 promoter region was low in the kidney, but high in HK-2 cells. A treatment with a histone deacetylase inhibitor trichostatin A (TSA) decreased nucleosome occupancy in the promoter region and increased SGLT2 expression levels in HK-2 cells. The upregulation of SGLT2 expression by histone acetylation was accompanied by a higher binding frequency of hepatocyte nuclear factor (HNF) 1α, a transcriptional modulator of SGLT2 in the human kidney, to the promoter region. The transfection of a HNF1α expression plasmid into HK-2 cells resulted in the upregulation of SGLT2 mRNA expression in the presence of TSA, but not in the treatment of dimethylsulfoxide as a control. Nucleosome occupancy in the promoter region was markedly higher in the liver and small intestine than the kidney. Our results indicate that tissue-specific nucleosome occupancy plays an important role in the regulation of SGLT2 gene expression via HNF1α binding at the SGLT2 promoter region.