Rabbit Anti-Human B2M Polyclonal antibody

The presence of non-autologous major histocompatibility complex class I (MHC-I) molecules on the surface of the grafted cells is one of the main reasons for their rejection in non-syngeneic hosts. We present a straightforward strategy to decrease the presence of MHC-I by shRNA inhibition of beta-2-microglobulin (B2M), a conservative light chain of MHC-I, on the surface of two main cell types that are used to engineer heart tissue constructs. Engineered heart tissue constructs can be generated by combining mouse WT19 fibroblasts and mouse embryonic stem cell-derived cardiac myocytes (mESC-CM). WT19 fibroblasts were stably transduced with an anti-B2M shRNA, which yielded a cell line with dramatically reduced B2M expression levels (16 +/- 11% of mock treated control cell line). Interferon gamma treatment increased the levels of B2M expression by >3-fold in both control and transduced fibroblasts; yet, B2M expression levels still remained very low in the transduced cells. When compared with their unmodified counterparts, transduced fibroblasts caused 5.7-fold lesser activation of cognate T-cells. B2M depletion in mESC-CM was achieved by 72 h transduction with anti-B2M shRNA lentiviral particles. Transduced mESC-CM exhibited regular beating and expressed classical cardiac markers. When compared with their unmodified counterparts, transduced mESC-CM caused 2.5-fold lesser activation of cognate T-cells. In vivo assessment of B2M downregulation was performed by analyzing the preferential survival of B2M-downregulated cells in the intraperitoneal cavity of allogeneic mice. Both B2M-downregulated fibroblasts and B2M-downregulated myocytes survived significantly better when compared to their unmodified counterparts (2.01 +/- 0.4 and 5.07 +/- 1.6 fold increase in survival, respectively). In contrast, when modified WT19 fibroblasts were injected into the intraperitoneal cavity of syngeneic C57Bl/6 mice, no significant survival advantage was observed. Notably, the preferential survival of B2M-downregulated cells persisted in allogeneic hosts with normal levels of natural killer cells, although the effect was lesser in magnitude. Use of shRNA against beta-2-microglobulin offers a simple and effective approach to minimize immunogenicity of the main cellular components of cardiac tissue constructs in non-syngeneic recipients.

To investigate the distinctive mechanism behind different types of fibers, this study compared the effects of inulin (INU), raw potato starch (RPS), pectin (PEC) enriched diets on the microbiota composition, and the mucosal transcriptome in pig colons. Results showed that PEC enriched diet significantly increased richness estimator (Chao) of colonic microbiota, relative abundances of Firmicutes and Proteobacteria, and decreased Bacteroidetes, whereas INU and RPS induced a roughly similar microbiota composition to the control. PEC changed the expression of genes (CD8A, B2M and CD19) involving antigen processing and presentation, and primary immunodeficiency pathways, and up-regulated 2 active genes (UGT2B31 and LOC100738495) involving the metabolism of important endogenous compounds (e.g. bile acids and steroid hormones). Results indicate that the consumption of apple pectin with high viscosity may lead to a distinct response on microbiota composition and gene expression in pig colons, and result in a potential negative impact on gut health.