Probes for INS

Objectives Spleen tyrosine kinase (SYK) is a cytoplasmic protein tyrosine kinase which plays a role in signalling via B cell and Fc receptors. Fc receptor engagement and signalling via SYK is thought to be important in anti-neutrophil cytoplasm antibody (ANCA) IgG-mediated neutrophil activation. In this study we investigate the role for SYK in ANCA induced myeloid cell activation and vasculitis pathogenesis. Methods Phosphorylation of SYK in myeloid cells from healthy controls and AAV patients was analysed using flow cytometry. The effect of SYK inhibition on MPO-ANCA IgG activation of cells was investigated using functional assays (IL-8 and ROS production) and targeted gene analysis using Nanostring. Total and phosphorylated SYK at sites of tissue inflammation in patients with AAV was assessed using immunohistochemistry and RNAscope in situ hybridisation. Results We identify increased phosphorylated SYK at critical activatory tyrosine residues in blood neutrophils and monocytes from patients with active AAV compared to remission patients or healthy controls. SYK is phosphorylated in vitro following MPO-ANCA IgG stimulation and SYK inhibition can prevent ANCA-mediated cellular responses. Using targeted gene expression analysis, we identify up-regulation of FcR and SYK-dependent signalling pathways following MPO-ANCA IgG stimulation. Finally, we show SYK is expressed and phosphorylated in tissue leucocytes at sites of organ inflammation in AAV. Conclusions These findings indicate that SYK plays a critical role in MPO-ANCA IgG-induced myeloid cell responses that SYK is activated in circulating and tissue immune cells in AAV, and SYK inhibition may therefore be a potential therapeutic option.

The progeny of intestinal stem cells (ISCs) dedifferentiate in response to ISC attrition. The precise cell sources, transitional states, and chromatin remodeling behind this activity remain unclear. In the skin, stem cell recovery after injury preserves an epigenetic memory of the damage response; whether similar memories arise and persist in regenerated ISCs is not known. We addressed these questions by examining gene activity and open chromatin at the resolution of single Neurog3-labeled mouse intestinal crypt cells, hence deconstructing forward and reverse differentiation of the intestinal secretory (Sec) lineage. We show that goblet, Paneth, and enteroendocrine cells arise by multilineage priming in common precursors, followed by selective access at thousands of cell-restricted cis-elements. Selective ablation of the ISC compartment elicits speedy reversal of chromatin and transcriptional features in large fractions of precursor and mature crypt Sec cells without obligate cell cycle re-entry. ISC programs decay and reappear along a cellular continuum lacking discernible discrete interim states. In the absence of gross tissue damage, Sec cells simply reverse their forward trajectories, without invoking developmental or other extrinsic programs, and starting chromatin identities are effectively erased. These findings identify strikingly plastic molecular frameworks in assembly and regeneration of a self-renewing tissue.

Black raspberries (BRBs) have colorectal cancer (CRC) chemo-preventative effects. As CRC originates from an intestinal stem cell (ISC) this study has investigated the impact of BRBs on normal and mutant ISCs.Mice with an inducible Apcfl mutation in either the ISC (Lgr5CreERT2 ) or intestinal crypt (AhCre/VillinCreERT2 ) are fed a control or 10% BRB-supplemented diet. This study uses immunohistochemistry, gene expression analysis, and organoid culture to evaluate the effect of BRBs on intestinal homeostasis. RNAscope is performed for ISC markers on CRC adjacent normal colonic tissue pre and post BRB intervention from patients. 10% BRB diet has no overt effect on murine intestinal homeostasis, despite a reduced stem cell number. Following Apc ISC deletion, BRB diet extends lifespan and reduces tumor area. In the AhCre model, BRB diet attenuates the "crypt-progenitor" phenotype and reduces ISC marker gene expression. In ex vivo culture BRBs reduce the self-renewal capacity of murine and human Apc deficient organoids. Finally, the study observes a reduction in ISC marker gene expression in adjacent normal crypts following introduction of BRBs to the human bowel.BRBs play a role in CRC chemoprevention by protectively regulating the ISC compartment and further supports the use of BRBs in CRC prevention.

Although reprogramming of cellular metabolism is a hallmark of cancer, little is known about how metabolic reprogramming contributes to early stages of transformation. Here, we show that the histone deacetylase SIRT6 regulates tumor initiation during intestinal cancer by controlling glucose metabolism. Loss of SIRT6 results in an increase in the number of intestinal stem cells (ISCs), which translates into enhanced tumor initiating potential in APCmin mice. By tracking down the connection between glucose metabolism and tumor initiation, we find a metabolic compartmentalization within the intestinal epithelium and adenomas, where a rare population of cells exhibit features of Warburg-like metabolism characterized by high pyruvate dehydrogenase kinase (PDK) activity. Our results show that these cells are quiescent cells expressing +4 ISCs and enteroendocrine markers. Active glycolysis in these cells suppresses ROS accumulation and enhances their stem cell and tumorigenic potential. Our studies reveal that aerobic glycolysis represents a heterogeneous feature of cancer, and indicate that this metabolic adaptation can occur in non-dividing cells, suggesting a role for the Warburg effect beyond biomass production in tumors.

Intestinal epithelial stem cells (ISCs) are responsible for intestinal epithelial barrier renewal; thereby, ISCs play a critical role in intestinal pathophysiology research. While transgenic ISC reporter mice are available, advanced translational studies lack a large animal model. This study validates ISC isolation in a new porcine Leucine Rich Repeat Containing G Protein-Coupled Receptor 5 (LGR5) reporter line and demonstrates the use of these pigs as a novel colorectal cancer (CRC) model. We applied histology, immunofluorescence, fluorescence-activated cell sorting, flow cytometry, gene expression quantification, and 3D organoid cultures to whole tissue and single cells from the duodenum, jejunum, ileum, and colon of LGR5-H2B-GFP and wild-type pigs. Ileum and colon LGR5-H2B-GFP, healthy human, and murine biopsies were compared by mRNA fluorescent in situ hybridization (FISH). To model CRC, adenomatous polyposis coli (APC) mutation was induced by CRISPR/Cas9 editing in porcine LGR5-H2B-GFP colonoids. Crypt-base, green fluorescent protein (GFP) expressing cells co-localized with ISC biomarkers. LGR5-H2B-GFPhi cells had significantly higher LGR5 expression (p < .01) and enteroid forming efficiency (p < .0001) compared with LGR5-H2B-GFPmed/lo/neg cells. Using FISH, similar LGR5, OLFM4, HOPX, LYZ, and SOX9 expression was identified between human and LGR5-H2B-GFP pig crypt-base cells. LGR5-H2B-GFP/APCnull colonoids had cystic growth in WNT/R-spondin-depleted media and significantly upregulated WNT/β-catenin target gene expression (p < .05). LGR5+ ISCs are reproducibly isolated in LGR5-H2B-GFP pigs and used to model CRC in an organoid platform. The known anatomical and physiologic similarities between pig and human, and those shown by crypt-base FISH, underscore the significance of this novel LGR5-H2B-GFP pig to translational ISC research.