SUMMARY It remains unclear whether basophils and mast cells are derived from a common progenitor. Furthermore, how basophil versus mast cell fate is specified has not been investigated. Here, we have identified a population of granulocyte-macrophage progenitors (GMPs), which were highly enriched in the capacity to differentiate into basophils and mast cells while retaining a limited capacity to differentiate into myeloid cells. We have designated these progenitor cells “pre-basophil and mast cell progenitors” (pre-BMPs). STAT5 signaling was required for the differentiation of pre-BMPs into both basophils and mast cells and was critical for inducing two downstream molecules: C/EBPα and MITF. We have identified C/EBPα as the critical basophil transcription factor for specifying basophil cell fate and MITF as the crucial transcription factor for specifying mast cell fate. C/EBPα and MITF silenced each other’s transcription in a directly antagonistic fashion. Our study reveals how basophil and mast cell fate is specified.

Factor H (FH) binds apoptotic cells to limit the inflammatory potential of complement. Here we report that FH is actively internalized by apoptotic cells to enhance cathepsin L-mediated cleavage of endogenously expressed C3, which results in increased surface opsonization with iC3b. In addition, internalized FH forms complexes with nucleosomes, facilitates their phagocytosis by monocytes and induces an anti-inflammatory biased cytokine profile. A similar cytokine response was noted for apoptotic cells coated with FH, confirming that FH diminishes the immunogenic and inflammatory potential of autoantigens. These findings were supported by in vivo observations from CFH − / − MRL-lpr mice, which exhibited higher levels of circulating nucleosomes and necrotic cells than their CFH +/+ littermates. This unconventional function of FH broadens the established view of apoptotic cell clearance and appears particularly important considering the strong associations with genetic FH alterations and diseases such as systemic lupus erythematosus and age-related macular degeneration. Factor H (FH), one of the most abundant plasma proteins, is the major soluble inhibitor of the alternative complement pathway. Apoptotic cells bind FH while triggering complement activation by binding of C1 complex, which ensures efficient opsonization and removal of apoptotic debris but prevents excessive complement activation and inflammation. 1,2 Dysregulation of complement contributes significantly to the pathology of many diseases. 3 Recently, novel roles and intracellular location for complement have been identified suggesting that its functions exceed our current understanding. 4 After previously identifying the ligands for FH on the apoptotic cell surface as dsDNA, histones and annexin A2, 5 we sought to explore the functional consequences of the FH-apoptotic cell interaction in the context of the chronic autoimmune disorder systemic lupus erythematosus (SLE) and age-related macular degeneration (AMD). Aberrant apoptosis and impaired clearance of apoptotic cells are of central importance in the pathogenesis of SLE and lead to formation of autoantibodies. 6-8 Anti-chromatin autoantibodies are a hallmark of SLE and anti-annexin A2 autoantibodies are also frequently observed in SLE patients. 9 Interestingly, the corresponding autoantigens are exactly those that we identified as ligands for FH on the apoptotic cell surface, suggesting a possibility of disturbance of FH function in SLE. Glomerulonephritis is one typical manifestation of human SLE 10 and mutations in FH and another complement inhibitor CD46 are associated with earlier onset of nephritis in SLE patients. 11 FH-deficient (CFH − / − ) mice spontaneously develop membranoproliferative glomerulonephritis, which is dependent on C3 activation. 12 When crossed with the MRL-lpr mouse strain, a model of lupus, the originated CFH − / − MRLlpr mice exhibit accelerated lupus nephritis and die at younger age than their CFH +/+ MRL-lpr littermates. 13,14 AMD is the leading cause of visual impairm...

The modern Western diet is rich in advanced glycation end products (AGEs). We have previously shown an association between dietary AGEs and markers of inflammation and oxidative stress in a population of end stage renal disease (ESRD) patients undergoing peritoneal dialysis (PD). In the current pilot study we explored the effects of dietary AGEs on the gut bacterial microbiota composition in similar patients. AGEs play an important role in the development and progression of cardiovascular (CVD) disease. Plasma concentrations of different bacterial products have been shown to predict the risk of incident major adverse CVD events independently of traditional CVD risk factors, and experimental animal models indicates a possible role AGEs might have on the gut microbiota population. In this pilot randomized open label controlled trial, twenty PD patients habitually consuming a high AGE diet were recruited and randomized into either continuing the same diet (HAGE, n = 10) or a one-month dietary AGE restriction (LAGE, n = 10). Blood and stool samples were collected at baseline and after intervention. Variable regions V3-V4 of 16s rDNA were sequenced and taxa was identified on the phyla, genus, and species levels. Dietary AGE restriction resulted in a significant decrease in serum Nε-(carboxymethyl) lysine (CML) and methylglyoxal-derivatives (MG). At baseline, our total cohort exhibited a lower relative abundance of Bacteroides and Alistipes genus and a higher abundance of Prevotella genus when compared to the published data of healthy population. Dietary AGE restriction altered the bacterial gut microbiota with a significant reduction in Prevotella copri and Bifidobacterium animalis relative abundance and increased Alistipes indistinctus, Clostridium citroniae, Clostridium hathewayi, and Ruminococcus gauvreauii relative abundance. We show in this pilot study significant microbiota differences in peritoneal dialysis patients’ population, as well as the effects of dietary AGEs on gut microbiota, which might play a role in the increased cardiovascular events in this population and warrants further studies.

Background Cholinergic neuronal loss is one of the hallmarks of AD related neurodegeneration; however, preclinical promise of α7 nAChR drugs failed to translate into humans. CHRFAM7A , a uniquely human fusion gene, is a negative regulator of α7 nAChR and was unaccounted for in preclinical models. Methods Molecular methods: Function of CHRFAM7A alleles was studied in vitro in two disease relevant phenotypic readouts: electrophysiology and Aβ uptake. Genome edited human induced pluripotent stem cells (iPSC) were used as a model system with the human context. Double blind pharmacogenetic study: We performed double-blind pharmacogenetic analysis on the effect of AChEI therapy based on CHRFAM7A carrier status in two paradigms: response to drug initiation and DMT effect. Mini Mental Status Examination (MMSE) was used as outcome measure. Change in MMSE score from baseline was compared by 2-tailed T-test. Longitudinal analysis of clinical outcome (MMSE) was performed using a fitted general linear model, based on an assumed autoregressive covariance structure. Model independent variables included age, sex, and medication regimen at the time of the first utilized outcome measure (AChEI alone or AChEI plus memantine), APOE4 carrier status (0, 1 or 2 alleles as categorical variables) and CHRFAM7A genotype. Findings The direct and inverted alleles have distinct phenotypes. Functional CHRFAM7A allele classifies the population as 25% non-carriers and 75% carriers. Induced pluripotent stem cell (iPSC) models α7 nAChR mediated Aβ neurotoxicity. Pharmacological readout translates into both first exposure ( p = 0.037) and disease modifying effect ( p = 0.0048) in two double blind pharmacogenetic studies. Interpretation CHRFAM7A accounts for the translational gap in cholinergic strategies in AD. Clinical trials not accounting for this uniquely human genetic factor may have rejected drug candidates that would benefit 25% of AD. Reanalyses of the completed trials using this pharmacogenetic paradigm may identify effective therapy. Funding:

Several lines of evidence suggest that gut bacterial microbiota is altered in patients with chronic kidney disease (CKD), though the mechanism of which this dysbiosis takes place is not well understood. Recent studies delineated changes in gut microbiota in both CKD patients and experimental animal models using microarray chips. We present 16S ribosomal RNA gene sequencing of both stool pellets and small bowel contents of C57BL/6J mice that underwent a remnant kidney model and establish that changes in microbiota take place in the early gastrointestinal tract. Increased intestinal urea concentration has been hypothesized as a leading contributor to dysbiotic changes in CKD. We show that urea transporters (UT)-A and UT-B mRNA are both expressed throughout the whole gastrointestinal tract. The noted increase in intestinal urea concentration appears to be independent of UTs' expression. Urea supplementation in drinking water resulted in alteration in bacterial gut microbiota that is quite different than that seen in CKD. This indicates that increased intestinal urea concentration might not fully explain the CKD- associated dysbiosis.