Chimeric antigen receptor T (CAR-T) cell therapy has produced impressive results in clinical trials for B-cell malignancies. However, safety concerns related to the inability to control CAR-T cells once infused into the patient remain a significant challenge. Here we report the engineering of recombinant antibody-based bifunctional switches that consist of a tumor antigen-specific Fab molecule engrafted with a peptide neo-epitope, which is bound exclusively by a peptide-specific switchable CAR-T cell (sCAR-T). The switch redirects the activity of the bio-orthogonal sCAR-T cells through the selective formation of immunological synapses, in which the sCAR-T cell, switch, and target cell interact in a structurally defined and temporally controlled manner. Optimized switches specific for CD19 controlled the activity, tissue-homing, cytokine release, and phenotype of sCAR-T cells in a dose-titratable manner in a Nalm-6 xenograft rodent model of B-cell leukemia. The sCAR–T-cell dosing regimen could be tuned to provide efficacy comparable to the corresponding conventional CART-19, but with lower cytokine levels, thereby offering a method of mitigating cytokine release syndrome in clinical translation. Furthermore, we demonstrate that this methodology is readily adaptable to targeting CD20 on cancer cells using the same sCAR-T cell, suggesting that this approach may be broadly applicable to heterogeneous and resistant tumor populations, as well as other liquid and solid tumor antigens.

Translocation of bacteria and their products across the intestinal barrier is common in patients with liver disease, and there is evidence that experimental liver fibrosis depends on bacterial translocation. The purpose of our study was to investigate liver fibrosis in conventional and germ‐free (GF) C57BL/6 mice. Chronic liver injury was induced by administration of thioacetamide (TAA) in the drinking water for 21 wk or by repeated intraperitoneal injections of carbon tetrachloride (CCl4). Increased liver fibrosis was observed in GF mice compared with conventional mice. Hepatocytes showed more toxin‐induced oxidative stress and cell death. This was accompanied by increased activation of hepatic stellate cells, but hepatic mediators of inflammation were not significantly different. Similarly, a genetic model using Myd88/Trif‐deficient mice, which lack downstream innate immunity signaling, had more severe fibrosis than wild‐type mice. Isolated Myd88/Trif‐deficient hepatocytes were more susceptible to toxin‐induced cell death in culture. In conclusion, the commensal microbiota prevents fibrosis upon chronic liver injury in mice. This is the first study describing a beneficial role of the commensal microbiota in maintaining liver homeostasis and preventing liver fibrosis.—Mazagova, M., Wang, L., Anfora, A. T., Wissmueller, M., Lesley, S. A., Miyamoto, Y., Eckmann, L., Dhungana, S., Pathmasiri, W., Sumner, S., Westwater, C., Brenner, D. A., Schnabl, B., Commensal microbiota is hepatoprotective and prevents liver fibrosis in mice. FASEB J. 29, 1043–1055 (2015). http://www.fasebj.org

Background Chronic alcohol abuse is associated with intestinal bacterial overgrowth, increased intestinal permeability, and translocation of microbial products from the intestine to the portal circulation and liver. Translocated microbial products contribute to experimental alcoholic liver disease. Aim To investigate the physiological relevance of the intestinal microbiota in alcohol-induced liver injury. Methods We subjected germ-free and conventional C57BL/6 mice to a model of acute alcohol exposure that mimics binge drinking. Results Germ-free mice showed significantly greater liver injury and inflammation after oral gavage of ethanol compared with conventional mice. In parallel, germ-free mice exhibited increased hepatic steatosis and upregulated expression of genes involved in fatty acid and triglyceride synthesis compared with conventional mice after acute ethanol administration. The absence of microbiota was also associated with increased hepatic expression of ethanol metabolizing enzymes, which led to faster ethanol elimination from the blood and lower plasma ethanol concentrations. Intestinal levels of ethanol metabolizing genes showed regional expression differences, and were overall higher in germ-free relative to conventional mice. Conclusion Our findings indicate that absence of the intestinal microbiota increases hepatic ethanol metabolism and the susceptibility to binge-like alcohol drinking.

Background & Aims Progression of liver fibrosis in experimental models depends on gut-derived bacterial products, but little is known about mechanisms of disruption of the mucosal barrier or translocation. We used a mouse model of cholestatic liver disease to investigate mechanisms of intestinal barrier disruption following liver injury. Methods Liver fibrosis and bacterial translocation were assessed in Toll-like receptor (TLR)2- and tumor necrosis factor receptor (TNFR)I-deficient mice subjected to bile duct ligation. Epithelial and lamina propria cells were isolated and analyzed by immunoblot analyses and flow cytometry. We analyzed bone-marrow chimeras and mice with a conditional gain-of-function allele for the TNFRI receptor. By crossing TNFRIflxneo/flxneo mice with mice that expressed the VillinCre transgene specifically in intestinal epithelial cells, we created mice that express functional TNFRI specifically on intestinal epithelial cells (VillinCreTNFRIflxneo/flxneo mice). Results Following bile duct ligation, TLR2-deficient mice had less liver fibrosis and intestinal translocation of bacteria and bacterial products than wild-type mice. Mice with hematopoietic cells that did not express TLR2 also had reduced bacterial translocation, indicating that TLR2 expression by hematopoietic cells regulates intestinal barrier function. The number of TLR2+ monocytes that produce TNF_ increased in the intestinal lamina propria of wild-type mice following bile duct ligation; bacterial translocation was facilitated by TNFRI-mediated signals on intestinal epithelial cells. Conclusion Intestinal inflammation and bacterial translocation contribute to liver fibrosis via TLR2 signaling on monocytes in the lamina propria and TNFRI signaling on intestinal epithelial cells in mice. Enteric TNFRI therefore is an important mediator of cholestatic liver fibrosis.

Chimeric antigen receptor T (CAR-T) cells have demonstrated promising results against hematological malignancies but have encountered significant challenges in translation to solid tumors. To overcome these hurdles, we have developed a switchable CAR-T cell platform in which the activity of the engineered cell is controlled by dosage of an antibody-based switch. Here, we apply this approach to Her2 expressing breast cancers by engineering switch molecules through site-specific incorporation of FITC or grafting of a peptide neo-epitope (PNE) into the anti-Her2 antibody trastuzumab (clone 4D5). We demonstrate that both switch formats can be readily optimized to redirect CAR-T cells (specific for the corresponding FITC or peptide epitope) to Her2 expressing tumor cells and afford dose-titratable activation of CAR-T cells ex vivo and complete clearance of tumor in rodent xenograft models. This strategy may facilitate the application of immunotherapy to solid tumors by affording comparable efficacy with improved safety owing to switch-based control of the CAR-T response.

The treatment of patients with acute myeloid leukemia (AML) with targeted immunotherapy is challenged by the heterogeneity of the disease and a lack of tumor-exclusive antigens. Conventional immunotherapy targets for AML such as CD33 and CD123 have been proposed as targets for chimeric antigen receptor (CAR)-engineered T-cells (CAR-T-cells), a therapy that has been highly successful in the treatment of B-cell leukemia and lymphoma. However, CD33 and CD123 are present on hematopoietic stem cells, and targeting with CAR-T-cells has the potential to elicit long-term myelosuppression. C-type lectin-like molecule-1 (CLL1 or CLEC12A) is a myeloid lineage antigen that is expressed by malignant cells in more than 90% of AML patients. CLL1 is not expressed by healthy Hematopoietic Stem Cells (HSCs), and is therefore a promising target for CAR-T-cell therapy. Here, we describe the development and optimization of an anti-CLL1 CAR-T-cell with potent activity on both AML cell lines and primary patient-derived AML blasts in vitro while sparing healthy HSCs. Furthermore, in a disseminated mouse xenograft model using the CLL1-positive HL60 cell line, these CAR-T-cells completely eradicated tumor, thus supporting CLL1 as a promising target for CAR-T-cells to treat AML while limiting myelosuppressive toxicity.

Nonalcoholic fatty liver disease (NAFLD) and obesity are characterized by altered gut microbiota, inflammation, and gut barrier dysfunction. Here, we investigated the role of mucin-2 (Muc2) as the major component of the intestinal mucus layer in the development of fatty liver disease and obesity. We studied experimental fatty liver disease and obesity induced by feeding wild-type and Muc2-knockout mice a high-fat diet (HFD) for 16 wk. Muc2 deficiency protected mice from HFD-induced fatty liver disease and obesity. Compared with wild-type mice, after a 16-wk HFD, Muc2-knockout mice exhibited better glucose homeostasis, reduced inflammation, and upregulated expression of genes involved in lipolysis and fatty acid β-oxidation in white adipose tissue. Compared with wild-type mice that were fed the HFD as well, Muc2-knockout mice also displayed higher intestinal and plasma levels of IL-22 and higher intestinal levels of the IL-22 target genes Reg3b and Reg3g. Our findings indicate that absence of the intestinal mucus layer activates the mucosal immune system. Higher IL-22 levels protect mice from diet-induced features of the metabolic syndrome.

OBJECTIVEDevelopment of micro- or macroalbuminuria is associated with increased risk of cardiorenal complications, particularly in diabetes. For prevention of transition to micro- or macroalbuminuria, more accurate prediction markers on top of classical risk markers are needed. We studied a promising new marker, growth-differentiation factor (GDF)-15, to predict transition to increasing stage of albuminuria in type 2 diabetes mellitus (T2DM). In addition, we looked at the GDF-15 potential in nondiabetic subjects with hypertension (HT).RESEARCH DESIGN AND METHODSCase and control subjects were selected from the PREVEND cohort, a large (n = 8,592), prospective general population study on the natural course of albuminuria, with >10 years of follow-up and repeated albuminuria measurements. We found 24 T2DM and 50 HT case subjects transitioning from normo- to macroalbuminuria and 9 T2DM and 25 HT case subjects transitioning from micro- to macroalbuminuria (average follow-up 2.8 years). Control subjects with stable albuminuria were pair matched for age, sex, albuminuria status, and diabetes duration. GDF-15 was measured in samples prior to albuminuria transition.RESULTSPrior to transition, GDF-15 was significantly higher in case subjects with T2DM than in control subjects (median [IQR] 1,288 pg/mL [885–1,546] vs. 948 pg/mL [660–1,016], P < 0.001). The odds ratio for transition in albuminuria increased significantly per SD of GDF-15 (2.9 [95% CI 1.1–7.5], P = 0.03). GDF-15 also improved prediction of albuminuria transition, with significant increases in C statistic (from 0.87 to 0.92, P = 0.03) and integrated discrimination improvement (0.148, P = 0.001). In HT, GDF-15 was also independently associated with transition in albuminuria stage (2.0 [1.1–3.5], P = 0.02) and improved prediction significantly.CONCLUSIONSWe identified GDF-15 as a clinically valuable marker for predicting transition in albuminuria stage in T2DM beyond conventional risk markers. These findings were confirmed in nondiabetic HT subjects.