γδ T cells control gut pathology in a chronic inflammatory model of colorectal cancer

Gut gd T cells are important intraepithelial lymphocytes with critical roles in maintenance of gut barrier integrity against infection and cancer, through unknown mechanisms. In addition to their role in barrier function, absence of gd T cells has been reported to lead to faster polyp formation in an inflammation unassociated model of colorectal cancer (CRC). The significant linkage between Inflammatory Bowel Disease and CRC is of strong relevance in gut translational research, and it necessitates a deeper understanding of the underlying cell-molecular mechanism causing inflammation associated CRC. In a new disease-relevant, chronic inflammation associated Colorectal cancer (CRC) model, we observed enhanced chronic colon pathology for both inflammation and polyp formation in mice lacking gd T cells. RNAseq analysis of colon from TCR d−/− mice treated with AOM-DSS revealed an early and profound dysregulated transcriptional landscape with reduced tumor suppressive genes, upregulated tumor induction and epithelial mesenchymal transition genes, and increased expression of inflammatory markers. As tumorigenesis progressed, colons lacking gd T cells harbored enhanced potentially immunosuppressive CD4 T cells in the epithelial layer but not in the lamina propria. Consistently, the gut gd T cell dependent tissue signature identified is positively correlated with different stages of colon adenocarcinoma in patients. Taken together, we demonstrate that gd T cells display broad tissue functions critical in gut homeostasis by controlling both epithelial and immune functions, and maintain tissue integrity against CRC.

Discovery of TAK-981, a First-in-Class Inhibitor of SUMO-Activating Enzyme for the Treatment of Cancer

SUMOylation is a reversible post-translational modification that regulates protein function through covalent attachment of small ubiquitin-like modifier (SUMO) proteins. The process of SUMOylating proteins involves an enzymatic cascade, the first step of which entails the activation of a SUMO protein through an ATP-dependent process catalyzed by SUMO-activating enzyme (SAE). Here, we describe the identification of TAK-981, a mechanism-based inhibitor of SAE which forms a SUMO-TAK-981 adduct as the inhibitory species within the enzyme catalytic site. Optimization of selectivity against related enzymes as well as enhancement of mean residence time of the adduct were critical to the identification of compounds with potent cellular pathway inhibition and ultimately a prolonged pharmacodynamic effect and efficacy in preclinical tumor models, culminating in the identification of the clinical molecule TAK-981.

A United Kingdom Multicenter Study of Icodextrin in Continuous Ambulatory Peritoneal Dialysis

While glucose remains the only osmotic agent used universally for peritoneal dialysis, its various shortcomings for the long dwell equilibration continuous ambulatory peritoneal dialysis (CAPD) has led to a search for alternative agents. The large molecular weight group has been of interest, because these agents theoretically would lead to greater ultrafiltration and a better metabolic profile. Mostsubstances (dextrans, charged macromolecules) have been found unsuitable for reasons of insolubility, allergenicity, and peritoneal toxicity. Short-chain polypeptides have been studied in humans, but the experience is limited, and there is the potential for allergenicity with long-term use.

The only large molecular weight agent that has been studied in some detail but hitherto in one center only and in a limited number of patients is glucose polymer (generic name, icodextrin). Because of the promise shown by these initial studies, a randomized controlled multicenter investigation of icodextrin in CAPD (MIDAS Study Group) was undertaken to evaluate the long-term safety and efficacy by comparing daily overnight (8 12 hours) use of a slightly hypo-osmolar solution (282 mOsm/ kg) with 1.36% (346 mOsm/kg) and 3.86% (484 mOsm/kg) glucose exchanges. Over a 6-month period 209 patients from 11 centers in the United Kingdom were randomized, with 106 allocated to receive icodextrin (study group) and 103 to remain on glucose (control group). One hundred and thirty-eight patients completed the 6-month study (71 control, 67 study).

The mean net ultrafiltration overnight with icodextrin was 3.5 times greater than 1.36% at 8 hours and 5.5 times greater at 12 hours (p<0.0001), but no different from that of 3.86% glucose at 8 and 12 hours (although for the latter dwell the net mean ultrafiltration volume was greater by about 140 mL). Biochemical profiles were no different except for a small fall in serum sodium and chloride in the icodextrin group. The mean serum maltose rose to a steady-state level of 1.2 g/L within 2 weeks and remained stable. The mean carbohydrate absorbed for icodextrin (29±5 g) was lower than with 3.86% glucose (62±5 g). The use of icodextrin did not increase the incidence of peritonitis, nor did it alter its outcome, affect uptake of icodextrin from the peritoneum, alter serum osmolality or sodium levels. There were no adverse effects associated with the use of icodextrin, and the overall CAPD-related symptom score was significantly better for icodextrin than control subjects.

This study and subsequent extensive use and clinical experience has demonstrated that the daily use of an iso-osmolar icodextrin solution is generally well tolerated, effective, and could replace the overnight use of hyperosmotic glucose solution. Its use was of equal efficacy in peritonitis and in diabetic patients. The elevated levels of maltose did not appear to have any clinical side effects.

Peritonitis Occurrence in a Multicenter Study of Icodextrin and Glucose in Capd

Objective

To compare peritonitis occurrence and outcome in a large U.K. study Multicentre Investigation of Icodextrin in Ambulatory Dialysis (MIDAS).

Design

Prospective, randomized, controlled 6-month comparison of icodextrin with glucose for the long dwell in continuous ambulatory peritoneal dialysis (CAPD) patients.

Setting

Eleven CAPD units in U.K. teaching hospitals.

Patients

A total of 209 patients established on CAPD for at least 3 months (103 control, 106 icodextrin). Twentythree control (C) and 22 icodextrin (I) patients experienced peritonitis during the study.

Intervention

Patients who had peritonitis remained on treatment (unless CAPD was withdrawn, temporarily or permanently).

Main Outcome Measures

The main outcome measures were the rate of peritonitis and duration of CAPD treatment prestudy; the rate of peritonitis episodes and their outcome during study; the effect of peritonitis on laboratory variables, serum icodextrin metabolites, and ultrafiltration efficacy.

Results

Prestudy: Nine (39%) of C but 14 (64%) of I patients had suffered previous peritonitis episode(s), with overall rates of 0.58 and 0.78 episodes per patientyear, respectively.

During study

There were 31 C episodes and 35 I episodes, with overall rates of 0.76 and 0.93 per patientyear, respectively. The increase in the C and I groups was 31% and 19%, respectively. Serum osmolality and sodium levels were unaffected by peritonitis, and there was no increase in serum icodextrin metabolites during peritonitis. Overnight ultrafiltration volume during peritonitis (mean±SD) declined slightly from 218±354 mL to 185±299 mL (NS) in the control group, but increased in the icodextrin group from 570±146 mL to 723±218 mL (p < 0.01).

Conclusions

Using icodextrin for the long dwell in CAPD does not increase the rate of peritonitis, nor does it alter the outcome of peritonitis. Peritonitis does not affect uptake of icodextrin from the peritoneum.

Fasiglifam (TAK-875) Alters Bile Acid Homeostasis in Rats and Dogs: A Potential Cause of Drug Induced Liver Injury

Fasiglifam (TAK-875), a Free Fatty Acid Receptor 1 (FFAR1) agonist in development for the treatment of type 2 diabetes, was voluntarily terminated in phase 3 due to adverse liver effects. A mechanistic investigation described in this manuscript focused on the inhibition of bile acid (BA) transporters as a driver of the liver findings. TAK-875 was an in vitro inhibitor of multiple influx (NTCP and OATPs) and efflux (BSEP and MRPs) hepatobiliary BA transporters at micromolar concentrations. Repeat dose studies determined that TAK-875 caused a dose-dependent increase in serum total BA in rats and dogs. Additionally, there were dose-dependent increases in both unconjugated and conjugated individual BAs in both species. Rats had an increase in serum markers of liver injury without correlative microscopic signs of tissue damage. Two of 6 dogs that received the highest dose of TAK-875 developed liver injury with clinical pathology changes, and by microscopic analysis had portal granulomatous inflammation with neutrophils around a crystalline deposition. The BA composition of dog bile also significantly changed in a dose-dependent manner following TAK-875 administration. At the highest dose, levels of taurocholic acid were 50% greater than in controls with a corresponding 50% decrease in taurochenodeoxycholic acid. Transporter inhibition by TAK-875 may cause liver injury in dogs through altered bile BA composition characteristics, as evidenced by crystalline deposition, likely composed of test article, in the bile duct. In conclusion, a combination of in vitro and in vivo evidence suggests that BA transporter inhibition could contribute to TAK-875-mediated liver injury in dogs.

A novel mouse model of rhabdomyosarcoma underscores the dichotomy of MDM2-ALT1 function in vivo

Alternative splicing of the oncogene murine double minute 2 (MDM2) is induced in response to genotoxic stress. MDM2-ALT1, the major splice variant generated, is known to activate the p53 pathway and impede full-length MDM2's negative regulation of p53. Despite this perceptible tumor-suppressive role, MDM2-ALT1 is also associated with several cancers. Furthermore, expression of MDM2-ALT1 has been observed in aggressive metastatic disease in pediatric rhabdomyosarcoma (RMS), irrespective of histological subtype. Therefore, we generated a transgenic MDM2-ALT1 mouse model that would allow us to investigate the effects of this splice variant on the progression of tumorigenesis. Here we show that when MDM2-ALT1 is ubiquitously expressed in p53 null mice it leads to increased incidence of spindle cell sarcomas, including RMS. Our data provide evidence that constitutive MDM2-ALT1 expression is itself an oncogenic lesion that aggravates the tumorigenesis induced by p53 loss. On the contrary, when MDM2-ALT1 is expressed solely in B-cells in the presence of homozygous wild-type p53 it leads to significantly increased lymphomagenesis (56%) when compared with control mice (27%). However, this phenotype is observable only at later stages in life (⩾18 months). Moreover, flow cytometric analyses for B-cell markers revealed an MDM2-ALT1-associated decrease in the B-cell population of the spleens of these animals. Our data suggest that the B-cell loss is p53 dependent and is a response mounted to persistent MDM2-ALT1 expression in a wild-type p53 background. Overall, our findings highlight the importance of an MDM2 splice variant as a critical modifier of both p53-dependent and -independent tumorigenesis, underscoring the complexity of MDM2 posttranscriptional regulation in cancer. Furthermore, MDM2-ALT1-expressing p53 null mice represent a novel mouse model of fusion-negative RMS.

Knockout of Mkp-1 exacerbates colitis in Il-10-deficient mice

Il-10-deficient mice develop colitis associated with exaggerated Th1/Th17 responses and are a valuable model of inflammatory bowel disease. Mkp-1 is a major negative regulator of MAPKs, and its expression is enhanced by IL-10. To understand the role of Mkp-1 in the regulation of intestinal mucosal immune responses, we studied the effect of Mkp-1 deletion on the pathogenesis of colitis in Il-10(-/-) mice. We found that knockout of Mkp-1 on an Il-10(-/-) background accelerated the development of colitis. Compared with Il-10(-/-) mice, colitis not only appeared earlier but also was more severe in Il-10(-/-)/Mkp-1(-/-) mice. Il-10(-/-) mice exhibited a mild intestinal inflammation in the specific pathogen-free environment, and rectal prolapse rarely appeared before 6 mo of age. In contrast, the majority of Il-10(-/-)/Mkp-1(-/-) mice developed severe colitis rapidly and presented with rectal prolapse after only 2-3 mo. The colon of Il-10(-/-)/Mkp-1(-/-) mice showed diffuse transmural chronic inflammation and mucosal hyperplasia, with significantly more proliferating crypt epithelial cells than those of Il-10(-/-) mice. In addition to the severe colitis, Il-10(-/-)/Mkp-1(-/-) mice also developed conjunctivitis and blepharitis. The colon of Il-10(-/-)/Mkp-1(-/-) mice contained significantly higher levels of proinflammatory cytokines and exhibited greater MAPK activities than did the colon of Il-10(-/-) mice. Splenocytes and lymphocytes from Il-10(-/-)/Mkp-1(-/-) mice produced higher levels of Th1 cytokines ex vivo upon activation than did cells from Il-10(-/-) mice. Our studies support a pivotal role of Mkp-1 as a negative regulator of mucosal immune responses and highlight its protective function against inflammatory bowel disease.

Knockout of mitogen-activated protein kinase phosphatase (Mkp)-1 exacerbates colitis development in interleukin-10-deficient mice (120.21)

Il-10-/- mice develop colitis associated with exaggerated Th1/Th17 responses. Mkp-1 is a negative regulator of MAPKs, and its expression is enhanced by IL-10. To understand the role of Mkp-1 in the regulation of mucosal immune responses, we studied the effect of Mkp-1 deletion on the pathogenesis of colitis in Il-10-/- mice. We found that deletion of Mkp-1 on an Il-10-/- background accelerated the development of colitis. Il-10-/- mice exhibited a mild intestinal inflammation in the SPF environment, and rectal prolapse rarely appeared before 6 months. In contrast, majority of the Mkp-1-/-/Il-10-/- mice developed severe colitis rapidly and presented with rectal prolapse after 2-3 months. Colons of Mkp-1-/-/Il-10-/- mice showed diffuse transmural chronic inflammation and mucosal hyperplasia, with significant more proliferating crypt epithelial cells than those of Il-10-/- mice. Moreover, Mkp-1-/-/Il-10-/- mice also developed conjunctivitis and blepharitis. Large intestines of Mkp-1-/-/Il-10-/- mice contained significantly higher levels of pro-inflammatory cytokines, and exhibited greater p38 and ERK activities than did colons of Il-10-/- mice. Splenocytes and lymphocytes from Mkp-1-/-/Il-10-/- mice produced higher levels of Th1 cytokines ex vivo than did cells from Il-10-/- mice upon activation. Our studies support a pivotal role of Mkp-1 as a negative regulator in the mucosal immune responses and highlight its protective function against the development of IBD.

Role of MKP-1 in an IL-10 knockout murine inflammatory bowel disease model (47.7)

IBD is a chronic intestinal inflammatory disease that often has extra-intestinal manifestations. We examined the role of the MAPK phosphatase Mkp-1 in a mouse model of IBD. Mkp-1+/+/Il-10+/+, Mkp-1-/-/Il-10+/+, Mkp-1+/+/Il-10-/-, and Mkp-1-/-/Il-10-/- (dKO) mice on a 129 background were housed in a specific pathogen-free environment. Colitis signs were evaluated using a clinical scoring system, histological examination, and cytokine analysis. Most dKO mice developed severe rectal prolapse, peri-ocular lesions, and high clinical scores, signs generally not seen in Il-10 KO mice. dKO colons had extensive chronic and neutrophilic colitis, mucosal hyperplasia, and higher histological IBD scores than Il-10 KO colons. dKO eyelids and conjunctival mucosa were thickened and had neutrophilic and lymphoplasmocytic conjunctivitis. After LPS treatment, splenocytes and lymph node cells isolated from dKO mice had more robust production of Th-1 cytokines than cells from Il-10 KO mice. dKO colons contained higher levels of Th-1 cytokines and IL-17, and exhibited greater p38 and ERK activation, than did Il-10 KO colons. These data indicate that loss of Mkp-1 skews host immunity towards an exaggerated Th-1/Th-17 response and provide novel insights on the interaction between Mkp-1 and IL-10 in colitis models. Our studies support a pivotal role of Mkp-1 as a brake in the mucosal immune response to limit IBD development.

Monoclonal antibody against angiotensin-converting enzyme: its use as a marker for murine, bovine, and human endothelial cells

A monoclonal antibody has been prepared against rat angiotensin-converting enzyme (ACE). By selection for antibody binding to endothelial cells of bovine rather than rat origin we have obtained a reagent that has broad cross-species binding properties and that can at the same time serve as a useful marker for the surface of endothelial cells. The IgM-producing clone that we have established, alpha-ACE 3.1.1, has been grown in ascites form to yield ascites fluid that binds selectively to immobilized ACE at a greater than 1:10,000 dilution. By use of enzyme-linked immunosorbent assays, immunofluorescence histology, and flow cytometry, we have demonstrated the presence of ACE on endothelial cells of murine, bovine, and human origin. By means of a fluorescence-activated cell sorter (FACS-IV) we have been able to selectively isolate viable endothelial cells from a mixture of endothelial cells and fibroblasts. We believe the antibody will be useful not only for the selection and in vitro cultivation of endothelial cells but also as a tool for the identification and pharmacological study of ACE.

Immunological reactivity of monoclonal antibodies prepared against large ganglion cells from bovine retina

This report describes the preparation of a highly specific reagent (monoclonal antibody) that reacts selectively with large ganglion cells of bovine retina. Other cells populations of bovine retina react weakly or not at all, but neurons in brain regions of ox other than retina also bind the immunoglobulins specifically. Species specificity was indicated by a weak reaction with cat and dog retinal neurons, and organ specificity was shown by lack of reaction with bovine liver. This highly specific reagent can be used to classify the subsets of large retinal ganglion cells on the basis of their antigenic properties and to identify neurons in different brains regions that share antigenic determinants.