Ulcerative colitis is a chronic condition in which a dysregulated immune response contributes to the acute intestinal inflammation of the colon. Current clinical therapies often exhibit limited efficacy and undesirable side effects. Here, programmable nanomicelles were designed for colitis treatment and loaded with RU.521, an inhibitor of the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway. STING-inhibiting micelles (SIMs) comprise hyaluronic acid-stearic acid conjugates and include a reactive oxygen species (ROS)-responsive thioketal linker. SIMs were designed to selectively accumulate at the site of inflammation and trigger drug release in the presence of ROS. Our in vitro studies in macrophages and in vivo studies in a murine model of colitis demonstrated that SIMs leverage HA-CD44 binding to target sites of inflammation. Oral delivery of SIMs to mice in both preventive and delayed therapeutic models ameliorated colitis's severity by reducing STING expression, suppressing the secretion of proinflammatory cytokines, enabling bodyweight recovery, protecting mice from colon shortening, and restoring colonic epithelium. In vivo end points combined with metabolomics identified key metabolites with a therapeutic role in reducing intestinal and mucosal inflammation. Our findings highlight the significance of programmable delivery platforms that downregulate inflammatory pathways at the intestinal mucosa for managing inflammatory bowel diseases.

Gastrointestinal illnesses and dysbiosis are among the most common comorbidities reported in patients with neurodevelopmental disorders. The manuscript reports that C. difficile infection (CDI), predisposed by antibiotic-induced gut dysbiosis, causes significant alterations in dopamine metabolism in major dopaminergic brain regions in mice (P < 0.05). In addition, C. difficile infected mice exhibited significantly reduced dopamine beta-hydroxylase (DBH) activity compared to controls (P < 0.01). Moreover, a significantly increased serum concentration of p-cresol, a DBH inhibiting gut metabolite produced by C. difficile, was also observed in C. difficile infected mice (P < 0.05). Therefore, this study suggests a potential mechanistic link between CDI and alterations in the brain dopaminergic axis. Such alterations may plausibly influence the precipitation and aggravation of dopamine dysmetabolism-associated neurologic diseases in infected patients. IMPORTANCE The gut-brain axis is thought to play a significant role in the development and manifestation of neurologic diseases. This study reports significant alterations in the brain dopamine metabolism in mice infected with C. difficile, an important pathogen that overgrows in the gut after prolonged antibiotic therapy. Such alterations in specific brain regions may have an effect on the precipitation or manifestation of neurodevelopmental disorders in humans.

Transitional cell carcinoma (TCC), also known as urothelial carcinoma, is the most common bladder cancer in humans and dogs. Approximately one-quarter of human TCCs are muscle-invasive and associated with a high risk of death from metastasis. Canine TCC (cTCC) tumours are typically high-grade and muscle-invasive. Shared similarities in risk factors, histopathology, and clinical presentation suggest that cTCC may serve as a model for the assessment of novel therapeutics that may inform therapies for human muscle-invasive TCC. The goal of this study was to characterize cTCC at the molecular level to identify drivers of oncogenesis and druggable targets. We performed whole exome sequencing (WES) of 11 cTCC tumours and three matched normal samples, identifying 583 variants in protein-coding genes. The most common variant was a V-to-E missense mutation in BRAF, identified in 4 out of 11 samples (36%) via WES. Sanger sequencing identified BRAF variants in 8 out of the same 11 cTCC samples, as well as in 22 out of 32 formalin-fixed paraffin embedded (FFPE) cTCC samples, suggesting an overall prevalence of 70%. RNA-Seq was performed to compare the gene expression profiles of cTCC tumours to normal bladder tissue. cTCC tumours exhibited up-regulation of genes involved in the cell cycle, DNA repair, and antiviral immunity. We also analysed the immune landscape of cTCC using immune gene signatures and immunohistochemical analysis. A subset of tumours had characteristics of a hot tumour microenvironment and exhibited high expression of signatures associated with complete response to PD-1/PD-L1 blockade in human bladder cancer.

Gastrointestinal illnesses are one of the most common comorbidities reported in patients with neurodevelopmental diseases, including autism spectrum disorders (ASD). Gut dysbiosis, overgrowth of C. difficile , and gut microbiota-associated alterations in central neurotransmission have been implicated in ASD, where the dopaminergic axis plays an important role in the disease pathogenesis. Human C. difficile strains produce a significant amount of the toxic metabolite p-cresol, an inhibitor of dopamine beta-hydroxylase (DBH), which catalyzes the conversion of dopamine (DA) to norepinephrine (NE). p-Cresol is known to precipitate and exacerbate autistic behavior in rodents by increasing DA levels and altering DA receptor sensitivity in brain regions relevant to ASD. Therefore, we hypothesized that C. difficile infection dysregulates dopaminergic metabolism by increasing p-cresol levels in the gut and systemic circulation, and by inhibiting brain DBH, ultimately leading to elevated DA in different brain regions. For testing this hypothesis, we induced antibiotic-associated C. difficile infection in mice and determined the gut and serum p-cresol levels, serum DBH activity, and dopamine and its metabolite levels in different brain regions relevant to ASD. The results showed that C. difficile infection causes a significant increase in striatal DA, accompanied by significantly altered levels of DA metabolites and NE in different brain regions (p < 0.05). In addition, significantly increased circulating p-cresol levels and reduced DBH activity were observed in C. difficile infected mice (p < 0.05). Therefore, the results from this study suggest a potential link between C. difficile infection and alterations in the dopaminergic axis implicated in the precipitation and aggravation of ASD.

Clostridioides difficile is an antibiotic-resistant bacterium that causes serious, toxin-mediated enteric disease in humans and animals. Gut dysbiosis and resultant alterations in the intestinal bile acid profile play an important role in the pathogenesis of C. difficile infection (CDI). Restoration of the gut microbiota and re-establishment of bacterial bile acid metabolism using fecal microbiota transplantation (FMT) has been established as a promising strategy against this disease, although this method has several limitations. Thus, a more defined and precise microbiota-based approach using bacteria that biotransform primary bile acids into secondary bile acids could effectively overcome these limitations and control CDI. Therefore, a screening pipeline was developed to isolate bile acid converting bacteria from fecal samples. Dogs were selected as a model CDI-resistant microbiota donor for this pipeline, which yielded a novel Peptacetobacter hiranonis strain that possesses unique anti- C. difficile properties, and both bile acid deconjugation and 7-α dehydroxylating activities to perform bile acid conversion. The screening pipeline included a set of in vitro tests along with a precision in vivo gut colonization and bile acid conversion test using altered Schadler flora (ASF) colonized mice. In addition, this pipeline also provided essential information on the growth requirements for screening and cultivating the candidate bacterium, its survival in a CDI predisposing environment, and potential pathogenicity. The model pipeline documented here yielded multiple bile acid converting bacteria, including a P. hiranonis isolate with unique anti- C. difficile biotherapeutic potential, which can be further tested in subsequent preclinical and human clinical trials.

Clostridioides difficile infection increases circulating p-cresol levels and dysregulates brain 1 dopamine metabolism: linking gut-brain axis to autism and other neurologic disorders? 2 Akhil A. Vinithakumari, Piyush Padhi, Belen Hernandez, Susanne Je-Han Lin, Aaron 3 Dunkerson-Kurzhumov, Lucas Showman, Mattew Breitzman, Caroline Stokes, Yousuf 4 Sulaiman, Chandra Tangudu, Deepa Ashwarya Kuttappan, Muhammed Shafeekh 5 Muyyarikkandy, Gregory J. Phillips, Vellareddy Anantharam, Ann Perera, Brett Sponseller, 6 Anumantha Kanthasamy, and Shankumar Mooyottu* 7

Clostridioides difficile, previously Clostrdium difficile, is a major cause of antibiotic-associated enteric disease in humans in hospital settings. Increased incidence of C. difficile infection (CDI) in community settings raises concerns over an alternative source of CDI for humans. The detection of genetically similar and toxigenic C. difficile isolates in companion animals, including asymptomatic pets, suggests the potential role of household pets as a source of community-associated CDI. The close association between companion animals and humans, in addition to the use of similar antibiotics in both species, could provide a selective advantage for the emergence of new C. difficile strains and thus increase the incidental transmission of CDI to humans. Therefore, screening household pets for C. difficile is becoming increasingly important from a public health standpoint and may become a part of routine testing in the future, for the benefit of susceptible or infected individuals within a household. In this review, we analyze available information on prevalence, pathophysiology, epidemiology, and molecular genetics of C. difficile infection, focusing on companion animals and evaluate the risk of pet-borne transmission of CDI as an emerging public health concern. Molecular epidemiological characterization of companion animal C. difficile strains could provide further insights into the interspecies transmission of CDI. The mosaic nature of C. difficile genomes and their susceptibility to horizontal gene transfer may facilitate the inter-mixing of genetic material, which could increase the possibility of the emergence of new community-associated CDI strains. However, detailed genome-wide characterization and comparative genome analysis are warranted to confirm this hypothesis.

Canine transitional cell carcinoma (TCC) of the bladder accounts for 2% of diagnosed canine cancers. Most TCCs are inoperable and unresponsive to traditional chemotherapy. Median survival time is typically less than a year for all treatments indicating a need for more effective therapies. Recent studies have discovered that approximately 70% of canine TCCs harbor mutations in the proto‐oncogene BRAF, a kinase involved in the mitogen‐activated protein kinase (MAPK) pathway that controls cell proliferation, differentiation, and apoptosis. BRAF mutations are present in several human cancers, most of which exhibit adaptive or intrinsic resistance to BRAF‐targeted inhibitors. The goals of this study were to (1) further characterize the role of mutant BRAF in canine TCC and (2) determine whether inhibition of the MAPK pathway alone or in combination with other gene targets may be an effective therapy for TCC treatment.Analysis of ERK1/2 phosphorylation following serum starvation indicates that TCC cell lines exhibit constitutive MAPK pathway activation independent of their BRAF mutation status. MAPK activity was further quantified using gene expression analysis of ten MAPK target genes, revealing that TCC cell lines have significantly higher MAPK pathway activity compared to other canine cancer cell lines. These data suggest a causative role for MAPK signaling in TCC pathogenesis. To determine whether the MAPK pathway could be a therapeutic target for TCC treatment we assessed the effect of BRAF and MEK inhibition on TCC cell proliferation and ERK1/2 phosphorylation. Four BRAF mutant human cell lines with varying degrees of sensitivity to BRAF‐targeted agents were used to determine the relative sensitivity of canine TCC cell lines. BRAF mutant TCC cell lines were sensitive to BRAF inhibition with the “paradox‐breaking” inhibitor PLX7904 (IC50: 0.2–1.2μM), but not vemurafenib (IC50: 7–21μM). Both BRAF wild type and mutant TCC cell lines were sensitive to MEK inhibition with selumetinib (IC50: 15–420nM) and trametinib (IC50: 0.4–8nM). ERK1/2 phosphorylation decreased after 6‐hour treatments with MAPK inhibitors, but rebounded by 24 hours suggesting the presence of resistance mechanisms. Microarray analysis indicated that the ErbB family of receptors and ligands are up‐regulated in TCC cell lines relative to other canine cancer cell lines (fold‐change > 2, q < 0.05). Combined BRAF and ErbB inhibition synergized in the BRAF mutant Bliley TCC cell line, while combined MEK and ErbB inhibition synergized in both Bliley and BRAF wild type Kinsey cells. These findings suggest that targeting ErbB receptors with MAPK inhibition is a potential therapy for canine TCC treatment. Additionally, our data indicate that canine TCC may serve as a naturally‐occurring model for the study of resistance mechanisms to MAPK inhibition in human cancers.Support or Funding InformationMorris Animal Foundation, Shipley University Chair in Comparative OncologyThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Transitional cell carcinoma (TCC) of the bladder comprises 2% of diagnosed canine cancers. TCC tumors are generally inoperable and unresponsive to traditional chemotherapy, indicating a need for more effective therapies. BRAF, a kinase in the mitogen-activated protein kinase (MAPK) pathway, is mutated in 70% of canine TCCs. In this study, we use BRAF mutant and wild-type TCC cell lines to characterize the role of BRAF mutations in TCC pathogenesis and assess the efficacy of inhibition of the MAPK pathway alone and in combination with other gene targets as a treatment for canine TCC. Analysis of MAPK target gene expression and assessment of extracellular signal-regulated kinase (ERK) 1/2 phosphorylation following serum starvation indicated constitutive MAPK activity in all TCC cell lines. BRAF mutant TCC cell lines were insensitive to the BRAF inhibitor vemurafenib, with IC50 values greater than 5 μM, but exhibited greater sensitivity to a paradox-breaking BRAF inhibitor (IC50: 0.2-1 μM). All TCC cell lines had IC50 values less than 7 nM to the mitogen-activated protein kinase kinase (MEK) 1/2 inhibitor trametinib independent of their BRAF mutation status. ERK1/2 phosphorylation decreased after 6-hour treatments with MAPK inhibitors, but rebounded by 24 hours, suggesting the presence of resistance mechanisms. Microarray analysis identified elevated expression of the ErbB family of receptors and ligands in TCC cell lines. The pan-ErbB inhibitor sapitinib synergized with BRAF inhibition in BRAF mutant Bliley TCC cells and synergized with MEK1/2 inhibition in Bliley and BRAF wild-type Kinsey cells. These findings suggest the potential for combined MAPK and ErbB receptor inhibition as a therapy for canine TCC. SIGNIFICANCE STATEMENT: The results of this study (1) identify a novel combination strategy for canine bladder cancer treatment: targeting the ErbB/MAPK signaling cascade and (2) establish the utility of canine bladder cancer as a naturally-occurring model for human MAPK-driven cancers.

Melanoma remains mostly an untreatable fatal disease despite advances in decoding cancer genomics and developing new therapeutic modalities. Progress in patient care would benefit from additional predictive models germane for human disease mechanisms, tumor heterogeneity, and therapeutic responses. Toward this aim, this review documents comparative aspects of human and naturally occurring canine melanomas. Clinical presentation, pathology, therapies, and genetic alterations are highlighted in the context of current basic and translational research in comparative oncology. Somewhat distinct from sun exposure-related human cutaneous melanomas, there is growing evidence that a variety of gene copy number alterations and protein structure/function mutations play roles in canine melanomas, in circumstances more analogous to human mucosal melanomas and to some extent other melanomas with murine sarcoma viral oncogene homolog B (BRAF), Neuroblastoma RAS Viral (V-Ras) Oncogene Homolog (NRAS), and neurofibromin 1 tumor suppressor NF1 triple wild-type genotype. Gaps in canine genome annotation, as well as an insufficient number and depth of sequences covered, remain considerable barriers to progress and should be collectively addressed. Preclinical approaches can be designed to include canine clinical trials addressing immune modulation as well as combined-targeted inhibition of Rat Sarcoma Superfamily/Mitogen-activated protein kinase (RAS/MAPK) and/or Phosphatidylinositol-3-Kinase/Protein Kinase B/Mammalian target of rapamycin (PI3K/AKT/mTOR) signal transduction, pathways frequently activated in both human and canine melanomas. Future investment should be aimed towards improving understanding of canine melanoma as a predictive preclinical surrogate for human melanoma and for mutually benefiting these uniquely co-dependent species.

Abstract Transitional cell carcinoma (TCC) accounts for approximately 2% of diagnosed malignancies in canines. The majority of canine TCCs are invasive, intermediate to high grade tumors sharing similarities with human muscle invasive TCCs in risk factors, histology, sites of metastasis, and therapeutic response to single agents. Whole exome sequencing of canine TCC tumors was performed to identify somatic mutations in known cancer driver and repressor genes that could potentially contribute to canine TCC pathogenesis. A valine to glutamic acid mutation in BRAF homologous to the activating V600E mutation identified in human melanoma, colorectal and thyroid cancers was identified in 70% of sequenced tumors. Sensitivity to the BRAFV600E inhibitor Vemurafenib was tested in three BRAF mutant canine TCC cell lines (Bliley, Tyler1 and Tyler2) and two BRAF wild type canine TCC cell lines (Angus1 and Kinsey). All five canine TCC cell lines exhibited IC50s greater than 10μM, with BRAF mutant cell lines being slightly more sensitive. These sensitivity ranges are similar to those of some mutant human colorectal cancer cell lines, indicating that additional mechanisms may contribute to Vemurafenib resistance. Western blot analysis was performed to measure relative abundance of pERK, a downstream target of BRAF, in canine TCCs in response to serum starvation. All TCC cell lines showed sustained pERK expression in the absence of serum, indicating constitutive activation of the MAPK pathway. The five canine TCC lines were treated with 15μM Vemurafenib for 6 and 24 hours and their lysates were analyzed for pERK protein expression. pERK abundance was decreased in only the BRAF mutant cell lines after 6 hours of treatment. However, this decrease was less pronounced after 24 hours, suggesting that resistance mechanisms are bypassing BRAF to activate ERK. Sequence analysis of an additional panel of formalin-fixed paraffin embedded canine TCCs also revealed a mutation in RanBP2 in 31% of samples. Strikingly, the RanBP2 mutation appeared to be mutually exclusive to BRAF V to E mutant tumors with only two of the analyzed samples carrying both mutations. Significant tumor heterogeneity was implicated due to low level mutant amplification in these samples. It has been reported that loss of RanBP2 is synthetic lethal in BRAF V600E mutant colorectal cancer. Since RanBP2 forms complexes with CRM1 at the nuclear pore complex for nuclear export and at the kinetochore during mitosis, canine TCC cell lines were treated with KPT-185, a CRM1 inhibitor. BRAF mutant TCC cell lines had IC50 values ranging from 45nM to 65nM and were approximately ten-fold more sensitive than wild type cell lines. Overall, this data indicates that the pathogenesis of canine TCC likely depends on driving factors in addition to constitutive BRAF signaling, but Vemurafenib resistant BRAF mutant tumors can be targeted through inhibition of the nucleopore complex. Citation Format: Kathryn Cronise, Belen Hernandez, Daniel L. Gustafson, Dawn L. Duval. Investigating the dependence of canine bladder transitional cell carcinoma on activated mutant BRAF [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 324. doi:10.1158/1538-7445.AM2017-324

Abstract Transitional cell carcinoma (TCC) is the most common bladder cancer in humans and their canine companions. Canine TCCs are usually papillary infiltrative TCCs of intermediate to high grade. Genetic defects identified in human TCCs aid in the diagnosis and therapy of human bladder cancer. We utilized whole exome sequencing to screen canine TCCs for gene mutations that contribute to pathogenesis. Genomic DNA was isolated from 11 canine TCCs, 3 matched normal tissue samples, and 2 canine TCC cell lines. Whole exome capture was conducted using the Canine Agilent Sure-select in-solution capture system, and captured fragments were sequenced using an Illumina HiSeq2000 platform. The sequences were mapped to the CanFam3.1 canine reference genome and somatic mutations were identified using Freebayes. Somatic mutations were characterized and compared to the Cancer Gene Census (COSMIC). Nonsense, missense, and insertion/deletion mutations were identified in 126 genes shown to be drivers or repressors in human cancer. Missense mutations were further screened using SIFT to identify alterations deleterious to protein function. The genes exhibiting in/dels, nonsense, or missense mutations with SIFT scores < 0.45 in at least 2 sites or 2 samples were: BRAF, RPL5, RANBP2, EWSR1, NONO, PTPRB, LYL1, JAK1, MSH2, PER1, PIM1, and WRN. In fact, an activating BRAF V to E mutation was identified in 5 of the tumors and both cell lines. The RPL5 and RANBP2 mutations were also hotspot mutations identified in 5 and 3 of the samples, respectively. Mutations were confirmed using Sanger sequencing of amplified genomic DNA. Interestingly, deleterious RANBP2 mutations were only observed in non-BRAF mutant samples. Drug sensitivity assays using the BRAF V600E targeting drug, Vemurafenib, were conducted in the BRAF mutant canine cell lines as well as the BRAF mutant human A375 melanoma cell line. As previously described, the IC50 for the sensitive A375 line was approximately 100 nM, while each of the BRAF mutant canine lines had an IC50 value ≥ 10 μM. Reverse transcriptase PCR was used to amplify the coding sequence for BRAF from the Bliley canine TCC cell line. The amplified transcript (2125 bp) was sequenced, confirming the heterozygous expression of the V548 to E mutant form of BRAF in this cell line. The sequence also indicated that the predicted expressed protein (AA 10 - 715 of XP_013975364.1, corresponding to predicted exons 1 through 20 of XM_014119889.1) exhibited 99% homology to human BRAF AA53 - 763 (NP_004324.2). BRAF protein expression in these cell lines was confirmed by Western blot analysis. Thus, insensitivity to Vemurafenib is not due to differences in canine BRAF, reduced expression, or alternative splicing of the expressed transcript as previously observed in some Vemurafenib resistant human melanomas. These data indicate that although constitutively active BRAF is expressed in canine TCC, other factors may contribute to pathogenesis. Citation Format: Belen Hernandez, Kathryn Cronise, James C. Costello, Rodney Page, Susan Lana, Kenneth L. Jones, Dawn L. Duval. Canine transitional cell carcinoma of the bladder expresses activated BRAF, but is not sensitive to vemurafenib. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 617.