Blimp-1 and c-Maf regulate immune gene networks to protect against distinct pathways of pathobiont-induced colitis.

Intestinal immune responses to microbes are controlled by the cytokine IL-10 to avoid immune pathology. Here, we use single-cell RNA sequencing of colon lamina propria leukocytes (LPLs) along with RNA-seq and ATAC-seq of purified CD4+ T cells to show that the transcription factors Blimp-1 (encoded by Prdm1) and c-Maf co-dominantly regulate Il10 while negatively regulating proinflammatory cytokines in effector T cells. Double-deficient Prdm1fl/flMaffl/flCd4Cre mice infected with Helicobacter hepaticus developed severe colitis with an increase in TH1/NK/ILC1 effector genes in LPLs, while Prdm1fl/flCd4Cre and Maffl/flCd4Cre mice exhibited moderate pathology and a less-marked type 1 effector response. LPLs from infected Maffl/flCd4Cre mice had increased type 17 responses with increased Il17a and Il22 expression and an increase in granulocytes and myeloid cell numbers, resulting in increased T cell-myeloid-neutrophil interactions. Genes over-expressed in human inflammatory bowel disease showed differential expression in LPLs from infected mice in the absence of Prdm1 or Maf, revealing potential mechanisms of human disease.

Vitamin D regulates microbiome-dependent cancer immunity.

A role for vitamin D in immune modulation and in cancer has been suggested. In this work, we report that mice with increased availability of vitamin D display greater immune-dependent resistance to transplantable cancers and augmented responses to checkpoint blockade immunotherapies. Similarly, in humans, vitamin D-induced genes correlate with improved responses to immune checkpoint inhibitor treatment as well as with immunity to cancer and increased overall survival. In mice, resistance is attributable to the activity of vitamin D on intestinal epithelial cells, which alters microbiome composition in favor of Bacteroides fragilis, which positively regulates cancer immunity. Our findings indicate a previously unappreciated connection between vitamin D, microbial commensal communities, and immune responses to cancer. Collectively, they highlight vitamin D levels as a potential determinant of cancer immunity and immunotherapy success.

Streptococcus zooepidemicus in dogs: Exploring a canine pathogen through multilocus sequence typing.

Streptococcus equi. subsp. zooepidemicus (S. zooepidemicus) associated diseases in dogs have emerged as a significant concern over recent decades. S. zooepidemicus occurs sporadically in dog populations globally, with increased prevalence in shelters/kennels. This study used multilocus sequence typing (MLST) of 149 independent canine S. zooepidemicus isolates to assess associations between sequence type and breed, country of origin, disease severity, sampling type, year, and behaviour within an outbreak. No clear associations for breed, country, sampling type and year were determined in this study. ST-10 and 123 strains were present within all disease categories, from no clinical signs to severe disease. Assessment of S. zooepidemicus infection in 3 UK outbreaks at the same location found ST-10, 18, 123 strains, and a ST-173 strain in a US outbreak, were associated with haemorrhagic pneumonia and persisted in kennelled populations over time. The ST-173 clonal complex has been noted to have severe virulence capabilities in dogs and other species. S. zooepidemicus seems to thrive in environments with a high risk of transmissibility, overcrowding, stress and naïve populations, particularly for those in shelters/kennels. MLST alone cannot determine the virulence phenotype of S. zooepidemicus in dogs. However, a level of conservancy and diversity within ST allelic loci aids the opportunity to cause severe disease in dogs. Thus, further research into whole genome sequencing and characterising the virulence factors of S. zooepidemicus is warranted in dogs.

Feline ventral abdominal wall angiosarcoma: haemangiosarcoma or lymphangiosarcoma? Clinical and pathological characteristics in nine cases.

OBJECTIVES: Angiosarcomas are rare malignant mesenchymal neoplasms of endothelial cell origin with a predilection to the ventral abdominal wall in cats. Larger case series describing this entity are lacking. METHODS: Two referral centre laboratory databases were searched for angiosarcoma of the ventral abdominal wall. Nine cases with a histological diagnosis were included. Immunohistochemistry (factor VIII and PROX-1 antibodies) was used to phenotype them as haemangiosarcoma or lymphangiosarcoma. RESULTS: All cats presented with a ventral abdominal mass, five of which were producing a serosanguinous discharge. Eight underwent tumour staging and pulmonary metastases were suspected in one cat (but not histologically confirmed). With histopathology alone, a diagnosis of angiosarcoma and lymphangiosarcoma was made in four and five cases, respectively. After immunohistochemistry, five cases had a haemangiosarcoma phenotype and four had a lymphangiosarcoma phenotype, including two cases of lymphangiosarcoma that were reclassified as hemangiosarcoma. Eight cats received treatment (either surgery with or without adjuvant therapies or medical management alone). Six cats were euthanased due to local disease progression. The median survival time for haemangiosarcoma was 166 days (range 137-381), and for lymphangiosarcoma it was 197 days (range 67-208). Two cats with haemangiosarcoma remained alive for a follow-up period of 329 and 580 days, respectively. CONCLUSIONS AND RELEVANCE: Feline ventral abdominal angiosarcomas are rare locally aggressive neoplasms. While histology often provides a diagnosis of angiosarcoma, immunohistochemistry is ultimately required to differentiate between haemangiosarcoma and lymphangiosarcoma phenotypes. Further studies are required to evaluate whether the different phenotypes have an impact on treatment response and outcome.

The role of APOBEC3B in lung tumor evolution and targeted cancer therapy resistance.

In this study, the impact of the apolipoprotein B mRNA-editing catalytic subunit-like (APOBEC) enzyme APOBEC3B (A3B) on epidermal growth factor receptor (EGFR)-driven lung cancer was assessed. A3B expression in EGFR mutant (EGFRmut) non-small-cell lung cancer (NSCLC) mouse models constrained tumorigenesis, while A3B expression in tumors treated with EGFR-targeted cancer therapy was associated with treatment resistance. Analyses of human NSCLC models treated with EGFR-targeted therapy showed upregulation of A3B and revealed therapy-induced activation of nuclear factor kappa B (NF-κB) as an inducer of A3B expression. Significantly reduced viability was observed with A3B deficiency, and A3B was required for the enrichment of APOBEC mutation signatures, in targeted therapy-treated human NSCLC preclinical models. Upregulation of A3B was confirmed in patients with NSCLC treated with EGFR-targeted therapy. This study uncovers the multifaceted roles of A3B in NSCLC and identifies A3B as a potential target for more durable responses to targeted cancer therapy.

Cross-species oncogenomics offers insight into human muscle-invasive bladder cancer.

BACKGROUND: In humans, muscle-invasive bladder cancer (MIBC) is highly aggressive and associated with a poor prognosis. With a high mutation load and large number of altered genes, strategies to delineate key driver events are necessary. Dogs and cats develop urothelial carcinoma (UC) with histological and clinical similarities to human MIBC. Cattle that graze on bracken fern also develop UC, associated with exposure to the carcinogen ptaquiloside. These species may represent relevant animal models of spontaneous and carcinogen-induced UC that can provide insight into human MIBC. RESULTS: Whole-exome sequencing of domestic canine (n = 87) and feline (n = 23) UC, and comparative analysis with human MIBC reveals a lower mutation rate in animal cases and the absence of APOBEC mutational signatures. A convergence of driver genes (ARID1A, KDM6A, TP53, FAT1, and NRAS) is discovered, along with common focally amplified and deleted genes involved in regulation of the cell cycle and chromatin remodelling. We identify mismatch repair deficiency in a subset of canine and feline UCs with biallelic inactivation of MSH2. Bovine UC (n = 8) is distinctly different; we identify novel mutational signatures which are recapitulated in vitro in human urinary bladder UC cells treated with bracken fern extracts or purified ptaquiloside. CONCLUSION: Canine and feline urinary bladder UC represent relevant models of MIBC in humans, and cross-species analysis can identify evolutionarily conserved driver genes. We characterize mutational signatures in bovine UC associated with bracken fern and ptaquiloside exposure, a human-linked cancer exposure. Our work demonstrates the relevance of cross-species comparative analysis in understanding both human and animal UC.

Endothelial AHR activity prevents lung barrier disruption in viral infection.

Disruption of the lung endothelial-epithelial cell barrier following respiratory virus infection causes cell and fluid accumulation in the air spaces and compromises vital gas exchange function1. Endothelial dysfunction can exacerbate tissue damage2,3, yet it is unclear whether the lung endothelium promotes host resistance against viral pathogens. Here we show that the environmental sensor aryl hydrocarbon receptor (AHR) is highly active in lung endothelial cells and protects against influenza-induced lung vascular leakage. Loss of AHR in endothelia exacerbates lung damage and promotes the infiltration of red blood cells and leukocytes into alveolar air spaces. Moreover, barrier protection is compromised and host susceptibility to secondary bacterial infections is increased when endothelial AHR is missing. AHR engages tissue-protective transcriptional networks in endothelia, including the vasoactive apelin-APJ peptide system4, to prevent a dysplastic and apoptotic response in airway epithelial cells. Finally, we show that protective AHR signalling in lung endothelial cells is dampened by the infection itself. Maintenance of protective AHR function requires a diet enriched in naturally occurring AHR ligands, which activate disease tolerance pathways in lung endothelia to prevent tissue damage. Our findings demonstrate the importance of endothelial function in lung barrier immunity. We identify a gut-lung axis that affects lung damage following encounters with viral pathogens, linking dietary composition and intake to host fitness and inter-individual variations in disease outcome.

Type I interferons drive MAIT cell functions against bacterial pneumonia.

Mucosal-associated invariant T (MAIT) cells are abundant in the lung and contribute to host defense against infections. During bacterial infections, MAIT cell activation has been proposed to require T cell receptor (TCR)-mediated recognition of antigens derived from the riboflavin synthesis pathway presented by the antigen-presenting molecule MR1. MAIT cells can also be activated by cytokines in an MR1-independent manner, yet the contribution of MR1-dependent vs. -independent signals to MAIT cell functions in vivo remains unclear. Here, we use Klebsiella pneumoniae as a model of bacterial pneumonia and demonstrate that MAIT cell activation is independent of MR1 and primarily driven by type I interferons (IFNs). During Klebsiella infection, type I IFNs stimulate activation of murine and human MAIT cells, induce a Th1/cytotoxic transcriptional program, and modulate MAIT cell location within the lungs. Consequently, adoptive transfer or boosting of pulmonary MAIT cells protect mice from Klebsiella infection, with protection being dependent on direct type I IFN signaling on MAIT cells. These findings reveal type I IFNs as new molecular targets to manipulate MAIT cell functions during bacterial infections.

Olfactory neuroblastoma in a domestic cat and review of the literature.

Nasal tumors account for less than 10% of all feline neoplasms, with lymphoma, followed by adenocarcinoma, and squamous cell carcinoma, the most commonly reported. Nasal neuroectodermal tumors, including olfactory neuroblastoma (ONB), are scarcely described, and their tumorigenesis is largely unknown. Here we report the cytological, histological, and immunohistochemical features of a feline ONB. We also provide a pathological review of nasal neuroendocrine neoplasms in cats. A 7-year-old Burmese cat was evaluated for sneezing, occasional epistaxis, and upper respiratory noise for 8 months. Computed tomography (CT) imaging revealed a 7 × 5 × 3 mm irregular mass effacing and expanding the nasal cavity, which extended to the nasopharynx. Cytologically, neoplastic cells were round to polygonal and had a round nucleus with finely stippled chromatin, a single small nucleolus, and abundant pale blue cytoplasm, which contained abundant fine pale pink granules. They exhibited mild cellular atypia, anisocytosis, and mild to occasionally moderate anisokaryosis. Rhinoscopic biopsies revealed a densely cellular, malignant neuroepithelial neoplasm. Cells were arranged in densely packed trabeculae and formed Homer Wright and Flexner-Wintersteiner-like rosettes, with rare mitotic figures and scant supportive fibrovascular stroma. Immunohistochemically, neoplastic cells were positive for vimentin, cytokeratin AE1/AE3, COX-2, and beta-tubulin and negative for S-100, chromogranin A, CD117, and epithelial membrane antigen (EMA). An ONB was diagnosed based on histological and immunohistochemical findings. Interestingly, and similar to nasal carcinomas, neoplastic cells diffusely neo-expressed COX-2. To the authors' knowledge, there is no previous evidence of COX-2 in feline ONB. Histopathology and immunohistochemistry are required for a definitive diagnosis of ONB.

Urinary bladder hemangiosarcoma in a cat treated with partial cystectomy and adjuvant metronomic cyclophosphamide and thalidomide.

Visceral hemangiosarcomas (HSA) are rare in cats and typically associated with aggressive biologic behavior and poor prognosis. A 4-year-old male neutered domestic shorthair cat was presented with a 3-month history of hematuria and stranguria; ultrasonography identified a large bladder mass. Complete excision was achieved by partial cystectomy. Histopathology and immunohistochemistry for von Willebrand factor confirmed HSA. The cat was treated using adjuvant cyclophosphamide, thalidomide, and meloxicam for 8 months. Abdominal ultrasonography repeated at 2 months and computed tomography repeated at 5 and 19 months after diagnosis showed no evidence of local recurrence or metastasis. The cat was alive at last follow-up (896 days). Although the cat described in this report experienced a more favorable prognosis compared to other visceral HSA locations, additional cases are needed to further understand the biological behavior of bladder HSAs and guide treatment decisions.

Veterinary Comparative Pathology, a Scientific Tool for a Thriving Planet.

In recent years, Earth has overcome unpredictable challenges [...].

Pathology and causes of death in captive meerkats (Suricata suricatta).

BACKGROUND: Meerkats (Suricata suricatta) are endemic carnivores of southern Africa and, although currently listed as 'least concern' by the International Union for Conservation of Nature (IUCN) red list, there is evidence of a significant decrease in wild populations mainly attributed to effects of climate change. Little is known about diseases associated with mortality in captive meerkats. AIM: To characterise macroscopic and microscopic lesions that accounted for the death or euthanasia in a series of captive meerkats. MATERIAL AND METHODS: Eight captive meerkats submitted for post-mortem examination between 2018 and 2022. RESULTS: Three animals died unexpectedly without clinical signs, 2 exhibited neurological signs, 2 collapsed after con-specific fighting and 1 showed gastrointestinal signs. Common pathological findings of this study that may be related to the death of captive meerkats included foreign bodies (trichobezoars or plastic materials) within the alimentary tract, traumatic penetrating injuries or starvation associated with abnormal social behaviours (bullying and con-specific attacks), verminous pneumonia and systemic atherosclerosis. Common incidental findings included pulmonary edema and congestion, cholesterol granulomas, pulmonary adenomas and vertebral spondylosis. CONCLUSIONS: Non-infectious diseases outreach infectious diseases as causes of mortality in captive meerkats including, foreign bodies within the alimentary tract, con-specific attacks and systemic atherosclerosis, which is described for the first time. These data should raise concern about appropriate husbandry (e.g. environmental enrichment, cleaning of facilities and diet formulation) by zookeepers and emphasise the need for further study of meerkat mortality in both captive and wild populations.

Lung adenocarcinoma promotion by air pollutants.

A complete understanding of how exposure to environmental substances promotes cancer formation is lacking. More than 70 years ago, tumorigenesis was proposed to occur in a two-step process: an initiating step that induces mutations in healthy cells, followed by a promoter step that triggers cancer development1. Here we propose that environmental particulate matter measuring ≤2.5 µm (PM2.5), known to be associated with lung cancer risk, promotes lung cancer by acting on cells that harbour pre-existing oncogenic mutations in healthy lung tissue. Focusing on EGFR-driven lung cancer, which is more common in never-smokers or light smokers, we found a significant association between PM2.5 levels and the incidence of lung cancer for 32,957 EGFR-driven lung cancer cases in four within-country cohorts. Functional mouse models revealed that air pollutants cause an influx of macrophages into the lung and release of interleukin-1ß. This process results in a progenitor-like cell state within EGFR mutant lung alveolar type II epithelial cells that fuels tumorigenesis. Ultradeep mutational profiling of histologically normal lung tissue from 295 individuals across 3 clinical cohorts revealed oncogenic EGFR and KRAS driver mutations in 18% and 53% of healthy tissue samples, respectively. These findings collectively support a tumour-promoting role for  PM2.5 air pollutants  and provide impetus for public health policy initiatives to address air pollution to reduce disease burden.

Clinical and clinicopathological features and outcomes of cats with suspected dietary induced pancytopenia.

BACKGROUND: After a strong epidemiological link to diet was established in an outbreak of pancytopenia in cats in spring 2021 in the United Kingdom, 3 dry diets were recalled. Concentrations of the hemato- and myelotoxic mycotoxins T-2, HT-2 and diacetoxyscirpenol (DAS) greater than the European Commission guidance for dry cat foods were detected in the recalled diets. OBJECTIVES: To describe clinical and clinicopathological findings in cats diagnosed with suspected diet induced pancytopenia. ANIMALS: Fifty cats presenting with pancytopenia after exposure to a recalled diet. METHODS: Multicenter retrospective case series study. Cats with known exposure to 1 of the recalled diets were included if presented with bi- or pancytopenia and underwent bone marrow examination. RESULTS: Case fatality rate was 78%. Bone marrow aspirates and biopsy examination results were available in 23 cats; 19 cats had a bone marrow aspirate, and 8 cats had a biopsy core, available for examination. Bone marrow hypo to aplasia-often affecting all cell lines-was the main feature in all 31 available core specimens. A disproportionately pronounced effect on myeloid and megakaryocytic cells was observed in 19 cats. Myelofibrosis or bone marrow necrosis was not a feature. CONCLUSION AND CLINICAL IMPORTANCE: Mycotoxin induced pancytopenia should be considered as differential diagnosis in otherwise healthy cats presenting with bi- or pancytopenia and bone marrow hypo- to aplasia.

Intrinsic host susceptibility among multiple species to intranasal SARS-CoV-2 identifies diverse virological, biodistribution and pathological outcomes.

SARS-CoV-2 exhibits a diverse host species range with variable outcomes, enabling differential host susceptibility studies to assess suitability for pre-clinical countermeasure and pathogenesis studies. Baseline virological, molecular and pathological outcomes were determined among multiple species-one Old World non-human primate (NHP) species (cynomolgus macaques), two New World NHP species (red-bellied tamarins; common marmosets) and Syrian hamsters-following single-dose, atraumatic intranasal administration of SARS-CoV-2/Victoria-01. After serial sacrifice 2, 10 and 28-days post-infection (dpi), hamsters and cynomolgus macaques displayed differential virus biodistribution across respiratory, gastrointestinal and cardiovascular systems. Uniquely, New World tamarins, unlike marmosets, exhibited high levels of acute upper airway infection, infectious virus recovery associated with mild lung pathology representing a host previously unrecognized as susceptible to SARS-CoV-2. Across all species, lung pathology was identified post-clearance of virus shedding (antigen/RNA), with an association of virus particles within replication organelles in lung sections analysed by electron microscopy. Disrupted cell ultrastructure and lung architecture, including abnormal morphology of mitochondria 10-28 dpi, represented on-going pathophysiological consequences of SARS-CoV-2 in predominantly asymptomatic hosts. Infection kinetics and host pathology comparators using standardized methodologies enables model selection to bridge differential outcomes within upper and lower respiratory tracts and elucidate longer-term consequences of asymptomatic SARS-CoV-2 infection.

Elevated angiotensin-converting enzyme 2 (ACE2) expression in cats with hypertrophic cardiomyopathy.

Angiotensin-converting enzyme 2 (ACE2) is an enzyme within the renin-angiotensin-aldosterone system that plays a role in regulating blood pressure. However, it is also a cellular receptor for infection with SARS coronaviruses. Although most cats develop subclinical or mild disease following infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) acquired from human patients, a previous study has suggested hypertrophic cardiomyopathy (HCM) is a potential risk factor for the development of severe disease in the cat. Herein we investigate the ACE2 protein expression in the lung, heart, and kidney from a small subset of cats with (n = 10) and without HCM (n = 10) by immunohistochemistry. The abundance and intensity of ACE2 expression is slightly elevated in alveoli (p = 0.09; 0.07, respectively) and bronchioles (p = 0.095; 0.37, respectively). However, statistically elevated abundance and intensity of ACE-2 expression was only evident in the heart of cats with HCM (p = 0.032; p = 0.011, respectively). Further investigation did not demonstrate a statistical correlation between the ACE2 expression in the heart in relation to the heart weight to body weight ratio, and the ventricular wall ratio. Current findings suggest an overexpression of ACE2 in HCM cases but follow up study is warranted to understand the pathophysiological process.

Histopathological description of iridophoromas resembling skin nodule syndrome in Siamese fighting fish Betta splendens.

Intensive breeding of the Siamese fighting fish Betta splendens, a species that inhabits marshlands in Thailand and other countries in south-east Asia, was traditionally focused on game fighting because the males are very territorial, but has evolved to become mainly devoted to ornamental purposes. Recently, a preliminarily named 'skin nodule syndrome' (SNS) has been described affecting this fish species in Thailand, with multiple bacterial infections suggested, including 4 species of Mycobacterium spp., although the etiology remains elusive. Here we describe the histopathological and immunohistochemical characteristics of 2 iridophoromas in 2 male Siamese fighting fish that strongly resemble the lesions described for SNS. Immunohistochemical analysis yielded negative results for Melan-A, PNL-2, and S-100, likely due to species-specific reasons. The results for molecular detection of mycobacterial DNA were also negative in both cases. The published histological lesions of SNS are very similar to the 4 chromatophoromas that have been reported affecting this species since 2015. Taken together with the present cases, we hypothesize that the preliminarily named SNS in fighting fish may be characterized as invasive chromatophoromas, although the true etiology remains to be elucidated and could include infectious and non-infectious causes. Further studies are necessary to examine whether commercial breeding of Siamese fighting fish has resulted in a possible genetic origin.

An Immunogenic Model of KRAS-Mutant Lung Cancer Enables Evaluation of Targeted Therapy and Immunotherapy Combinations.

Mutations in oncogenes such as KRAS and EGFR cause a high proportion of lung cancers. Drugs targeting these proteins cause tumor regression but ultimately fail to elicit cures. As a result, there is an intense interest in how to best combine targeted therapies with other treatments, such as immunotherapies. However, preclinical systems for studying the interaction of lung tumors with the host immune system are inadequate, in part due to the low tumor mutational burden in genetically engineered mouse models. Here we set out to develop mouse models of mutant KRAS-driven lung cancer with an elevated tumor mutational burden by expressing the human DNA cytosine deaminase, APOBEC3B, to mimic the mutational signature seen in human lung cancer. This failed to substantially increase clonal tumor mutational burden and autochthonous tumors remained refractory to immunotherapy. However, establishing clonal cell lines from these tumors enabled the generation of an immunogenic syngeneic transplantation model of KRAS-mutant lung adenocarcinoma that was sensitive to immunotherapy. Unexpectedly, antitumor immune responses were not directed against neoantigens but instead targeted derepressed endogenous retroviral antigens. The ability of KRASG12C inhibitors to cause regression of KRASG12C -expressing tumors was markedly potentiated by the adaptive immune system, highlighting the importance of using immunocompetent models for evaluating targeted therapies. Overall, this model provides a unique opportunity for the study of combinations of targeted and immunotherapies in immune-hot lung cancer. SIGNIFICANCE: This study develops a mouse model of immunogenic KRAS-mutant lung cancer to facilitate the investigation of optimal combinations of targeted therapies with immunotherapies.

Early Isolates of SARS-CoV-2 Result in Different Pathogenesis in the Transduced Mouse Model of COVID-19.

A transduced mouse model of SARS-CoV-2 infection was established using Balb/c mice. This was achieved through the adenovirus-vectored delivery of the hACE2 gene, to render the mice transiently susceptible to the virus. The model was characterised in terms of the dissemination of hACE2 receptor expression, the dissemination of three SARS-CoV-2 virus variants in vivo up to 10 days following challenge, the resulting histopathology and the clinical signs induced in the mice. In transduced mice, the infection was short-term, with a rapid loss in body weight starting at day 2 with maximum weight loss at day 4, followed by subsequent recovery until day 10. The induced expression of the hACE2 receptor was evident in the lungs, but, upon challenge, the SARS-CoV-2 virus disseminated beyond the lungs to spleen, liver and kidney, peaking at day 2 post infection. However, by day 10 post infection, the virus was undetectable. The lung histopathology was characterised by bronchial and alveolar inflammation, which was still present at day 10 post infection. Transduced mice had differential responses to viral variants ranking CVR-Glasgow 1 > Victoria-1 > England-2 isolates in terms of body weight loss. The transduced mouse model provides a consistent and manipulatable model of SARS-CoV-2 infection to screen viral variants for their relative virulence and possible interventions.