Vitamin D status in cats with feline immunodeficiency virus

Feline immunodeficiency virus (FIV) is a lentivirus that can lead to a syndrome of acquired immune dysfunction. Infected cats often remain asymptomatic for several years before immune dysfunction leads to an increased risk for the development of systemic diseases, neoplasia and opportunistic infections. FIV is structurally related to human immunodeficiency virus (HIV) and the pathogenesis of FIV‐related disease is similar to that seen in HIV‐infected patients. Observational studies have documented an association between low plasma vitamin D and HIV infection. Vitamin D status has been shown to be associated with HIV‐related disease progression, morbidity and mortality. The objective of this study was to examine the hypothesis that vitamin D status, as assessed by serum 25‐hydroxyvitamin D [25(OH)D] concentrations, are lower in cats with FIV infection compared to healthy control cats. Serum 25(OH)D concentrations were measured in 20 healthy cats, 39 hospitalized ill cats and 59 cats infected with FIV. Cats which were FIV infected had significantly lower 25(OH)D concentrations compared to healthy control cats. Serum 25(OH)D concentrations were not significantly different between FIV‐infected cats and hospitalized ill cats. Further investigations are warranted to determine whether vitamin D status influences the prognosis of cats infected with FIV

Low vitamin D status is associated with systemic and gastrointestinal inflammation in dogs with a chronic enteropathy

Vitamin D is traditionally known for its role in calcium homeostasis and bone metabolism. However, it has been demonstrated that numerous types of cells express the vitamin D receptor and it is now clear that the physiological roles of vitamin D extend beyond the maintenance of skeletal health. Vitamin D insufficiency, which is typically assessed by measuring the major circulating form of vitamin D, 25 hydroxyvitamin D (25(OH)D), has been associated with a number of disorders in people including hypertension, diabetes, cardiovascular diseases, cancer, autoimmune conditions and infectious diseases. Meta-analyses have demonstrated that serum 25(OH)D concentrations are an important predictor of survival in people with a wide variety of illnesses and have been linked to all-cause mortality in the general human population. The role of vitamin D in non-skeletal disorders in cats and dogs is poorly understood. This is surprising since cats and dogs could act as excellent models for probing the biology of vitamin D. Vitamin D status in people is largely dependent on cutaneous production of vitamin D. This is influenced by many factors such as season, latitude and exposure to ultraviolet (UV) radiation. The interpretation of human studies investigating the effects vitamin D status on disease outcomes are therefore influenced by a number of confounding variables. Unlike humans, domesticated cats and dogs do not produce vitamin D cutaneously and obtain vitamin D only from their diet. The physiological functions and regulation of vitamin D are otherwise similar to humans. Most pets are fed commercial diets containing a relatively standard amount of vitamin D. Consequently, companion animals are attractive model systems in which to examine the relationship vitamin D status and health outcomes. Furthermore, spontaneously occurring model systems which did not require disease to be induced in healthy animals would allow the numbers of animals used in scientist research to be reduced. This thesis aimed to define vitamin D homeostasis in companion animals in three disease settings; in cats with feline immunodeficiency virus (FIV) infection, dogs with chronic enteropathies (CE) and in hospitalised ill cats. Additional aims were to assess the prognostic significance of serum 25(OH)D concentrations in companion animals and the relationship between serum 25(OH)D concentrations and markers of inflammation. The hypothesis of this thesis was that vitamin status D would negatively correlate with presence of disease, markers of inflammation and disease outcomes. As similar findings have been demonstrated in human medicine, the hypothesis was that cats and dogs would be suitable models to investigate the role of vitamin D in human disease. This thesis demonstrates that in dogs with a CE serum 25(OH)D concentrations are negatively correlated with inflammation and are predictive of clinical outcomes. Vitamin D status was also lower in cats with FIV and importantly vitamin D status was predictive of short term mortality in hospitalised ill cats. This research will be of interest to veterinary surgeons and opens the possibility for clinical trials which examine if low vitamin D status is causally associated with ill health and whether vitamin D supplementation results in superior treatment outcomes in companion animals. This thesis also demonstrates the potential of cats and dogs as model systems in which to examine the role of vitamin D in human health

Vitamin d status predicts 30 day mortality in hospitalised cats

Vitamin D insufficiency, defined as low serum concentrations of the major circulating form of vitamin D, 25 hydroxyvitamin D (25(OH)D), has been associated with the development of numerous infectious, inflammatory, and neoplastic disorders in humans. In addition, vitamin D insufficiency has been found to be predictive of mortality for many disorders. However, interpretation of human studies is difficult since vitamin D status is influenced by many factors, including diet, season, latitude, and exposure to UV radiation. In contrast, domesticated cats do not produce vitamin D cutaneously, and most cats are fed a commercial diet containing a relatively standard amount of vitamin D. Consequently, domesticated cats are an attractive model system in which to examine the relationship between serum 25(OH)D and health outcomes. The hypothesis of this study was that vitamin D status would predict short term, all-cause mortality in domesticated cats. Serum concentrations of 25(OH)D, together with a wide range of other clinical, hematological, and biochemical parameters, were measured in 99 consecutively hospitalised cats. Cats which died within 30 days of initial assessment had significantly lower serum 25(OH)D concentrations than cats which survived. In a linear regression model including 12 clinical variables, serum 25(OH)D concentration in the lower tertile was significantly predictive of mortality. The odds ratio of mortality within 30 days was 8.27 (95% confidence interval 2.54-31.52) for cats with a serum 25(OH)D concentration in the lower tertile. In conclusion, this study demonstrates that low serum 25(OH)D concentration status is an independent predictor of short term mortality in cats

Phenotyping the tumour microenvironment in non-small lung cancer using patient derived samples

Lung cancers accounts for more deaths than other types cancer making it a significant cause of morbidity and mortality. Non-small cell lung cancer (NSCLC) is potentially curable via surgical resection, if diagnosed in the early stages of the disease. However, as clinical signs of NSCLC are often absent until extensive disease is present, most patients are diagnosed at time where curative intent surgery is no longer a treatment option. Improving lung cancer outcomes in an unmet clinical need, which in part can be achieved by earlier diagnosis of patients. One way in which this may be achieved is via cancer screening programmes. Currently the most readily available option for NSCLC screening is the use of low dose computer tomography (CT). However, while CT can identify lesions in the lung it is not possible to definitively diagnose lung cancer with this technology. This thesis describes the approaches taken to use patient derived materials to identify novel biomarkers of Non-Small Cell Lung Cancer (NSCLC), which could be used to develop targeted molecular imaging agents to improve the diagnostic specificity of CT for lung cancer diagnosis. As imaging agents are best able to access targets of the surface of cell membranes and in the extracellular environment these regions were targeted for biomarker discovery. This thesis first discusses attempts to isolate surface proteins on cancer epithelial cells found in malignant pleural fluid and tissue samples. Despite attempts at epithelial cell enrichment, these tissues were not a viable option for biomarker discovery as the samples were largely composed of stromal cells and leukocytes. Therefore, alternative approaches were used to look for NSCLC biomarkers in the tumour microenvironment. These included using liquid chromatography tandem mass spectrometry (LC-MS/MS) to look at matrisome proteins in small tissue samples and isolating leukocytes, the most abundant cell type in tumour samples to identify subtypes of tumour infiltrating myeloid cells using flow cytometry. Key findings from exploration of matrisome proteins included that 161 matrisome proteins were differentially expressed between matched tumour and non-tumour samples collected from patients with early-stage disease. Novel biomarkers differentially expressed between tumour and non-tumour tissues include the enzymes ADAMST16 and peroxidasin. Collagen molecules and many other core extracellular matrix proteins were relatively more abundant in non-tumour tissues. We also detected a relative increase in tumour samples of enzymes such involved in protein hydroxylation and a post-translational difference in the hydroxylation of lysine residues in collagen compared to non-tumour tissues. These changes may suggest that cross-linking of collagen and extracellular matrix stiffness differs between tumour and non tumour tissues. To investigate novel markers targeting cancer associated myeloid cells in tissue samples, flow cytometry was performed for surface markers, which early stage or pre-clinical research suggest may be of immunoregulatory importance. These ligands included PD-L1, PD-L2, c-MET and Lox-1. PD-L1 expressing neutrophils were increased in tumour tissue compared to non-tumour lung tissue and PD-L1 appears to be a marker for potentially immunosuppressive (low density neutrophils) in circulation. These results indicate that neutrophils expressing PD-L1, a ligand with known immunosuppressant actions may identify a subset of tumour associated neutrophils in non-small cell lung cancer patients. The results presented in this thesis indicate there are differences in matrisome proteins and leukocytes found in the tumour stroma compared to non-tumour lung tissue. These proteins are worthy of further investigation to determine their utility as biomarkers which can discriminate between cancerous and benign pulmonary nodules, with the view to developing imaging agents which may improve on existing technologies for lung cancer diagnosis and thus improve patient outcomes by diagnosing patients at an early stage of their disease

Relationship between vitamin D status and leukocytes in hospitalised cats

ObjectivesVitamin D deficiency, as assessed by serum 25-hydroxyvitamin D (25[OH]D) concentrations, has been linked to markers of systemic inflammation in human and canine medicine. However, the relationship between vitamin D status and inflammation has not been previously investigated in cats. The aim of this study was to examine the relationship between serum 25(OH)D concentrations and leukocyte counts in hospitalised sick cats.MethodsSerum 25(OH)D concentrations and haematology profiles were measured in 170 consecutive hospitalised sick cats. A binary logistical regression model examined the relationship between serum 25(OH)D concentration, age, sex, breed and neutrophil, monocyte, eosinophil and lymphocyte counts.ResultsCats with neutrophilia had lower serum 25(OH)D concentrations than cats with neutrophil concentrations below the upper limit of the reference interval (RI). There were no differences in serum 25(OH)D concentrations in cats with monocyte, lymphocyte or eosinophil counts above their respective RI compared with cats with counts below the upper limit of the RI.Conclusions and relevanceHospitalised cats with a neutrophil count above the RI had lower vitamin D status. There is a need to establish whether lower vitamin D status is a cause or consequence of increased neutrophil counts.</jats:sec

Box and whisker plot of serum 25(OH)D concentrations by cluster.

<p>The box extends from 25% to 75% percentile with the median and the whiskers extend to limits of the data.</p

Results of logistic regression model of inflammatory parameters on serum 25(OH)D concentrations.

<p>*denotes statistical significance P<0.05</p><p>Results of logistic regression model of inflammatory parameters on serum 25(OH)D concentrations.</p

Pair-wise scatter plot of number of neutrophils (neut), monocytes (mono), eosinophils (eosino) and lymphocytes (lymph) labelled by cluster (red cluster 1, green cluster 2, blue cluster 3).

<p>Values on x and y axis denote cell concentrations x10⁹/l.</p

Box and whiskers plot of serum concentrations of 25(OH)D in nmol/l in cats which died or were alive at 30 days post admission.

<p>Box extends from 25^th-75^th percentiles with solid line representing the median value. Whiskers extend to 5^th-95^th percentiles.</p