Effect of a Weight Loss Program on Biochemical and Immunological Profile, Serum Leptin Levels, and Cardiovascular Parameters in Obese Dogs

This study aimed to investigate the effects of a weight loss program (WLP) on biochemical and immunological profile, and cardiovascular parameters in a cohort of dogs with naturally occurring obesity. Eleven obese dogs [body condition scoring (BCS), ≥7/9] were enrolled into the study and underwent clinical and cardiovascular examination, and blood testing before (T0) and after 6 months (T1) of WLP. Eleven normal weight (BCS, 4/5) healthy dogs were used as a control (CTR) group. Compared to the CTR group, at T0 obese dogs expressed higher serum leptin concentrations (p < 0.0005) that significantly decreased after weight loss (p < 0.005) but remained higher than the CTR group. Furthermore, obese dogs showed considerably lower levels (p < 0.0005) of regulatory T cell (Treg) compared to the CTR group, but they did not change after weight loss at T1. In obese dogs, tumor necrosis factor (TNF)-α and interleukin (IL)-6 concentrations were substantially reduced at T1 (p < 0.0001 and p < 0.005). Regarding the cardiovascular parameters, only one obese dog was hypertensive at T0, and systolic blood pressure values showed no significant differences at the end of the WLP. The ratio of interventricular septal thickness in diastole to left ventricle internal diameter in diastole (IVSd/LVIDd) was significantly greater in obese dogs at T0 than in the CTR group (p < 0.005). It decreased after weight loss (p < 0.05). In obese dogs, troponin I level significantly reduced with weight loss (p < 0.05), while endothelin-1 level did not differ statistically. The results suggest that the immune dysregulation in the presence of high leptin levels and reduced number of Treg could affect obese dogs as well as humans. Based on our findings, we may speculate that a more complete immune-regulation restore could be obtained by a greater reduction in fat mass and a longer-term WLP. Finally, left ventricular remodeling may occur in some obese dogs. However, in canine species, further studies are needed to investigate the impact of obesity and related WLP on cardiovascular system

Superoxide dismutase-1 intracellular content in T lymphocytes associates with increased regulatory T cell level in multiple sclerosis subjects undergoing immune-modulating treatment

Reactive oxygen species (ROS) participate in the T-cell activation processes. ROS-dependent regulatory networks are usually mediated by peroxides, which are more stable and able to freely migrate inside cells. Superoxide dismutase (SOD)-1 represents the major physiological intracellular source of peroxides. We found that antigen-dependent activation represents a triggering element for SOD-1 production and secretion by human T lymphocytes. A deranged T-cell proinflammatory response characterizes the pathogenesis of multiple sclerosis (MS). We previously observed a decreased SOD-1 intracellular content in leukocytes of MS individuals at diagnosis, with increasing amounts of such enzyme after interferon (IFN)-b 1b treatment. Here, we analyzed in depth SOD-1 intracellular content in T cells in a cohort of MS individuals undergoing immune-modulating treatment. Higher amounts of the enzyme were associated with increased availability of regulatory T cells (Treg) prefer-entially expressing Foxp3-exon 2 (Foxp3-E2), as described for effective Treg. In vitro administration of recombinant human SOD-1 to activated T cells, significantly increased their IL-17 production, while SOD-1 molecules lacking dismutase activity were unable to interfere with cytokine production by activated T cells in vitro. Furthermore, hydrogen peroxide addition was observed to mimic, in vitro, the SOD-1 effect on IL-17 production. These data add SOD-1 to the molecules involved in the molecular pathways contributing to re-shaping the T-cell cytokine profile and Treg differentiation

Natural killer expansion, human leukocyte antigens-E expression and CD14+ CD56+ monocytes in a myelodysplastic syndrome patient

Myelodysplastic syndromes (MDS) are clonal disorders characterized by ineffective hematopoiesis and possible evolution to acute leukemia. Occurrence of stem cell defects and of immune-mediated mechanisms was evidenced as relevant for pathophysiology of MDS. Here, we described one case of MDS patient carrying CD14(+) CD56(+) monocytes in bone marrow (BM), in the presence of a defective human leukocyte antigen (HLA)-E expression on peripheral blood (PB) cells and of natural killer (NK) cell expansion in PB and BM. The defective HLA-E expression and the NK expansion are proposed to be relevant for the pathogenesis of myelodysplasia in those patients showing CD14(+) CD56(+) monocytes in BM

Reduced regulatory T cells (Treg) in bone marrow preferentially associate with the expansion of cytotoxic T lymphocytes in low risk MDS patients.

The myelodysplastic syndromes (MDS) include clonal bone marrow (BM) disorders characterised by the emergence/dominance of dysplastic progenitors in the context of ineffective haematopoiesis, peripheral cytopenias and increased risk of acute myeloid leukaemia (AML). The link between immune dysregulation and MDS has been suggested . Autoimmune attack to normal precursors as well as the activity of bystander T cells, recruited during an immune‐response against dysplastic antigens, were hypothesised as relevant for the selection of dysplastic clones that are able to escape immune‐mediated damage. The involvement of Natural Killer cells was also described

Oscillatory mTOR inhibition and Treg increase in kidney transplantation

Intracellular metabolic pathways dependent upon the mammalian target of rapamycin (mTOR) play a key role in immune-tolerance control. In this study, we focused on long-term mTOR-dependent immune-modulating effects in kidney transplant recipients undergoing conversion from calcineurin inhibitors (CNI) to mTOR inhibitors (everolimus) in a 1-year follow-up. The conversion to everolimus is associated with a decrease of neutrophils and of CD8(+) T cells. In addition, we observed a reduced production of interferon (IFN)-γ by CD8(+) T cells and of interleukin (IL)-17 by CD4(+) T lymphocytes. An increase in CD4(+) CD25(+) forkhead box protein 3 (FoxP3)(+) [regulatory T cell [(Treg )] numbers was also seen. Treg increase correlated with a higher proliferation rate of this regulatory subpopulation when compared with the CD4(+) FoxP3(-) effector counterpart. Basal phosphorylation level of S6 kinase, a major mTOR-dependent molecular target, was substantially maintained in patients treated with everolimus. Moreover, oscillations in serum concentration of everolimus were associated with changes in basal and activation-dependent S6 kinase phosphorylation of CD4(+) and CD8(+) T cells. Indeed, T cell receptor (TCR) triggering was observed to induce significantly higher S6 kinase phosphorylation in the presence of lower everolimus serum concentrations. These results unveil the complex mTOR-dependent immune-metabolic network leading to long-term immune-modulation and might have relevance for novel therapeutic settings in kidney transplants

Circulating regulatory T cells (Treg), leptin and induction of proinflammatory activity in obese Labrador Retriever dogs.

Over-nutrition and obesity have been associated with impaired immunity and low-grade inflammation in humans and mouse models. In this context, a causal role for unbalanced T regulatory cell (Treg)-dependent mechanisms has been largely suggested. Obesity is the most common nutritional disorder in dogs. However, it is not defined whether canine obesity may influence circulating Treg as well as if their number variation might be associated with the occurrence of systemic inflammation. The present study investigated the immune profile of healthy adult obese dogs belonging to the Labrador Retriever breed, in comparison with the normal weight counterpart. Indeed, obesity has been described as particularly evident in this dogs. With this purpose, 26 healthy dogs were enrolled and divided into two groups based on body condition score (BCS): controls (CTR: BCS 4-5) and obeses (OB: BCS ≥ 7). Our data indicate that adult obese Labrador Retrievers are characterised by the inverse correlation between leptin serum concentration and circulating Treg (CD4+CD25highFoxp3+) levels. In addition, an increased number of cytotoxic T cell effectors (CD3+CD8+) and a higher IFN-γ production by cytotoxic T lymphocytes were observed in OB group. These results may provide new insights into the immunological dysregulation frequently associated to obesity in humans and still undefined in dogs

Effect of a Weight Loss Program on Metabolic and Immunological Profile, Blood Leptin Level and Cardiovascular Parameters in Obese Dogs

In these last years, the increasing obesity incidence in canine species has enshrined its relevance as an important worldwide disease. Recently, obesity has been associated with impaired immunity and chronic low-grade inflammation in humans as well as mouse models. Increased concentration of leptin and other pro-inflammatory cytokines have been described in obese dogs. A reduced number of T regulatory cells (Treg) has been reported in visceral adipose tissue and blood of obese humans, and recently also in Labrador retriever obese dogs. Moreover, some evidences addressed the possible impact of obesity on cardiovascular apparatus in dogs. The aim of this study was to investigate the effect of a weight loss program on metabolic and immunological profile, blood leptin level and cardiovascular parameters in obese dogs. Ten overweight dogs (OB) (BCS>7/9) were recruited into the study, and they underwent blood testing (complete blood count, serum biochemistry, blood level assay of CD3+CD4+, CD3+CD8+T cells, CD4/CD8 ratio, CD21+B cells, Treg cells by immune-fluorescence and flow cytometry and measurement of serum leptin by species-specific ELISA kit) and assessment of cardiovascular function (blood pressure measurement, electrocardiography and echocardiography) before (T0) and after five months (T1) of commercially available weight loss diet. Ten normal weight (BCS 4–5) healthy dogs represented a control group (CTR). Regarding metabolic profile, a mild no significant decrease in total cholesterol but a significant decrease in triglycerides serum levels (p<0.05) were observed in the obese dogs at T1. There were no significant differences in the other biochemical parameters as well as in haematological values between the two observation times. Concerning the cardiovascular parameters, no significant differences were observed at T1, and particularly systolic arterial blood pressure values were in the reference range in both times. OB had elevated serum leptin concentrations that decrease significantly (p<0.005) after weight loss, however remaining higher compared to CTR. OB dogs showed significant low levels (p<0.005) of Treg compared to CTR but they did not increase after weight loss. Our data suggested that a deranged immune-regulation, combined with high leptin levels, might characterize obese dogs in the absence of cardiovascular alterations. Furthermore, on the basis of our results we may suggest that probably in dogs a greater reduction in fat mass, and long-term weight loss programs, are necessary in order to restore immunological balance

T cell activation induces CuZn superoxide dismutase (SOD)-1 intracellular re-localization, production and secretion

Reactive oxygen species (ROS) behave as second messengers in signal transduction for a series of receptor/ligand interactions. A major regulatory role is played by hydrogen peroxide (H2O2), more stable and able to freely diffuse through cell membranes. Copper-zinc superoxide dismutase (CuZn-SOD)-1 is a cytosolic enzyme involved in scavenging oxygen radicals to H2O2 and molecular oxygen, thus representing a major cytosolic source of peroxides. Previous studies suggested that superoxide anion and H2O2 generation are involved in T cell receptor (TCR)-dependent signaling. Here, we describe that antigen-dependent activation of human T lymphocytes significantly increased extracellular SOD-1 levels in lymphocyte cultures. This effect was accompanied by the synthesis of SOD-1-specific mRNA and by the induction of microvesicle SOD-1 secretion. It is of note that SOD-1 increased its concentration specifically in T cell population, while no significant changes were observed in the "non-T" cell counterpart. Moreover, confocal microscopy showed that antigen-dependent activation was able to modify SOD-1 intracellular localization in T cells. Indeed, was observed a clear SOD-1 recruitment by TCR clusters. The ROS scavenger N-acetylcysteine (NAC) inhibited this phenomenon. Further studies are needed to define whether SOD-1-dependent superoxide/peroxide balance is relevant for regulation of T cell activation, as well as in the functional cross talk between immune effectors. © 2013 Elsevier B.V