Effect of ovarian hormones on periodical changes in immune resistance associated with estrous cycle in the beagle bitch

The role of nutritional-immunological indices in estimating serum LPS and antioxidant enzyme activity and sepsis status in female dogs with pyometra caused by E. coli

The aim of this study was to diagnose pyometra and related sepsis status using cost-effective nutritional-immunological indices, antioxidants, and toxin levels in dogs and to investigate the utility of the indices in predicting toxin and antioxidant status. A total of 29 dogs were enrolled into the present study. Among these, 9 female dogs in their diestrus stages, were allocated for elective ovariohysterectomy. The pyometra group was also separated into two subgroups as Sepsis (+) and Sepsis (-). Blood samples were collected into two tubes containing EDTA for hematological analysis; without anticoagulant for serum progesterone, LPS concentration, and antioxidant levels at the time of diagnosis. Bacteriological and tissue samples of the uterus were collected after the ovariohysterectomy. Antioxidant activity, progesterone, and toxin concentration were determined by using commercial ELISA kits. Statistical analyses were performed using Stata version 16.1 and MedCalc 16 statistical software. Receiver operating characteristics curves were used for the threshold for evaluating pyometra and sepsis status. Pairwise comparisons were carried out of the area under the curve (AUC) for thresholds of nutritional immunologic indices (hemoglobin, albumin, lymphocyte, platelet (HALP) score; prognostic nutritional index (PNI); Albumin hemoglobin index (AHI)), serum LPS and antioxidant activity. Linear regression model was used for the estimation of serum LPS and antioxidant activity by using indices. Mean serum progesterone, LPS concentrations, and Nitric Oxide (NO) production were greater, while serum superoxide dismutase (SOD), tissue SOD, and glutathione peroxidase (GPx) activities were lower in dogs with pyometra. All nutritional-immunologic indices were lower in pyometra cases. Nutritional-immunologic indices (AUC of HALP:0.759; PNI:0.981; AHI 0.994), NO (AUC: 0.787) and SOD (AUC: 0.784) levels were useful for pyometra diagnosis. AHI and LPS were useful for the determination of sepsis status with the AUC values of 0.850 and 0.740, respectively. While AHI was useful for the estimation of serum LPS and NO concentration (p < 0.001), PNI was useful for serum SOD concentration (p = 0.003). In conclusion, PNI, HALP and AHI can be used in the diagnosis of pyometra, however, only AHI and LPS levels can be used in the diagnosis of sepsis. SOD and NO can be used to determine pyometra but have no effect on determining sepsis status. Additionally, the estimation of the levels of serum LPS, NO, and SOD activities can be done using the AHI and PNI values.

Effect of systemic inflammatory response syndrome (SIRS) on prostaglandin metabolite and oxidative stress in canine pyometra

Pyometra, either open or closed cervix, inevitably progresses to systemic inflammatory response syndrome (SIRS), if ovariohysterectomy is not done timely. The aim of the study was to investigate the effect of pyometra led SIRS on certain serum biochemical and prostaglandin metabolite, 13,14-dihydro-15-keto PGF2 alpha (PGFM) and oxidative stress indices in the canine. The pyometra positive bitches were categorized as SIRS+ (n=29) and SIRS- (n =16) based on temperature (<100.5 or >102.5°F), respiration rate (>20/min), heart rate (>102/min), and total leukocytes count (<6×103 or >16×103 per μL). The SIRS+ bitches showed hypoalbuminemia, hyperglobulinemia, elevated blood urea nitrogen and creatinine, decreased super oxide dismutase (SOD) activity with moderate increase in the lipid peroxidation. Further, the SIRS+ bitches had significantly higher serum PGFM concentration (6.83±0.7 vs. 4.12±0.4 ng/mL) than SIRS- and the level was influenced by cervical patency. It was concluded that elevated serum PGFM along with hyperglobunemia, blood urea nitrogen, creatinine would be useful in diagnosis and monitoring of pyometra led SIRS in bitch.

Leishmania infantum is present in vaginal secretions of naturally infected bitches at lower levels in oestrogenized bitches than in non-oestrogenized bitches

Naturally Leishmania infantum infected bitches were divided into oestrogenized (n = 11) and non-oestrogenized (n = 6) groups. Vaginal secretions were collected for polymerase chain reaction (PCR), and vulval, vaginal and uterine tissues were collected for the immunohistochemical (IHQ) identification of L. infantum. Parasite DNA was identified in vaginal secretions of non-oestrogenized (41.8%) and oestrogenized (18.2%) bitches (P<0.05; Fisher's Exact test). IHQ was positive in vulvar dermis (23.5%) and vaginal mucosa (17.7%) but negative in endometrium of all bitches. Poor association between positive vaginal secretion PCR and tissue IHQ (Kappa index) were observed. The results showed that genital secretions are a potential source for dog contamination.

Canine pyometra: a model for the analysis of serum CXCL8 in inflammation

Interleukin-8 (IL-8 or CXCL8) is a highly selective pro-inflammatory chemokine, that is elevated in sera of humans and animals with various inflammatory diseases. CXCL8 is possibly involved in uncontrolled inflammation and the development of a systemic inflammatory response syndrome (SIRS) and sepsis. Nevertheless, its behavior and precise properties in the course of inflammation are not fully understood. Thus, we used naturally occurring canine pyometra as a model of inflammation, in order to examine the behavior of serum CXCL8 in relation to the disease intensity and commonly analyzed inflammatory mediators. Using a commercially available canine ELISA kit, a significant increase of CXCL8 was determined in the serum of 23 dogs with pyometra compared with 35 healthy dogs. Interestingly, serum CXCL8 did not increase in severely diseased patients and behaved contrary to white blood cells (WBC), neutrophils and C-reactive protein (CRP). The measurement of serum CXCL8 may provide valuable information about the extent of ongoing lesions and could be a useful complement for existing laboratory tests.

Effect of ovarian hormones on maturation of dendritic cells from peripheral blood monocytes in dogs

Previously, we reported that ovarian hormones affect the immune response against E. coli isolated from the dogs affected with pyometra. In order to investigate mechanisms underlying the immune modulation, we examined the effects of ovarian hormones on the generation of dendritic cells (DCs), the most potent antigen presenting cell. DCs were differentiated from peripheral blood monocytes (PBMOs) using a cytokine cocktail. Both estrogen receptor and progesterone receptors were expressed by the PBMOs and immature DCs. When various ovarian hormones were added to the culture for the DC differentiation, progesterone significantly decreased the expression of DC maturation markers, such as CD1a, CD80 and CD86, on mature DCs. Conversely, the addition of estrogen to the cultures increased the expression of CD86, but not other maturation makers. Furthermore, DCs differentiated in the presence of progesterone did not stimulate allogeneic mononuclear cells in PB. Taken together, these results indicate that progesterone diminishes the maturation of DCs, leading to decreased immune responses against invading pathogens.

Bacterial colonization of the ovarian bursa in dogs with clinically suspected pyometra and in controls

Septic peritonitis occurs relatively commonly in dogs. Secondary septic peritonitis is usually associated with perforation of intestines or infected viscera, such as the uterus in pyometra cases. The aim of this study was to evaluate the bacterial flora in the ovarian bursae of intact bitches as a potential source of contamination. One hundred forty dogs, clinically suspected of pyometra, were prospectively enrolled. The control group consisted of 26 dogs that underwent elective ovariohysterectomies and 18 dogs with mammary gland tumors that were neutered at the time of mastectomy. Bacteriology samples were taken aseptically at the time of surgery from the bursae and the uterus in all dogs. Twenty-two dogs that were clinically suspected of pyometra had sterile uterine content ("mucometra" cases); the remaining 118 had positive uterine cultures ("pyometra" cases) and septic peritoneal fluid was present in 10% of these cases. Of the 118 pyometra cases, 9 had unilateral and 15 had bilateral bacterial colonization of their ovarian bursae. However, the bacteria from the ovarian bursa were similar to those recovered from the uterine pus in only half of the cases. Furthermore, positive bursae were also seen in one mucometra dog (unilateral) and in four control dogs (two unilateral and two bilateral). The data illustrate that the canine ovarian bursa can harbor bacteria. The biological importance of these isolations remains unclear.

Lack of in vitro effect of aglepristone on IFN-γ and IL-4 production by resting and mitogen-activated T cells of luteal bitches

Background

Aglepristone (RU534) is an antiprogestin used for pregnancy termination, parturition induction and conservative pyometra treatment in bitches. Its molecular structure is similar to mifepristone, an antiprogestin used in human medicine. Mifepristone has been shown to suppress proliferation and cytokine production by T cells, whereas the effect of aglepristone on T cell function remains elusive. The purpose of this project was to investigate the in vitro influence of RU534 on IFN-γ and IL-4 synthesis by peripheral blood T cells isolated from healthy bitches (N = 16) in luteal phase. The peripheral blood mononuclear cells (PBMCs) were incubated with three different dosages of aglepristone, or dimethyl sulfoxide (DMSO), with or without mitogen. The production of cytokines by resting or mitogen-activated T cells was determined by intercellular staining and flow cytometry analysis or ELISA assay, respectively.

Results

Our results showed no statistically significant differences in the percentage of IFN-γ and IL-4-synthesizing CD4⁺ or CD8⁺ resting T cells between untreated and aglepristone-treated cells at 24 and 48 hours post treatment. Moreover, mitogen-activated PBMCs treated with RU534 displayed similar concentration of IFN-γ and IL-4 in culture supernatants to those observed in mitogen-activated DMSO-treated PBMCs. Presented results indicate that administration of aglepristone for 48 hours has no influence on IFN-γ and IL-4 synthesis by resting and mitogen-activated T cells isolated from diestral bitches.

Conclusions

We conclude that antiprogestins may differentially affect T cell function depending on the animal species in which they are applied.

A retrospective study of pyometra at five RSPCA hospitals in the UK: 1728 cases from 2006 to 2011

A retrospective cross-sectional study was used to analyse pyometra cases at five RSPCA Animal Hospitals across the UK from 2006 to 2011. A total of 1728 cases of pyometra were recovered from a female dog outpatient caseload of 78,469 animals, giving a total prevalence of 2.2 per cent over the study period. There was an annual increase in the incidence of pyometra within the population, while elective ovariohysterectomy caseload has declined. There were variations in breed and age at presentation. Bullmastiffs (P<0.0001), golden retrievers (P=0.001) and dogue de Bordeaux (P=0.008) were over-represented in the pyometra population when compared with the female dog outpatient caseload. Mean age at presentation was 7.7 years. Some breeds presented at a significantly lower age, including dogue de Bordeaux (mean age 3.3 years) and bullmastiffs (mean age 5.4 years), while others presented as older dogs, including Yorkshire terriers (mean age 9.4 years) and border collies (mean age 10.3 years). Surgical mortality rate at the Greater Manchester Animal Hospital was 3.2 per cent. Pyometra is of significant welfare concern, and also has cost implications, particularly in charity practice. These results serve to highlight this condition so that future change in charity practice caseload can be anticipated and strategies can be directed to improve animal welfare.

Clinical, ultrasonography and haematology of aglepristone-induced mid-gestation pregnancy terminations in rabbits

Aglepristone is a safe abortifacient in cats, dogs and rabbits. Although no serious side effects have been reported, there is no information available about the effects of the medicine on haematological parameters. For the first time clinical and ultrasonographic features and haematological profiles were evaluated in rabbits treated with aglepristone 15 and 16 days after mating. Ten healthy 10-14 month-old New Zealand White female rabbits were mated with fertile bucks and pregnancies were confirmed by ultrasound 15 days later. Of these, 5 does were treated with aglepristone (test group, n = 5) whilst the remaining five (control group, n = 5) were treated with a saline solution (0.9% NaCl). The treatment dose was 10 mg/kg body weight, administered subcutaneously once daily on two consecutive days (day 15 and 16 post mating). Ultrasonographic, clinical and haematological assessments were performed daily. Aglepristone treatment induced embryonic fluid resorptions without foetal death in mid-gestation terminations. Following ultrasonographic and haematological examinations, it was established that aglepristone is a safe abortifacient in rabbits.

Findings in uterine biopsies obtained by laparotomy from bitches with unexplained infertility or pregnancy loss: an observational study

Surgical uterine biopsies (SUBs) were obtained by laparotomy from 14 bitches with unexplained infertility whose pregnancy was not confirmed (NCP group) and from 7 bitches that had experienced unexplained pregnancy loss (PL). SUBs were obtained during the luteal phase of the cycle in 16 of 21 bitches. Overall, the biopsied uterine tissues presented obvious alterations in 17 of 21 cases. In the NCP group, 11 of 14 bitches had varying degrees of uterine lesions. In this group, six of nine bitches with macroscopically normal uteri presented histopathologic changes in the endometrium. All bitches with macroscopic modifications (five of 14) presented endometrial changes. Cytologic examination of the uterine fluid revealed eosinophilic amorphous material, erythrocytes, and a low number of degenerated leukocytes. On histopathologic examination, the most common lesion was fibrosis with degeneration of the endometrial glands (FDEGs six of 11), followed by endometritis (four of 11), cystic endometrial hyperplasia (CEH) (two of 11) and pseudoplacentational endometrial hyperplasia (PEH) (two of 11). Other lesions were adenomyosis, mucometra, and an endometrial polyp (one each of 11). Mixed lesions were present in four of the 11 bitches. In the PL group, macroscopic modifications consisted of intraluminal uterine dilatation (seven of seven) and presence of ovarian cysts (three of 7). Cytologic examination of the uterine content revealed high leukocyte counts. Histopathologic endometrial changes were found in six of seven bitches and included endometritis (three of seven), PEH (two of 6), pyometra (one of six), and CEH together with mucometra (one of six). Research of infectious agents was performed in 20 of 21 cases. Surprisingly, no bacteria or viruses were isolated from the uterine lumen in any of the cases. When the SUB was performed in diestrus, a medical treatment with aglepristone or with prostaglandins was established to avoid the risk of postoperative-induced pyometra. One case of complete uterine stenosis was the only side effect observed in the bitches that were not ovariohysterectomized after the collection of a biopsy (17 of 21). In conclusion, the most common findings in our biopsy specimens were FDEGs, endometritis, and hyperplastic remodeling of the endometrium (CEH and PEH). SUBs might provide useful information regarding the cause of infertility or PL. This technique allows visual inspection and palpation of the whole uterus and ovaries before the selection of a precise site for the biopsy. The size of the tissue sample collected can be large enough for an accurate diagnosis and samples for research of infectious agents can be obtained with no risk of contamination. Risk of side effects seems low when SUBs are performed according to this protocol, including postsurgery treatment with aglepristone or prostaglandins.

Analysis of In Vitro Effects of Sex Steroids on Lymphocyte Responsiveness in Murrah Buffaloes (Bubalus bubalis)

Present study was carried out on forty four apparently healthy Murrah buffaloes of different age groups of both sexes to investigate the effects of sex steroids on cell mediated immunity in vitro. Estrogen inhibited proliferation in mitogen-stimulated lymphocytes from prepubertal but not post pubertal buffaloes of either sex. Estrogen at 100 pg/mL concentration stimulating the proliferation significantly (P < 0.05). in all groups and had higher stimulatory effect in lymphocytes from day 10 than day 0 of estrous cycle. Progesterone inhibited lymphocyte proliferation, and inhibition was directly related to the dose, in all groups of either sex. Testosterone did not inhibit proliferation at any dose level and did not show any consistent and lucid effects on lymphocyte proliferation. Present study revealed that buffalo lymphocytes produce appreciable amounts of NO in culture system after treatment with estradiol. Significantly high levels of NO in culture supernatant were found in prepubertal buffalo calves and least in post pubertal buffaloes, which had an inverse relation with lymphocyte proliferation in presence of estradiol. NO in culture supernatant was high at the lowest dose of progesterone which was proportional to the lymphocyte proliferation when treated with progesterone. No significant difference in NO culture supernatant was observed between different concentrations of testosterone treatment.

Effect of progesterone on the in vitro response of peripheral blood mononuclear cells stimulated by Escherichia coli in mares

Escherichia coli(E. coli) isolated from the uterus of a Thoroughbred mare with bacterial endometritis was used to evaluate the effect of progesterone (P(4)) on the immune response of mares. Peripheral blood mononuclear cells (PBMCs) were collected from 10 nonpregnant clinically healthy adult mares (range, 4-12 years) during diestrus, four Thoroughbreds and six Hokkaido native horses. Cell proliferation and expression of cytokine mRNA, including interferon (IFN)-γ, tumor necrosis factor (TNF)-α and interleukin (IL)-10, of PBMCs stimulated with E. coli and P(4) were examined in vitro. P(4) was shown to have significantly inhibited E. coli induced proliferation and expression of IFN-γ in PBMCs. These results indicate that P(4) inhibits the immune response to E. coli in mares.

Reproductive cycles of the domestic bitch

Domestic dogs are monoestrous, typically non-seasonal, polytocous, spontaneous ovulators and have a spontaneous luteal phase slightly longer (by approx 5 day) than the 64±1day luteal phases of a 65±1day pregnancy, a phase followed by an obligate anestrus before the next 2-3 week "heat" (proestrus-estrus). The resulting inter-estrus intervals of 5-12 months are variable among bitches, commonly 6-7 months, and range from highly variable to regular (to perhaps within±5-10 day of sequential 7 month cycle, for instance) within bitches, and across studies and do not vary significantly between pregnant and non-pregnant cycles. Hormone levels reported are those observed in this laboratory using previously reported assays and canine gonadotropin standards unless stated otherwise. Endocrine sequences for dog cycles are not unlike those of many other mammals, including selection of ovulatory follicles by increased LH pulsatility, the occurrence of estrus behavior and LH surge during a decline in the estrogen: progestin ratio, a pronounced preovulatory luteinization as in humans and rodents, and luteotrophic roles for both LH and prolactin. Non-pregnant bitches have a spontaneously prolonged luteal phase, often longer and with a more protracted decline in serum progesterone than in pregnancy as there is no uterine luteolytic mechanism. The obligate anestrus of 8-40 weeks is terminated by poorly understood interactions of environment (e.g. pheromones, possibly photoperiod) and a potential endogenous circannual cycle in sensitivities of hypothalamic dopaminergic, serotonergic and/or opioid pathways.

Establishment of an IFN-gamma specific reporter cell line in fish

An interferon (IFN)-gamma responsive stable cell line RTG-3F7 has been developed for rainbow trout by modifying the RTG-2 cell line through transfection with a plasmid construct (pGL4.14[luc2/hygro]-PrTAP2) containing a promoter element from the IFN-gamma responsive gene TAP2 linked to a luciferase reporter gene and a hygromycin resistance gene. Following transfection single clones were selected in 96 well plates using hygromycin B, and those showing specific activation after rIFN-gamma stimulation were maintained. Five clones that showed the highest reporter activity to rIFN-gamma were incubated with different stimuli to examine specificity. No significant induction of luciferase was observed following exposure to recombinant type I IFN, LPS, PHA or poly I:C. The cell line was responsive to rIFN-gamma at concentrations between 150 pg and 20 ng ml(-1). Supernatants of primary cultures of head kidney leucocytes stimulated with PHA, known to induce IFN-gamma gene expression, were also used to assess the reporter activity of the stable cell line. A dose-dependent induction of the promoter activity was observed with these supernatants indicating the presence of IFN-gamma. These results indicate that the stable cell line RTG-3F7 is an excellent tool for monitoring the presence of trout IFN-gamma in biological samples, and in addition, enables the study of intracellular signalling pathways of IFNs, their receptor interactions, and other closely related signalling networks.

Epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor expression and localization in the canine endometrium during the estrous cycle and in bitches with pyometra

Gene expression and immunohistochemical localization of epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), and epidermal growth factor receptor (EGF-R) were compared between the endometrium of bitches (Canis familiaris) with pyometra accompanied by cystic endometrial hyperplasia (CEH) and that of healthy bitches at similar stages of the estrous cycle. In normal bitches, endometrial TGF-alpha mRNA levels were highest at proestrus and gradually decreased as the cycle progressed to anestrus. Epidermal growth factor receptor mRNA levels were not significantly affected by the stage of the estrous cycle. Epidermal growth factor mRNA levels were higher at Day 35 of diestrus than at other stages of the estrous cycle (P<0.05). In bitches with pyometra, endometrial TGF-alpha and EGF-R mRNA levels did not differ significantly from those at diestrus in normal bitches, but EGF mRNA levels were lower than those at Day 35 of diestrus in normal bitches (P<0.05). In normal bitches, positive immunohistochemical staining for TGF-alpha, EGF, and EGF-R was mainly present in the glandular and luminal epithelial cells of the endometrium. In contrast, in bitches with pyometra, immunoreactivity for EGF was clearly present in endometrial stromal cells. Inflammatory cells that had infiltrated the endometrial stroma stained strongly for TGF-alpha and EGF-R. Luminal and glandular epithelial cells also stained positive for EGF-R. In conclusion, expression of TGF-alpha by inflammatory cells and a low level of expression and differential localization of EGF may be involved in aberrant growth of endometrial glands and development of CEH.

Naturally Occurring and Melengestrol Acetate-associated Reproductive Tract Lesions in Zoo Canids

As husbandry practices have improved, safe and effective contraception for captive wildlife management has become a necessity. Melengestrol acetate (MGA), a synthetic progestin, is highly effective and has been used in many zoo species. Long-term use of MGA has been associated with uterine lesions in zoo felids, but effects in zoo canids have not been evaluated. This retrospective study documented spontaneously occurring lesions and investigated the impact of MGA on the reproductive health of zoo canids. Reproductive tracts from adult females were submitted by US zoos to the Association of Zoos & Aquariums' Wildlife Contraception Center Health Surveillance Program. Reproductive tracts were sampled and processed for histopathologic examination following standard protocols. Microscopic evaluations were performed without prior knowledge of MGA treatment status. Prevalence of uterine lesions was evaluated and compared between MGA-treated animals (n = 20) and control (untreated) animals (n = 61). Common lesions within the study population as a whole included endometrial hyperplasia (predominantly cystic) (53%), hydrometra (33%), and adenomyosis (25%). Treatment with MGA was a risk factor for endometrial hyperplasia, hydrometra, fibrosis, and adenomyosis. Uterine mineralization occurred exclusively in MGA-treated animals. Results indicate that MGA contraception can lead to lesions that may permanently impair the fertility of females. Therefore, if long-term contraception of zoo canids is necessary, the use of alternate methods of reproductive control such as gonadotropin-releasing hormone (GnRH) analogs or GnRH vaccines that reduce gonadal hormone exposure should be pursued.

Coxsackievirus B3-induced myocarditis: infection of females during the estrus phase of the ovarian cycle leads to activation of T regulatory cells

Transgenic female mice expressing the TNFalpha gene under the cardiac myosin promoter (TNF1.6) develop substantially increased myocarditis and increased numbers of CD4+Th1 (interferon gamma+) cells when infected with coxsackievirus B3 (CVB3) during the diestrus and proestrus phases of the estrus cycle compared to females infected during the estrus and metestrus phases. Cardiac virus titers were increased in females infected in estrus compared to females infected during the other phases. T regulatory cells (CD4+CD25+FoxP3+) were increased in both peripheral blood and inflammatory cells in the heart in females infected during estrus. Exogenous administration of 200 ng/mouse 17-beta-estradiol to females protected against CVB3 induced myocarditis and increased CD4+CD25+FoxP3+ cells. These results demonstrate that hormonal fluctuations occurring in normally cycling females can determine T regulatory cell response and control virus-induced pathogenesis.

Clinical presentation of canine pyometra and mucometra: a review

Cystic endometrial hyperplasia (CEH) in the bitch can result in either pyometra, hematometra, or hydrometra, and many facets of these uterine diseases can make them difficult to differentiate. The conditions differ in their systemic effects, since pyometra, particularly closed-cervix pyometra, can be a life-threatening condition that must be recognized, managed, and treated expeditiously. Mucometra is an accumulation of sterile intraluminal mucoid fluid, hematometra is an accumulation of sterile, bloody fluid, and hydrometra is an accumulation of sterile, watery fluid; none of which have any significant systemic outward clinical signs. This paper will describe the definitions, signalment, historical findings, incidence, clinical signs, physical exam findings, and diagnostic findings in canine pyometra and mucometra, and hematometra and hydrometra.

Age-related alteration of arginase activity impacts on severity of leishmaniasis

Background

The leishmaniases are a group of vector-borne parasitic diseases that represent a major international public health problem; they belong to the most neglected tropical diseases and have one of the highest rates of morbidity and mortality. The clinical outcome of infection with Leishmania parasites depends on a variety of factors such as parasite species, vector-derived products, genetics, behaviour, and nutrition. The age of the infected individuals also appears to be critical, as a significant proportion of clinical cases occur in children; this age-related higher prevalence of disease is most remarkable in visceral leishmaniasis. The mechanisms resulting in this higher incidence of clinical disease in children are poorly understood. We have recently revealed that sustained arginase activity promotes uncontrolled parasite growth and pathology in vivo. Here, we tested the hypothesis that arginase-mediated L-arginine metabolism differs with age.

Methodology

The age distribution of patients with visceral or cutaneous leishmaniasis was determined in cohorts of patients in our clinics in endemic areas in Ethiopia. To exclude factors that are difficult to control in patients, we assessed the impact of ageing on the manifestations of experimental leishmaniasis. We determined parasite burden, T cell responses, and macrophage effector functions in young and aged mice during the course of infection.

Results

Our results show that younger mice develop exacerbated lesion pathology and higher parasite burdens than aged mice. This aggravated disease development in younger individuals does not correlate with a change in T helper cytokine profile. To address the underlying mechanisms responsible for the more severe infections in younger mice, we investigated macrophage effector functions. Our results show that macrophages from younger mice do not have an impaired capacity to kill parasites; however, they express significantly higher levels of arginase 1 than aged mice and promote parasite growth more efficiently. Thus, our results demonstrate that ageing differentially impacts on L-arginine metabolism and subsequent effector functions of physiologically distinct macrophage subsets.

Conclusions

Here, we show that arginase-mediated L-arginine metabolism is modulated with age and affects the capacity of macrophages to express arginase; the increased capacity to upregulate this enzyme in younger individuals results in a more permissive environment for parasite growth, increased disease severity and pathology. These results suggest that the difference in arginase-mediated L-arginine catabolism is likely to be an important factor contributing to the increased incidence of clinical cases in children. Thus, targeting L-arginine metabolism might be a promising therapeutic strategy against leishmaniasis, especially in children and young adults.

It is well documented that ageing alters many aspects of immune responses; however, a causal relation between impaired immune functions in ageing individuals and the response to infection has not been established. Experimental leishmaniasis is an excellent model to analyse protective and pathological immune responses. Leishmania parasites are obligate intracellular pathogens and invade mainly macrophages, which have dual function: they can kill the parasites or promote their growth. We have recently shown that arginase, an enzyme induced in infected macrophages, is a key factor for parasite survival. Here, we show that ageing reduces the expression levels of arginase in macrophages, resulting in more efficient control of parasite growth. Our results suggest that age-related differences in the metabolism of arginase in macrophages might contribute to the higher susceptibility of children to leishmaniasis.

Generation of canine dendritic cells from peripheral blood monocytes without using purified cytokines

Dendritic cells (DCs), which differentiate in vitro from peripheral blood monocytes (PBMOs) or bone marrow precursors, are a promising candidate for immunotherapy against cancer. The dog, which suffers common types of cancers along with humans, make an ideal large animal model for cancer studies. Monocyte-derived DCs in the dog have not been well characterized, however, since the appropriate condition for in vitro differentiation has not been established. To tackle this problem, we have developed a conditioned media by culturing T cells with immobilized anti-canine CD3 antibody, and sought to induce differentiation of DCs from PBMOs. When purified CD14+ PBMOs were cultured in the presence of 25% T cell conditioned medium (TCCM), the PBMOs increased size and had extended dendritic processes by day 12 of the culture. The cultured PBMOs were found to increase the expression of MHC class II and CD1a molecules, and significantly increased stimulatory activity for allogeneic T cells in the mixed leukocyte reaction. Moreover, the cells significantly increased their expression of IL-18 and IFN-gamma when stimulated with polyinosinic-polycytidylic acid (Poly (I:C)). The cells have a reduced phagocytic activity, which is a common defect in mature DCs. It follows from these results that TCCM does induce the differentiation of DCs from PBMOs.

Canine pyometra

Pyometra, literally meaning pus in the uterus, is a common disease entity of intact bitches. Similar conditions occur, including hydrometra and mucometra [De Bosschere H, Ducatelle R, Vermeirsch H, Van Den Broeck W, Coryn M. Cystic endometrial hyperplasia-pyometra complex in the bitch: should the two entities be disconnected? Theriogenology 2001;55:1509-19]. The exact etiology is unknown; however the repeated and prolonged response to estrogen followed by long intervals of progesterone dominance in the intact bitch leads to hormonally mediated changes in the endometrium. The endometrium changes when impacted by bacterial infiltration; changes in endometrial steroid receptors can result in the clinical syndrome described as pyometra. This paper will describe the signalment, risk factors, prevalence, proposed etiologic events, and both medical and surgical therapies. In addition, the prognosis for successful outcome and effects on future reproduction will also be described.

Lactoferrin expression in the canine uterus during the estrous cycle and with pyometra

The expression of lactoferrin, a non-specific antimicrobial defence, in the canine uterus during the normal estrous cycle and in bitches with pyometra was examined. Using polymerase chain reaction analysis, lactoferrin gene transcripts were detected in the endometrium at all stages of the estrous cycle, with the highest levels in estrus. In normal bitches, endometrial lactoferrin mRNA increased from proestrus to estrus (P<0.05). Thereafter, it dramatically decreased from estrus to Day 10 of diestrus (P<0.05), and stayed low at Day 35 of diestrus and anestrus; this was consistent with blood estrogen concentrations. Levels of lactoferrin mRNA were higher in bitches with pyometra than in normal diestrus (P<0.05). With immunohistochemistry, distinct staining of lactoferrin was detected in the luminal and glandular epithelial cells of the endometrium at proestrus and estrus, but little staining was detected at Day 10 of diestrus. At Day 35 of diestrus and anestrus, a partial and weak reaction was present in the same region. In bitches with pyometra, the glandular epithelial cells and many cells in the uterine stroma were strongly stained. Staining cells in the stroma were morphologically similar to neutrophils. No lactoferrin staining was seen in the uterine stromal cells or myometrium in any section. These results suggest that, in the canine uterus, lactoferrin expression is related to the blood concentration of estrogen, and that the dramatic reduction in lactoferrin observed at the early stage of diestrus may impair antimicrobial defense. Also, enhanced expression of lactoferrin mRNA in the endometrium with pyometra may be associated with neutrophil invasion into the uterus to combat the infection.