Immune-endocrine interactions in treated and untreated cats naturally infected with FIV

Feline immunodeficiency virus (FIV) is a lentivirus that causes a progressive disruption of immune function in cats. The neuroendocrine and immune systems communicate bidirectionally, mediated by cytokines such as tumour necrosis factor-α (TNF), several interleukins (IL-1, IL-6, IL-10), and through signals induced by the ratio of IL-10 to IL-12. FIV can affect both pituitary adrenal and thyroid axis function. Twenty FIV-infected cats in similar stages of the disease were evaluated for six months. A cross-sectional study in which the twenty cats were divided into two groups was performed. Ten were treated with Zidovudine (ZDV: 5mg/kg/d, PO, q12h, for six months) and 10 were untreated. Plasma concentrations of adrenocorticotropic hormone (ACTH), cortisol, T4, FT4, T3, IL-10, IL-12 and viral load (VL) were evaluated after six months. ACTH was found in significantly lower concentrations (p<0.0001) in the treated group whereas cortisol did not show significant differences between the two groups. Both T4 and FT4 had high values in untreated individuals (p<0.001) compared with Zidovudine treated cats. T3 did not show significant differences between the two groups. Both IL-10 and IL-12 were found in significantly higher concentrations in ZDV treated cats (p<0.001). By contrast, the IL10/IL-12 ratio values were significantly lower in untreated cats. Viral load was significantly lower in the treated cats after six months of therapy, compared with values detected pre-treatment (p<0.002). Untreated cats showed a significant increase of VL (p<0.04) compared with the values at the beginning of the study. In treated cats, VL showed lower numbers of viral copies than in untreated cats (p<0.01). In summary, Zidovudine treatment appeared to contribute to the normalization of both the adrenal and thyroid axes. This effect could be attributed to the decrease observed in VL, resulting in a change in cytokine patterns.     

Distribution of eosinophil granulocytes and mast cells in the reproductive tract of female goats in the preimplantation phase

Changes in eosinophil granulocytes and mast cells post-insemination may affect conceptus implantation, but information regarding the numbers of such cells in the mammalian reproductive tract is limited. This study investigated the preimplantation distribution of eosinophil granulocytes and mast cells (MCs) in the reproductive tract organs of female goats. Uterus, uterine cervix and uterine tubes samples were obtained at slaughter. Cornu uteri were washed in phosphate buffer solution (each animal contained at least one embryo). Tissues were fixed in 10% neutral buffered formol, Carnoy solution and Mota’s fixative (basic lead acetate) for 48 h and embedded in paraffin. Six-micrometre-thick sections were stained with Congo red (for eosinophil granulocytes) and toluidine blue in 1% aqueous solution at pH 1.0 for 5 min (for MCs). In the uterus, MCs occurred in highest numbers in the myometrium. Higher MC numbers were observed in uterus, uterine and uterine tubes in the preimplantation (experimental) group (cycle synchronised through 7 days intravaginal sponge with 0.3 g P₄) compared with the control group (P < 0.05). Eosinophil granulocyte numbers were significantly higher in the experimental group than in the control group (P < 0.05). These results indicate preimplantation-related changes in numbers of eosinophil granulocytes and MCs in goat reproductive tract organs.     

Inflammation in the bovine female reproductive tract

Inflammation of the reproductive tract of a cow occurs when the physical and functional barriers to contamination are breached or specific infection occurs. Commonly, contamination occurs at parturition and to a lesser extent at estrus. Uterine contamination following calving is common, but most healthy cows are able to clear the uterus of bacteria in the first 2 to 3 wk after calving. Persistent infections are more likely to be caused by Actinomyces pyogenes. Specific venereal infections tend to be more host-adapted and produce a lower grade inflammation. Nonspecific bacterial contamination of the endometrium generally induces a neutrophilic influx into the stratum compactum and uterine lumen. Neutrophils phagocytize bacteria with the aid of opsonins in the uterine fluid. Mast cells and eosinophils may also contribute to the inflammatory reaction, which may damage the surface epithelium and release vasoactive substances that allow leakage of serum antibodies into the uterine secretions. Specific antibodies of immunoglobulin (Ig) isotype A, M, G1, and G2 in uterine secretions have been described. In model species, the immune capability of the uterus is influenced by steroid hormones, especially estradiol, which increases secretory component and both IgA and IgG content in uterine secretions and increases the activity of antigen-presenting cells in the uterus. Similar cyclic fluctuations in immune components have been described for cows, including changes in the population of subsurface cytotoxic and helper T cells and changes in the expression of major histocompatibility II antigen on surface cells.     

Immunity in the female sheep reproductive tract

Immune surveillance in the female reproductive tract is dependent on the interplay of many factors that include the expression of pattern recognition receptors on epithelial cells, resident leukocyte populations and hormones, none of which are uniform. The lower reproductive tract must accommodate the presence of commensal organisms whereas the upper reproductive tract is sterile. However, the upper female reproductive tract has its own immunological challenge in that it must tolerate the presence of a semi-allogeneic fetus if pregnancy is to succeed. So, immune activation and effector mechanisms to control pathogens may be qualitatively and quantitatively different along the reproductive tract. Our knowledge of innate and adaptive immunity in the sheep is less comprehensive than that of human or mouse. Nevertheless, comparative studies suggest that there are likely to be conserved innate immune sensory mechanisms (e.g. Toll-like receptors) and defence mechanisms (anti-proteases, defensins) that combine to limit infection in its early stages while shaping the adaptive response that leads to immunological memory and long-term protection. There are many pathogens that target the reproductive tract, and in particular the placenta, where specialised immunoregulatory mechanisms are operational. Among such pathogens are bacteria belonging to the genera Chlamydia/Chlamydophila that chronically infect the reproductive tracts of sheep and humans and ultimately cause disease through inflammation and tissue damage. An understanding of the immunological microenvironment of the reproductive tract is important for the design of novel control strategies to control chlamydial disease.     

Sperm interaction with the female reproductive tract

Sperm transit in the female tract is a critical event for the success of fertilization. From their deposition in the vagina to final migration in the oviduct, sperm pass through the different compartments of the genital tract in which they encounter different environments. The cervix and the uterotubal junction (UTJ) are two barriers with different relative importance according to the species. The protein composition, the degree of glycosylation and the hydration of the cervical mucus change during the oestrous cycle. Several sperm surface proteins are associated with their migration through the cervical mucus and the UTJ. Data regarding the interaction of sperm with secretions of the epithelial tissue lining the different compartments of the female genital tract during the sperm transit are reviewed, with a particular emphasis on the migration of sperm through the cervix.     

Interaction of Tritrichomonas foetus with the reproductive tract of experimentally infected female BALB/c mice: ultrastructural evaluation

The interaction of Tritrichomonas foetus with its host is a complex process that involves colonisation, attachment and persistence. The goal of the present study was to describe the interaction of T. foetus with the genital tract using a model of non-oestrogenised female BALB/c mice which had been intravaginally infected with a suspension of T. foetus during oestrus. Animals were sacrificed after 10 weeks and the uteri fixed and processed for light and electron microscopy. Ultrastructural analysis showed that the attached protozoa interacted with the mucosa through a somal projection. With an amorphous secretion at the protozoa-host cell interface. There was no direct contact between the protozoal plasma membrane and the epithelial cell membrane. Our results demonstrated the participation of an active phagocytosis and the destruction of T. foetus by eosinophils.     

Antibody responses to Toxoplasma gondii antigens in aqueous and cerebrospinal fluids of cats infected with T. gondii and FIV.

Antibodies to antigens of Toxoplasma gondii were measured in the aqueous and cerebrospinal fluid (CSF) of 16 specific-pathogen free kittens experimentally infected with feline immunodeficiency virus (FIV), T. gondii, or both pathogens. The results indicated that all cats infected with T. gondii had antibody responses to antigens of T. gondii in both aqueous fluids and CSF. Co-infection with FIV did not affect antibody levels. Aqueous fluids from eyes of cats with toxoplasmic retinochoroiditis did not necessarily have higher antibody levels than those from eyes without lesions. Antibodies to T. gondii were also detected in the CSF of two cats from whose brains no parasites were isolated by in vivo mouse inoculation. Total IgG did not increase significantly in the aqueous fluids and CSF of cats infected with T. gondii whether or not they were also infected with FIV.     

Ability of CD8+ T cell anti-feline immunodeficiency virus (FIV) activity and FIV proviral DNA load in mononuclear cells in FIV-infected cats

We investigated the relationship between CD8+ T cell anti-feline immunodeficiency virus (FIV) activity and FIV proviral DNA load integrated in mononuclear cells. The anti-FIV activity and the proviral DNA load were correlated, and the number of proviral DNA copies was high in cats with decreased anti-FIV activity. Particularly, no anti-FIV activity was detected in the cats staged as having an acquired immunodeficiency syndrome (AIDS)-related complex or AIDS, and the number of proviral DNA copies was obviously increased compared to those in the cats in the asymptomatic stage. These results suggest that decreased anti-FIV activity destroys the control of in vivo FIV replication, which leads to an increased proviral DNA load with the progression of the clinical stage of disease.     

Oral Recombinant Feline Interferon-Omega as an alternative immune modulation therapy in FIV positive cats: Clinical and laboratory evaluation

Recombinant-Feline Interferon-Omega (rFeIFN-ω) is an immune-modulator licensed for use subcutaneously in Feline Immunodeficiency virus (FIV) therapy. Despite oral protocols have been suggested, little is known about such use in FIV-infected cats. This study aimed to evaluate the clinical improvement, laboratory findings, concurrent viral excretion and acute phase proteins (APPs) in naturally FIV-infected cats under oral rFeIFN-ω therapy (0.1 MU/cat rFeIFN-ω PO, SID, 90 days). 11 FIV-positive cats were treated with oral rFeIFN-ω (PO Group). Results were compared to previous data from 7 FIV-positive cats treated with the subcutaneous licensed protocol (SC Group). Initial clinical scores were similar in both groups. Independently of the protocol, rFeIFN-ω induced a significant clinical improvement of treated cats. Concurrent viral excretion and APP’s variation were not significant in the PO Group. Oral rFeIFN-ω can be an effective alternative therapy for FIV-infected cats, being also an option for treatment follow-up in cats submitted to the licensed protocol.     

Immunoglobulins and immunoglobulin-containing cells in the reproductive tract of normal rams

The levels of the immunoglobulins IgA, IgG1, IgG2, and IgM were measured in serum and fluid from various locations in the reproductive tract of normal rams. These fluids included semen, preputial washings, and fluid from the accessory sex glands (ASG), vasa deferens, rete testes, and tissue fluid from the seminal vesicles, bulbourethral glands, epididymal tails and efferent ducts. In addition, the prevalence of specific Ig-containing cells (ICC) was measured in sections of formalin fixed tissues stained by an indirect peroxidase-antiperoxidase labelling technique. Mean IgA levels in semen (1.23 mg/ml) and ASG fluid (0.46 mg/ml), were higher than in serum (0.19 mg/ml) and were at levels higher than IgG1 or IgG2 levels in semen, ASG fluid, and preputial washings, thus confirming the existence of a local immune system primarily in the ASG of ram genitalia. Relatively low concentrations of IgA and IgG in other genital fluids and IgG levels in these fluids were consistent with diffusion from serum. The relatively high prevalence of IgA-containing cells in bulbourethral (56% of all ICC) and prostate (49%) glands confirmed these tissues as major sites of local Ig production. ICC were also found in large numbers beneath pelvic urethral and preputial epithelia, but these were predominantly IgG-containing (88 and 72% respectively).     

Mechanisms of sperm storage in the female reproductive tract: an interspecies comparison

Once semen has been collected for artificial insemination, it is diluted into extenders designed to prevent its deterioration over the period prior to insemination. If the semen is not frozen, the extenders provide protection for a period of a few hours to a few days, depending on species. Despite the efforts of biotechnologists to increase the duration of storage without compromising fertility, there has been relatively little progress for many years. However, comparative studies in diverse species have revealed that long-term sperm storage (up to months and years) within the female reproductive tract is relatively commonplace in reptiles, fishes, birds and amphibians. Even among mammals, some species of bat have evolved mechanisms for storing spermatozoa for several months in the uterus or oviduct so that they can mate in the autumn but postpone fertilization until the spring. We currently know little about the mechanisms that support such long-term sperm storage, mainly because evidence from such species is either absent or fragmentary. Nevertheless, parallels between mammalian and other systems, where spermatozoa are sequestered in sperm storage tubules, suggest that the enclosure of spermatozoa within pockets of epithelial cells may be sufficient to achieve long-term sperm storage. In addition, recent evidence from sperm-storing bats has suggested an alternative, or additional, hypothesis that the modulation of apoptosis within epithelial cells is important in controlling sperm survival. Despite a lack of direct experimental evidence from a wide variety of species, I propose that there is now enough evidence to warrant investigation of these hypotheses.     

Immunohistological studies of the local immune system in the reproductive tract of the mare

The immunoperoxidase technique was adapted for the identification of free immunoglobulin and immunoglobulin producing cells in equine tissues. Staining specific for free IgG, IgA and IgM was detected at all levels of the reproductive tract, and secretory component staining was present in the uterine epithelium but not in the oviduct, cervix or vagina. Immunoglobulin producing cells were present at all levels of the tract, with IgG and IgA cells at equivalent concentrations, but with fewer IgM cells. There was no cyclical trend in free immunoglobulin staining, or plasma cell numbers. IgG and IgM plasma cell numbers declined from uterus to vagina, as did epithelial staining, and the ratio of IgG:IgA cells declined from oviduct to vagina.     

Granular cell lesions in the distal female reproductive tract of aged Sprague-Dawley rats

During the review of a rat carcinogenicity study, a spectrum of granular cell lesions was recognized in the distal female reproductive tract. To verify the diagnoses, cell populations of nine granular cell alterations of the cervix or vagina were characterized immunohistochemically and four were evaluated ultrastructurally. Immunoreactivity was demonstrated in 8/9 cases with S100 protein, 6/9 cases with neuron-specific enolase, and 7/9 cases with Leu-7. Granular cells were negative for smooth muscle-specific actin and calretinin. The immunohistochemical profile of these lesions was similar to that previously reported in other species, including humans. Ultrastructurally, as expected many lysosomal bodies were present in the cytoplasm of granular cells in all specimens evaluated. Based on the detailed evaluation of a series of lesions, we adopted the following diagnostic criteria and nomenclature for the granular cell changes of the female reproductive tract of rats. Granular cell aggregates were non-space-occupying lesions composed of clusters of typical granular cells. Benign granular cell tumors were space occupying lesions that typically contained prominent interstitial collagen and were either discrete masses or were difficult to discern from the surrounding tissues. Some benign tumors also contained foci of spindle cells with decreased granularity. Malignant tumors exhibited pleomorphism and an increased nucleus: cytoplasm ratio morphologically but had the same biologic behavior as the benign tumors. We applied these diagnostic criteria during the review of controls from 9 carcinogenicity studies. Up to 23% of control females in those carcinogenicity studies had granular cell lesions that could be classified into one of the three categories. Granular cell lesions appear to be common in the cervix/vagina of the Sprague-Dawley rat, and tumors may develop from granular cell aggregates.     

Local pulmonary immune responses in domestic cats naturally infected with Cytauxzoon felis

Cytauxzoonosis is a hemoprotozoal disease of cats and wild felids in the South and Southeastern United States caused by Cytauxzoon felis. Although the causative agent has been recognized since the seventies, no study has examined the local immune response in affected organs, such as the lung, and compared them to the lungs of uninfected domestic cats. Previous studies have suggested that the histopathologic findings in the lungs of C. felis-infected cats are caused by the release of pro-inflammatory mediators, such as cytokines and increased production of inducible nitric oxide synthase (iNOS), by the infected macrophages. Our laboratory had previously found an upregulation of the adhesion molecule CD18, which can stimulate the release of these pro-inflammatory mediators. The objective of this study was to characterize local pulmonary immune responses in cats naturally infected with C. felis. Immunohistochemistry was performed to detect tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, iNOS, and major histocompatibility complex (MHC) II in 19 lungs from affected cats that died between 2005 and 2013. Results showed increased expression of all of these molecules when compared to lungs from uninfected, healthy cats. Furthermore, MHC II is expressed in the endothelium of C. felis naturally infected cats. These results support that there is a marked, local, pro-inflammatory immune response that can contribute to the pathogenesis of cytauxzoonosis in the lungs.