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To address whether the burst of systemic interleukin-12 (IL-12) influences intestinal inflammation elicited by luminal stimuli, we induced IL-12 release by cDNA injection in C57BL/6 mice and simultaneously started dextran sulphate sodium administration. The sequence of the inflammatory response triggered by IL-12 release was characterized by assessing myeloperoxidase activity and histological damage in colon samples on days 1, 3, 5 and 7 after colitis induction. To evaluate the persistence of IL-12 priming, colitis was induced in mice 7 or 60 days after cDNA injection. Under IL-12 influence, the development of acute colitis presented a faster and selective infiltration of inflammatory mononuclear cells in the lamina propria. Recruitment was driven by systemic cytokines rather than luminal antigens. Interestingly, when colitis was triggered 7 or 60 days after the cytokine storm, cells maintained the ability to worsen clinical signs of intestinal inflammation. Together, a systemic IL-12 burst effectively primed intestinal cells that became more prone to develop inflammatory responses. Activation was long-lasting because intestinal cells maintained their inflammatory potential and their ability to aggravate colitis. Fil: Pedrotti, Luciano Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Sena, Angela A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Rodriguez Galán, María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Cejas, Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Correa, Silvia Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina

We evaluated whether the lack of TNF-α signaling increases mucosal levels of annexin A1 (AnxA1); the hypothesis stems from previous findings showing that TNF-α neutralization in Crohn´s disease patients up-regulates systemic AnxA1 expression. Biopsies from healthy volunteers and patients under anti-TNF-α therapy with remittent ulcerative colitis (UC) showed higher AnxA1 expression than those with active disease. We also evaluated dextran sulfate sodium (DSS)-acute colitis in TNF-α receptor 1 KO (TNFR1-/-) strain with impaired TNF-α signaling and C57BL/6 (WT) mice. Although both strains developed colitis, TNFR1-/- mice showed early clinical recovery, lower myeloperoxidase (MPO) activity and milder histopathological alterations. Colonic epithelium from control and DSS-treated TNFR1-/- mice showed intense AnxA1 expression and AnxA1+ CD4+ and CD8+ T cells were more frequent in TNFR1-/- animals, suggesting an extra supply of AnxA1. The pan antagonist of AnxA1 receptors exacerbated the colitis outcome in TNFR1-/- mice, supporting the pivotal role of AnxA1 in the early recovery. Our findings demonstrate that the TNF-α signaling reduction favors the expression and biological activity of AnxA1 in inflamed intestinal mucosa. Fil: Sena, Angela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Pedrotti, Luciano Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Barrios, Bibiana Elisabet. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Cejas, Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Balderramo, Domingo. Hospital Privado Centro Medico de Córdoba; Argentina Fil: Diller, Ana. Hospital Privado Centro Medico de Córdoba; Argentina Fil: Correa, Silvia Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina

We evaluated the host metabolic response to chronic varied stress during infection with the fungus Candida albicans. We used four groups of female Wistar rats: normal uninfected and unstressed, stressed, C. albicans infected and infected, and stressed. Infected rats reacted with rapid metabolic adjustments, evident as anorexia and body weight loss, partly mediated by glucocorticoids and TNF-á. Higher circulating levels of IL-6 and glucose (p < 0.05) revealed the progress and catabolic effect of the inflammatory response. Infected and stressed rats instead showed anorexia associated with infection and weight loss as the result of reduced food intake. This group exhibited a prompt reduction in circulating leptin on day 3 (p < 0.05), reduction in glucose levels and depletion of hepatic glycogen depots. We also evaluated the contribution of TNF-á, glucocorticoids, and food deprivation to liver damage. Lipid peroxidation in liver detected in the infected and infected-stressed groups was exacerbated by the glucocorticoid receptor antagonist RU 486, suggesting the modulatory activity of glucocorticoids, while hepatic fat accumulation and glycogen depletion decreased with anti-TNF-á treatment. Food deprivation exacerbated liver injury while the response to stress contributed to greater fungal colonization. Our findings emphasize the impact of metabolic alterations on tissue damage when the host immune activity is modulated by stress mediators. Fil: Rodriguez Galan, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Porporatto, Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones y Transferencia de Villa María. Universidad Nacional de Villa María. Centro de Investigaciones y Transferencia de Villa María; Argentina Fil: Sotomayor, Claudia Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Cano, Roxana Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Cejas, Hugo. Universidad Nacional de Córdoba. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Correa, Silvia Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina

The yeast Candida albicans belongs to the microflora of healthy individuals, although it can infect a variety of tissues ensuing changes in the host's immune status. To evaluate the effect of neuroendocrine input on the early immune response during the fungal infection, we use a 3-day paradigm of chronic varied stress in Wistar rats infected with C. albicans. We find that stress mediators contribute to the spread of the fungus and downregulate critical functions of phagocytic cells at the infection site. Phenotypic and functional alterations of effector cells account for the decreased resistance to candidiasis and condition the development of the adaptive response. Stressed hosts exhibit a higher fungal burden in kidneys and livers associated with hyphal forms. The hepatic inflammatory reaction is compromised with severe steatosis, increment of functional enzymes, marked lipid peroxidation and hepatocyte apoptosis. Moreover, infection-related sickness symptoms are significantly increased by exposure to stress with anorexia, weight loss, lack of leptin and depletion of glycogen depots. Food deprivation exacerbates the liver injury. Stress mediators perturb the complex immune and metabolic program that operates early during fungal spread and promotes severe tissue damage Fil: Rodriguez Galan, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Sotomayor, Claudia Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Cano, Roxana Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Porporatto, Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Renna, Maria Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Paraje, María Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Cejas, Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Correa, Silvia Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina

Microcalcifications can be the early and only presenting sign of breast cancer. One shared characteristic of breast cancer is the appearance of mammographic mammary microcalcifications that can routinely be used to detect breast cancer in its initial stages, which is of key importance due to the possibility that early detection allows the application of more conservative therapies for a better patient outcome. The mechanism by which mammary microcalcifications are formed is still largely unknown but breast cancers presenting microcalcifications are more often associated with a poorer prognosis. We combined Capillary Electrochromatography, histology, and gene expression (qRT-PCR) to analyze patient-matched normal breast tissue vs. breast tumor. Potential carcinogenicity of oxalate was tested by its inoculation into mice. All data were subjected to statistical analysis. To study the biological significance of oxalates within the breast tumor microenvironment, we measured oxalate concentration in both human breast tumor tissues and adjoining non-pathological breast tissues. We found that all tested breast tumor tissues contain a higher concentration of oxalates than their counterpart non-pathological breast tissue. Moreover, it was established that oxalate induces proliferation of breast cells and stimulates the expression of a pro-tumorigenic gene c-fos. Furthermore, oxalate generates highly malignant and undifferentiated tumors when it was injected into the mammary fatpad in female mice, but not when injected into their back, indicating that oxalate does not induce cancer formation in all types of tissues. Moreover, neither human kidney-epithelial cells nor mouse fibroblast cells proliferate when are treated with oxalate. We found that the chronic exposure of breast epithelial cells to oxalate promotes the transformation of breast cells from normal to tumor cells, inducing the expression of a proto-oncogen as c-fos and proliferation in breast cancer cells. Furthermore, oxalate has a carcinogenic effect when injected into the mammary fatpad in mice, generating highly malignant and undifferentiated tumors with the characteristics of fibrosarcomas of the breast. As oxalates seem to promote these differences, it is expected that a significant reduction in the incidence of breast cancer tumors could be reached if it were possible to control oxalate production or its carcinogenic activity.

For more than a decade, the cytokine interleukin-12 (IL-12) has been utilized, either alone or in combination with otherdrugs, as a treatment for cancer. The numerous anti-tumor properties of IL-12 still generate interest in the clinical use of thiscytokine, even though it has demonstrated toxicity when administrated systemically. As an approach to overcome thistoxicity, numerous laboratories have attempted to induce IL-12 expression at the site of the tumor. However for tumors thatare difficult to remove surgically or for the treatment of disseminated metastases, systemic expression of this cytokine stillremains as the most efficient method of administration. Nevertheless, finding alternative approaches for the use of IL-12 inthe treatment of cancer and unraveling the basis of IL-12-side effects remain a challenge. In the present work wedemonstrate that systemic expression of IL-12 through hydrodynamic injection of IL-12 cDNA is able to induce differenttypes of liver lesions associated with a toxic pathology. However we report here that hepatic toxicity is diminished andsurvival of mice enhanced in the absence of tumor necrosis factor alpha (TNFa). This observation is in contrast to severalmurine models and clinical trials that postulate interferon gamma (IFNc) as the main cytokine responsible for IL-12 toxicity.Moreover, our work demonstrates that when IL-12 cDNA is co-injected with IL-18 cDNA or when mice are pre-treated with alow dose of IL-12 cDNA prior to receiving a high dose of IL-12 cDNA, systemic levels of TNFaare almost completelyabrogated, resulting in improved survival and less hepatic damage. Importantly, abrogation of TNFasignaling does notaffect the strong anti-tumor activity of IL-12. Thus, neutralizing TNFawith antagonists already approved for human useoffers a promising approach to abrogate IL-12 side effects during the use of this cytokine for the treatment of cancer. Fil: Barrios, Bibiana Elisabet. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Baez, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Reynolds, Della. National Cancer Institute. Maryland; Estados Unidos Fil: Iribarren, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Cejas, Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Young, Howard A.. National Cancer Institute. Maryland; Estados Unidos Fil: Rodriguez Galan, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina

Objective: Candidiasis is a prototypic opportunistic fungal disease that may follow severe modulations of the immune system of the host. The purpose of this study was to evaluate which innate immune mechanisms involved in the protection against fungal invasion are impaired under stress conditions. Methods: Wistar rats were infected intraperitoneally with Candida albicans and immediately exposed to chronic varied stress (CVS) over 10 days (CVS; Ca-S); the fungal burden (CFU), histopathological lesion and ACTH levels were evaluated. Additionally, functional assessment of peritoneal cells (PC) included the phagocytic and anticandidacidal activities and the production of H2O2 and NO. Results: In the only infected animals (Ca), C. albicans colonization stimulated an efficient inflammatory response, while in Ca-S rats poor tissue reactions were associated with increased CFU in livers and kidneys (p < 0.05, Ca vs. Ca-S). Whereas the phagocytic process was not modified, the candidacidal activity of PC was significantly decreased after the application of CVS (p < 0.001, Ca vs. Ca-S). The H2O2 production by macrophages and neutrophils was downregulated by the infection, and while at early intervals these cells possessed a residual oxidative capacity, by day 10, the production of this metabolite was blocked. Spontaneous NO production by macrophages was significantly increased in both Ca and Ca-S animals (p < 0.001), but in stressed rats, this reactive nitrogen intermediate was noticeably downregulated (p < 0.05, Ca vs. Ca-S). The hyperactivity of hypothalamus-pituitary-adrenal axis after exposure to stress was confirmed by an increase in baseline plasma ACTH levels. Conclusion: These results show that during infection with C. albicans, the exposure to CVS contributes to the spread of the fungus and downregulates critical functions of phagocytic cells involved in the control of this opportunistic pathogen.

Members of the IL-17 cytokine family play an important role in protection against pathogens through the induction of different effector mechanisms. We determined that IL-17A, IL-17E and IL-17F are produced during the acute phase of T. cruzi infection. Using IL-17RA knockout (KO) mice, we demonstrate that IL-17RA, the common receptor subunit for many IL-17 family members, is required for host resistance during T. cruzi infection. Furthermore, infected IL-17RA KO mice that lack of response to several IL-17 cytokines showed amplified inflammatory responses with exuberant IFN-γ and TNF production that promoted hepatic damage and mortality. Absence of IL-17RA during T. cruzi infection resulted in reduced CXCL1 and CXCL2 expression in spleen and liver and limited neutrophil recruitment. T. cruzi-stimulated neutrophils secreted IL-10 and showed an IL-10-dependent suppressive phenotype in vitro inhibiting T-cell proliferation and IFN-γ production. Specific depletion of Ly-6G+ neutrophils in vivo during T. cruzi infection raised parasitemia and serum IFN-γ concentration and resulted in increased liver pathology in WT mice and overwhelming wasting disease in IL-17RA KO mice. Adoptively transferred neutrophils were unable to migrate to tissues and to restore resistant phenotype in infected IL-17RA KO mice but migrated to spleen and liver of infected WT mice and downregulated IFN-γ production and increased survival in an IL-10 dependent manner. Our results underscore the role of IL-17RA in the modulation of IFN-γ-mediated inflammatory responses during infections and uncover a previously unrecognized regulatory mechanism that involves the IL-17RA-mediated recruitment of suppressive IL-10-producing neutrophils., Author Summary IL-17 family is comprised for six members (IL-17A to F) that have been reported to play protective effects in bacterial and fungal infections and contradictory roles in parasite infections. Using mice deficient in IL-17RA, the common receptor subunit for many IL-17 family members, we determined that these cytokines are required for host protection against the parasite Trypanosoma cruzi. In absence of IL-17 signaling, mice developed an aggravated infection with similar levels of parasite in blood but increased inflammation and tissue damage of vital organs such as liver. We evaluated the mechanisms underlying this increased susceptibility and determined that the absence of IL-17RA caused a reduced arrival of neutrophils to organs such as spleen and liver. Neutrophils are phagocytic cells with abilities to directly destroy pathogens and also to regulate the inflammatory response. Indeed, we determined that neutrophils from T. cruzi infected mice are poisoned to secrete the regulatory cytokine IL-10. Finally, by experiments of depletion and adoptive transfer of neutrophils we determined that, during T. cruzi infection, IL-17RA is required for the recruitment of neutrophils that destroy the parasite and that also regulate inflammatory responses and collateral tissue damage by secreting IL-10.

We investigated Chlamydia trachomatis infection and its pathogenic consequences in the male rodent genital tract.Male rats were inoculated in the meatal urethra with Chlamydia muridarum. We sought bacterial DNA at early and late times after inoculation in different parts of the male genital tract. Histological alterations and the immune response against prostate antigens were analyzed.Male rats showed ascending infection with wide dissemination of bacteria in the genital tract at an early time point after inoculation. At later stages bacteria persisted only in some parts of the genital tract and in the prostate gland. C. muridarum was also detected in semen in a high proportion of rats irrespective of an acute or chronic stage of infection. Histological alterations that accompanied C. muridarum were especially observed in the prostate and mainly composed of CD3+ cell infiltration. Positive humoral and cellular responses against prostate antigens were noted in a considerable number of infected rats. NOD mice, an autoimmune, prostatitis prone strain, showed a similar pattern with C. muridarum in the prostate of 100% of infected mice, which was again accompanied by mononuclear cell infiltration and antibodies against prostate antigens at early and late times after inoculation.Results reveal that C. muridarum infects the male rodent genitourinary tract with special persistence in the prostate gland, where it causes chronic inflammation that in turn may act as a trigger factor for self-immune reactions in susceptible hosts.

Gastrointestinal stromal tumors (GISTs) constitute the largest category of primary nonepithelial neoplasms of the stomach and small bowel. They represent about 1-2% from all neoplasms of the digestive tract. They occur most commonly in the stomach and small bowel, but small series of comparable tumors have also been reported in all the other parts of the tubular gastrointestinal tract, including esophagus, colon, rectum and anus. They can also involve omentum, mesentery, uterus, retroperitoneum, mesocolon and soft tissues. Originally recognized in 1960 by Martin et. al. as a distinctive type of stromal neoplasm of the bowel, they were subsequently reported by Stout, who introduced the term leiomyoblastoma. Because of difficulties in accurately predicting the biologic behavior of these tumors, the term "smooth muscle tumor of uncertain malignant potential" (SMTUMP) has been introduced for borderline tumors. In 1983, Mazur and Clark coined the term gastrointestinal stromal tumor and suggested that these neoplasms might arise from the myenteric nervous system. Some studies have reported evidence of neuronal cell differentiation in a proportion of GISTs and the term "gastrointestinal autonomic nerve tumor (GANT) has been introduced. Kindblom et al are providing cogent arguments to suggest that GISTs show differentiation toward interstitial Cajal cells (pacemaker cells of the gastrointestinal tract). Inmunohistochemically the GISTs often reveal inmunoreactivity for vimentin. CD34 and CD 117. The aim of this paper is to perform and analysis of the historic evolution and conceptual of the GISTs.

The liver constitutes the first barrier in the control of hematogenous dissemination for Candida albicans of intestinal origin. The ability of this organ to limit the growth of the yeast and to mount an efficient inflammatory reaction is crucial in determining the outcome of the fungal infection. When rats infected with C. albicans are exposed to chronic varied stress, the cell recruitment is impaired at the site of the infection, the tissue reaction is highly disorganized in target organs and the infection evolution is more severe. At hepatic level, higher fungal burden is associated with hyphal form and the consistent presence of steatosis (fatty liver). Herein we aimed at characterizing the steatosis associated with C. albicans infection and to provide molecular evidence of the correlation among liver injury markers, stress products and the initiation of the inflammatory tissue reaction. After 3 days of stress and infection, we observed micro and macro steatosis in acinar zone 1 (specific lipid stain), higher lipid peroxidation and increased levels of serum alanine aminotransferase and gamma glutamil transferase. While infection triggered hepatic NO production and arginase activity, stress down-modulated both. Remarkably, defects in levels of TNF-alpha and NO were observed during the first step of the inflammatory response. Our results demonstrate that stress mediators down-regulate the acute inflammatory reaction in the hepatic scenario, promoting a major liver injury with particular immunopathological traits.

From the first description of Pretl in 1944, many authors have shown different morphological and immunohistochemical studies related to prostatic neuroendocrine cells. These cells belong to a neuroendocrine system, wide disseminated network, that is found in many human tissues. They secret neuroendocrine peptides and play an important role in the glandular epithelium regulation (growing, differentiation, and exocrine secretion), in both normal and hyperplastic glands. They are also present in ordinary prostatic adenocarcinoma and in unusual small cell carcinoma. Recently, it has been suggested that prostatic neuroendocrine cells may be related to prognosis in prostatic carcinoma, particularly in cases with hormonal therapy resistant. In this study, there are 23 prostatic disorders: 11 nodular hyperplasias and 12 adenocarcinomas, and also areas of normal gland. The objective is the morphologic identification of these cells with silver impregnation technique, in normal tissue, nodular hyperplasia and adenocarcinoma. In normal gland and nodular hyperplasia, the NE cells can be seen along most of the gland or near the urethra, solitary or in small clusters. These cells are located between acinar epithelium cells and basement membrane, but they are also found within the stroma in relation to nerve endings. They characteristically contain argyrophil and argentaffin granules in the cytoplasm and exhibit cytoplasmatic processes extended to acinar or urethral lumen. Within the stroma, they are seen isolated with dendritic or ribbon-like cytoplasmatic processes. In this study, there is only one adenocarcinoma of high grade with NE cells. In this neoplasm they are increase in number, and appear isolated and more polymorphic.

The aim of this study was to evaluate the kinetics of the cytokines interferon-gamma, interleukin-2, interleukin-10 and interleukin-4 produced by spleen mononuclear cells stimulated by Con A during an experimental infection in rats with Fasciola hepatica. The proliferative response to Con A of Spm cells from rats infected with F. hepatica was significantly decreased on day 7 post-infection (P

The aim of the present study was to evaluate the proliferative response of spleen mononuclear cells (Spm) to mitogens in rats infected with Fasciola hepatica and its correlation with Spm and peritoneal cell (PC) nitric oxide (NO) production on Days 1, 3, 7, 14, 30, and 60 postinfection. In addition, histological changes in the liver were also studied. The proliferative response to Con A of F. hepatica-infected Spm was significantly decreased on Day 7 postinfection (P < 0.01). However, a pronounced increase of the proliferative response was detected from Day 3 until Day 60 when Spm were stimulated with LPS. In order to determine whether NO levels were modified during F. hepatica infections, we quantified nitrite in Spm and PC supernatants in cultures. Our results indicate a profound decrease of nitrite production by LPS-stimulated PC on the first and second weeks postinfection, and an increase in the levels of this mediator on LPS-stimulated Spm at the same postinfection time. The F. hepatica excretory-secretory antigen (ESA) was in part involved in the decrease of nitrite production by LPS-stimulated PC. A mechanism to avoid an immune response during the first stages of liver penetration could explain the transient suppression observed in Spm proliferative responses. On the other hand, the decrease in NO production by rat-infected PC could also be one of the strategies of the parasite to avoid the potential killing effect of NO during peritoneal migration.

Background B cells and antibodies are involved not only in controlling the spread of blood circulating Trypanosoma cruzi, but also in the autoreactive manifestations observed in Chagas disease. Acute infection results in polyclonal B cell activation associated with hypergammaglobulinemia, delayed specific humoral immunity and high levels of non-parasite specific antibodies. Since TNF superfamily B lymphocyte Stimulator (BAFF) mediates polyclonal B cell response in vitro triggered by T. cruzi antigens, and BAFF-Tg mice show similar signs to T. cruzi infected mice, we hypothesized that BAFF can mediate polyclonal B cell response in experimental Chagas disease. Methodology/Principal Findings BAFF is produced early and persists throughout the infection. To analyze BAFF role in experimental Chagas disease, Balb/c infected mice were injected with BR3:Fc, a soluble receptor of BAFF, to block BAFF activity. By BAFF blockade we observed that this cytokine mediates the mature B cell response and the production of non-parasite specific IgM and IgG. BAFF also influences the development of antinuclear IgG and parasite-specific IgM response, not affecting T. cruzi-specific IgG and parasitemia. Interestingly, BAFF inhibition favors the parasitism in heart. Conclusions/Significance Our results demonstrate, for the first time, an active role for BAFF in shaping the mature B cell repertoire in a parasite infection., Author Summary Chagas disease, caused by the protozoan Trypanosoma cruzi, is endemic in Central and South America. It affects 20 million people and about 100 million people are at risk of infection in endemic areas. Some cases have been identified in non-endemic countries as a consequence of blood transfusion and organ transplantation. Chagas disease presents three stages of infection. The acute phase appears one to two weeks after infection and includes fever, swelling around the bite site, enlarged lymph glands and spleen, and fatigue. This stage is characterized by circulating parasites and many immunological disturbances including a massive B cell response. In general, the acute episode self-resolves in about 2 months and is followed by a clinically silent indeterminate phase characterized by absence of circulating parasites. In about one-third of the cases, the indeterminate phase evolves into a chronic phase with clinically defined cardiac or digestive disturbances. Current knowledge suggests that the persistence of parasites coupled with an unbalanced immune response sustain inflammatory response in the chronic stage. We believe that an effective treatment for chronic Chagas disease should combine antiparasitic drugs with immunomodulators aimed at reducing inflammation and autoreactive response. Our findings enlighten a new role of BAFF-BAFF-R signaling in parasite infection that partially controls polyclonal B cell response but not parasitespecific class-switched primary effectors B cells.