Zinc Supplementation Attenuates Cardiac Remodeling After Experimental Myocardial Infarction.

BACKGROUND/AIMS: The objective of our study was to evaluate the effects of zinc supplementation on cardiac remodeling following acute myocardial infarction in rats. METHODS: Animals were subdivided into 4 groups and observed for 3 months: 1) Sham Control; 2) Sham Zinc: Sham animals receiving zinc supplementation; 3) Infarction Control; 4) Infarction Zinc. After the followup period, we studied hypertrophy and ventricular geometry, functional alterations in vivo and in vitro, changes related to collagen, oxidative stress, and inflammation, assessed by echocardiogram, isolated heart study, western blot, flow cytometer, morphometry, and spectrophotometry. RESULTS: Infarction induced a significant worsening of the functional variables. On the other hand, zinc attenuated both systolic and diastolic cardiac dysfunction induced by infarction. Considering the infarct size, there was no difference between the groups. Catalase and superoxide dismutase decreased in infarcted animals, and zinc increased its activity. We found higher expression of collagens I and III in infarcted animals, but there was no effect of zinc supplementation. Likewise, infarcted animals had higher levels of IL-10, but without zinc interference. Nrf-2 values were not different among the groups. Infarction increased the amount of Treg cells in the spleen as well as the amount of total lymphocytes. Zinc increased the amount of CD4+ in infarcted animals, but we did not observe effects in relation to Treg cells. CONCLUSION: zinc attenuates cardiac remodeling after infarction in rats; this effect is associated with modulation of antioxidant enzymes, but without the involvement of collagens I and III, Nrf-2, IL-10, and Treg cells.

Aging does not affect the ability of human monocyte-derived dendritic cells to phagocytose Candida albicans.

BACKGROUND: Dendritic cells (DCs) are the most potent antigen-presenting cells, playing a key role in induction of both innate and adaptive immunity. Immunosenescence refers to age-associated changes in the immune system, which may be associated with susceptibility to infections and their clinical complications. The precise effects of aging on DCs in immunity to infections are not well understood. Among the common pathogenic microorganisms, the fungus Candida albicans is an important pathogen for the development of invasive infections, especially in immunocompromised individuals, as well as during aging. AIMS: To make a comparative in vitro evaluation of the immunomodulatory function of DCs challenged with C. albicans, by phagocytosis of the fungal cells, and determine the involvement of TLR2 and TLR4 receptors. For this purpose, DCs were generated with the use of peripheral blood monocytes from healthy young and aged subjects. RESULTS: The phagocytosis of C. albicans is developed by DCs in TLR2- and TLR4-dependent way. This mechanism is not affected by aging. CONCLUSION: Given the important role of the DCs in responses against the fungus, it is evident that if changes in phagocytosis occurred with aging, impairment in the elderly could develop. However, the evidence that phagocytosis of this fungus by DCs is not impaired with aging, brings us to the question of which are the mechanisms truly associated with the prevalence of certain diseases in the elderly.

Interferon-gamma production by human neutrophils upon stimulation by IL-12, IL-15 and IL-18 and challenge with Paracoccidioides brasiliensis.

Paracoccidiodomycosis is a systemic mycosis caused by the fungus Paracoccidioides brasiliensis (Pb), which is endemic in Latin America. The host innate immune response against the fungus has been well characterized and several studies have shown the important role played by phagocytic cells. Our laboratory has studied the relationship between human neutrophils (PMNs)/Pb, focusing the effector mechanisms of these cells against the fungus. However, in last years, studies have shown that in addition to their phagocytic and killer functions, PMNs can modulate and instruct the immune response, since these cells have been shown to produce and release several cytokines. Thus, we evaluated whether PMNs stimulated with Pb can modulate the immune response to a Th1 phenotype through the production of IFN-γ, as well as the role of "pattern-recognition receptors" (PRRs) such as TLR2, TLR4 and Dectin-1 in this production. Furthermore, we asked whether activation of the cells with the cytokines IL-12, IL-15 and IL-18 could result in increased levels of this cytokine. Peripheral blood PMNs obtained from 20 healthy donors were nonactivated or activated with IL-12, IL-15 or IL-18 in different concentrations and challenged with strain 18 Pb (Pb18) for 2 h, 4 h, 12 h, 24 h and 48 h and evaluated for IFN-γ production, by ELISA. In other experiments, PMNs were treated with monoclonal antibodies anti-TLR2, TLR4 and Dectin-1, challenged with Pb and evaluated for IFN-γ production. We found that Pb induces human PMNs to produce IFN-γ, probably by binding to TLR4 and Dectin-1 receptors expressed by these cells. Moreover, IFN-γ levels were significantly increased when cells were activated with each of the tested cytokines or a combination of two of them, being the association IL-12 plus IL-15 the most effective. The results support our hypothesis that during infection by Pb, human PMNs modulate the adaptive immune response to a Th1 response pattern, via IFN-γ production.

Human neutrophils produce IL-12, IL-10, PGE2 and LTB4 in response to Paracoccidioides brasiliensis. Involvement of TLR2, mannose receptor and dectin-1.

The functions of phagocytic cells against pathogens are initiated by the interaction between membrane receptors and molecular structures which compose the cell wall of these microorganisms. Thus our study aimed to identify the neutrophil receptors involved in the recognition of different strains of Paracoccidioides brasiliensis and the consequent modulation of immune response through the production of cytokines and inflammatory mediators. Neutrophils did not produce TNF-alfa in response to both strains. However, these cells produce IL-12, mainly in response to Pb 265, with participation of TLR2 and dectin-1. These cells also produce L-10, whose levels were higher for Pb 18 with involvement of TLR2 and MR and only TLR2 for Pb 265. The production of PGE2 and LTB4 was detected similarly for the two strains. For PGE2, MR and dectin-1 were involved, while in relation to LTB4, none of them. In summary, we demonstrated that neutrophils have a dynamic role during host immune response to P. brasiliensis, since in addition to their role as effector cells of innate immunity; they have the capacity to modulate innate and adaptative immune response against this fungus by producing cytokines and lipidic mediators. This modulation may be toward a pró- or anti-inflammatory pattern in a dependence of P. brasiliensis strains and PRR involved in fungus recognition by these cells.

Low Concentration of 5-Fluorouracil Increases the Effectiveness of Tumor RNA to Activate Murine Dendritic Cells.

AIM: Considering the central role of dendritic cells (DCs) on the development of an antitumor immune response, in this study we used a murine model to evaluate how DC transfection with drug-treated tumor cell RNA changes their phenotype, and whether transfection enhances the in vivo effectiveness of a DC-based antitumor vaccine. MATERIALS AND METHODS: MC-38 colorectal tumor cells were pretreated with the minimum effective concentration of 5-fluorouracil (5-FU), then their total RNA was extracted and transfected into DCs. These DCs were inoculated into C57Bl/6 mice bearing subcutaneous MC-38 tumor. RESULTS: DC transfection with drug-treated tumor RNA increases the percentages of CD40+ (from 37.6% to 61.4%), CD86+ (from 39.8% to 53.4%), and major histocompatibility complex class II+ (from 51.2% to 75.3%) cells, whereas significantly increases the in vivo generation of interferon-γ producer lymphocytes. CONCLUSION: These results reinforce our view that treatment of tumor cells with 5-FU induces transcriptional changes that can be transferred to DCs by RNA transfection, enhancing their ability to stimulate an antitumor response.

Vitamin D Deficiency and Rheumatoid Arthritis.

Vitamin D (VitD) is a hormone primarily synthesized in human skin under the stimulation of ultraviolet radiation. Beyond its endocrine role in bone metabolism, VitD is endowed with remarkable immunomodulatory properties. The effects of VitD on the immune system include the enhancement of microbicidal ability of monocytes/macrophages and the down-modulation of inflammatory cytokines produced by T lymphocytes. VitD deficiency is involved in many health problems, including immune-mediated diseases such as autoimmune disorders. Rheumatoid arthritis (RA) is a chronic inflammatory systemic autoimmune disease that compromises the joints, causing cartilage destruction and bone erosion. RA treatment usually consists of combined therapies that generally suppress the entire immune response leading to increased susceptibility to infections. This review describes the main effects of VitD on innate and adaptive immune system and also VitD status in inflammatory rheumatic diseases such as RA. Despite some controversies, the majority of reports reinforce the idea that lower VitD levels correlate with more severe clinical manifestations in RA and other rheumatic diseases. Therefore, supplementation with VitD to achieve normal serum levels is worthwhile as an aforethought. Original data concerning the potential applicability of 1,25-dihydroxyvitamin D3 (VitD3), the active form of vitamin D, as a tolerogenic adjuvant are also included. In this sense, the effect of VitD3 associated with proteoglycan (PG), which is a specific cartilage antigen, was tested in the course of experimental arthritis. This association significantly lowered clinical scores and local histopathological alterations. Even though local analysis of T cell subsets and cytokine production did not reveal any difference between the experimental groups, VitD3+PG association significantly reduced cytokine production by spleen cells. These results suggest that VitD3 played a role as a tolerogenic adjuvant by down-modulating the course of experimental RA. Considering this tolerogenic effect of VitD3+PG association, further investigations will reveal its plausible use in human RA.

Cryoprotective effect of different glycerol concentrations on domestic cat spermatozoa.

Cryopreservation of spermatozoa is a pivotal tool in assisted reproduction, and studies aiming to establish optimal freezing/thawing protocols are essential to enhance sperm survival. The objectives of the present study were to (1) compare the cryoprotective efficiency of three different glycerol concentrations (3%, 5%, and 7%) on the basis of post-thaw sperm quality and (2) investigate whether the incidence of morphologically abnormal sperm in fresh samples is related to cryodamage sensitivity. Semen was collected from six tomcats using an artificial vagina (total 18 ejaculates). Each ejaculate was diluted using Tris-egg yolk-based extender (TEY), evaluated, equally divided into three aliquots, and rediluted using TEY with and without glycerol to achieve final concentrations of 3%, 5%, and 7%. Samples were loaded into 0.25 mL straws, equilibrated for 60 minutes at 5 °C, frozen, and then thawed at 46 °C for 12 seconds. Fresh and frozen-thawed samples were evaluated for sperm motion parameters (computer-assisted sperm analysis), plasma membrane integrity (PMI; propidium iodide and carboxyfluorescein diacetate), and DNA integrity (acridine orange). Plasma and acrosomal membrane integrity were assessed by flow cytometry (propidium iodide and fluorescein isothiocyanate-conjugated pea (Pisum sativum) agglutinin) immediately after thawing. Sperm motion parameters were also evaluated at 30 and 60 minutes of postincubation. For all treatment groups, cryopreservation significantly impaired the PMI and sperm motion parameters, except for straightness and amplitude of lateral head displacement. DNA integrity showed a slight reduction (P < 0.05) when 3% glycerol was used. The percentage of total motility, progressive motility, and rapid spermatozoa were significantly lower immediately after thawing and up to 60 minutes of incubation for the 3% glycerol group when compared with 5% and 7%. No difference (P > 0.05) was found for PMI, acrosome integrity, and DNA integrity among post-thaw groups. However, higher (P < 0.05) incidence of viable cells with reacted acrosome and dead cells with intact acrosome were observed with 7% and 3% glycerol, respectively. Percentage of morphologically abnormal spermatozoa in fresh sample was positively correlated with PMI only in the 3% glycerol group and negatively correlated with sperm motility in the 5% and 7% groups. In conclusion, the final concentration of 5% glycerol offered better cryoprotective effect for ejaculated cat sperm, and the relationship found between prefreezing sperm morphology and post-thaw sperm quality showed to be dependent on final glycerol concentration.