Effect of Diet and Exercise on the Peripheral Immune System in Young Balb/c Mice.

Although diet and exercise clearly have an influence on immune function, studies are scarce on the effect caused by exercise and the consumption of a carbohydrate-rich or fat-rich diet on the peripheral immune system. The aim of the present study was to evaluate the effect of exercise and the two aforementioned unbalanced diets on young Balb/c mice, especially in relation to BMI, the level of glucose, and the percentage of lymphocyte subpopulations in peripheral blood. The changes found were then related to the synthesis of leptin and adiponectin as well as the production of oxidative stress. The increase in BMI found with the carbohydrate-rich and fat-rich diets showed correlation with the levels of leptin and adiponectin. An increase in leptin and a decrease in adiponectin directly correlated with an increase in total lymphocytes and CD4+ cells and with a decrease in B cells. The increase in leptin also correlated with an increase in CD8+ cells. Glycemia and oxidative stress increased with the two unbalanced diets, negatively affecting the proliferation of total lymphocytes and the percentage of B cells, apparently by causing alterations in proteins through carbonylation. These alterations caused by an unbalanced diet were not modified by moderate exercise.

Intermittent fasting promotes bacterial clearance and intestinal IgA production in Salmonella typhimurium-infected mice.

The impact of intermittent fasting versus ad libitum feeding during Salmonella typhimurium infection was evaluated in terms of duodenum IgA levels, bacterial clearance and intestinal and extra-intestinal infection susceptibility. Mice that were intermittently fasted for 12 weeks or fed ad libitum were infected with S. typhimurium and assessed at 7 and 14 days post-infection. Next, we evaluated bacterial load in the faeces, Peyer's patches, spleen and liver by plate counting, as well as total and specific intestinal IgA and plasmatic corticosterone levels (by immunoenzymatic assay) and lamina propria IgA levels in plasma cells (by cytofluorometry). Polymeric immunoglobulin receptor, α- and J-chains, Pax-5 factor, pro-inflammatory cytokine (tumour necrosis factor-α and interferon-γ) and anti-inflammatory cytokine (transforming growth factor-ß) mRNA levels were assessed in mucosal and liver samples (by real-time PCR). Compared with the infected ad libitum mice, the intermittently fasted infected animals had (1) lower intestinal and systemic bacterial loads; (2) higher SIgA and IgA plasma cell levels; (3) higher mRNA expression of most intestinal parameters; and (4) increased or decreased corticosterone levels on day 7 and 14 post-infection, respectively. No contribution of liver IgA was observed at the intestinal level. Apparently, the changes following metabolic stress induced by intermittent fasting during food deprivation days increased the resistance to S. typhimurium infection by triggering intestinal IgA production and presumably, pathogen elimination by phagocytic inflammatory cells.

TUNEL-positive cells in the surgical border of an amputation due to infected diabetic foot.

Diabetic infected foot is the outcome of progressive vascular and neurological damage caused by persistent chronic hyperglycemia. Due to acute hypoxia and infection, the tissues develop extensive necrosis and gangrene, which often require amputation. The decision regarding the level of amputation relies mainly on the personal experience of the surgeon who must identify the healthy tissue without necrosis. However, tissue cells under stress may succumb before clear evidence of necrosis is present. In this study, dying cells with DNA damage were identified in the necrotic lesions and surgical borders of amputations. Therefore, the main purpose of this study was to identify apoptosis in the surgical borders of amputations required to treat infected diabetic foot. Apoptosis was identified by terminal deoxynucleotidyl transferase-mediated bio-dUTP nick-end labeling (TUNEL) in the superficial and deep tissues of wounds, and in the surgical borders of 10 consecutive adult patients with diabetes mellitus type 2 (DM2) who underwent amputation due to infected diabetic foot. The severity of the disease was classified by the Acute Physiological and Chronic Health Evaluation II (APACHE II) score on admission, and laboratory data were collected and bacteriological cultures were obtained from the lesions. The ankle/arm blood pressure index was measured, the blood flow in the affected limb was evaluated by high-resolution ultrasonography and color Doppler and pulse oximetry were performed during surgery. A total of 5 males and 5 females, aged 45-84 years (58.8 ± 14.1), were included. The APACHE II score was 2-18 points (8 ± 5.7). A total of 9 patients developed sepsis and 2 succumbed. A total of 5 patients required above-ankle amputation, and 5 required toe disarticulation. The ankle/arm blood pressure index ranged from 0.23-0.85 (0.51 ± 0.23). Apoptotic cells were found in ulcers and abscesses, and in areas without necrosis. In the surgical borders of the amputations, apoptotic cells were found in skeletal muscle, blood vessels and peripheral nerves, particularly Schwann cells. Morphometric analysis revealed that the extent of apoptosis was 2-3 logarithms higher in the surgical borders of the infected diabetic foot compared to the venous ulcers, which were used as the reference. In conclusion, apoptosis was identified in regenerating tissues within diabetic foot wounds and in the surgical borders of amputations, where the surgeon considered the tissues to be undamaged. This information suggests that apoptosis may be present before visible signs of necrosis appear in the diabetic foot and may be caused by hypoxia, acidosis or proinflammatory cytokines. The extent of apoptosis in tissues proximal to necrotic areas may anticipate the development of diabetic foot and help the surgeon to make decisions regarding the need and extent of amputation.

Myeloperoxidase binds to and kills Entamoeba histolytica trophozoites.

During amebic invasion, neutrophils are a key component in either protecting against invading trophozoites or contributing to tissue damage. Upon degranulating or being lysed, neutrophils release toxic substances that can kill amebas as well as damage host tissue. In a previous study we identified a protein from nonspecifically stimulated peritoneal exudates of hamster that has peroxidase and marked amebicidal activity. In the current study we analyzed the in vitro amebicidal effect of purified hamster myeloperoxidase (MPO). The results demonstrate that MPO must bind directly to the surface of Entamoeba histolytica trophozoites in order to carry out amebicidal activity by using the H(2) O(2) produced by the amebas themselves. Myeloperoxidase-incubated amebas showed important morphological and ultrastructural alterations that increased with incubation time. Changes included an increase of vacuoles in the cytoplasm, a decrease of glycogen, alterations of nuclear morphology and disturbances in the plasma membrane culminating in complete ameba destruction.

Hypophysectomy and neurointermediate pituitary lobectomy decrease humoral immune responses to T-independent and T-dependent antigens.

In rats, hypophysectomy (HYPOX) or neurointermediate pituitary lobectomy (NIL) reduce humoral and cell-mediated immune responses. However, to our knowledge, the differences in the effects of anterior versus posterior pituitary hormones on the immune responses have not been studied to date. We compared in rats, the effects of sham surgery (SHAM), HYPOX, and NIL on humoral immune responses to T cell-independent (TI) type 1 antigen DNP-LPS and to TI type 2 antigen DNP-FICOLL, as well as to T cell-dependent (TD) antigens ovalbumin (OVA) and bovine serum albumin (BSA). The results showed that: (1) both HYPOX and NIL induced a similar and significant decrease in IgM responses towards TI-1 antigens, (2) NIL but not HYPOX induced a decreased IgM response to TI-2 antigens, and (3) both HYPOX and NIL induced similar and significant decrease in IgG responses to TI-2 antigens. Compared with the SHAM group, IgM responses to both TD antigens did not change in HYPOX and NIL animals, whereas the IgG responses to OVA and BSA significantly decreased in HYPOX and NIL animals. These results indicate that hormones of the anterior and posterior pituitary play their own role in the regulation of humoral immune responses.

Hypophysectomy and neurointermediate pituitary lobectomy decrease humoral immune responses to T-independent and T-dependent antigens

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In rats, hypophysectomy (HYPOX) or neurointermediate pituitary lobectomy (NIL) reduce humoral and cell-mediated immune responses. However, to our knowledge, the differences in the effects of anterior versus posterior pituitary hormones on the immune responses have not been studied to date. We compared in rats, the effects of sham surgery (SHAM), HYPOX, and NIL on humoral immune responses to T cell-independent (TI) type 1 antigen DNP-LPS and to TI type 2 antigen DNP-FICOLL, as well as to T cell-dependent (TD) antigens ovalbumin (OVA) and bovine serum albumin(BSA). The results showed that: (1) both HYPOX and NIL induced a similar and significant decrease in IgM responses towards TI-1 antigens, (2) NIL but not HYPOX induced a decreased IgM response to TI-2 antigens, and (3) both HYPOX and NIL induced similar and significant decrease in IgG responses to TI-2 antigens. Compared with the SHAM group, IgM responses to both TD antigens did not change in HYPOX and NIL animals, whereas the IgG responses to OVA and BSA significantly decreased in HYPOX and NIL animals. These results indicate that hormones of the anterior and posterior pituitary play their own role in the regulation of humoral immune responses (AU)

Expression of immune modulator cytokines in human fulminant amoebic colitis.

Human fulminant amoebic colitis (FAC) is characterized by ulceration and inflammation of the colon. The specific mixture of pro-inflammatory and anti-inflammatory cytokines may participate in either the host defense or in the pathogenesis of amoebic colitis. Therefore, we studied the expression of IL-8, IL-10, IL-4, TGF-beta and IFN-gamma in human FAC patients and controls through immunohistochemistry analysis. The number of cells expressing IL-8, IL-4 and IL-10 was significantly enhanced in all FAC samples compared to the control samples. However, the expression of TGF- beta in patients was low in the colonic mucosa and high in the lamina propria compared with the control. No expression of IFN-gamma was found in the controls or FAC samples. The production of IL-8 by intestinal epithelial cells may play a role in the pathogenesis of amoebic infection, because this cytokine attracts neutrophils, which lead to an inflammatory reaction that results in tissue damage. The predominant expression of the macrophage down-regulating cytokines, IL-4, IL-10 and TGF-beta, or the Th2-type immune response could inhibit a cell-mediated immune response, which in turn would facilitate parasite invasion in these tissues.

Trophozoites of Entamoeba histolytica express a CD59-like molecule in human colon.

In vitro studies have proved the presence of epitopes of CD59 in the surface of trophozoites of Entamoeba histolytica (E. histolytica). However, it has not been proved if CD59 molecules are expressed in the surface during the trophozoites' tissue invasion. The aim of the present study was to determine whether the complement-regulatory protein CD59 is present on trophozoites of E. histolytica in human colon. Eleven specimens of amoebic colitis were studied by immunohistochemistry and electron microscopy techniques with a monoclonal antibody against human CD59 molecule. Our results show that a CD59-like molecule is expressed in trophozoites of E. histolytica found in colonic amebic lesions. Also, a CD59-like molecule was detected by western blot analysis in whole lysate of E. histolytica as well as on the plasma membrane by immunocytochemistry. These results suggest that E. histolytica can use CD59-like protein against the lytic action of membrane attack complex.

Human amoebic hepatic abscess: in situ interactions between trophozoites, macrophages, neutrophils and T cells.

Amoebic liver abscesses (ALA) are the most frequent and severe extraintestinal clinical presentations of amoebiasis. During the early establishment of amoebae in the liver parenchyma, as well as during the extension of the tissue necrosis, parasites interact with the parenchymal liver cells and, as a consequence of these interactions, hepatocytes can be destroyed and host immune cells can become activated. However, little is known about the nature of these interactions in the liver or about the factors involved in the local immune response. In this investigation we studied the localization of Entamoeba histolytica trophozoites, TCD4+, TCD8+ cells, CD68+ macrophages and CD15+ neutrophils in human ALA using immunohistochemical techniques. Trophozoites were found close to undamaged hepatocytes in both lysed and non-lysed areas with either sparse or abundant inflammatory infiltrate. CD8+ cells were more abundant than CD4+ T cells. CD 68+ macrophages and CD15+ neutrophils were also detected, suggesting that neutrophils, macrophages and T cells might be related to the local host immune mechanisms in ALA. We also found that E. histolytica possesses proteins recognized by antibodies raised against inducible nitric oxide synthase.

Entamoeba histolytica: immunohistochemical study of hepatic amoebiasis in mouse. Neutrophils and nitric oxide as possible factors of resistance.

Studies in mice have not rendered conclusive data on cell and humoral factors to support the resistance of this rodent to Entamoeba histolytica infection. In Balb/c and C3H/HeJ mice inoculated with live or fixed trophozoites, we studied the evolution of the hepatic lesion, the kinetics of inflammatory cells, and the participation of some humoral factors in the development of the hepatic amoebic lesion. From the first hour, amoebae were surrounded by neutrophils containing inducible nitric oxide synthase (iNOS); macrophages also expressing iNOS appeared lately, whereas NK cells were not part of the inflammatory infiltrates. On the fourth day, neutrophils, macrophages, T and B lymphocytes, plasma cells, and some NK cells limited the lesions and anti-amoeba antibodies appeared when most parasites had been eliminated. Therefore, the resistance of the mice to E. histolytica probably lies in non-specific immune responses, among which the activation of neutrophils and the production of nitric oxide (NO) may be important amoebicide factors.

[Mast cells in Peyer's patches in the mouse]. / Mastocitos en placa de Peyer de ratón.

Mast Cells participate in immediate and late hypersensitivity activities, immunoregulation and inflammation. Recently two groups of them have been detected on the basis to its morphology, content of granules and function: a) Those who are localized in connective tissue and b) Those of the intestinal mucosa. Those of the intestinal mucosa are T dependent and proliferate in parasitic as well as in intestinal hypersensitivity conditions to diverse antigens, in turn, Peyer's Patches (PP) are considered antigen catcher and initiators of intestinal immune responses; these are subject to the influence of diverse substances, several of which are within mast cells (for example: histamine, prostaglandins, etc); for which in this work we investigate the morphology relation between PP and mast cells. Balb/c mice small intestine segments with muscular layer and PP of proximal, middle and distal levels where studied; were histologically processed, toluidine blues stained and mast cells counted in different intestinal layers (PP underlying zone, rest of the muscular, corium and submucosa. Data were analyzed by the paired double T test for mean differences. A greater Quantity of mast cells were observed at the marginal zone of the PP in comparison to the rest of the muscular layer, submucosa and corium. The abundance of mast cells in relation to the PP possibly indicates its modulatory influence on the function of lymphoid cells of the PP.