Maternal stress increases risk of allergic lung inflammation in adult mice

BACKGROUND

Allergies are increasing worldwide. The presence of atopic diseases in the mother propagates the onset of allergic diseases in the offspring with a considerably stronger penetrance than atopic diseases of the father. Such observation challenges genetic predispositions as the sole cause of allergic diseases. Epidemiological studies suggest that caregiver stress in the perinatal period may predispose offspring to asthma. Only one group has studied the link between prenatal stress and neonatal asthma susceptibility in a murine model.

OBJECTIVES

We aimed to study if the neonatal increased risk of developing allergic lung inflammation persists after puberty and if there are sex differences in susceptibility.

METHODS

Pregnant BALB/c mice were subjected to a single restraint stress exposure at day 15 of gestation. Pups were separated by gender and subjected to a well-known sub-optimal asthma model after puberty.

RESULTS

Adult mice born to stressed dams were more susceptible to developing allergic pulmonary inflammation since an increase in the number of eosinophils in bronchoalveolar lavage (BAL), a greater peribronchial and perivascular infiltrate, a higher proportion of mucus-producing cells, and increased IL-4 and IL-5 levels in BAL were detected compared to control mice. These effects were more profound in females than males. Moreover, only females from stressed dams showed an increase in IgE levels.

CONCLUSIONS

Increased litter susceptibility to develop allergic lung inflammation induced by maternal stress persists after puberty and is more potent in females than in male mice.

Chronic infection with the protozoan Toxoplasma gondii prevents the development of experimental atopic dermatitis in mice

BACKGROUND

Supporting the hypothesis thatT. gondii infection protects against allergy in humans we previously demonstrated that this infection can modulate not only the susceptibility to develop respiratory allergies in mice but also suppresses allergic responses at systemic level. This latter finding suggests that T. gondii infection could prevent the onset of other allergic diseases, such as atopic dermatitis. At present, few studies have investigated the modulation of atopic dermatitis by parasite infections.

OBJECTIVE

Here, we sought to investigate whether chronic infection with T. gondii is capable of modulating the development of atopic dermatitis.

METHODS

Chronically infected mice were sensitized by repeated epicutaneous ovalbumin administration. Skin histopathology, humoral response, cytokine production and innate type-II lymphoid cells (ILC2) were assessed.

RESULTS

A marked reduction in epidermal thickness and dermal inflammatory infiltrate along with a reduction in mast cell count was observed in infected mice compared to non-infected mice. These results correlated with a diminished T_H2 and T_H1 allergen specific response. Reduced type-II IL-4 and IL-5 cytokines were already detected during the first 24 h of allergen sensitization in splenocytes and draining lymph nodes from infected mice. Moreover, this reduced type-II profile in chronically infected animals correlated with diminished ILC2 number in draining lymph nodes.

CONCLUSION

Chronic infection withT. gondii prevents the development of atopic dermatitis. The diminished susceptibility seems to result from changes in type-II innate immune response that may lead to the induction of a deficient T_H2 response and consequently to a lower susceptibility to develop atopic dermatitis.

Possible senescence associated change in the predominant a-Na+/K+ ATP-ase isoform in the renal cortex of the rat

With aging the kidney exhibits progressive deterioration, with a decrease in renal function. Most of the filtered Na+ is actively reabsorbed in the proximal tubules through different transporters located in apical membrane. This process is possible because basolateral Na+/K+-ATP-ase generates electrochemical conditions necessary for energetically favorable Na+ transport. The a-subunit is the catalytic domain of Na+/K+-ATP-ase. There are three isoforms of the a/subunit present in rat kidney. The present study was undertaken to examine the expression pattern of rat a-Na+/K+-ATP-ase during senescence. We tested the impact of aging on mRNA expression of a-Na+/K+-ATP-ase in cortex and medulla of aged Wistar rats. We observed a significant expression decrease in mRNA levels and a possible change of isoform in the cortex of aged animals. These expression changes observed for a subunit could be contributing to affect the renal function in conditions of water and salt stress.

The dynamics of erythrocyte infection in bovine anaplasmosis: a flow cytometry-based analysis

Anaplasma marginale (A. marginale) is an obligate intracellular bacterium that infects bovine erythrocytes causing extravascular hemolysis and anemia. In the present work, we combine SYTO16 labeling of parasitized cells with the statistical power of flow cytometry to study the evolution of erythrocyte infection during bovine anaplasmosis.

Inhibition of connexin 43 in cardiac muscle during intense physical exercise

Endurance training is accompanied by important adaptations in both cardiovascular and autonomic nervous systems. Previous works have shown that the main component of gap junctions in the ventricular myocardium (connexin 43 (Cx43) can be regulated by adrenergic stimulus. On the other hand, training raises vagal and decreases sympathetic tone, while augmenting myocardial sensitivity to sympathetic stimulation during exercise. We therefore evaluated the regulation of Cx43 expression by sympathetic tone during exercise in trained and sedentary mice. Training induced an increase in the protein level of Cx43 by 45-70% under resting conditions. The expression of Cx43 was inhibited in trained but not in untrained mice in response to a 60 min exercise bout. Normal basal expression was restored after 60 min of resting. Cx43 reached a minimum that was not different from basal expression in untrained mice. In accordance, electrocardiography and action potential analysis did not reveal major electrophysiological implications for the drop in Cx43 abundance in trained-exercise mice. We prevented Cx43 inhibition using propranolol, and observed increased basal mRNA levels of β-adrenergic receptors without significant changes in the ratio β1 to β2. In conclusion, we showed that Cx43 expression is transiently inhibited by β-adrenergic stimulus in trained mice during acute exercise.

Flow cytometry to evaluate Anaplasma marginale parasitemia using a fluorescent nucleic acid stain

In this work we describe a flow cytometry-based method using SYTO16 (a DNA intercalating agent) to quantify Anaplasma marginale-infected erythrocytes in blood from bovine animals. The linearity and reproducibility of the results obtained with SYTO16 labeling followed by flow cytometry analysis make it a suitable approach for measurement of parasitemia in A. marginale infections.

Analysis of world strains of Anaplasma marginale using major surface protein 1a repeat sequences

Anaplasma marginale is a tick-borne pathogen of cattle that causes the disease bovine anaplasmosis worldwide. Major surface proteins (MSPs) are involved in host-pathogen and tick-pathogen interactions and have been used as markers for the genetic characterization of A. marginale strains and phylogenetic studies. MSP1a is involved in the adhesion and transmission of A. marginale by ticks and varies among geographic strains in the number and sequence of amino-terminal tandem repeats. The aim of this study was to characterize the genetic diversity of A. marginale strains collected from countries in North and South America, Europe, Asia, Africa and Australia, inclusive of all continents. In this study, we characterized 131 strains of A. marginale using 79 MSP1a repeat sequences. These results corroborated the genetic heterogeneity of A. marginale strains in endemic regions worldwide. The phylogenetic analyses of MSP1a repeat sequences did not result in clusters according to the geographic origin of A. marginale strains but provided phylogeographic information. Seventy-eight percent of the MSP1a repeat sequences were present in strains from a single geographic region. Strong (> or =80%) support was found for clusters containing sequences from Italian, Spanish, Chinese, Argentinean and South American strains. The phylogenetic analyses of MSP1a repeat sequences suggested tick-pathogen co-evolution and provided evidence of multiple introductions of A. marginale strains from various geographic locations worldwide. These results contribute to the understanding of the genetic diversity and evolution of A. marginale and tick-pathogen interactions.

Detection of antibodies against Anaplasma marginale in milk using a recombinant MSP5 indirect ELISA

An indirect enzyme linked immunosorbent assay (iELISA) for diagnosis of anaplasmosis using undiluted individual milk samples from dairy cows was developed. The recombinant 19 kDa major surface protein 5 (rMSP5) of Anaplasma marginale was used as antigen. A monoclonal antibody against bovine IgG1 conjugated with peroxidase and the chromogen 3,5,3',5'-tetramethylbenzidine were used in the test. Strong and weak, positive and negative milk samples were set up as reference controls. Results were expressed as percentage of positivity (PP) contrasting with the strongest positive control. The test was evaluated in two groups (G1 and G2) of lactating dairy cows from herds located in A. marginale non-endemic areas of Argentina. The infection status of both groups, G1 (n=128) sampled after anaplasmosis outbreak, and G2 (n=216) free of anaplasmosis was established by polymerase chain reaction (PCR). Serum samples of cows from G1 and G2 were analyzed by card agglutination test (CAT) and competitive ELISA (cELISA), while the novel iELISA was evaluated in their corresponding milk samples. At a cutoff of 42 PP, the ELISA has 98% sensitivity and 95% specificity. A significant difference (P<0.0001) was found between the mean PP value of negative samples from G1 (17.4+/-14.9), and G2 (8.6+/-7.1). The agreement and kappa (kappa) value between iELISA and PCR was 96%, kappa=0.919; between iELISA and CAT was 97%, kappa=0.880; and between iELISA and cELISA was 97%, kappa=0.899. These results strongly support the usefulness of iELISA to detect A. marginale antibodies in milk. Additional studies are necessary to define the ability of the milk iELISA to detect not only acutely infected, but also carrier cattle.