Hypoargininemia exacerbates airway hyperresponsiveness in a mouse model of asthma

Abstract Background Asthma is a chronic respiratory condition, with airway hyperresponsiveness (AHR) and inflammation as hallmarks. The hypothesis that the substantially increased expression of arginase 1 in activated macrophages limits the availability of L-arginine for nitric oxide synthesis, and thus increases AHR in lungs of mice with experimentally induced allergic asthma was recently refuted by several studies. In the present study, we tested the hypothesis that, instead, a low circulating concentration of arginine aggravates AHR in the same murine asthma model. Female FVB F/A2 tg/tg transgenic mice, which overexpress rat arginase 1 in their enterocytes, exhibit a ~ 50% decrease of their plasma L-arginine concentration. Methods Adult female F/A2 tg/tg mice and their wild-type littermates (F/A2 wt/wt ) were sensitized and challenged with ovalbumin (OVA/OVA). Lung function was assessed with the flexiVent™ system. Adaptive changes in the expression of arginine-metabolizing or -transporting enzymes, chemokines and cytokines, and lung histology were quantified with qPCR, ELISA, and immunohistochemistry, respectively. Results Reduction of circulating L-arginine concentration significantly increased AHR in OVA/OVA-treated mice and, to a lesser extent, even in PBS/OVA-treated mice. The pulmonary inflammatory response in OVA/OVA-treated F/A2 tg/tg and F/A2 wt/wt mice was comparable. OVA/OVA-treated F/A2 tg/tg mice differed from similarly treated female mice, in which arginase 1 expression in lung macrophages was eliminated, by a complete absence of an adaptive increase in the expression of arginine-metabolizing or –transporting enzymes. Conclusion A reduction of the circulating L-arginine concentration rather than the macrophage-mediated increase of arginine catabolism worsens AHR

Additional file 2: of Hypoargininemia exacerbates airway hyperresponsiveness in a mouse model of asthma

Tables S1. Primer pairs used for genotyping and quantitative PCR. Table S2. Amino-acid concentrations in venous plasma (ÎźM Âą SEM) of F/A2 wt/wt and F/A2 tg/tg female mice. (DOCX 21 kb

Additional file 1: of Hypoargininemia exacerbates airway hyperresponsiveness in a mouse model of asthma

Figure S1. Arg1, Nos2, and Cd68 expression in lungs of OVA-sensitized FVB mice before (Control, n=4) and after 1 (n=12) or 6 (n=12) challenges with aerosolized OVA. (PDF 374 kb

Arginase 1 deletion in myeloid cells affects the inflammatory response in allergic asthma, but not lung mechanics, in female mice

(Over-)expression of arginase may limit local availability of arginine for nitric oxide synthesis. We investigated the significance of arginase1 (ARG1) for the development of airway hyperresponsiveness (AHR) and lung inflammation in female mice with ovalbumin (OVA)-induced allergic asthma. Arg1 was ablated in the lung by crossing Arg1 fl/fl and Tie2Cre tg/- mice. OVA sensitization and challenge were conducted, and AHR to methacholine was determined using the Flexivent system. Changes in gene expression, chemokine and cytokine secretion, plasma IgE, and lung histology were quantified using RT-qPCR, ELISA, and immunohistochemistry, respectively. Arg1 ablation had no influence on the development of OVA-induced AHR, but attenuated OVA-induced increases in expression of Arg2 and Nos2, Slc7a1, Slc7a2, and Slc7a7 (arginine transporters), Il4, Il5 and Il13 (TH2-type cytokines), Ccl2 and Ccl11 (chemokines), Ifng (TH1-type cytokine), Clca3 and Muc5ac (goblet cell markers), and OVA-specific IgE. Pulmonary IL-10 protein content increased, but IL-4, IL-5, IL-13, TNFα and IFNγ content, and lung histopathology, were not affected. Arg1 elimination also decreased number and tightness of correlations between adaptive changes in lung function and inflammatory parameters in OVA/OVA-treated female mice. OVA/OVA-treated female mice mounted a higher OVA-IgE response than males, but the correlation between lung function and inflammation was lower. Arg1-deficient OVA/OVA-treated females differed from males in a more pronounced decline of arginine-metabolizing and -transporting genes, higher plasma arginine levels, a smaller OVA-specific IgE response, and no improvement of peripheral lung function. Complete ablation of Arg1 in the lung affects mRNA abundance of arginine-transporting and -metabolizing genes, and pro-inflammatory genes, but not methacholine responsiveness or accumulation of inflammatory cell

The ongoing risk of Leishmania donovani transmission in eastern Nepal : an entomological investigation during the elimination era

Abstract: Background Visceral leishmaniasis (VL), a life-threatening neglected tropical disease, is targeted for elimination from Nepal by the year 2026. The national VL elimination program is still confronted with many challenges including the increasingly widespread distribution of the disease over the country, local resurgence and the questionable efficacy of the key vector control activities. In this study, we assessed the status and risk of Leishmania donovani transmission based on entomological indicators including seasonality, natural Leishmania infection rate and feeding behavior of vector sand flies, Phlebotomus argentipes, in three districts that had received disease control interventions in the past several years in the context of the disease elimination effort. Methods We selected two epidemiologically contrasting settings in each survey district, one village with and one without reported VL cases in recent years. Adult sand flies were collected using CDC light traps and mouth aspirators in each village for 12 consecutive months from July 2017 to June 2018. Leishmania infection was assessed in gravid sand flies targeting the small-subunit ribosomal RNA gene of the parasite (SSU-rRNA) and further sequenced for species identification. A segment (similar to 350 bp) of the vertebrate cytochrome b (cytb) gene was amplified from blood-fed P. argentipes from dwellings shared by both humans and cattle and sequenced to identify the preferred host. Results Vector abundance varied among districts and village types and peaks were observed in June, July and September to November. The estimated Leishmania infection rate in vector sand flies was 2.2% (1.1%-3.7% at 95% credible interval) and 0.6% (0.2%-1.3% at 95% credible interval) in VL and non-VL villages respectively. The common source of blood meal was humans in both VL (52.7%) and non-VL (74.2%) villages followed by cattle. Conclusions Our findings highlight the risk of ongoing L. donovani transmission not only in villages with VL cases but also in villages not reporting the presence of the disease over the past several years within the districts having disease elimination efforts, emphasize the remaining threats of VL re-emergence and inform the national program for critical evaluation of disease elimination strategies in Nepal

Male predominance in reported Visceral Leishmaniasis cases: Nature or nurture? A comparison of population-based with health facility-reported data.

BackgroundBangladesh, India, and Nepal aim for the elimination of Visceral Leishmaniasis (VL), a systemic parasitic infectious disease, as a public health problem by 2020. For decades, male patients have comprised the majority of reported VL cases in this region. By comparing this reported VL sex ratio to the one observed in population-based studies conducted in the Indian subcontinent, we tested the working hypothesis that mainly socio-cultural gender differences in healthcare-seeking behavior explain this gender imbalance.Methodology/principal findingsWe compared the observed sex ratio of male versus female among all VL cases reported by the health system in Nepal and in the two most endemic states in India with that observed in population-based cohort studies in India and Nepal. Also, we assessed male sex as a potential risk factor for seroprevalence at baseline, seroconversion, and VL incidence in the same population-based data. The male/female ratio among VL cases reported by the health systems was 1.40 (95% CI 1.37-1.43). In the population cohort data, the age- and study site-adjusted male to female risk ratio was 1.27 (95% CI 1.08-1.51). Also, males had a 19% higher chance of being seropositive at baseline in the population surveys (RR 1.19; 95% CI 1.11-1.27), while we observed no significant difference in seroconversion rate between both sexes at the DAT cut-off titer defined as the primary endpoint.Conclusions/significanceOur population-based data show that male sex is a risk factor for VL, and not only as a socio-cultural determinant. Biological sex-related differences likely play an important role in the pathogenesis of this disease

Additional file 2: Figure S1. of Arginase 1 deletion in myeloid cells affects the inflammatory response in allergic asthma, but not lung mechanics, in female mice

Correlation of lung-function, abundance of pulmonary mRNAs and proteins, pulmonary histopathology, and concentrations of plasma amino acids in wild-type male and female mice. The lower-left triangle refers to data obtained female and the upper-right triangle to data from male Arg1-Con mice. The numbers show the correlation coefficients between parameters indicated above and to the left of the columns and rows, respectively, as measured in all 15 or 16 male and female Arg1-Con mice studied, that is, both the PBS/OVA- and the OVA/OVA-treated groups. The significance of the correlations is color-coded according to the P-value of the correlation coefficient: yellow: 0.05 > P > 0.01, orange: 0.01 > P > 0.001, and red: P < 0.001. Note the difference in the degree of cross-correlations of parameters between the categories named in the title in males and females. (PDF 219 kb

Additional file 1: Tables S1-S3. of Arginase 1 deletion in myeloid cells affects the inflammatory response in allergic asthma, but not lung mechanics, in female mice

Table S1. Primers pairs used in genotyping and quantitative PCR. Table S2. Amino-acid concentrations in venous plasma (μM ± SEM) of Arg1-Con and Arg1-KOTie2Cre mice *: P < 0.05 OVA/OVA vs. PBS/OVA Arg1-Con; #: P < 0.05 OVA/OVA vs. PBS/OVA Arg1-KOTie2. Table S3. Differences between male and female Arg1-Con mice after treatment with the OVA/OVA protocol. (DOCX 24 kb