Angiotensin-(1-7) reduces doxorubicin-induced cardiac dysfunction in male and female Sprague-Dawley rats through antioxidant mechanisms.

Doxorubicin (Dox) is an effective chemotherapeutic for a variety of pediatric malignancies. Unfortunately, Dox administration often results in a cumulative dose-dependent cardiotoxicity that manifests with marked oxidative stress, leading to heart failure. Adjunct therapies are needed to mitigate Dox cardiotoxicity and enhance quality of life in pediatric patients with cancer. Angiotensin-(1-7) [Ang-(1-7)] is an endogenous hormone with cardioprotective properties. This study investigated whether adjunct Ang-(1-7) attenuates cardiotoxicity resulting from exposure to Dox in male and female juvenile rats. Dox significantly reduced body mass, and the addition of Ang-(1-7) had no effect. However, adjunct Ang-(1-7) prevented Dox-mediated diastolic dysfunction, including markers of decreased passive filling as measured by reduced early diastole mitral valve flow velocity peak (E) (P < 0.05) and early diastole mitral valve annulus peak velocity (e'; P < 0.001) and increased E/e' (P < 0.001), an echocardiographic measure of diastolic dysfunction. Since Dox treatment increases reactive oxygen species (ROS), the effect of Ang-(1-7) on oxidative by-products and enzymes that generate or reduce ROS was investigated. In hearts of male and female juvenile rats, Dox increased NADPH oxidase 4 (P < 0.05), a major cardiovascular NADPH oxidase isozyme that generates ROS, as well as 4-hydroxynonenal (P < 0.001) and malondialdehyde (P < 0.001), markers of lipid peroxidation; Ang-(1-7) prevented these effects of Dox. Cotreatment with Dox and Ang-(1-7) increased the antioxidant enzymes SOD1 (male: P < 0.05; female: P < 0.01) and catalase (P < 0.05), which likely contributed to reduced ROS. These results demonstrate that Ang-(1-7) prevents diastolic dysfunction in association with a reduction in ROS, suggesting that the heptapeptide hormone may serve as an effective adjuvant to improve Dox-induced cardiotoxicity.NEW & NOTEWORTHY Ang-(1-7) is a clinically safe peptide hormone with cardioprotective and antineoplastic properties that could be used as an adjuvant therapy to improve cancer treatment and mitigate the long-term cardiotoxicity associated with doxorubicin in pediatric patients with cancer.

Antibiotics ameliorate lupus-like symptoms in mice.

Gut microbiota and the immune system interact to maintain tissue homeostasis, but whether this interaction is involved in the pathogenesis of systemic lupus erythematosus (SLE) is unclear. Here we report that oral antibiotics given during active disease removed harmful bacteria from the gut microbiota and attenuated SLE-like disease in lupus-prone mice. Using MRL/lpr mice, we showed that antibiotics given after disease onset ameliorated systemic autoimmunity and kidney histopathology. They decreased IL-17-producing cells and increased the level of circulating IL-10. In addition, antibiotics removed Lachnospiraceae and increased the relative abundance of Lactobacillus spp., two groups of bacteria previously shown to be associated with deteriorated or improved symptoms in MRL/lpr mice, respectively. Moreover, we showed that the attenuated disease phenotype could be recapitulated with a single antibiotic vancomycin, which reshaped the gut microbiota and changed microbial functional pathways in a time-dependent manner. Furthermore, vancomycin treatment increased the barrier function of the intestinal epithelium, thus preventing the translocation of lipopolysaccharide, a cell wall component of Gram-negative Proteobacteria and known inducer of lupus in mice, into the circulation. These results suggest that mixed antibiotics or a single antibiotic vancomycin ameliorate SLE-like disease in MRL/lpr mice by changing the composition of gut microbiota.

Control of lupus nephritis by changes of gut microbiota.

BACKGROUND: Systemic lupus erythematosus, characterized by persistent inflammation, is a complex autoimmune disorder with no known cure. Immunosuppressants used in treatment put patients at a higher risk of infections. New knowledge of disease modulators, such as symbiotic bacteria, can enable fine-tuning of parts of the immune system, rather than suppressing it altogether. RESULTS: Dysbiosis of gut microbiota promotes autoimmune disorders that damage extraintestinal organs. Here we report a role of gut microbiota in the pathogenesis of renal dysfunction in lupus. Using a classical model of lupus nephritis, MRL/lpr, we found a marked depletion of Lactobacillales in the gut microbiota. Increasing Lactobacillales in the gut improved renal function of these mice and prolonged their survival. We used a mixture of 5 Lactobacillus strains (Lactobacillus oris, Lactobacillus rhamnosus, Lactobacillus reuteri, Lactobacillus johnsonii, and Lactobacillus gasseri), but L. reuteri and an uncultured Lactobacillus sp. accounted for most of the observed effects. Further studies revealed that MRL/lpr mice possessed a "leaky" gut, which was reversed by increased Lactobacillus colonization. Lactobacillus treatment contributed to an anti-inflammatory environment by decreasing IL-6 and increasing IL-10 production in the gut. In the circulation, Lactobacillus treatment increased IL-10 and decreased IgG2a that is considered to be a major immune deposit in the kidney of MRL/lpr mice. Inside the kidney, Lactobacillus treatment also skewed the Treg-Th17 balance towards a Treg phenotype. These beneficial effects were present in female and castrated male mice, but not in intact males, suggesting that the gut microbiota controls lupus nephritis in a sex hormone-dependent manner. CONCLUSIONS: This work demonstrates essential mechanisms on how changes of the gut microbiota regulate lupus-associated immune responses in mice. Future studies are warranted to determine if these results can be replicated in human subjects.

Leaky Gut As a Danger Signal for Autoimmune Diseases.

The intestinal epithelial lining, together with factors secreted from it, forms a barrier that separates the host from the environment. In pathologic conditions, the permeability of the epithelial lining may be compromised allowing the passage of toxins, antigens, and bacteria in the lumen to enter the blood stream creating a "leaky gut." In individuals with a genetic predisposition, a leaky gut may allow environmental factors to enter the body and trigger the initiation and development of autoimmune disease. Growing evidence shows that the gut microbiota is important in supporting the epithelial barrier and therefore plays a key role in the regulation of environmental factors that enter the body. Several recent reports have shown that probiotics can reverse the leaky gut by enhancing the production of tight junction proteins; however, additional and longer term studies are still required. Conversely, pathogenic bacteria that can facilitate a leaky gut and induce autoimmune symptoms can be ameliorated with the use of antibiotic treatment. Therefore, it is hypothesized that modulating the gut microbiota can serve as a potential method for regulating intestinal permeability and may help to alter the course of autoimmune diseases in susceptible individuals.