Streptococcus pneumoniae-induced pneumonia and Citrobacter rodentium-induced gut infection differentially alter vitamin A concentrations in the lung and liver of mice

Early-life vitamin A treatment rescues neonatal infection-induced durably impaired tolerogenic properties of celiac lymph nodes

Gut-draining mesenteric and celiac lymph nodes (mLNs and celLNs) critically contribute to peripheral tolerance toward food and microbial antigens by supporting the de novo induction of regulatory T cells (Tregs). These tolerogenic properties of mLNs and celLNs are stably imprinted within stromal cells (SCs) by microbial signals and vitamin A (VA), respectively. Here, we report that a single, transient gastrointestinal infection in the neonatal, but not adult, period durably abrogates the efficient Treg-inducing capacity of celLNs by altering the subset composition and gene expression profile of celLNSCs. These cells carry information about the early-life pathogen encounter until adulthood and durably instruct migratory dendritic cells entering the celLN with reduced tolerogenic properties. Mechanistically, transiently reduced VA levels cause long-lasting celLN functional impairment, which can be rescued by early-life treatment with VA. Together, our data highlight the therapeutic potential of VA to prevent sequelae post gastrointestinal infections in infants.

Integration of multiomics analysis to reveal the major pathways of vitamin A deficiency aggravates acute respiratory distress syndrome in neonatal rats

Acute respiratory distress syndrome (ARDS) is a major disease that threatens the life and health of neonates. Vitamin A (VA) can participate in early fetal lung development and affect lung immune function. Researches revealed that the serum VA level in premature infants with ARDS was lower than that in premature infants without ARDS of the same gestational age, and premature infants with VA deficiency (VAD) were more likely to develop ARDS. Moreover, the VA levels can be used as a predictor of the development and severity of neonatal ARDS. However, the critical question here is; Does ARDS develop due to VAD in these systemic diseases? Or does ARDS develop because these diseases cause VAD? We hypothesize that VAD may aggravate neonatal ARDS by affecting immunity, metabolism, barriers and other pathways. In this article, we used multiomics analysis to find that VAD may aggravate ARDS mainly through the Fc epsilon RI signaling pathway, the HIF-1 signaling pathway, glutathione metabolism, and valine, leucine and isoleucine degradation signaling pathways, which may provide the molecular pathogenic mechanism behind the pathology of VAD-aggravated ARDS and can also provide potential molecular targets for subsequent research on ARDS.

Transcriptional Profiling of the Small Intestine and the Colon Reveals Modulation of Gut Infection with Citrobacter rodentium According to the Vitamin A Status

Vitamin A (VA) deficiency and diarrheal diseases are both serious public health issues worldwide. VA deficiency is associated with impaired intestinal barrier function and increased risk of mucosal infection-related mortality. The bioactive form of VA, retinoic acid, is a well-known regulator of mucosal integrity. Using Citrobacter rodentium-infected mice as a model for diarrheal diseases in humans, previous studies showed that VA-deficient (VAD) mice failed to clear C. rodentium as compared to their VA-sufficient (VAS) counterparts. However, the distinct intestinal gene responses that are dependent on the host’s VA status still need to be discovered. The mRNAs extracted from the small intestine (SI) and the colon were sequenced and analyzed on three levels: differential gene expression, enrichment, and co-expression. C. rodentium infection interacted differentially with VA status to alter colon gene expression. Novel functional categories downregulated by this pathogen were identified, highlighted by genes related to the metabolism of VA, vitamin D, and ion transport, including improper upregulation of Cl⁻ secretion and disrupted HCO₃⁻ metabolism. Our results suggest that derangement of micronutrient metabolism and ion transport, together with the compromised immune responses in VAD hosts, may be responsible for the higher mortality to C. rodentium under conditions of inadequate VA.

A single early-in-life antibiotic course increases susceptibility to DSS-induced colitis

Background

There is increasing evidence that the intestinal microbiota plays a crucial role in the maturation of the immune system and the prevention of diseases during childhood. Early-life short-course antibiotic use may affect the progression of subsequent disease conditions by changing both host microbiota and immunologic development. Epidemiologic studies provide evidence that early-life antibiotic exposures predispose to inflammatory bowel disease (IBD).

Methods

By using a murine model of dextran sodium sulfate (DSS)-induced colitis, we evaluated the effect on disease outcomes of early-life pulsed antibiotic treatment (PAT) using tylosin, a macrolide and amoxicillin, a beta-lactam. We evaluated microbiota effects at the 16S rRNA gene level, and intestinal T cells by flow cytometry. Antibiotic-perturbed or control microbiota were transferred to pups that then were challenged with DSS.

Results

A single PAT course early-in-life exacerbated later DSS-induced colitis by both perturbing the microbial community and altering mucosal immune cell composition. By conventionalizing germ-free mice with either antibiotic-perturbed or control microbiota obtained 40 days after the challenge ended, we showed the transferrable and direct effect of the still-perturbed microbiota on colitis severity in the DSS model.

Conclusions

The findings in this experimental model provide evidence that early-life microbiota perturbation may increase risk of colitis later in life.

Vitamin A supplement after neonatal Streptococcus pneumoniae pneumonia inhibits the progression of experimental asthma by altering CD4+T cell subsets

Studies demonstrated that pneumonia can decrease vitamin A productions and vitamin A reduction/deficiency may promote asthma development. Our previous study showed that neonatal Streptococcus pneumoniae (S. pneumoniae) infection promoted asthma development. Whether neonatal S. pneumoniae pneumonia induced asthma was associated with vitamin A levels remains unclear. The aim of this study was to investigate the effects of neonatal S. pneumoniae pneumonia on vitamin A expressions, to explore the effects of vitamin A supplement after neonatal S. pneumoniae pneumonia on adulthood asthma development. Non-lethal S. pneumoniae pneumonia was established by intranasal inoculation of neonatal (1-week-old) female BALB/c mice with D39. S. pneumoniae pneumonia mice were supplemented with or without all-trans retinoic acid 24 hours after infection. Vitamin A concentrations in lung, serum and liver were measured post pneumonia until early adulthood. Four weeks after pneumonia, mice were sensitized and challenged with OVA to induce allergic airway disease (AAD). Twenty-four hours after the final challenge, the lungs and bronchoalveolar lavage fluid (BALF) were collected to assess AAD. We stated that serum vitamin A levels in neonatal S. pneumoniae pneumonia mice were lower than 0.7µmol/L from day 2-7 post infection, while pulmonary vitamin A productions were significantly lower than those in the control mice from day 7-28 post infection. Vitamin A supplement after neonatal S. pneumoniae pneumonia significantly promoted Foxp3⁺Treg and Th1 productions, decreased Th2 and Th17 cells expressions, alleviated airway hyperresponsiveness (AHR) and inflammatory cells infiltration during AAD. Our data suggest that neonatal S. pneumoniae pneumonia induce serum vitamin A deficiency and long-time lung vitamin A reduction, vitamin A supplement after neonatal S. pneumoniae pneumonia inhibit the progression of asthma by altering CD4⁺T cell subsets.

Vitamin A and vitamin D regulate the microbial complexity, barrier function, and the mucosal immune responses to ensure intestinal homeostasis

Diet is an important regulator of the gastrointestinal microbiota. Vitamin A and vitamin D deficiencies result in less diverse, dysbiotic microbial communities and increased susceptibility to infection or injury of the gastrointestinal tract. The vitamin A and vitamin D receptors are nuclear receptors expressed by the host, but not the microbiota. Vitamin A- and vitamin D-mediated regulation of the intestinal epithelium and mucosal immune cells underlies the effects of these nutrients on the microbiota. Vitamin A and vitamin D regulate the expression of tight junction proteins on intestinal epithelial cells that are critical for barrier function in the gut. Other shared functions of vitamin A and vitamin D include the support of innate lymphoid cells that produce IL-22, suppression of IFN-γ and IL-17 by T cells, and induction of regulatory T cells in the mucosal tissues. There are some unique functions of vitamin A and D; for example, vitamin A induces gut homing receptors on T cells, while vitamin D suppresses gut homing receptors on T cells. Together, vitamin A- and vitamin D-mediated regulation of the intestinal epithelium and mucosal immune system shape the microbial communities in the gut to maintain homeostasis.

Impact of Micronutrients on the Immune Response of Animals

Vitamins and minerals (micronutrients) play an important role in regulating and shaping an immune response. Deficiencies generally result in inadequate or dysregulated cellular activity and cytokine expression, thereby affecting the immune response. Decreased levels of natural killer, granulocyte, and phagocytic cell activity and T and B cell proliferation and trafficking are associated with inadequate levels of micronutrients, as well as increased susceptibility to various adverse health conditions, including inflammatory disorders, infection, and altered vaccine efficacy. In addition, most studies of micronutrient modulation of immune responses have been done in rodents and humans, thus limiting application to the health and well-being of livestock and companion animals. This exploratory review elucidates the role of vitamins and minerals on immune function and inflammatory responses in animals (pigs, dogs, cats, horses, goats, sheep, and cattle), with reference to rodents and humans.

Vitamin A-Deficient Hosts Become Nonsymptomatic Reservoirs of Escherichia coli-Like Enteric Infections

Vitamin A deficiency (A(-)) remains a public health concern in developing countries and is associated with increased susceptibility to infection. Citrobacter rodentium was used to model human Escherichia coli infections. A(-) mice developed a severe and lethal (40%) infection. Vitamin A-sufficient (A(+)) mice survived and cleared the infection by day 25. Retinoic acid treatment of A(-) mice at the peak of the infection eliminated C. rodentium within 16 days. Inflammation levels were not different between A(+) and A(-) mouse colons, although the A(-) mice were still infected at day 37. Increased mortality of A(-) mice was not due to systemic cytokine production, an inability to clear systemic C. rodentium, or increased pathogenicity. Instead, A(-) mice developed a severe gut infection with most of the A(-) mice surviving and resolving inflammation but not eliminating the infection. Improvements in vitamin A status might decrease susceptibility to enteric pathogens and prevent potential carriers from spreading infection to susceptible populations.