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Allergic contact dermatitis (ACD) is a common allergic skin disease that affects individuals subjected to different antigen exposure conditions and significantly impacts the quality of life of those affected. Numerous studies have demonstrated that probiotics suppress inflammation through immunomodulatory effects. In this study, we aimed to evaluate the effect of the probiotic Bifidobacterium longum 51A as a preventive treatment for ACD using an oxazolone-induced murine model. We demonstrated that B. longum 51A exerted a prophylactic effect on oxazolone-induced ACD-like skin inflammation via reductions in ear and dermal thickness and leucocyte infiltration. The administration of inactivated B. longum 51A did not affect oxazolone-induced ACD-like skin inflammation, suggesting that the bacteria must be alive to be effective. Given that B. longum 51A is an acetate producer, we treated mice with acetate intraperitoneally, which also prevented ear and dermal thickening. Moreover, the tissue levels of the inflammatory cytokines and chemokines interleukin (IL)-10, IL-33, tumour necrosis factor-α, chemokine (C-C motif) ligand 2/monocyte chemoattractant protein-1 and chemokine (C-C motif) ligand 5/RANTES were significantly reduced after probiotic treatment, but only IL-33 and IL-10 were reduced when the mice were treated with acetate. These results show that B. longum 51A exerted a potential prophylactic effect on skin inflammation and that acetate represents one potential mechanism. However, other factors are likely involved since these two treatments do not yield the same results.

The phenotypes of allergic airway diseases are influenced by the interplay between host genetics and the gut microbiota, which may be modulated by probiotics. We investigated the probiotic effects on allergic inflammation in A/J and C57BL/6 mice. C57BL/6 mice had increased gut microbiota diversity compared to A/J mice at baseline. Acetate producer probiotics differentially modulated and altered the genus abundance of specific bacteria, such as Akkermansia and Allistipes, in mouse strains. We induced airway inflammation followed by probiotic treatment and found that only A/J mice exhibited decreased inflammation, and the beneficial effects of probiotics in A/J mice were partially due to acetate production. To understand the relevance of microbial composition colonization in the development of allergic diseases, we implanted female C57BL/6 mice with A/J embryos to naturally modulate the microbial composition of A/J mice, which increased gut microbiota diversity and reduced eosinophilic inflammation in A/J. These data demonstrate the central importance of microbiota to allergic phenotype severity. Video Abstract Supplementary Information The online version contains supplementary material available at 10.1186/s40168-021-01081-2.

Asthma is an inflammatory lung disease that affects more women than men in adulthood. Clinical evidence shows that hormonal fluctuation during the menstrual cycle and menopause are related to increased asthma severity in women. Considering that life expectancy has increased and that most women now undergo menopause, strategies to prevent the worsening of asthma symptoms are particularly important. A recent study from our group showed that re-exposure of ovariectomised allergic mice to antigen (ovalbumin) leads to an exacerbation of lung inflammation that is similar to clinical conditions. However, little is known about the role of probiotics in the prevention of asthma exacerbations during the menstrual cycle or menopause. Thus, our objective was to evaluate the effects of supplementation with kefir, a popular fermented dairy beverage, as a preventive strategy for modulating allergic disease. The results show that the preventive kefir administration decreases the influx of inflammatory cells in the airways and exacerbates the production of mucus and the interleukin 13 cytokine. Additionally, kefir changes macrophage polarisation by decreasing the number of M2 macrophages, as shown by RT-PCR assay. Thus, kefir is a functional food that potentially prevents allergic airway inflammation exacerbations in ovariectomised mice.

Asthma is a worldwide public health issue, affecting the sufferer's quality of life. Many researchers are extensively studying the cellular processes involved in the affected airways. Experimental asthma using animals has been performed for a long time, mainly applying murine models due to well-known advantages. The aim of this study is to present an allergic airway inflammation protocol in mice. Basically, the allergic airway inflammation is induced by intraperitoneal sensitization and intratracheal challenge with ovalbumin (OVA). The model provided here mimics acute asthma characteristics including excessive mucus production, airway hyperresponsiveness, and eosinophilic airway inflammation.

Estrogen and ovarian function decline are relevant characteristics of menopause period. Numerous physiological, metabolic and immunological alterations in the female body occur in the menopause period and some of these changes remain uncertain. The animal model that mimics menopause phase is an important approach to better comprehend the biological process involved in this period of women life. Ovariectomy is a procedure where ovaries are surgically excised and have been a valuable tool for understanding estrogen deficiency through animal experiments. Despite the diversity of ovariectomy protocols, the aim of this chapter is to provide a comprehensive guideline in performing ovariectomy in mice. Furthermore, isoflurane anesthesia system, postoperative care and surgery success evaluation will be described. We highlight that all procedures must be carried out by a qualified and trained professional, respecting ethical and safety principles.