Reovirus type-2 infection in newborn DBA/1J mice reduces the development of late allergic asthma

Establishing a high microbial load maternal-offspring asthma model in adult mice

BACKGROUND

Although it is widely accepted that the "hygiene hypothesis" explains the increased incidence of asthma, the lack of suitable animal models hinders further in-depth studies of the underlying molecular immune mechanisms. Therefore, we aimed to develop a robust mouse asthma model to investigate the role of bacteria in preventing asthma.

METHODS

BALB/c female mice were fed a mixture of eight common bacterial lysates (BL; Broncho-Vaxom®) and a commercial probiotic (Bifidobacterium tetravaccine tablets) at different concentrations before and during pregnancy to simulate different microbial load levels. Faeces from the mother mice were subjected to bacterial 16S rRNA sequencing to quantify the maternal microbial load. TLR2/4 expression and the proportion of regulatory T cells (Tregs) in the intestinal tract of female mice were determined, and the safety of the microbial load was evaluated. An asthma model was established in the offspring mice after weaning, and the extent of pulmonary pathological changes and Treg proportion were evaluated.

RESULTS

A BL concentration of 1 mg/kg enriched the intestinal flora, increased the proportion of Tregs, and increased the expression of TLR2/4 in the maternal mice. The proportion of peripheral blood Tregs was increased, whereas the risk of asthma decreased only in the offspring from mothers with a high microbial load relative to control mice.

CONCLUSION

This study established a safe and stable high microbial load maternal-offspring mouse asthma model, laying the foundation for a study on the molecular mechanism underlying the protective effects of a high microbial load against asthma.

Regulation of the development of asthmatic inflammation by in situ CD4(+)Foxp3 (+) T cells in a mouse model of late allergic asthma

CD4(+)Foxp3(+)T cells (Tregs) mediate homeostatic peripheral tolerance by suppressing helper T2 cells in allergy. However, the regulation of asthmatic inflammation by local (in situ) Tregs in asthma remains unclear. BALB/c mice sensitized and challenged with ovalbumin (OVA) (asthma group) developed asthmatic inflammation with eosinophils and lymphocytes, but not mast cells. The number of Tregs in the circulation, pulmonary lymph nodes (pLNs), and thymi significantly decreased in the asthma group compared to the control group without OVA sensitization and challenge in the effector phase. The development of asthmatic inflammation is inversely related to decreased Tregs with reduced mRNA expression such as interleukin (IL)-4, transforming growth factor-β1, and IL-10, but not interferon-γ, in pLNs. Moreover, M2 macrophages increased in the local site. The present study suggests that Tregs, at least in part, may regulate the development of asthmatic inflammation by cell-cell contact and regional cytokine productions.

Polarization toward Th1-type response in active, but not in inactive, lupus inhibits late allergic rhinitis in lupus-prone female NZB×NZWF(1) mice

The association of allergic diseases and disease activity in systemic lupus erythematosus (SLE, lupus) is controversial. The study investigates lupus activity-related differences in the induction of late allergic rhinitis (LAR) in the female NZB×NZW(B/W)F(1) mouse model for lupus. The LAR, which is induced by ovalbumin, was examined during the preactive (before clinical onset) and active (after clinical onset) phases in mice. Induction of LAR was less severe in mice with active lupus in contrast to clinically healthy lupus mice that developed a more severe allergic rhinitis. Inhibition of the development of LAR may be due to reduced eosinophilia and local interleukin-4 secretion during active autoimmune disease. In addition, systemic interferon-γ, but not IL-4, production increased during the active phase, but not the preactive phase. This suggests that the predominating Th1 lineage commitment in mice with active lupus may be responsible for the inhibition of the allergic Th2 response. The present study may shed some light on the controversy of the prevalence of allergic diseases in SLE patients.