Lactobacillus paracasei feeding improves immune control of influenza infection in mice

Abstract

Respiratory tract infections such as flu cause severe morbidity and mortality and are among the leading causes of death in children and adults worldwide. Commensal microbiota is critical for orchestrating tissue homeostasis and immunity in the intestine. Probiotics represent an interesting source of immune modulators and several clinical studies have addressed the potential beneficial effects of probiotics against respiratory infections. Therefore, we have investigated the mechanisms of protection conferred by L. paracasei CNCM I-1518 strain in a mouse model of influenza infection. Notably, local myeloid cells accumulation is generated in the lungs after seven days feeding with L. paracasei prior to viral infection. L. paracasei-fed mice showed reduced susceptibility to the influenza infection, associated with less accumulation of inflammatory cells in the lungs, faster viral clearance and general health improvement. Interestingly, Allobaculum was significantly increased in L. paracasei-fed mice 7 days after influenza infection, even if the gut microbiota composition was not altered overall. L. paracasei-purified peptidoglycan partially recapitulated the protective phenotype observed with the entire bacteria. Collectively, our results demonstrate that oral consumption of L. paracasei CNCM I-1518 modulates lung immunity was associated with an improved control of influenza infection. These results further extend the beneficial role for certain lactobacilli to alleviate the burden of respiratory tract infections.

The role of the lung microbiota and the gut-lung axis in respiratory infectious diseases

“…Until now, most studies in mice have focused on two infection models-influenza and pneumonia-in which a beneficial effect of oral or nasal probiotic administration has been characterised by improved survival, decreased weight loss, decreased viral titre or bacterial load in the lung, and decreased bronchial epithelium damage (summarised in Table 1). These studies report that the protective effect was mediated by specific immune modulation, distinguished by an early recruitment in the lung of innate leucocytes displaying potent killing properties, such as alveolar macrophages (Park et al, 2013;Vieira et al, 2016), neutrophils (Racedo et al, 2006), or natural killer lymphocytes (Belkacem et al, 2017;Kawahara et al, 2015), and elevated levels of pro-inflammatory cytokines (e.g., TNF-α, IL-6). This inflammatory boost then rapidly diminished, likely due the subsequent increase of anti-inflammatory factors, such as Treg cells and IL-10 in the lungs, reducing lung injuries observed in nontreated mice (Khailova et al, 2013).…”

The Intestinal Microbiota Contributes to the Control of Highly Pathogenic H5N9 Influenza Virus Replication in Ducks

“…In addition, microbiota dysbiosis can also indirectly promote the spread and burden of infectious diseases by impairing the response to vaccines (46–48). In conclusion, further studies are needed to evaluate the consequences of microbiota dysbiosis and of possible interventions with probiotics on the burden of infectious diseases (47, 49).…”

In vitro Study of Lactobacillus paracasei CNCM I-1518 in Healthy and Clostridioides difficile Colonized Elderly Gut Microbiota

“…Lactobacillus paracasei CNCM I-1518 (L. paracasei) is a candidate probiotic strain that belongs to the Lactobacillus casei group (consisting of L. casei, L. paracasei subspecies paracasei, and L. rhamnosus). This strain can survive gastrointestinal transit and to modulate immune function (23)(24)(25)(26)(27). Fermented milk product containing L. paracasei CNCM I-1518 was associated with a decreased duration of common gastrointestinal and respiratory infections (28), and consumption of fermented milk containing the same strain reduced the incidence of antibiotic-and C. difficile-associated diarrhea in elderly patients taking antibiotics (29).…”

“…(C) Model 3. C. difficile NCTC 13307 spores were inoculated on day 1 and 2 into DC_CR and DC_LpC mimicking the distal colon section; DC_LpC was treated with L. paracasei twice daily at days 11-35; DC_CR and DC_LpC were treated with metronidazole (days[16][17][18][19][20][21][22][23][24][25] and recovery was observed at days[26][27][28][29][30][31][32][33][34][35]. In all models sampling for qPCR and HPLC was performed daily.…”