Orally administered Lactobacillus rhamnosus modulates the respiratory immune response triggered by the viral pathogen-associated molecular pattern poly(I:C)

Are the immunomodulatory properties of Lactobacillus rhamnosus CRL1505 peptidoglycan common for all Lactobacilli during respiratory infection in malnourished mice?

Previously, we reported that Lactobacillus rhamnosus CRL1505 peptidoglycan (PG05) improves the innate immune response in immunocompromised-malnourished mice after Streptococcus pneumoniae infection. This study extends those previous findings by demonstrating that the dietary recovery of malnourished mice with nasal administration of PG05 improves not only the innate immune response but the respiratory and systemic adaptive humoral response as well. PG05 enhanced the Th2 response, the recovery of B cells, and the concentration and opsonophagocytic activity of anti-pneumococcal antibodies. In addition, by performing comparative studies with the peptidoglycans from lactobacilli of the same species (L. rhamnosus CRL534) or with similar immunomodulatory properties (L. plantarum CRL1506), we demonstrated here that PG05 has unique immunomodulatory properties that cannot be extended to peptidoglycans from other probiotic strains. However, the knowledge of the molecular characteristics of PG05 is indispensable to understand immunomodulatory abilities of L. rhamnosus CRL1505.

Pulmonary Susceptibility of Neonates to Respiratory Syncytial Virus Infection: A Problem of Innate Immunity?

Human respiratory syncytial virus (RSV) is a common and highly contagious viral agent responsible for acute lower respiratory infection in infants. This pathology characterized by mucus hypersecretion and a disturbed T cell immune response is one of the major causes of infant hospitalization for severe bronchiolitis. Although different risk factors are associated with acute RSV bronchiolitis, the immunological factors contributing to the susceptibility of RSV infection in infants are not clearly elucidated. Epidemiological studies have established that the age at initial infection plays a central role in the severity of the disease. Thus, neonatal susceptibility is intrinsically linked to the immunological characteristics of the young pulmonary mucosa. Early life is a critical period for the lung development with the first expositions to external environmental stimuli and microbiota colonization. Furthermore, neonates display a lung immune system that profoundly differs to those from adults, with the predominance of type 2 immune cells. In this review, we discuss the latest information about the lung immune environment in the early period of life at a steady state and upon RSV infection and how we can modulate neonatal susceptibility to RSV infection.

Respiratory Commensal Bacteria Corynebacterium pseudodiphtheriticum Improves Resistance of Infant Mice to Respiratory Syncytial Virus and Streptococcus pneumoniae Superinfection

Corynebacterium pseudodiphtheriticum is a Gram-positive bacterium found as a member of the normal microbiota of the upper respiratory tract. It was suggested that C. pseudodiphtheriticum may be potentially used as a next-generation probiotic for nasal application, although no deep studies were performed in this regard. We hypothesized that human isolate C. pseudodiphtheriticum strain 090104 is able to modulate the respiratory innate immune response and beneficially influence the resistance to viral and bacterial infections. Therefore, in the present study we investigated how the exposure of infant mice to nasal priming with viable or non-viable C. pseudodiphtheriticum 090104 influences the respiratory innate immune response triggered by Toll-like receptor (TLR)-3 activation, the susceptibility to primary Respiratory Synsytial Virus (RSV) infection, and the resistance to secondary Streptococcus pneumoniae pneumonia. We demonstrated that the nasal priming with viable C. pseudodiphtheriticum 090104 differentially modulated TLR3-mediated innate antiviral immune response in the respiratory tract of infant mice, improving their resistance to primary RSV infection, and secondary pneumococcal pneumonia. In association with the protection against RSV-pneumococcal superinfection, we found that viable C. pseudodiphtheriticum improved lung CD3⁺CD4⁺IFN-γ⁺, and CD3⁺CD4⁺IL-10⁺ T cells as well as CD11c⁺SiglecF⁺IFN-β⁺ alveolar macrophages. Of interest, non-viable bacteria did not have the same protective effect, suggesting that C. pseudodiphtheriticum colonization is needed for achieving its protective effect. In conclusion, we present evidence that nasal application of viable C. pseudodiphtheriticum could be thought as an alternative to boost defenses against RSV and secondary pneumococcal pneumonia, which should be further studied and validated in clinical trials. Due to the absence of a long-lasting immunity, re-infection with RSV throughout life is common. Thus, a possible perspective use could be a seasonal application of a nasal probiotic spray to boost respiratory innate immunity in immunocompetent subjects.

Peptidoglycan from Immunobiotic Lactobacillus rhamnosus Improves Resistance of Infant Mice to Respiratory Syncytial Viral Infection and Secondary Pneumococcal Pneumonia

Several research works have demonstrated that beneficial microbes with the capacity to modulate the mucosal immune system (immunobiotics) are an interesting alternative to improve the outcome of bacterial and viral respiratory infections. Among the immunobiotic strains with the capacity to beneficially modulate respiratory immunity, Lactobacillus rhamnosus CRL1505 has outstanding properties. Although we have significantly advanced in demonstrating the capacity of L. rhamnosus CRL1505 to improve resistance against respiratory infections as well as in the cellular and molecular mechanisms involved in its beneficial activities, the potential protective ability of this strain or its immunomodulatory cellular fractions in the context of a secondary bacterial pneumonia has not been addressed before. In this work, we demonstrated that the nasal priming with non-viable L. rhamnosus CRL1505 or its purified peptidoglycan differentially modulated the respiratory innate antiviral immune response triggered by toll-like receptor 3 activation in infant mice, improving the resistance to primary respiratory syncytial virus (RSV) infection, and secondary pneumococcal pneumonia. In association with the protection against RSV-pneumococcal superinfection, we found that peptidoglycan from L. rhamnosus CRL1505 significantly improved lung CD3⁺CD4⁺IFN-γ⁺, and CD3⁺CD4⁺IL-10⁺ T cells as well as CD11c⁺SiglecF⁺IFN-β⁺ alveolar macrophages with the consequent increases of IFN-γ, IL-10, and IFN-β in the respiratory tract. Our results also showed that the increase of these three cytokines is necessary to achieve protection against respiratory superinfection since each of them are involved in different aspect of the secondary pneumococcal pneumonia that have to be controlled in order to reduce the severity of the infectious disease: lung pneumococcal colonization, bacteremia, and inflammatory-mediated lung tissue injury.

Inorganic salts and intracellular polyphosphate inclusions play a role in the thermotolerance of the immunobiotic Lactobacillus rhamnosus CRL 1505

In this work, the thermotolerance of Lactobacillus rhamnosus CRL1505, an immunobiotic strain, was studied as a way to improve the tolerance of the strain to industrial processes involving heat stress. The strain displayed a high intrinsic thermotolerance (55°C, 20 min); however, after 5 min at 60°C in phosphate buffer a two log units decrease in cell viability was observed. Different heat shock media were tested to improve the cell survival. Best results were obtained in the mediumcontaining inorganic salts (KH₂PO₄, Na₂HPO₄, MnSO₄, and MgSO₄) likely as using 10% skim milk. Flow cytometry analysis evinced 25.0% live cells and a large number of injured cells (59.7%) in the inorganic salts medium after heat stress. The morphological changes caused by temperature were visualized by transmission electronic microscopy (TEM). In addition, TEM observations revealed the presence of polyphosphate (polyP) granules in the cells under no-stress conditions. A DAPI-based fluorescence technique, adjusted to Gram-positive bacteria for the first time, was used to determine intracellular polyP levels. Results obtained suggest that the high initial polyP content in L. rhamnosus CRL 1505 together with the presence of inorganic salts in the heat shock medium improve the tolerance of the cells to heat shock. To our knowledge, this is the first report giving evidence of the relationship between polyP and inorganic salts in thermotolerance of lactic acid bacteria.

Immune Response of Healthy Adults to the Ingested Probiotic Lactobacillus casei Shirota

Daily ingestion of a probiotic drink containing Lactobacillus casei Shirota (LcS; 1.3 × 10¹⁰ live cells) by healthy adults for (1) 4-week LcS, (2) 6-week discontinuation of LcS and (3) a final 4 weeks of LcS was investigated. There was a significant increase in expression of the T cell activation marker CD3⁺ CD69⁺ in ex vivo unstimulated blood cells at weeks 10 and 14, and there was a significant increase in the NK cell marker CD3⁺ CD16/56⁺ in ex vivo unstimulated blood cells at weeks 4, 10 and 14. Expression of the NK cell activation marker CD16/56⁺ CD69⁺ in ex vivo unstimulated blood cells was 62% higher at week 10 and 74% higher at week 14. Intracellular staining of IL-4 in ex vivo unstimulated and PMA-/ionomycin-stimulated CD3⁺ β7⁺ integrin blood cells was significantly lower at weeks 10 and 14. Intracellular staining of IL-12 in ex vivo unstimulated and LPS-stimulated CD14⁺ blood cells was significantly lower at weeks 4, 10 and 14. Intracellular staining of TNF-α in LPS-stimulated CD14⁺ blood cells was significantly lower at weeks 4, 10 and 14. Mucosal salivary IFN-γ, IgA1 and IgA2 concentrations were significantly higher at week 14, but LcS did not affect systemic circulating influenza A-specific IgA or IgG and tetanus-specific IgG antibody levels. In addition to the decrease in CD3⁺ β7⁺ integrin cell IL-4 and a reduced CD14⁺ cell pro-inflammatory cytokine profile, at week 14 increased expression of activation markers on circulating T cells and NK cells and higher mucosal salivary IgA1 and IgA2 concentration indicated a secondary boosting effect of LcS.

Transcriptomic Analysis of the Innate Antiviral Immune Response in Porcine Intestinal Epithelial Cells: Influence of Immunobiotic Lactobacilli

Lactobacillus rhamnosus CRL1505 and Lactobacillus plantarum CRL1506 are immunobiotic strains able to increase protection against viral intestinal infections as demonstrated in animal models and humans. To gain insight into the host–immunobiotic interaction, the transcriptomic response of porcine intestinal epithelial (PIE) cells to the challenge with viral molecular associated pattern poly(I:C) and the changes in the transcriptomic profile induced by the immunobiotics strains CRL1505 and CRL1506 were investigated in this work. By using microarray technology and reverse transcription PCR, we obtained a global overview of the immune genes involved in the innate antiviral immune response in PIE cells. Stimulation of PIE cells with poly(I:C) significantly increased the expression of IFN-α and IFN-β, several interferon-stimulated genes, cytokines, chemokines, adhesion molecules, and genes involved in prostaglandin biosynthesis. It was also determined that lactobacilli differently modulated immune gene expression in poly(I:C)-challenged PIE cells. Most notable changes were found in antiviral factors (IFN-α, IFN-β, NPLR3, OAS1, OASL, MX2, and RNASEL) and cytokines/chemokines (IL-1β, IL-6, CCL4, CCL5, and CXCL10) that were significantly increased in lactobacilli-treated PIE cells. Immunobiotics reduced the expression of IL-15 and RAE1 genes that mediate poly(I:C) inflammatory damage. In addition, lactobacilli treatments increased the expression PLA2G4A, PTGES, and PTGS2 that are involved in prostaglandin E2 biosynthesis. L. rhamnosus CRL1505 and L. plantarum CRL1506 showed quantitative and qualitative differences in their capacities to modulate the innate antiviral immune response in PIE cells, which would explain the higher capacity of the CRL1505 strain when compared to CRL1506 to protect against viral infection and inflammatory damage in vivo. These results provided valuable information for the deeper understanding of the host–immunobiotic interaction and their effect on antiviral immunity. The comprehensive transcriptomic analyses successfully identified a group of genes (IFN-β, RIG1, RNASEL, MX2, A20, IL27, CXCL5, CCL4, PTGES, and PTGER4), which can be used as prospective biomarkers for the screening of new antiviral immunobiotics in PIE cells and for the development of novel functional food and feeds, which may help to prevent viral infections.

Respiratory Antiviral Immunity and Immunobiotics: Beneficial Effects on Inflammation-Coagulation Interaction during Influenza Virus Infection

Influenza virus (IFV) is a major respiratory pathogen of global importance, and the cause of a high degree of morbidity and mortality, especially in high-risk populations such as infants, elderly, and immunocompromised hosts. Given its high capacity to change antigenically, acquired immunity is often not effective to limit IFV infection and therefore vaccination must be constantly redesigned to achieve effective protection. Improvement of respiratory and systemic innate immune mechanisms has been proposed to reduce the incidence and severity of IFV disease. In the last decade, several research works have demonstrated that microbes with the capacity to modulate the mucosal immune system (immunobiotics) are a potential alternative to beneficially modulate the outcome of IFV infection. This review provides an update of the current status on the modulation of respiratory immunity by orally and nasally administered immunobiotics, and their beneficial impact on IFV clearance and inflammatory-mediated lung tissue damage. In particular, we describe the research of our group that investigated the influence of immunobiotics on inflammation–coagulation interactions during IFV infection. Studies have clearly demonstrated that hostile inflammation is accompanied by dysfunctional coagulation in respiratory IFV disease, and our investigations have proved that some immunobiotic strains are able to reduce viral disease severity through their capacity to modulate the immune-coagulative responses in the respiratory tract.

Immunobiotic Lactobacillus strains reduce small intestinal injury induced by intraepithelial lymphocytes after Toll-like receptor 3 activation

OBJECTIVE

Intestinal intraepithelial lymphocytes (IELs) play critical roles in disrupting epithelial homeostasis after Toll-like receptor (TLR)-3 activation with genomic rotavirus dsRNA or the synthetic dsRNA analog poly(I:C). The capacity of immunobiotic Lactobacillus rhamnosus CRL1505 (Lr1505) or Lactobacillus plantarum CRL1506 (Lp1506) to beneficially modulate IELs response after TLR3 activation was investigated in vivo using a mice model.

RESULTS

Intraperitoneal administration of poly(I:C) induced inflammatory-mediated intestinal tissue damage through the increase of inflammatory cells (CD3(+)NK1.1(+), CD3(+)CD8αα(+), CD8αα(+)NKG2D(+)) and pro-inflammatory mediators (TNF-α, IL-1β, IFN-γ, IL-15, RAE1, IL-8). Increased expression of intestinal TLR3, MDA5, and RIG-I was also observed after poly(I:C) challenge. Treatment with Lr1505 or Lp1506 prior to TLR3 activation significantly reduced the levels of TNF-α, IL-15, RAE1, and increased serum and intestinal IL-10. Moreover, CD3(+)NK1.1(+), CD3(+)CD8αα(+), and CD8αα(+)NKG2D(+) cells were lower in lactobacilli-treated mice when compared to controls. The immunomodulatory capacities of lactobacilli allowed a significant reduction of intestinal tissue damage.

CONCLUSIONS

This work demonstrates the reduction of TLR3-mediated intestinal tissue injury by immunobiotic lactobacilli through the modulation of intraepithelial lymphocytes response. It is a step forward in the understanding of the cellular mechanisms involved in the antiviral capabilities of immunobiotic strains.

Draft Genome Sequence of Lactobacillus plantarum CRL1506, an Immunomodulatory Strain Isolated from Goat Milk

This report describes a draft genome sequence of Lactobacillus plantarum CRL1506, a probiotic strain with immunomodulatory properties isolated from goat milk. The reads generated by a whole-genome shotgun (WGS) strategy on an Illumina MiSeq sequencer were assembled into contigs with a total size of 3,228,096 bp. The draft genome sequence of L. plantarum CRL1506 will be useful for further studies of specific genetic features of this strain and for understanding the mechanisms of its immunobiotic properties.

Probiotics and Prebiotics for Prevention of Viral Respiratory Tract Infections

This chapter introduces the importance of viral upper respiratory tract infections and evidence that probiotics, prebiotics, and synbiotics may reduce not only their incidence, but also their duration and severity. It starts by explaining the importance of viral respiratory infections and the common cold including their prevalence, morbidity, mortality, and cost. The mechanisms of action are discussed next. Later, it represents the clinical trials using probiotics and prebiotics for the prevention of viral infection in different age groups. At the end of the chapter, a summary of latest evidences is presented.

Live and Heat-Killed Lactobacillus rhamnosus ATCC 7469 May Induce Modulatory Cytokines Profiles on Macrophages RAW 264.7

This study aimed to evaluate the capacity of Lactobacillus rhamnosus and/or its products to induce the synthesis of cytokines (TNF-α, IL-1β, IL-4, IL-6, IL-10, and IL-12) by mouse macrophages (RAW 264.7). Three microorganism preparations were used: live L. rhamnosus (LLR) suspension, heat-killed L. rhamnosus (HKLR) suspension, and the supernatant of a heat-killed L. rhamnosus (SHKLR) suspension, which were cultured with macrophages (37°C, 5% CO₂) for 2 h and 30 min. After that, cells were cultured for 16 h. The supernatants were used for the quantitation of cytokines, by ELISA. The results were compared with the synthesis induced by lipopolysaccharide (LPS) and analysed, using ANOVA and Tukey test, 5%. LLR and HKLR groups were able to significantly increase the production of TNF-α, IL-6, and IL-10 (P < 0.05). SHKLR also significantly increased the production of TNF-α and IL-10 (P < 0.05) but not IL-6 (P > 0.05). All the L. rhamnosus suspensions were not able to produce detectable levels of IL-1β or significant levels of IL-4 and IL-12 (P > 0.05). In conclusion, live and heat-killed L. rhamnosus suspensions were able to induce the synthesis of different cytokines with proinflammatory (TNF-α and IL-6) or regulatory (IL-10) functions, suggesting the role of strain L. rhamnosus ATCC 7469 in the modulation or in the stimulation of immune responses.

Role of short-term use of L. acidophilus DDS-1 and B. lactis UABLA-12 in acute respiratory infections in children: a randomized controlled trial

BACKGROUND/OBJECTIVES

Evidence suggests that the long-term consumption of probiotics may help in reducing the incidence of or modifying acute respiratory infection (ARI). We assessed the role of the short-term use of probiotics in ARI in children.

SUBJECTS/METHODS

This was a randomized, double-blind, controlled study that enrolled 315 children with 90 dropouts. On the first day of appearance of a sick household member, otherwise healthy children of both sexes aged 3-12 years were allocated to receive Lactobacillus acidophilus DDS-1 and Bifidobacterium lactis UABLA-12 (Up4-Junior) in a dose of 5 billion colony-forming units daily with 50 mg of fructooligosaccharide (the probiotic group) or rice maltodexrin (the control group). Test supplementation and follow-up lasted for 2 weeks or until the end of the secondary ARI in a child. The primary outcome measure was the incidence of ARI. Time to resolution and the severity of ARI served the secondary outcome measures.

RESULTS

In all, 64 of 113 children in the probiotic group (57%) and 73 of 112 children in the control group (65%) developed ARI (P=0.261). Time to resolution of the secondary ARI was shorter in the probiotic group (5.0 (interquartile range (IQR): 4.0-6.0) vs 7.0 (IQR: 6.0-8.0) days, P<0.001). The median severity of ARI was 240 (IQR: 163-350) score-days in the probiotic vs 525 (IQR: 364-736) score-days in the control group (P<0.001).

CONCLUSIONS

The short-term use of probiotics does not reduce the incidence, but shortens ARI in preschool and elementary school children.

Consecutive oral administration of Bifidobacterium longum MM-2 improves the defense system against influenza virus infection by enhancing natural killer cell activity in a murine model

Bifidobacterium, one of the major components of intestinal microflora, shows anti-influenza virus (IFV) potential as a probiotic, partly through enhancement of innate immunity by modulation of the intestinal immune system. Bifidobacterium longum MM-2 (MM-2), a very safe bacterium in humans, was isolated from healthy humans and its protective effect against IFV infection in a murine model shown. In mice that were intranasally inoculated with IFV, oral administration of MM-2 for 17 consecutive days improved clinical symptoms, reduced mortality, suppressed inflammation in the lower respiratory tract, and decreased virus titers, cell death, and pro-inflammatory cytokines such as IL-6 and TNF-α in bronchoalveolar lavage fluid. The anti-IFV mechanism of MM-2 involves innate immunity through significant increases in NK cell activities in the lungs and spleen and a significant increase in pulmonary gene expression of NK cell activators such as IFN-γ, IL-2, IL-12 and IL-18. Even in non-infected mice, MM-2 administration also induced significant enhancement of both IFN-γ production by Peyer's patch cells (PPs) and splenetic NK cell activity. Oral administration of MM-2 for 17 days activates systemic immunoreactivity in PPs, which contributes to innate immunity, including NK cell activation, resulting in an anti-IFV effect. MM-2 as a probiotic may function as a prophylactic agent in the management of an IFV epidemic.

Probiotics for the treatment of upper and lower respiratory-tract infections in children: systematic review based on randomized clinical trials

OBJECTIVES

Evaluate the effect of probiotics on the symptoms, duration of disease, and the occurrence of new episodes of upper and lower respiratory infections in healthy children.

SOURCES

In order to identify eligible randomized controlled trials, two reviewers accessed four electronic databases [MEDLINE/PubMed, Scopus (Elsevier), Web of Science, and Cochrane (Cochrane VHL)], as well as ClinicalTrials.gov until January 2015. Descriptors were determined by using the Medical Subject Headings tool, following the same search protocol.

SUMMARY OF THE FINDINGS

Studies showed to be heterogeneous regarding strains of probiotics, the mode of administration, the time of use, and outcomes. The present review identified 11 peer-reviewed, randomized clinical trials, which analyzed a total of 2417 children up to 10 incomplete years of age. In the analysis of the studies, reduction in new episodes of disease was a favorable outcome for the use of probiotics in the treatment of respiratory infections in children. It is noteworthy that most of these studies were conducted in developed countries, with basic sanitation, health care, and strict, well-established and well-organized guidelines on the use of probiotics. Adverse effects were rarely reported, demonstrating probiotics to be safe.

CONCLUSIONS

Despite the encouraging results - reducing new episodes of respiratory infections - the authors emphasize the need for further research, especially in developing countries, where rates of respiratory infections in children are higher when compared to the high per capita-income countries identified in this review.

Novel microbiome-based therapeutics for chronic rhinosinusitis

The human microbiome, i.e. the collection of microbes that live on, in and interact with the human body, is extraordinarily diverse; microbiota have been detected in every tissue of the human body interrogated to date. Resident microbiota interact extensively with immune cells and epithelia at mucosal surfaces including the airways, and chronic inflammatory and allergic respiratory disorders are associated with dysbiosis of the airway microbiome. Chronic rhinosinusitis (CRS) is a heterogeneous disease with a large socioeconomic impact, and recent studies have shown that sinus inflammation is associated with decreased sinus bacterial diversity and the concomitant enrichment of specific sinus pathogens. Here, we discuss the potential role for probiotic supplementation for CRS in light of this increasing understanding of the airway microbiome and microbial interactions with the host. We focus on the ecological significance of microbiome-based probiotic supplementation and potential interactions with the gastrointestinal tract and consider microbial administration methods for treatment of CRS.

Cochrane Commentary: Probiotics For Prevention of Acute Upper Respiratory Infection

BACKGROUND

Probiotics may improve a person's health by regulating their immune function. Some trials have shown that probiotic strains can prevent respiratory infections. Even though the previous version of our review showed benefits of probiotics for acute upper respiratory tract infections (URTIs), several new studies have been published.

OBJECTIVES

To assess the effectiveness and safety of probiotics (any specified strain or dose), compared with placebo, in the prevention of acute URTIs in people of all ages, who are at risk of acute URTIs.

SEARCH METHODS

We searched CENTRAL (2014, Issue 6), MEDLINE (1950 to July week 3, 2014), EMBASE (1974 to July 2014), Web of Science (1900 to July 2014), the Chinese Biomedical Literature Database, which includes the China Biological Medicine Database (from 1978 to July 2014), the Chinese Medicine Popular Science Literature Database (from 2000 to July 2014) and the Masters Degree Dissertation of Beijing Union Medical College Database (from 1981 to July 2014). We also searched the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) and ClinicalTrials.gov for completed and ongoing trials on 31 July 2014.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing probiotics with placebo to prevent acute URTIs.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the eligibility and quality of trials, and extracted data using the standard methodological procedures expected by The Cochrane Collaboration.

MAIN RESULTS

We included 13 RCTs, although we could only extract data to meta-analyze 12 trials, which involved 3720 participants including children, adults (aged around 40 years) and older people. We found that probiotics were better than placebo when measuring the number of participants experiencing episodes of acute URTI [at least one episode: odds ratio (OR): 0.53; 95% CI = 0.37-0.76, P < .001, low quality evidence; at least three episodes: OR: 0.53; 95% CI = 0.36-0.80, P = .002, low quality evidence]; the mean duration of an episode of acute URTI [mean difference (MD): -1.89; 95% CI = -2.03 to -1.75, P < .001, low quality evidence]; reduced antibiotic prescription rates for acute URTIs (OR: 0.65; 95% CI = 0.45-0.94, moderate quality evidence) and cold-related school absence (OR: 0.10; 95% CI = 0.02-0.47, very low quality evidence). Probiotics and placebo were similar when measuring the rate ratio of episodes of acute URTI (rate ratio: 0.83; 95% CI = 0.66-1.05, P = .12, very low quality evidence) and adverse events (OR: 0.88; 95% CI = 0.65-1.19, P = .40, low quality evidence). Side effects of probiotics were minor and gastrointestinal symptoms were the most common. We found that some subgroups had a high level of heterogeneity when we conducted pooled analyses and the evidence level was low or very low quality.

AUTHORS' CONCLUSIONS

Probiotics were better than placebo in reducing the number of participants experiencing episodes of acute URTI, the mean duration of an episode of acute URTI, antibiotic use and cold-related school absence. This indicates that probiotics may be more beneficial than placebo for preventing acute URTIs. However, the quality of the evidence was low or very low.

Gut ecosystem: how microbes help us

The human gut houses one of the most complex and abundant ecosystems composed of up to 1013-1014 microorganisms. Although the anthropocentric concept of life has concealed the function of microorganisms inside us, the important role of gut bacterial community in human health is well recognised today. Moreover, different microorganims, which are commonly present in a large diversity of food products, transit through our gut every day adding in some cases a beneficial effect to our health (probiotics). This crosstalk is concentrated mainly in the intestinal epithelium, where microbes provide the host with essential nutrients and modulation of the immune system. Furthermore, microorganisms also display antimicrobial activities maintaining a gut ecosystem stable. This review summarises some of the recent findings on the interaction of both commensal and probiotic bacteria with each other and with the host. The aim is to highlight the cooperative status found in healthy individuals as well as the importance of this crosstalk in the maintenance of human homeostasis.

Advanced application of porcine intramuscular adipocytes for evaluating anti-adipogenic and anti-inflammatory activities of immunobiotics

We previously established a clonal porcine intramuscular preadipocyte (PIP) line and we were able to establish a protocol to obtain functional mature adipocytes from PIP cells. We hypothesized that both PIP cells and mature adipocytes are likely to be useful in vitro tools for increasing our understanding of immunobiology of adipose tissue, and for the selection and study of immunoregulatory probiotics (immunobiotics) able to modulate adipocytes immune responses. In this study, we investigated the immunobiology of PIP cells and mature adipocytes in relation to their response to TNF-α stimulation. In addition, we evaluated the possibility that immunobiotic microorganisms modify adipogenesis and immune functions of porcine adipose tissue through Peyer’s patches (PPs) immune-competent cells. We treated the porcine PPs immune cells with different probiotic strains; and we evaluated the effect of conditioned media from probiotic-stimulated immune cells in PIP cells and mature adipocytes. The Lactobacillus GG and L. gasseri TMC0356 showed remarkable effects, and were able to significantly reduce the expression of pro-inflammatory factors and negative regulators (A20, Bcl-3, and MKP-1) in adipocytes challenged with TNF-α. The results of this study demonstrated that the evaluation of IL-6, and MCP-1 production, and A20 and Bcl-3 down-regulation in TNF-α-challenged adipocytes could function as biomarkers to screen and select potential immunobiotic strains. Taking into consideration that several in vivo and in vitro studies clearly demonstrated the beneficial effects of Lactobacillus GG and L. gasseri TMC0356 in adipose inflammation, the results presented in this work indicate that the PIP cells and porcine adipocytes could be used for the screening and the selection of new immunobiotic strains with the potential to functionally modulate adipose inflammation when orally administered.

Influence of a probiotic Lactobacillus casei strain on the colonisation with potential pathogenic streptococci and Staphylococcus aureus in the nasopharyngeal space of healthy men with a low baseline NK cell activity

The effect of a daily intake of the probiotic strain Lactobacillus casei Shirota (LcS) on the colonisation of pathogens, specifically streptococci and Staphylococcus aureus, in the nose and throat of healthy human volunteers with low natural killer cell activity, was investigated in a randomised and controlled intervention study. The study consisted of a 2-week run-in phase, followed by a 4-week intervention phase. The probiotic treatment group received a fermented milk drink with LcS, while the placebo group received an equally composed milk drink without the probiotic additive. To isolate potential pathogenic streptococci and Staph. aureus, samples from the pharynx, as well as of both middle nasal meati, were taken, once after the run-in phase and once at the end of the intervention phase. Isolated bacteria were identified as either Staph. aureus and α- or β-haemolytic streptococci in a polyphasic taxonomical approach based on phenotypic tests, amplified ribosomal DNA restriction analysis genotyping, and 16S rRNA gene sequencing of representative strains. Salivary secretory immunoglobulin A (SIgA) was used as marker of protective mucosal immunity to evaluate whether LcS treatment influenced SIgA production. No statistically significant effect could be determined for intervention with LcS on the incidence of Staph. aureus in the nasal space, Staph. aureus in the pharyngeal space or for β-haemolytic streptococci and Streptococcus pneumoniae in the pharyngeal space. Thus, the intervention did not influence the nasopharyngeal colonisation with Gram-positive potential pathogens. Production of salivary SIgA as a potential means of microbiota modulation was also not affected.

Soluble factors from Lactobacillus reuteri CRL1098 have anti-inflammatory effects in acute lung injury induced by lipopolysaccharide in mice

We have previously demonstrated that Lactobacillus reuteri CRL1098 soluble factors were able to reduce TNF-α production by human peripheral blood mononuclear cells. The aims of this study were to determine whether L. reuteri CRL1098 soluble factors were able to modulate in vitro the inflammatory response triggered by LPS in murine macrophages, to gain insight into the molecular mechanisms involved in the immunoregulatory effect, and to evaluate in vivo its capacity to exert anti-inflammatory actions in acute lung injury induced by LPS in mice. In vitro assays demonstrated that L. reuteri CRL1098 soluble factors significantly reduced the production of pro-inflammatory mediators (NO, COX-2, and Hsp70) and pro-inflammatory cytokines (TNF-α, and IL-6) caused by the stimulation of macrophages with LPS. NF-kB and PI3K inhibition by L. reuteri CRL1098 soluble factors contributed to these inhibitory effects. Inhibition of PI3K/Akt pathway and the diminished expression of CD14 could be involved in the immunoregulatory effect. In addition, our in vivo data proved that the LPS-induced secretion of the pro-inflammatory cytokines, inflammatory cells recruitment to the airways and inflammatory lung tissue damage were reduced in L. reuteri CRL1098 soluble factors treated mice, providing a new way to reduce excessive pulmonary inflammation.

Immunobiotic Lactobacillus rhamnosus strains differentially modulate antiviral immune response in porcine intestinal epithelial and antigen presenting cells

Background

Previous findings suggested that Lactobacillus rhamnosus CRL1505 is able to increase resistance of children to intestinal viral infections. However, the intestinal cells, cytokines and receptors involved in the immunoregulatory effect of this probiotic strain have not been fully characterized.

Results

We aimed to gain insight into the mechanisms involved in the immunomodulatory effect of the CRL1505 strain and therefore evaluated in vitro the crosstalk between L. rhamnosus CRL1505, porcine intestinal epithelial cells (IECs) and antigen presenting cells (APCs) from swine Peyer’s patches in order to deepen our knowledge about the mechanisms, through which this strain may help preventing viral diarrhoea episodes. L. rhamnosus CRL1505 was able to induce IFN–α and –β in IECs and improve the production of type I IFNs in response to poly(I:C) challenge independently of Toll-like receptor (TLR)-2 or TLR9 signalling. In addition, the CRL1505 strain induced mRNA expression of IL-6 and TNF-α via TLR2 in IECs. Furthermore, the strain significantly increased surface molecules expression and cytokine production in intestinal APCs. The improved Th1 response induced by L. rhamnosus CRL1505 was triggered by TLR2 signalling and included augmented expression of MHC-II and co-stimulatory molecules and expression of IL-1β, IL-6, and IFN-γ in APCs. IL-10 was also significantly up-regulated by CRL1505 in APCs.

Conclusions

It was recently reviewed the emergence of TLR agonists as new ways to transform antiviral treatments by introducing panviral therapeutics with less adverse effects than IFN therapies. The use of L. rhamnosus CRL1505 as modulator of innate immunity and inductor of antiviral type I IFNs, IFN-γ, and regulatory IL-10 clearly offers the potential to overcome this challenge.

Modulation of Respiratory TLR3-Anti-Viral Response by Probiotic Microorganisms: Lessons Learned from Lactobacillus rhamnosus CRL1505

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract illness in infants and young children. Host immune response is implicated in both protective and immunopathological mechanisms during RSV infection. Activation of Toll-like receptor (TLR)-3 in innate immune cells by RSV can induce airway inflammation, protective immune response, and pulmonary immunopathology. A clear understanding of RSV–host interaction is important for the development of novel and effective therapeutic strategies. Several studies have centered on whether probiotic microorganisms with the capacity to stimulate the immune system (immunobiotics) might sufficiently stimulate the common mucosal immune system to improve defenses in the respiratory tract. In this regard, it was demonstrated that some orally administered immunobiotics do have the ability to stimulate respiratory immunity and increase resistance to viral infections. Moreover, during the last decade scientists have significantly advanced in the knowledge of the cellular and molecular mechanisms involved in the protective effect of immunobiotics in the respiratory tract. This review examines the most recent advances dealing with the use of immunobiotic bacteria to improve resistance against viral respiratory infections. More specifically, the article discuss the mechanisms involved in the capacity of the immunobiotic strain Lactobacillus rhamnosus CRL1505 to modulate the TLR3-mediated immune response in the respiratory tract and to increase the resistance to RSV infection. In addition, we review the role of interferon (IFN)-γ and interleukin (IL)-10 in the immunoregulatory effect of the CRL1505 strain that has been successfully used for reducing incidence and morbidity of viral airways infections in children.

Do children's upper respiratory tract infections benefit from probiotics?

Background

The microbiota of the gastrointestinal tract have profound influence at multiple levels, even on the development and maintenance of lung immunity and inflammation. Aim of this review is to evaluate the current knowledge about the specific impact on children’s respiratory tract infections from probiotics, live microbes with the power to modify intestinal microbial populations and exert subsequent benefits for the host.

Discussion

The role of probiotics in gastrointestinal and allergic diseases has been largely assessed, but the number of studies performed so far in the field of respiratory tract infections is small, though some data show that probiotic administration might display clinical advantages. Probiotic strain identity and host genetic differences may account for differential modulation of immune responses by probiotics. Current laboratory and clinical data regarding the possibility of the role of probiotics on preventing the development of respiratory tract infections are contradictory, and are somewhat insufficient to recommend strongly their routine use. Further study of gastrointestinal-respiratory interactions is likely to yield important insights into the pathogenesis of different pulmonary diseases, and improve our knowledge in the prophylactic role of probiotics in children affected by recurrent upper respiratory tract infections.

Summary

A better understanding of the effects of different probiotic strains and a deeper insight into their mechanisms of action are needed for the validation of specific strains carrying a potential to modify the frequency and severity of RTIs in infants and children. No data have been collected in pediatric patients with chronic underlying diseases, and yet there are no published data concerning treatment of RTIs with probiotics. The very few studies published so far do not indicate which micro-organism or administration regimen might exert beneficial effects as a prevention tool of RTIs both in healthy children and in those with recurrent RTIs. Further research to establish the role of probiotics in the treatment and prevention of RTIs, including those involving the lower respiratory tract, are required and should also clarify if any susceptible subgroups of respiratory diseases exist, and how these subgroups benefit from supplementation with certain probiotic strains.

Immunobiotic lactobacilli reduce viral-associated pulmonary damage through the modulation of inflammation-coagulation interactions

The exacerbated disease due to immune- and coagulative-mediated pulmonary injury during acute respiratory viruses infection results in severe morbidity and mortality. Identifying novel approaches to modulate virus-induced inflammation-coagulation interactions could be important alternatives for treating acute respiratory viruses infections. In this study we investigated the effect of the probiotic strain Lactobacillus rhamnosus CRL1505 on lung TLR3-mediated inflammation, and its ability to modulate inflammation-coagulation interaction during respiratory viral infection. Our findings reveal for the first time that a probiotic bacterium is able to influence lung immune-coagulative reaction triggered by TLR3 activation, by modulating the production of proinflammatory and anti-inflammatory cytokines as well as expression of tissue factor and thrombomodulin in the lung. We also demonstrated that the preventive treatment with the probiotic bacteria beneficially modulates the fine tune balance between clearing respiratory viruses (respiratory syncytial virus and influenza virus) and controlling immune-coagulative responses in the lung, allowing normal lung function to be maintained in the face of a viral attack. Our data also pinpoint a crucial role for IL-10 in the immune protection induced by L. rhamnosus CRL1505 during respiratory viral infections. These observations might be helpful to propose new preventive or therapeutic approaches to better control virus-inflammatory lung damage using probiotic functional foods.

Prebiotic and probiotic supplementation prevents rhinovirus infections in preterm infants: a randomized, placebo-controlled trial

Background

Simple and safe strategies for the prevention of viral respiratory tract infections (RTIs) are needed.

Objective

We hypothesized that early prebiotic or probiotic supplementation would reduce the risk of virus-associated RTIs during the first year of life in a cohort of preterm infants.

Methods

In this randomized, double-blind, placebo-controlled trial (ClinicalTrials.gov no. NCT00167700), 94 preterm infants (gestational age, ≥32 + 0 and ≤36 + 6 weeks; birth weight, >1500 g) treated at Turku University Hospital, Turku, Finland, were allocated to receive oral prebiotics (galacto-oligosaccharide and polydextrose mixture, 1:1), a probiotic (Lactobacillus rhamnosus GG, ATCC 53103), or placebo (microcrystalline cellulose) between days 3 and 60 of life. The primary outcome was the incidence of clinically defined virus-associated RTI episodes confirmed from nasal swabs by using nucleic acid testing. Secondary outcomes were the severity and duration of RTIs.

Results

A significantly lower incidence of RTIs was detected in infants receiving prebiotics (rate ratio [RR], 0.24; 95% CI, 0.12-0.49; P < .001) or probiotics (RR, 0.50; 95% CI, 0.28-0.90; P = .022) compared with those receiving placebo. Also, the incidence of rhinovirus-induced episodes, which comprised 80% of all RTI episodes, was found to be significantly lower in the prebiotic (RR, 0.31; 95% CI, 0.14-0.66; P = .003) and probiotic (RR, 0.49; 95% CI, 0.24-1.00; P = .051) groups compared with the placebo group. No differences emerged among the study groups in rhinovirus RNA load during infections, duration of rhinovirus RNA shedding, duration or severity of rhinovirus infections, or occurrence of rhinovirus RNA in asymptomatic infants.

Conclusions

Gut microbiota modification with specific prebiotics and probiotics might offer a novel and cost-effective means to reduce the risk of rhinovirus infections.

Lactobacillus rhamnosus CRL1505 beneficially modulates the immuno-coagulative response after pneumococcal infection in immunocompromised malnourished mice

This work evaluated the effect of orally or nasally administered Lactobacillus rhamnosus CRL1505 on the resistance of immunocompromised protein-malnourished mice to pneumococcal infection. In particular, we aimed to gain knowledge of the mechanism involved in the immunomodulatory effect of L. rhamnosus CRL1505 in malnourished hosts by evaluating its impact on the immuno-coagulative response. Malnutrition significantly increased lung tissue damage caused by Streptococcus pneumoniae infection. Lung damage was associated with a deregulated activation of coagulation and an altered inflammatory response. Pneumococcal colonization of lung and bacteremia were significantly reduced (p < 0.05) in malnourished mice receiving the CRL1505 strain. Moreover, mice repleted with supplemental L. rhamnosus CRL1505 showed the least alteration of the alveolar–capillary barrier and cell damage in lungs after the infectious challenge, especially when the CRL1505 strain was administered by nasal route. Besides, mice treated with L. rhamnosus CRL1505 showed an improved respiratory innate immune response and a lower activation of coagulation. The results of this work indicate that L. rhamnosus CRL1505 is able to beneficially modulate the inflammation–coagulation interaction after respiratory infections in malnourished hosts.

Probiotics and Prevention of Pediatric Upper Respiratory Tract Infections

There is a certain consensus that some probiotics can significantly help in preventing and relieving the symptoms of gastrointestinal diseases and atopic diseases in general, but their use in respiratory tract infections has only been marginally investigated. The main aim of this review is to evaluate what is known about the impact of probiotics on pediatric respiratory tract infections in order to verify whether more data are needed before they can be used on infants and children with respiratory problems. Analysis of the literature shows that our knowledge is limited to the prevention of upper respiratory tract infections (URTIs). The very few studies carried out so far seem to indicate that probiotic administration may have some advantages in this regard, but the great limitation is that nothing is known about the susceptible micro-organisms or treatment regimens. Furthermore, URTIs are very limited clinical problems and it seems unreasonable to use a treatment whose efficacy and safety has not been completely clarified as means of preventing them. No data are available concerning the treatment of URTIs. There is a need for further research into the role of probiotics in treating respiratory infections and preventing more severe respiratory problems, including those involving the lower respiratory tract.

Nasally administered Lactobacillus rhamnosus strains differentially modulate respiratory antiviral immune responses and induce protection against respiratory syncytial virus infection

Background

Some studies have shown that nasally administered immunobiotics had the potential to improve the outcome of influenza virus infection. However, the capacity of immunobiotics to improve protection against respiratory syncytial virus (RSV) infection was not investigated before.

Objective

The aims of this study were: a) to evaluate whether the nasal administration of Lactobacillus rhamnosus CRL1505 (Lr05) and L. rhamnosus CRL1506 (Lr06) are able to improve respiratory antiviral defenses and beneficially modulate the immune response triggered by TLR3/RIG-I activation; b) to investigate whether viability of Lr05 or Lr06 is indispensable to modulate respiratory immunity and; c) to evaluate the capacity of Lr05 and Lr06 to improve the resistance of infant mice against RSV infection.

Results

Nasally administered Lr05 and Lr06 differentially modulated the TLR3/RIG-I-triggered antiviral respiratory immune response. Lr06 administration significantly modulated the production of IFN-α, IFN-β and IL-6 in the response to poly(I:C) challenge, while nasal priming with Lr05 was more effective to improve levels of IFN-γ and IL-10. Both viable Lr05 and Lr06 strains increased the resistance of infant mice to RSV infection while only heat-killed Lr05 showed a protective effect similar to those observed with viable strains.

Conclusions

The present work demonstrated that nasal administration of immunobiotics is able to beneficially modulate the immune response triggered by TLR3/RIG-I activation in the respiratory tract and to increase the resistance of mice to the challenge with RSV. Comparative studies using two Lactobacillus rhamnosus strains of the same origin and with similar technological properties showed that each strain has an specific immunoregulatory effect in the respiratory tract and that they differentially modulate the immune response after poly(I:C) or RSV challenges, conferring different degree of protection and using distinct immune mechanisms. We also demonstrated in this work that it is possible to beneficially modulate the respiratory defenses against RSV by using heat-killed immunobiotics.

Immunobiotic Lactobacillus rhamnosus improves resistance of infant mice against respiratory syncytial virus infection

Previously we showed that orally administered Lactobacillus rhamnosus CRL1505 beneficially regulated the balance between pro- and anti-inflammatory mediators in the lungs of poly(I:C)-challenged mice, allowing an effective inflammatory response against the TLR3/RIG-I agonist but at the same time reducing tissue damage. The aim of the present study was to investigate whether oral administration of the CRL1505 strain was able to improve resistance against respiratory syncytial virus (RSV) infection in infant mice and to evaluate the immunological mechanisms involved in the immunobiotic effect. We demonstrated that treatment of 3-week old BALB/c mice with L. rhamnosus CRL1505 significantly reduce lung viral loads and tissue injuries after the challenge with RSV. Moreover, we showed that the protective effect achieved by the CRL1505 strain is related to its capacity to differentially modulate respiratory antiviral immune response. Our results shows that IFN-γ and IL-10 secreted in response to L. rhamnosus CRL1505 oral stimulation would modulate the pulmonary innate immune microenvironment conducting to the activation of CD103(+) and CD11b(high) dendritic cells and the generation of CD3(+)CD4(+)IFN-γ(+) Th1 cells with the consequent attenuation of the strong and damaging Th2 reactions associated with RSV challenge. Our results indicate that modulation of the common mucosal immune system by immunobiotics could favor protective immunity against respiratory viral pathogens with a high attack rate in early infancy, such as RSV.