Resistance Against Leishmania major Infection Depends on Microbiota-Guided Macrophage Activation.

Innate immune cells present a dual role during leishmaniasis: they constitute the first line of host defense but are also the main host cells for the parasite. Response against the infection that results in the control of parasite growth and lesion healing depends on activation of macrophages into a classical activated phenotype. We report an essential role for the microbiota in driving macrophage and monocyte-derived macrophage activation towards a resistance phenotype against Leishmania major infection in mice. Both germ-free and dysbiotic mice showed a higher number of myeloid innate cells in lesions and increased number of infected cells, mainly dermal resident and inflammatory macrophages. Despite developing a Th1 immune response characterized by the same levels of IFN-γ production as the conventional mice, germ-free mice presented reduced numbers of iNOS+ macrophages at the peak of infection. Absence or disturbance of host microbiota impaired the capacity of bone marrow-derived macrophage to be activated for Leishmania killing in vitro, even when stimulated by Th1 cytokines. These cells presented reduced expression of inos mRNA, and diminished production of microbicidal molecules, such as ROS, while presenting a permissive activation status, characterized by increased expression of arginase I and il-10 mRNA and higher arginase activity. Colonization of germ-free mice with complete microbiota from conventional mice rescued their ability to control the infection. This study demonstrates the essential role of host microbiota on innate immune response against L. major infection, driving host macrophages to a resistance phenotype.

Depletion of PD-1 or PD-L1 did not affect the mortality of mice infected with Mycobacterium avium.

The programmed cell death-1 (PD-1) and programmed cell death-ligand 1 (PD-L1) pathway could affect antimicrobial immune responses by suppressing T cell activity. Several recent studies demonstrated that blocking of the PD-1/PD-L1 pathway exacerbated Mycobacterium tuberculosis infection. However, the effect of blocking this pathway in pulmonary Mycobacterium avium-intracellulare complex (MAC) infection is not fully understood. Wild-type, PD-1-deficient mice, and PD-L1-deficient mice were intranasally infected with Mycobacterium avium bacteria. Depletion of PD-1 or PD-L1 did not affect mortality and bacterial burden in MAC-infected mice. However, marked infiltration of CD8-positive T lymphocytes was observed in the lungs of PD-1 and PD-L1-deficient mice compared to wild-type mice. Comprehensive transcriptome analysis showed that levels of gene expressions related to Th1 immunity did not differ according to the genotypes. However, genes related to the activity of CD8-positive T cells and related chemokine activity were upregulated in the infected lungs of PD-1 and PD-L1-deficient mice. Thus, the lack of change in susceptibility to MAC infection in PD-1 and PD-L1-deficient mice might be explained by the absence of obvious changes in the Th1 immune response. Furthermore, activated CD8-positive cells in response to MAC infection in these mice seemed to not be relevant in the control of MAC infection.

Mycobacterium-Induced Th1, Helminths-Induced Th2 Cells and the Potential Vaccine Candidates for Allergic Asthma: Imitation of Natural Infection.

Bronchial asthma is one of the most chronic pulmonary diseases and major public health problems. In general, asthma prevails in developed countries than developing countries, and its prevalence is increasing in the latter. For instance, the hygiene hypothesis demonstrated that this phenomenon resulted from higher household hygienic standards that decreased the chances of infections, which would subsequently increase the occurrence of allergy. In this review, we attempted to integrate our knowledge with the hygiene hypothesis into beneficial preventive approaches for allergic asthma. Therefore, we highlighted the studies that investigated the correlation between allergic asthma and the two different types of infections that induce the two major antagonizing arms of T cells. This elucidation reflects the association between various types of natural infections and the immune system, which is predicted to support the main objective of the current research on investigating of the benefits of natural infections, regardless their immune pathways for the prevention of allergic asthma. We demonstrated that natural infection with Mycobacterium tuberculosis (Mtb) prevents the development of allergic asthma, thus Bacille Calmette-Guérin (BCG) vaccine is suggested at early age to mediate the same prevention particularly with increasing its efficiency through genetic engineering-based modifications. Likewise, natural helminth infections might inhabit the allergic asthma development. Therefore, helminth-derived proteins at early age are good candidates for designing vaccines for allergic asthma and it requires further investigation. Finally, we recommend imitation of natural infections as a general strategy for preventing allergic asthma that increased dramatically over the past decades.

Lactobacillus acidipiscis Induced Regulatory Gamma Delta T Cells and Attenuated Experimental Autoimmune Encephalomyelitis.

Multiple sclerosis is a chronic autoimmune disease involving the central nervous system, and shows a high disability rate. Its pathogenesis is complicated, and there is no good treatment. In recent years, with in-depth studies on the regulation of gastrointestinal flora, the relationship between the mammalian immune system and the intestinal flora has been extensively explored. Changes in the composition and structure of the gastrointestinal flora can affect the characteristics and development of the host immune system and even induce a series of central nervous system inflammation events. The occurrence and development of multiple sclerosis are closely related to the continuous destruction of the intestinal barrier caused by intestinal dysbacteriosis. In this study, we analyzed Lactobacillus acidipiscis in a mouse model of experimental autoimmune encephalomyelitis (EAE). We found that the amount of L. acidipiscis in the intestinal tract was inversely proportional to the progress of EAE development. In addition, the number of CD4+ FOXP3+ regulatory T cells in the mesenteric lymph nodes of mice increased significantly after the mice were fed with L. acidipiscis, and the differentiation of CD4+ T cells to Th1 and Th17 cells was inhibited. However, the protective effect of L. acidipiscis was lost in γδ T cell-deficient mice and hence was concluded to depend on the presence of regulatory γδ T cells in the intestinal epithelium. Moreover, including L. acidipiscis enhanced the development of Vγ1+γδ T cells but suppressed that of Vγ4+γδ T cells. In summary, our results demonstrated the ability of L. acidipiscis to induce generation of regulatory γδ T cells that suppress the development of the encephalomyelitic Th1 and Th17 cells and the progress of EAE.

Pulmonary MTBVAC vaccination induces immune signatures previously correlated with prevention of tuberculosis infection.

To fight tuberculosis, better vaccination strategies are needed. Live attenuated Mycobacterium tuberculosis-derived vaccine, MTBVAC, is a promising candidate in the pipeline, proven to be safe and immunogenic in humans so far. Independent studies have shown that pulmonary mucosal delivery of Bacillus Calmette-Guérin (BCG), the only tuberculosis (TB) vaccine available today, confers superior protection over standard intradermal immunization. Here we demonstrate that mucosal MTBVAC is well tolerated, eliciting polyfunctional T helper type 17 cells, interleukin-10, and immunoglobulins in the airway and yielding a broader antigenic profile than BCG in rhesus macaques. Beyond our previous work, we show that local immunoglobulins, induced by MTBVAC and BCG, bind to M. tuberculosis and enhance pathogen uptake. Furthermore, after pulmonary vaccination, but not M. tuberculosis infection, local T cells expressed high levels of mucosal homing and tissue residency markers. Our data show that pulmonary MTBVAC administration has the potential to enhance its efficacy and justifies further exploration of mucosal vaccination strategies in preclinical efficacy studies.

Non-infectious outer membrane vesicles derived from Brucella abortus S19Δper as an alternative acellular vaccine protects mice against virulent challenge.

The prime human and animal safety issues accentuate the search of promising newer alternative vaccine candidates to resolve complications associated with the live attenuated Brucella abortus strain19 (S19) vaccine. Outer membrane vesicles (OMVs S19 Δper) extracted from Brucella abortus S19Δper (S19Δper) as an alternative subunit vaccine candidate has been explored in the present study as OMVs are endowed with immunogenic molecules, including LPS and outer membrane proteins (OMPs) and do not cause infection by virtue of being an acellular entity. The LPS defective S19Δper released a higher amount of OMVs than its parent strain S19. Under transmission electron microscopy (TEM), OMVs were seen as nano-sized outward bulge from the surface of Brucella. Dynamic light scattering analysis of OMVs revealed that OMVs S19Δper showed the less polydispersity index (PDI) than OMVs S19 pointing towards relatively more homogenous OMVs populations. Both OMVs S19Δper and OMVs S19 with or without booster dose and S19 vaccine were used for immunization of mice and subsequently challenged with 2 × 105 CFU virulent Brucella abortus strain 544 (S544) to assess protective efficacy of vaccines. The less splenic weight index and less S544 count in OMVs immunized mice in comparison to unimmunized mice after S544 challenge clearly indicated good protective efficacy of OMVs. OMVs S19 Δper induced relatively high titer of IgG than OMVs S19 but conferred nearly equal protection against brucellosis. An ELISA based determination of IgG and its isotype response, Cytometric Bead Array (CBA) based quantitation of serum cytokines and FACS based enumeration of CD4+ and CD8+ T cells revealed high titer of IgG, production of both Th1 (IgG2a) and Th2 (IgG1) related antibodies, stimulation of IL-2, TNF (Th1) and IL-4, IL-6, IL-10 (Th2) cytokines, and induced T cell response suggested that OMVs S19Δper elicited Th1 and Th2 type immune response and ensured protection against S544 challenge in murine model.

Th2-like T Follicular Helper Cells Promote Functional Antibody Production during Plasmodium falciparum Infection.

CD4+ T follicular helper cells (Tfh) are key drivers of antibody development. During Plasmodium falciparum malaria in children, the activation of Tfh is restricted to the Th1 subset and not associated with antibody levels. To identify Tfh subsets that are associated with antibody development in malaria, we assess Tfh and antibodies longitudinally in human volunteers with experimental P. falciparum infection. Tfh cells activate during infection, with distinct dynamics in different Tfh subsets. Th2-Tfh cells activate early, during peak infection, while Th1-Tfh cells activate 1 week after peak infection and treatment. Th2-Tfh cell activation is associated with the functional breadth and magnitude of parasite antibodies. In contrast, Th1-Tfh activation is not associated with antibody development but instead with plasma cells, which have previously been shown to play a detrimental role in the development of long-lived immunity. Thus, our study identifies the contrasting roles of Th2 and Th1-Tfh cells during experimental P. falciparum malaria.

Mycobacterium vaccae Lysate Induces Anti-Allergic Immune Response In Vitro.

Mycobacterium vaccae is a soil saprophyte which exerts anti-allergic properties. There are data that mechanism of action of M. vaccae when used in the treatment of human and animal allergic diseases is associated with Th1-phenotype switch. Here we studied the properties of sonicated M. vaccae lysate in co-cultures of dendritic cells and CD4+T cells. M. vaccae lysate stimulated IL-10 synthesis in co-cultures and CD86 expression in dendritic cells, being more potent than heat-killed M. vaccae. The reported clinical data and the mechanism of action of M. vaccae lysate suggest that its use is a feasible option for the primary prevention of allergic diseases, in particular atopic dermatitis.

Antigen Epitope Developed Based on Acinetobacter baumannii MacB Protein Can Provide Partial Immune Protection in Mice.

Acinetobacter baumannii (A. baumannii) is an important opportunistic pathogen widely present in medical environment. Given its complex drug resistance, A. baumannii poses a serious threat to the safety of critically ill patients. Given the limited alternative antibiotics, nonantibiotic-based functional anti-A. baumannii infection proteins must be developed. In this study, we firstly used a series of biological software to predict potential epitopes in the MacB protein sequence and verified them by antibody recognition and lymphocyte proliferation tests. We finally screened out B cell epitope 2, CD8+ T cell epitope 7, and CD4+ T cell epitope 11 and connected them to construct a recombinant antigen epitope (RAE). The determination of IgG in the serum of immunised mice and cytokines in the supernatant of lymphocytes showed that the constructed epitope induced an immune response mediated by Th-1 cells. Finally, the challenge experiment of A. baumannii infection in mice confirmed that the epitope developed based on MacB, especially RAE, provided incomplete immune protection for mice.

Effects of hypoxic exposure on immune responses of intestinal mucosa to Citrobacter colitis in mice.

OBJECTIVE: The pathogenesis and mechanism of colitis may be related to intestinal flora, genetic susceptibility, environmental and immune factors. Among these various factors, the importance of environmental factors in the pathogenesis of colitis has been increasingly recognized. The purpose of this study was to investigate the effects of hypoxia on intestinal mucosal immunity. METHODS: Experimental colitis was induced by oral gavage of Citrobacter rodentium (C. rodentium) in mice, then divided into normoxia group and hypoxia group. Mice were sacrificed after 2 weeks. Physiological and blood biochemical indicators were monitored to verify the hypoxia model. The body weight, fecal bacterial output, colon length and colon histopathology were observed to evaluate severity of colitis. The concentration of cytokines in colonic tissues were detected by ELISA. The percentage of CD4+ IFN-γ+ (Th1) and CD4+ IL-17+ (Th17) cells in mesenteric lymph nodes (MLN) were detected by flow cytometry. The levels of mucosal antimicrobial peptides (AMPs), related inflammatory factors and transcription factors in colon tissues were detected by qRT-PCR. RESULTS: Mice in hypoxic C. rodentium infection (Hypoxia + C.r.) group exhibited significant decrease in body weight, increase in fecal bacterial pathogen output, and more severe histopathological damage in the colon compared with the C. rodentium infection (Nomoxia + C.r.) group. Meanwhile, the level of NF-κB, TLR4, COX-2, IL-6 and TNF-α of colonic tissue were increased, while IL17, IL-22, and Reg3γ were decreased. The percentage of CD4+ IFN-γ+ (Th1) and CD4+ IL-17+ (Th17) cells in MLN were significantly decreased in mice of Hypoxia + C.r. group, accompanied by the decreased of IFN-γ and IL-17. In addition, the level of the T-bet, RORγt, IL-12 and IL-23 were decreased in mice of Hypoxia + C.r. group. CONCLUSIONS: Hypoxic exposure significantly exacerbates the symptoms and the pathological damage of mice with colitis and influences the immune function by down-regulating Th1 and Th17 responses in C. rodentium-induced colitis in mice.

Pulmonary Mycobacterium tuberculosis control associates with CXCR3- and CCR6-expressing antigen-specific Th1 and Th17 cell recruitment.

Mycobacterium tuberculosis-specific (M. tuberculosis-specific) T cell responses associated with immune control during asymptomatic latent tuberculosis infection (LTBI) remain poorly understood. Using a nonhuman primate aerosol model, we studied the kinetics, phenotypes, and functions of M. tuberculosis antigen-specific T cells in peripheral and lung compartments of M. tuberculosis-infected asymptomatic rhesus macaques by longitudinally sampling blood and bronchoalveolar lavage, for up to 24 weeks postinfection. We found substantially higher frequencies of M. tuberculosis-specific effector and memory CD4+ and CD8+ T cells producing IFN-γ in the airways compared with peripheral blood, and these frequencies were maintained throughout the study period. Moreover, M. tuberculosis-specific IL-17+ and IL-17+IFN-γ+ double-positive T cells were present in the airways but were largely absent in the periphery, suggesting that balanced mucosal Th1/Th17 responses are associated with LTBI. The majority of M. tuberculosis-specific CD4+ T cells that homed to the airways expressed the chemokine receptor CXCR3 and coexpressed CCR6. Notably, CXCR3+CD4+ cells were found in granulomatous and nongranulomatous regions of the lung and inversely correlated with M. tuberculosis burden. Our findings provide insights into antigen-specific T cell responses associated with asymptomatic M. tuberculosis infection that are relevant for developing better strategies to control TB.

Circulating and Pulmonary T-cell Populations Driving the Immune Response in Non-HIV Immunocompromised Patients with Pneumocystis jirovecii Pneumonia.

Background: Previous studies in human subjects have mostly been confined to peripheral blood lymphocytes for Pneumocystis infection. We here aimed to compare circulating and pulmonary T-cell populations derived from human immunodeficiency virus (HIV)-uninfected immunocompromised patients with Pneumocystis jirovecii pneumonia (PCP) in order to direct new therapies. Methods: Peripheral blood and bronchoalveolar lavage samples were collected from patients with and without PCP. Populations of Th1/Tc1, Th2/Tc2, Th9/Tc9, and Th17/Tc17 CD4+ and CD8+ T cells were quantified using multiparameter flow cytometry. Results: No significant differences were found between PCP and non-PCP groups in circulating T cells. However, significantly higher proportions of pulmonary Th1 and Tc9 were observed in the PCP than in the non-PCP group. Interestingly, our data indicated that pulmonary Th1 was negatively correlated with disease severity, whereas pulmonary Tc9 displayed a positive correlation in PCP patients. Conclusions: Our findings suggest that pulmonary expansion of Th1 and Tc9 subsets may play protective and detrimental roles in PCP patients, respectively. Thus, these specific T-cell subsets in the lungs may serve as targeted immunotherapies for patients with PCP.

Loss of PTPN22 abrogates the beneficial effect of cohousing-mediated fecal microbiota transfer in murine colitis.

Fecal microbiota transfer (FMT) is a very efficient approach for the treatment of severe and recurring C. difficile infections. However, the beneficial effect of FMT in other disorders such as ulcerative colitis (UC) or Crohn's disease remains unclear. Furthermore, it is currently unknown how disease-associated genetic variants in donors or recipients influence the effect of FMT. We found that bacteria-transfer from wild-type (WT) donors via cohousing was efficient in inducing recovery from colitis in WT mice, but not in mice deficient in protein-tyrosine phosphatase non-receptor type 22 (PTPN22), a known risk gene for several chronic inflammatory diseases. Also cohousing of PTPN22-deficient mice with diseased WT mice failed to induce faster recovery. Our data indicate that the genetic background of the donor and the recipient influences the outcome of microbiota transfer, and offers a potential explanation why transfer of fecal microbes from some, but not all donors is efficient in UC patients.

Cyclooxygenase inhibitors impair CD4 T cell immunity and exacerbate Mycobacterium tuberculosis infection in aerosol-challenged mice.

Tuberculosis, caused by infection with Mycobacterium tuberculosis (Mtb), kills over 1.6 million people each year despite availability of antibiotics. The increase in drug resistant Mtb strains is a major public health emergency and host-directed therapy as adjunct to antibiotic treatment has gained increased interest. Cyclooxygenase inhibitors (COXi) are frequently used drugs to alleviate tuberculosis related symptoms. Mouse studies of acute intravenous Mtb infection have suggested a potential benefit of COXi for host-directed therapy. Here we show that COXi treatment (ibuprofen and celecoxib) is detrimental to Mtb control in different mouse models of respiratory infection. This effect links to impairments of the Type-1 helper (Th1) T-cell response as CD4 T-cells in COXi-treated animals have significantly decreased Th1 differentiation, reduced IFNγ expression and decreased protective capacity upon adoptive transfer. If confirmed in clinical trials, these findings could have major impact on global health and question the use of COXi for host-directed therapy.

PPE39 of the Mycobacterium tuberculosis strain Beijing/K induces Th1-cell polarization through dendritic cell maturation.

In a previous study, we have identified MTBK_24820, the complete protein form of PPE39 in the hypervirulent Mycobacterium tuberculosis (Mtb) strain Beijing/K by using comparative genomic analysis. PPE39 exhibited vaccine potential against Mtb challenge in a murine model. Thus, in this present study, we characterize PPE39-induced immunological features by investigating the interaction of PPE39 with dendritic cells (DCs). PPE39-treated DCs display reduced dextran uptake and enhanced MHC-I, MHC-II, CD80 and CD86 expression, indicating that this PPE protein induces phenotypic DC maturation. In addition, PPE39-treated DCs produce TNF-α, IL-6 and IL-12p70 to a similar and/or greater extent than lipopolysaccharide-treated DCs in a dose-dependent manner. The activating effect of PPE39 on DCs was mediated by TLR4 through downstream MAPK and NF-κB signaling pathways. Moreover, PPE39-treated DCs promoted naïve CD4+ T-cell proliferation accompanied by remarkable increases of IFN-γ and IL-2 secretion levels, and an increase in the Th1-related transcription factor T-bet but not in Th2-associated expression of GATA-3, suggesting that PPE39 induces Th1-type T-cell responses through DC activation. Collectively, the results indicate that the complete form of PPE39 is a so-far-unknown TLR4 agonist that induces Th1-cell biased immune responses by interacting with DCs.This article has an associated First Person interview with the first author of the paper.

Candida spp. Determination and Th1/Th2 Mixed Cytokine Profile in Oral Samples From HIV+ Patients With Chronic Periodontitis.

Background: Chronic periodontitis (CP), caused by bacteria and fungi, appears in up to 66% of HIV-patients. The impact and association of HIV-treatment (HAART) and Candida itself has not been properly evaluated in the development and progression of CP. The immunopathogenesis is characterized by CD4+ T-cells activation and the balance between the T-helper 1 (Th1) and T-helper 2 (Th2) or a mixed cytokine profile. Currently, the associated causes of an immune response in HIV-patients with CP is controversial. Our aims were the determination of Candida spp. and cytokine profile in oral samples from HIV-positive patients with CP, considering the CD4+ T cells levels and HAART use. Methods: From 500 HIV-positive patients evaluated, 228 patients were enrolled. Patients were separated in groups: (A) n = 53 (≤200 CD4+ T-cells on HAART); (B) n = 57 (≤200 CD4+ T-cells without HAART); (C) n = 50 (>200 CD4+ T-cells without HAART); (D) n = 68 (>200 CD4+ T-cells on HAART). Candida spp. were isolated from the oral biofilm and crevicular fluid in CHROMagar and confirmed by endpoint PCR. Cytokine levels were measured by beads-based immunoassay in saliva by flow cytometry. Results: 147 patients (64.5%) were positive to Candida spp. and 204 strains were isolated; 138 (67.6%) were C. albicans and the remaining C. non-albicans species (C. glabrata>C. tropicalis>C. krusei>C. dubliniensis). In this study, CHROMagar showed good sensitivity (95%) but poor specificity (68%); since of the 152 samples identified as C. albicans, only 131 were confirmed by PCR; from the 10 samples identified as C. glabrata, only six were confirmed. Finally, of the 42 samples detected as C. tropicalis, only five were confirmed. When evaluating Candida spp. presence, group A and D had higher isolation, while group B had the highest species diversity. Whereas, group C had a significant reduction of Candida spp. Despite the presence of Candida and HAART, we found a Th1/Th2 hybrid profile in the saliva of patients with low CD4+ T-cell count (group A). Conclusion: Abundance and diversity of the Candida spp. detected in HIV-patients with CP could be related to HAART and low CD4+ T-cells levels. Also, the immunosuppression might promote a local Th1/Th2 hybrid cytokine profile.

Bordetella Colonization Factor A (BcfA) Elicits Protective Immunity against Bordetella bronchiseptica in the Absence of an Additional Adjuvant.

Bordetella bronchiseptica is an etiologic agent of respiratory diseases in animals and humans. Despite the widespread use of veterinary B. bronchiseptica vaccines, there is limited information on their composition and relative efficacy and on the immune responses that they elicit. Furthermore, human B. bronchiseptica vaccines are not available. We leveraged the dual antigenic and adjuvant functions of Bordetella colonization factor A (BcfA) to develop acellular B. bronchiseptica vaccines in the absence of an additional adjuvant. BALB/c mice immunized with BcfA alone or a trivalent vaccine containing BcfA and the Bordetella antigens FHA and Prn were equally protected against challenge with a prototype B. bronchiseptica strain. The trivalent vaccine protected mice significantly better than the canine vaccine Bronchicine and provided protection against a B. bronchiseptica strain isolated from a dog with kennel cough. Th1/17-polarized immune responses correlate with long-lasting protection against bordetellae and other respiratory pathogens. Notably, BcfA strongly attenuated the Th2 responses elicited by FHA and Prn, resulting in Th1/17-skewed responses in inherently Th2-skewed BALB/c mice. Thus, BcfA functions as both an antigen and an adjuvant, providing protection as a single-component vaccine. BcfA-adjuvanted vaccines may improve the efficacy and durability of vaccines against bordetellae and other pathogens.

The imbalance of gut microbiota and its correlation with plasma inflammatory cytokines in pemphigus vulgaris patients.

Pemphigus vulgaris (PV) is an autoimmune disease characterized by the production of IgG autoantibodies owing to an imbalance in the Th1/Th2 and Th17/Tregs cell pathways. The role of gut microbiota in the development of immune system and autoimmune diseases has been unraveled in the last two decades. However, data pertaining to gut microbiota of PV patients is largely lacking. We aimed to compare the gut microbiota of PV patients and healthy controls and assessed potential correlation with circulating cytokines of Th1/Th2/Th17 cell. Faecal bacterial diversity was analysed in 18 PV patients and 14 age- and gender-matched healthy individuals using hypervariable tag sequencing of the V3-V4 region of the 16S rRNA gene. Plasma levels of 20 inflammatory cytokines were assessed using the Luminex screening system. As a result, we identified 10 differentially abundant taxa between patients and controls. At the genera level, Lachnospiracea_incertae_sedis and Coprococcus decreased, while Granulicatella, Flavonifractor enriched in PV. Plasma levels of C5a, interleukin (IL)-2R, IL-6, IL-8, IL-7, IL-1ß, IL17A, IL-5 and IL-21 were significantly increased in PV Flavonifractor exhibited a positive correlation with C5a, IL-6, IL-8, IL-7, IL-1ß, IL17A and IL-21. Lachnospiracea_incertae_sedis and Coprococcus showed a negative correlation with IL-17A. Our results are consistent with the hypothesis that PV patients have gut microbial dysbiosis which might contribute to the immune disorder and the development of PV.

Intestinal Immunomodulation and Shifts on the Gut Microbiota of BALB/c Mice Promoted by Two Bifidobacterium and Lactobacillus Strains Isolated from Human Samples.

Bifidobacterium animalis subsp. lactis IPLA 20020 and Lactobacillus gasseri IPLA 20212, two strains isolated from human samples, were evaluated for safety and influence over the intestinal microbiota and cytokine production by the intestinal tissue of adult BALB/c mice. Mice were divided into four groups receiving during 8 days PBS or a suspension of each strain, prepared fresh or lyophilized (bifidobacteria), at an amount of 4x108 viable cells/day. This dose could be comparable to the probiotic intake of a human adult who consumed about 100-200 mL of functional fermented milk per day, considering the usual level of probiotics in commercial products. No microbial translocation to liver or alterations in food intake, weight, and behavior were observed in treated mice. Intestinal content of secretory immunoglobulin A (s-IgA) was not affected, discarding any adverse effect on the mucosa-associated immunity. The profile of intestinal proinflammatory/regulatory cytokines after intervention evidenced that the microbial strain administered and its cellular state (fresh or lyophilized) as well as the host tissue analyzed (small or large intestine) influenced the immune response and suggests a moderate shift towards a T helper 1 profile (Th1) in the large intestine after the administration of both strains. Changes on relative levels of some intestinal microbial groups were evidenced after intervention. It is noteworthy that butyrate was positively associated with a balanced pro-Th1 immune response. Therefore, B. animalis subsp. lactis IPLA20020 and L. gasseri IPLA 20212 could be considered potential probiotic candidates to be included in functional foods for balancing the intestinal immune response.

IL-4 subverts mycobacterial containment in Mycobacterium tuberculosis-infected human macrophages.

Protective immunity against Mycobacterium tuberculosis is poorly understood. The role of interleukin (IL)-4, the archetypal T-helper type 2 (Th2) cytokine, in the immunopathogenesis of human tuberculosis remains unclear.Blood and/or bronchoalveolar lavage fluid (BAL) were obtained from participants with pulmonary tuberculosis (TB) (n=23) and presumed latent TB infection (LTBI) (n=22). Messenger RNA expression levels of interferon (IFN)-γ, IL-4 and its splice variant IL-4δ2 were determined by real-time PCR. The effect of human recombinant (hr)IL-4 on mycobacterial survival/containment (CFU·mL-1) was evaluated in M. tuberculosis-infected macrophages co-cultured with mycobacterial antigen-primed effector T-cells. Regulatory T-cell (Treg) and Th1 cytokine levels were evaluated using flow cytometry.In blood, but not BAL, IL-4 mRNA levels (p=0.02) and the IL-4/IFN-γ ratio (p=0.01) was higher in TB versus LTBI. hrIL-4 reduced mycobacterial containment in infected macrophages (p<0.008) in a dose-dependent manner and was associated with an increase in Tregs (p<0.001), but decreased CD4+Th1 cytokine levels (CD4+IFN-γ+ p<0.001; CD4+TNFα+ p=0.01). Blocking IL-4 significantly neutralised mycobacterial containment (p=0.03), CD4+IFNγ+ levels (p=0.03) and Treg expression (p=0.03).IL-4 can subvert mycobacterial containment in human macrophages, probably via perturbations in Treg and Th1-linked pathways. These data may have implications for the design of effective TB vaccines and host-directed therapies.