Brucella infection is frequently acquired by inhalation, but the pathogen disseminates systemically from the lungs. However, little is known about the interaction of Brucella spp. with the airways. Using a 3D air-exposed organotypic human bronchial tissue model (polarized 16HBE14o- bronchial epithelial cells grown over a collagen matrix containing MRC-5 lung fibroblasts), we analyzed Brucella abortus replication, translocation and cytokine responses over prolonged post-infection times. Apically inoculated B. abortus invaded, replicated and persisted during the whole follow-up (16 days) within the bronchial tissue without inducing cytotoxicity. Viable bacteria were also detected in the conditioned medium (CM) since day five post-infection, indicating release from the basolateral side. In parallel experiments, no invasion or bacterial release was detected for Escherichia coli. The levels of IL-6, IL-8 and MCP-1 were increased in CM from Brucella-infected 3D cultures and in monocultures of polarized bronchial epithelial cells or lung fibroblasts. Collagenase/gelatinase activity was increased in 3D cultures and MRC-5 monocultures. Infection transference from bronchial cells to lung fibroblasts was documented using monocultures. An immune cross-talk was detected, as cytokine levels were increased in fibroblasts stimulated with bronchial CM, and vice versa. These results suggest that the bronchial mucosa can sustain B. abortus persistence, replication and dissemination, and that it induces a proinflammatory response to which both epithelial cells and fibroblasts contribute.

Baccharis salicifolia Pers (Ruiz Pav.) has been employed as an anti-inflammatory and vermifuge agent in traditional herbal medicine. Helminth infections remain an international concern since these infections can become chronic and even public health emergencies. This study seeks to evaluate the efficacy of B. salicifolia aqueous extracts on Trichinella spiralis, a nematode parasite whose life cycle consists of three phases: intestinal, migrant and muscular. B. salicifolia pure aqueous extracts (22 mg/mL) were diluted to 1:2, 1:10, and 1:100 for in vitro assays against the three parasite stages: muscle larvae (ML), adult worms (AW) and newborn larvae (NBL). In vivo anthelmintic properties of pure B. salicifolia aqueous extracts were tested in Balb/c mice infected with T. spiralis employing three different treatment schemes (A: days 3–5 p.i.; B: days 6–8 p.i.; and C: days 3–8 p.i.) with a single daily dose for all the schemes (220 mg/kg body weight/per dose), and ML burden was evaluated. Intestinal AW burden was determined at days 4 and 6 p.i., and the fecundity index (NBL production from gravid AW) was determined at day 6. In vitro assays showed that B. salicifolia aqueous extracts exerted helminthotoxic effects on T. spiralis. While ML and AW required 24 h exposure for significant mortality (P < 0.05), NBL showed rapid susceptibility, with near-complete mortality at 3 h (P < 0.01) in a dose-dependent manner. Phytochemical profiling of the aqueous extracts via HPLC-DAD and HPLC-MS/MS identified flavonoids (quercetin, apigenin, sakuranetin, naringenin) and the coumarin scopoletin. In vivo, all treatment schemes significantly reduced ML burden (P < 0.001 vs. vehicle), and scheme A additionally decreased AW burden (P < 0.001) and fecundity index (P < 0.0001). For the first time, we provide evidence about B. salicifolia aqueous extracts anthelmintic activity, supporting the efficacy of its popular use and its importance for the development of novel natural drugs against helminths with reduced cost as compared to conventional therapies.

Malnutrition and helminth infections are known to be associated conditions. Malnutrition, which refers to excesses, deficiencies, or imbalances in intake of energy and/or nutrients, affects millions of people worldwide and is the most common cause of immunodeficiency in the world. In helminth-infected individuals, malnutrition has been associated with an augmented morbidity rate, a higher parasitic load, and prolonged infections, and may also contribute to increased mortality. Helminth infections affect millions of people worldwide, particularly in non-industrialized countries, leading to chronic infections. This review focuses on the bidirectional relationships between macronutrient malnutrition and helminth infections. Relevant scientific articles published until May 2024 were retrieved from PubMed and Google Scholar. The data extracted were parameters of immunology, hematology, parasitology, disease, and nutrition. Malnutrition leads to alterations in the immune responses to helminth infections, including innate responses (Heligmosomoides polygyrus, hookworms, Trichinella spp., Trichuris spp.), T-cell-mediated responses (Ascaris spp., H. polygyrus, Trichuris spp.), and antibody responses (Ascaris spp., H. polygyrus, Schistosoma spp., Trichinella spp., Trichuris spp.), frequently resulting in increased parasite load and worm fecundity. However, in some cases malnutrition may have negative effects on the life cycle of helminths, including reductions in worm weight, egg production, worm size, and parasite fecundity. Malnutrition has a notorious influence on both host and parasite. The consequences for the host would be related to the severity and type of malnutrition condition, and the helminth involved.

IntroductionSwine brucellosis, caused by Brucella suis, is a worldwide infectious zoonotic disease. Currently, there are no available human or porcine vaccines to protect against B. suis infection, which is primarily acquired through the mucosa. We recently described B. suis MapB, the homologous protein of TamB, the inner membrane component of the TAM system. Our findings indicate that MapB is involved in bacterial cell envelope homeostasis. In this study, we characterize the outer membrane vesicles (OMVs) of B. suis 1330 (wt) and those of B. suis ΔmapB (ΔmapB) mutant strain and evaluate their vaccine potential in mice.MethodsOMVs were isolated using the ultracentrifugation method and characterized through electron microscopy, Dynamic Light Scattering, SDS-PAGE and proteomics. Immunogenicity was assessed by intramuscular immunization of mice with wt OMVs or ΔmapB OMVs, followed by the measurement of antigen-specific antibody levels and functional assays to evaluate the protective capacity of the antibodies. Cellular immunity was assessed by characterizing cytokine secretion through ELISA after in vitro stimulation of spleen cells with heat-killed B. suis. To determine the level of protection conferred by immunization, mice were challenged with virulent B. suis via intraperitoneal or intratracheal routes, and the bacterial load was quantified post-challenge.ResultsDynamic Light Scattering of the OMVs from both strains revealed the presence of spherical structures of 90-130 nm. Proteomic analysis identified 94 and 95 proteins in the wt and ΔmapB OMVs, respectively, including several known Brucella immunogens. Both OMVs showed immunoreactivity with sera from Brucella-infected pigs. Intramuscular immunization of mice with both OMVs induced antigen-specific IgG in serum, with the ΔmapB OMVs group showing higher titers compared to the wt OMVs group. Serum antibodies from both OMVs groups reduced B. suis adherence and invasion of lung epithelial cells and enhanced its phagocytosis by macrophages. Upon in vitro antigen stimulation, spleen cells from mice immunized with ΔmapB OMVs secreted higher levels of interleukin-17 and especially gamma interferon compared to cells from mice immunized with wt OMVs, suggesting the induction of a stronger T helper 1 response in the ΔmapB OMVs group. While immunization with both wt and ΔmapB OMVs achieved the same level of protection following intratracheal infection with B. suis (p<0.01), immunization with ΔmapB OMVs provided higher levels of protection against intraperitoneal infection.DiscussionOverall, these results demonstrate that the B. suis ΔmapB OMVs are immunogenic and capable of inducing both cellular and humoral immune responses that protect against mucosal and systemic B. suis challenges.

Despite the importance of the respiratory route for Brucella transmission, the lung immune response to this pathogen is scarcely characterized. We investigated the role of the cGAS/STING pathway of microbial DNA recognition in the control of respiratory Brucella infection. After in vitro B. abortus infection, CFU numbers were significantly higher in alveolar macrophages (AM) and lung explants from STING KO mice than in samples from wild type (WT) mice, but no difference was observed for cGAS KO samples. CFU were also increased in WT AM and lung epithelial cells preincubated with the STING inhibitor H151. Several proinflammatory cytokines (TNF-α, IL-1β, IL-6, IP-10/CXCL10) were diminished in Brucella -infected lung explants and/or AM from STING KO mice and cGAS KO mice. These cytokines were also reduced in infected AM and lung epithelial cells pretreated with H151. After intratracheal infection with B. abortus , STING KO mice exhibited increased CFU in lungs, spleen and liver, a reduced expression of IFN-β mRNA in lungs and spleen, and reduced levels of proinflammatory cytokines and chemokines in bronchoalveolar lavage fluid (BALF) and lung homogenates. Increased lung CFU and reduced BALF cytokines were also observed in cGAS KO mice. In summary, the cGAS/STING pathway induces the production of proinflammatory cytokines after respiratory Brucella infection, which may contribute to the STING-dependent control of airborne brucellosis.

Infection by Brucella species in pregnant animals and humans is associated with an increased risk of abortion, preterm birth, and transmission of the infection to the offspring. The pathogen has a marked tropism for the placenta and the pregnant uterus and has the ability to invade and replicate within cells of the maternal-fetal unit, including trophoblasts and decidual cells. Placentitis is a common finding in infected pregnant animals. Several proinflammatory factors have been found to be increased in both the placenta of Brucella-infected animals and in trophoblasts or decidual cells infected in vitro. As normal pregnancies require an anti-inflammatory placental environment during most of the gestational period, Brucella-induced placentitis is thought to be associated with the obstetric complications of brucellosis. A few studies suggest that the blockade of proinflammatory factors may prevent abortion in these cases.

The goal of this study was to analyse the effects of a protein‐deficient (PD) diet on antibody‐dependent cell‐mediated cytotoxicity (ADCC) in vitro against newborn larvae (NBL) of Trichinella spiralis in the lungs of infected rats. Two groups of weaning Wistar rats received a PD diet (6.5% casein) and other two received a control diet (C, 20% casein). After ten days, one group of each diet was infected (PD I and C I ) with muscle larvae. Lung tissue extracts (LTE) and lung cell suspension (LCS) were obtained. PD I had lower titres of anti‐NBL antibodies in LTE than C I . In ADCC assays using control cells, NBL mortality percentage was lower with LTE from PD I than LTE from C I ( P < .01). In assays using control cytotoxic sera, ADCC was exerted by LCS from C I at all days post‐infection (p.i.), but only by LCS from 13 days p.i. from PD I . ADCC assays combining LTE and LCS from the same group showed a lower response for PD I than for C I ( P < .0001). LCS from PD I contained lower numbers of neutrophils, eosinophils and FcεRI + cells than C I . PD may diminish ADCC activity against T spiralis NBL in lungs through alterations in specific antibodies and effector cells.

Adhesion to host cells is a key step for successful infection of many bacterial pathogens and may define tropism to different host tissues. To do so, bacteria display adhesins on their surfaces. Brucella is an intracellular pathogen capable of proliferating in a wide variety of cell types. It has been described that BmaC, a large protein that belongs to the classical (type Va) autotransporter family, is required for efficient adhesion of Brucella suis strain 1330 to epithelial cells and fibronectin. Here we show that B. suis 1330 harbors two other type Va autotransporters (BmaA and BmaB), which, although much smaller, share significant sequence similarities with BmaC and contain the essential domains to mediate proper protein translocation to the bacterial surface. Gain and loss of function studies indicated that BmaA, BmaB, and BmaC contribute, to a greater or lesser degree, to adhesion of B. suis 1330 to different cells such as synovial fibroblasts, osteoblasts, trophoblasts, and polarized epithelial cells as well as to extracellular matrix components. It was previously shown that BmaC localizes to a single bacterial pole. Interestingly, we observed here that, similar to BmaC, the BmaB adhesin is localized mostly at a single cell pole, reinforcing the hypothesis that Brucella displays an adhesive pole. Although Brucella species have strikingly similar genomes, they clearly differ in their host preferences. Mainly, the differences identified between species appear to be at loci encoding surface proteins. A careful in silico analysis of the putative type Va autotransporter orthologues from several Brucella strains showed that the bmaB locus from Brucella abortus and both, the bmaA and bmaC loci from Brucella melitensis are pseudogenes in all strains analyzed. Results reported here evidence that all three autotransporters play a role in the adhesion properties of B. suis 1330. However, Brucella spp. exhibit extensive variations in the repertoire of functional adhesins of the classical autotransporter family that can be displayed on the bacterial surface, making them an interesting target for future studies on host preference and tropism.

Helminths are a major health concern as over one billion people are infected worldwide and, despite the multiple efforts made, there is still no effective human vaccine against them. The most important drugs used nowadays to control helminth infections belong to the benzimidazoles, imidazothiazoles (levamisole) and macrocyclic lactones (avermectins and milbemycins) families. However, in the last 20 years, many publications have revealed increasing anthelmintic resistance in livestock which is both an economical and a potential health problem, even though very few have reported similar findings in human populations. To deal with this worrying limitation of anthelmintic drugs, alternative treatments based on plant extracts or probiotics have been developed. Probiotics are defined by the Food and Agriculture Organization as live microorganisms, which, when consumed in adequate amounts, confer a health benefit to the host. It has been proven that probiotic microbes have the ability to exert an immunomodulatory effect both at the mucosa and the systemic level. The immune response against gastrointestinal helminths is characterized as a type 2 response, with high IgE levels, increased numbers and/or activity of Th2 cells, type 2 innate lymphoid cells, eosinophils, basophils, mast cells, and alternatively activated macrophages. The oral administration of probiotics may contribute to controlling gastrointestinal helminth infections since it has been demonstrated that these microorganisms stimulate dendritic cells to elicit a type 2 or regulatory immune response, among other effects on the host immune system. Here we review the current knowledge about the use of probiotic bacteria as anthelmintic therapy or as a complement to traditional anthelmintic treatments. Considering all research papers reviewed, we may conclude that the effect generated by probiotics on helminth infection depends not only on the parasite species, their stage and localization but also on the administration scheme.

Brucella infection is frequently acquired through the respiratory route. The pathogen disseminates systemically from the lungs to infect peripheral organs. In this review we summarize the existing data on the pathogenesis of inhalational Brucella infection, the pulmonary immune response to the pathogen, and potential strategies for inducing protective lung immunity.

A central aspect of Brucella pathogenicity is its ability to invade, survive, and replicate in diverse phagocytic and non-phagocytic cell types, leading to chronic infections and chronic inflammatory phenomena. Adhesion to the target cell is a critical first step in the invasion process. Several Brucella adhesins have been shown to mediate adhesion to cells, extracellular matrix components (ECM), or both. These include the sialic acid-binding proteins SP29 and SP41 (binding to erythrocytes and epithelial cells, respectively), the BigA and BigB proteins that contain an Ig-like domain (binding to cell adhesion molecules in epithelial cells), the monomeric autotransporters BmaA, BmaB, and BmaC (binding to ECM components, epithelial cells, osteoblasts, synoviocytes, and trophoblasts), the trimeric autotransporters BtaE and BtaF (binding to ECM components and epithelial cells) and Bp26 (binding to ECM components). An in vivo role has also been shown for the trimeric autotransporters, as deletion mutants display decreased colonization after oral and/or respiratory infection in mice, and it has also been suggested for BigA and BigB. Several adhesins have shown unipolar localization, suggesting that Brucella would express an adhesive pole. Adhesin-based vaccines may be useful to prevent brucellosis, as intranasal immunization in mice with BtaF conferred high levels of protection against oral challenge with B. suis.

Brucella spp. have been associated with abortion in humans and animals. Although the mechanisms involved are not well established, it is known that placental Brucella infection is accompanied by inflammatory phenomena. The ability of Brucella abortus to infect and survive in human endometrial stromal cells (T-HESC cell line) and the cytokine response elicited were evaluated. B. abortus was able to infect and proliferate in both non-decidualized and decidualized T-HESC cells. Intracellular proliferation depended on the expression of a functional virB operon in the pathogen. B. abortus internalization was inhibited by cytochalasin D and to a lower extent by colchicine, but was not affected by monodansylcadaverine. The infection did not induce cytotoxicity and did not alter the decidualization status of cells. B. abortus infection elicited the secretion of IL-8 and MCP-1 in either decidualized or non-decidualized T-HESC, a response also induced by heat-killed B. abortus and outer membrane vesicles derived from this bacterium. The stimulation of T-HESC with conditioned media from Brucella-infected macrophages induced the production of IL-6, MCP-1 and IL-8 in a dose-dependent manner, and this effect was shown to depend on IL-1β and TNF-α. The proinflammatory responses of T-HESC to B. abortus and to factors produced by infected macrophages may contribute to the gestational complications of brucellosis.

Brucella enters their hosts mostly through mucosae from where it spreads systemically. Adhesion to extracellular matrix (ECM) components or to host cells is important for the infectious process, and is mediated by several adhesins, including the BtaF trimeric autotransporter. Although Th1 responses and gamma interferon (IFN-γ) are important for protection, antibodies able to block adhesions might also contribute to prevent Brucella infection. We evaluated the importance of BtaF for respiratory Brucella infection, and characterized the immune response and protection from mucosal challenge induced by nasal vaccination with recombinant BtaF. While lung CFU numbers did not differ at day 1 p.i. between mice intratracheally inoculated with B. suis M1330 (wild type) and those receiving a ΔbtaF mutant, they were reduced in the latter group at 7 and 30 days p.i. For vaccination studies the BtaF passenger domain was engineered and expressed as a soluble trimeric protein. Mice were immunized by the nasal route with BtaF or saline (control group) plus the mucosal adjuvant c-di-AMP. Specific anti-BtaF antibodies (IgG and IgA) were increased in serum, including a mixed IgG2a/IgG1 response. In vitro, these antibodies reduced bacterial adhesion to A549 alveolar epithelial cells. Specific IgA antibodies were also increased in several mucosae. Spleen cells from BtaF immunized mice significantly increased their IL-2, IL-5, IL-17, and IFN-γ secretion upon antigen stimulation. In cervical draining lymph nodes, antigen-experienced CD4+ T cells were maintained mainly as central memory cells. A BtaF-specific delayed-type hypersensitivity response was detected in BtaF immunized mice. Lung cells from the latter produced high levels of IFN-γ upon antigen stimulation. Although nasal immunization with BtaF did not protect mice against B. suis respiratory challenge, it conferred significant protection from intragastric challenge; the splenic load of B. suis was reduced by 3.28 log CFU in immunized mice. This study shows that nasal vaccination with BtaF+c-di-AMP protects against intragastric challenge with B. suis by inducing local and systemic antibody responses, central memory CD4+ T cells and strong Th1 responses. Therefore, although BtaF vaccination did not protect from B. suis respiratory infection, this adhesin constitutes a promising immunogen against mucosal B. suis infection.

Objectives: We aimed to analyze the effect of a protein-deficient diet on mucosal and systemic immunity during a Trichinella spiralis infection. Methods: Two groups of weaning Wistar rats received a protein-deficient diet (6.5% casein) and the other two groups received a control diet (20% casein). After 10 d, one group of each diet was infected (PDI and C-I) with muscle larvae (infecting stage). Food intake and body weight were assessed over time. Blood eosinophils counts, antibodies in serum, and tissue extracts were assessed at different days postinfection. Histologic studies were done in the lungs and intestines, and adult worm (AW) fecundity index score and muscle parasite burden were determined. Results: Food and protein intake were lower in PDI than in C-I. Body weight was lower in PDI than in a non-infected protein-deficient diet. Eosinophils counts were lower in PDI than in C-I. Total and specific antibodies were lower in PDI than C-I. PDI had a reduced number of mast and goblet cells in the lungs and intestines compared with C-I. The persistence of AW in the intestines and migrant larvae at the lungs was longer in PDI than in C-I. The AW fecundity index score was higher in PDI than in C-I. Finally, PDI evidenced a higher muscular parasite burden than C-I. Conclusions: Protein deficiency affects the mucosal and systemic immune response to Trichinella spiralis and delays the expulsion and increases the fecundity index score of AW, which leads to a higher parasite burden in the muscles. (C) 2018 Elsevier Inc. All rights reserved.

Brucella spp. infection is frequently acquired through contaminated aerosols. The role of interleukin-1 beta (IL-1β) in the early pulmonary response to respiratory Brucella infection is unknown. As shown here, IL-1β levels in lung homogenates and bronchoalveolar lavage fluid (BALF) of mice intratracheally inoculated with B. abortus were increased at 3 and 7 days p.i. At 7 days p.i., pulmonary CFU numbers were higher in IL-1 receptor (IL-1R) knockout (KO) mice than in wild type (WT) mice. At different times p.i. CFU in lungs and BALF were higher in mice lacking some inflammasome components (caspase-1, AIM2, NLRP3) than in WT mice. At 2 days p.i. pulmonary levels of IL-1β and CXCL1 (neutrophils chemoattractant) were lower in caspase-1/11 KO mice. At day 3 p.i., neutrophils counts in BALF were lower in caspase-1/11 KO mice than in WT mice. During in vitro infections, IL-1β secretion was lower in alveolar macrophages from caspase-1/11, NLRP3 or AIM2 KO mice than in WT controls. Similarly, IL-1β production by B. abortus-infected alveolar epithelial cells was reduced by pretreatment with a specific caspase-1 inhibitor. This study shows that IL-1R, probably through IL-1β action, and the NLRP3 and AIM2 inflammasomes are involved in pulmonary innate immune protective mechanisms against respiratory B. abortus infection.

Although inhalation of infected aerosols is a frequent route for Brucella infection in humans, it rarely causes pulmonary clinical manifestations, suggesting a mild or nearly absent local inflammatory response. The goal of this study was to characterize the early innate immune response to intratracheal infection with Brucella abortus in mice and to evaluate whether it is modulated by this pathogen. After infection with 106 CFU of B. abortus, the pulmonary bacterial burden at 7 days post-infection (p.i.) was comparable to the initial inoculum, despite an initial transient decline. Brucella was detected in spleen and liver as early as 1 day p.i. IL-1β and MCP-1 increased at 3 days p.i., whereas IL-12, KC, TNF-α, and IFN-γ only increased at 7 days p.i. Histological examination did not reveal peribronchial or perivascular infiltrates in infected mice. Experiments were conducted to evaluate if the limited inflammatory lung response to B. abortusis caused by a bacterial mechanism of TLR signaling inhibition. Whereas inoculation of E. coli LPS to control mice [phosphate-buffered saline (PBS)/LPS] caused lung inflammation, almost no histological changes were observed in mice preinfected intratracheally with B. abortus (WT/LPS). We speculated that the Brucella TIR-containing proteins (Btps) A and B, which impair TLR signaling in vitro, may be involved in this modulation. After LPS challenge, mice preinfected with the B. abortus btpAbtpB double mutant exhibited a stronger pulmonary polymorphonuclear infiltrate than WT/LPS mice, although milder than that of the PBS/LPS group. In addition, lungs from B. abortus btpAbtpB-infected mice presented a stronger inflammatory infiltrate than those infected with the WT strain, and at day 7 p.i., the pulmonary levels of KC, MCP-1, and IL-12 were higher in mice infected with the mutant. This study shows that B. abortus infection produces a mild proinflammatory response in murine lungs, partially due to immune modulation by its Btp proteins. This may facilitate its survival and dissemination to peripheral organs.