Commensal Microflora Research Articles

Glaucoma and the Human Microbiome.

To explore a view of the human microbiome as an interconnected, functional, dynamic system that may be linked to the pathogenesis and progression of glaucoma. A literature review was undertaken that included publications from 1966 to 2023. Bacterial lipopolysaccharides (LPS) activate toll-like receptors (TLR) and mediate the human immune response. The LPS-TLR4 pathway is a potential avenue for the ocular, gut, and oral microbiomes to interface and/or influence ocular disease. Studies of gut dysbiosis have shown that alterations in the healthy microbiota can predispose the host to immune-mediated inflammatory and neurodegenerative conditions, while oral and ocular surface dysbiosis has been correlated with glaucoma. While developmental exposure to commensal microflora has shown to be necessary for the autoimmune and neurodegenerative responses to elevated intraocular pressure to take place, commensal bacterial products like short-chain fatty acids have regulatory effects protective against glaucoma. Alterations to human microbiotas have been associated with changes in intestinal permeability, gene regulation, immune cell differentiation, and neural functioning, which may predispose the host to glaucoma. Select microbes have been highlighted for their potential contributions to glaucoma disease progression or protection, raising the potential for microbiota-based treatment modalities. Current topical glaucoma treatments may disrupt the ocular surface microbiota, potentially having ramifications on host health. Further study of the relationships between human microbiome and glaucoma is needed.

Evaluation of ZnO nanoparticles from ‘Monsooned Malabar Robusta Coffee’ husk as a potential antioxidant and biocidal candidate: A sustainable valorization approach

Nanotechnology has become a sustainable strategy to combat drug resistance. As agro-waste management has become a concern, efficient management of produced waste has been an imposing global issue. This study evaluated antioxidant, as well as antibacterial and antibiofilm potential of zinc oxide nanoparticles (ZnO NPs) synthesized by hydrothermal approach using ethanolic extract of ‘Monsooned Malabar Robusta coffee’ husk against multi-drug-resistant (MDR) strains of enteroaggregative Escherichia coli, Salmonella Enteritidis, S. Typhimurium and methicillin-resistant Staphylococcus aureus. The fabrication of ZnO NPs was confirmed by spectroscopy, whereas thermogravimetric analysis-differential thermogravimetric analysis confirmed stability of ZnO NPs, while the X-ray diffraction pattern confirmed the wurtzite crystalline structure. The agglomerated nature of ZnO NPs with a nearly spherical shape was evident with scanning electron microscopy, whereas transmission electron microscopy revealed a poly-crystalline nature with a mean diameter of 26.33 ± 3.778 nm. The microbroth dilution technique revealed a minimum inhibitory concentration (MIC) of 250 μg/mL and a minimum bactericidal concentration (MBC) of 500 μg/mL for the ZnO NPs. Furthermore, ZnO NPs exhibited significant antibiofilm activity against the MDR-test strains. Moreover, ZnO NPs were tested safe at MIC and MBC doses in chicken erythrocytes, and commensal gut microflora tested were not inhibited. Besides, a dose-dependent antioxidant property was exhibited by ZnO NPs. Additionally, in vitro time-kill kinetic assay of MDR-test strains treated with ZnO NPs revealed a complete bacterial clearance at 24 h. Overall, the synthesis of ZnO NPs from coffee husk demonstrated a simple, eco-friendly and valorization approach that could be devised as a potential delivery molecule.

Oral streptococci: modulators of health and disease.

Streptococci are primary colonizers of the oral cavity where they are ubiquitously present and an integral part of the commensal oral biofilm microflora. The role oral streptococci play in the interaction with the host is ambivalent. On the one hand, they function as gatekeepers of homeostasis and are a prerequisite for the maintenance of oral health - they shape the oral microbiota, modulate the immune system to enable bacterial survival, and antagonize pathogenic species. On the other hand, also recognized pathogens, such as oral Streptococcus mutans and Streptococcus sobrinus, which trigger the onset of dental caries belong to the genus Streptococcus. In the context of periodontitis, oral streptococci as excellent initial biofilm formers have an accessory function, enabling late biofilm colonizers to inhabit gingival pockets and cause disease. The pathogenic potential of oral streptococci fully unfolds when their dissemination into the bloodstream occurs; streptococcal infection can cause extra-oral diseases, such as infective endocarditis and hemorrhagic stroke. In this review, the taxonomic diversity of oral streptococci, their role and prevalence in the oral cavity and their contribution to oral health and disease will be discussed, focusing on the virulence factors these species employ for interactions at the host interface.

Estriol and commensal microflora strains regulate innate lymphoid cells functional activity in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune neurodegenerative disease in which the immune system attacks myelin basic protein of nerve axons. Recently, there has been growing interest in studying the role of a newly described population of immunity cells – innate lymphoid cells (ILCs) in the pathogenesis of the disease. At the same time, it was found that during pregnancy there is a weakening of Th1-mediated autoimmune pathologies manifestations, including MS. In this work, we studied phenotypic characteristics of ILC in MS patients in comparison with healthy donors after 48 h incubation with pregnancy hormone estriol (E3) and commensal microflora cells. To activate ILC, strains of Ecsherichia coli K12 and Lactobacillus plantarum 8R-A3 were used. ILC phenotype was assessed by flow cytometry using monoclonal antibody staining. It has been established that E3 and bacterial factors are able to regulate the maturation of ILC subtypes and their cytokines in different ways. In general, the studied factors influence the phenotypic changes in ILC cells, leading to the transition from one type to another, both in healthy donors and in MS patients.

NK-клетки, предобработанные эстриолом и клетками комменсальной флоры, регулируют созревание Treg и Th17 из CD4+ лимфоцитов у больных рассеянным склерозом и здоровых доноров

Multiple sclerosis (MS) is an inflammatory chronic disease of the central nervous system, one of the pathogenetic mechanisms of which is an immune-mediated attack to the myelin sheath of nerve axons under the control of autoreactive T cells. NK cells, one of subtypes of ILC cells, have the ability to regulate autoimmune mechanisms through the production of cytokines or cytotoxic effects directly against effector cells, such as autoreactive T cells or antigen-presenting cells. At the same time, they can also lyse microglial, astrocyte, and oligodendrocyte cells, indicating a dual function of NK cells in MS. The influence of the pregnancy hormone estriol (E3) and commensal microflora on the ability of NK cells to modulate the level of T regulatory (Treg) and IL-17-producing (Th17) lymphocytes from patients with multiple sclerosis (MS) in comparison with healthy donors was studied. To activate NK cells, Ecsherichia coli K12 and Lactobacillus plantarum 8R-A3 strains were used. The phenotype of Treg and Th17 cells was assessed by flow cytometry using monoclonal antibody staining. It was found that NK cells incubated with E3 and E. coli stimulate the formation of Tregs, and pretreatment of NK cells with L. plantarum inhibits the formation of Th17 from CD4+ lymphocytes. In general, regulatory lymphocytes from MS patients turned out to be more sensitive to the influence of NK cells than cells from healthy donors.

Host-gut microbiota derived secondary metabolite mediated regulation of Wnt/β-catenin pathway: a potential therapeutic axis in IBD and CRC.

The intestinal tract encompasses one of the largest mucosal surfaces with a well-structured layer of intestinal epithelial cells supported by a network of underlying lamina propria immune cells maintaining barrier integrity. The commensal microflora in this environment is a major contributor to such functional outcomes due to its prominent role in the production of secondary metabolites. Of the several known metabolites of gut microbial origin, such as Short Chain Fatty Acids (SCFAs), amino acid derivatives, etc., secondary bile acids (BAs) are also shown to exhibit pleiotropic effects maintaining gut homeostasis in addition to their canonical role in dietary lipid digestion. However, dysbiosis in the intestine causes an imbalance in microbial diversity, resulting in alterations in the functionally effective concentration of these secondary metabolites, including BAs. This often leads to aberrant activation of the underlying lamina propria immune cells and associated signaling pathways, causing intestinal inflammation. Sustained activation of these signaling pathways drives unregulated cell proliferation and, when coupled with genotoxic stress, promotes tumorigenesis. Here, we aimed to discuss the role of secondary metabolites along with BAs in maintaining immune-gut homeostasis and regulation of inflammation-driven tumorigenesis with emphasis on the classical Wnt/β-Catenin signaling pathway in colon cancer.

Иммунологические аспекты бесплодия при хроническом эндометрите

Over the past decades, chronic endometritis (CE) has been the focus of scientists and infertility specialists due to its potential association with reproductive disorders. The pathogenesis of CE is conventionally associated with the impairment of endometrial commensal microbiota and pathogenic microflora entering the uterus through the cervical canal. A necessary prerequisite for preserving female reproductive health is the balance between the microbiota and local immunity of the endometrium. To date, no unified concept of the immunopathogenesis of infertility associated with CE has been established, which precludes the ability to fully resolve reproductive disorders arising from this condition. An analysis of current published data on the association between CE and infertility and reproductive losses illustrates the necessity to expand the ideas about the role of immune disorders in the pathogenesis of CE and the possibility of optimizing diagnostic tools for CE using local and systemic immunity indicators. In light of the aforementioned considerations, the aim of this paper is to provide a comprehensive review of recent published data on the local immunity of the endometrium in both healthy and chronically inflamed states, as well as to elucidate the immunological mechanisms underlying infertility associated with CE. KEYWORDS: endometrium, local immunity, systemic immunity, chronic endometritis, infertility, reproductive losses. FOR CITATION: Kolesnikova N.V., Filippov E.F. Immunologic aspects of infertility in chronic endometritis. Russian Medical Inquiry. 2024;8(3):155–162 (in Russ.). DOI: 10.32364/2587-6821-2024-8-3-6.

Cross-regulation of antibody responses against the SARS-CoV-2 Spike protein and commensal microbiota via molecular mimicry

The commensal microflora provides a repertoire of antigens that illicit mucosal antibodies. In some cases, these antibodies can cross-react with host proteins, inducing autoimmunity, or with other microbial antigens. We demonstrate that the oral microbiota can induce salivary anti-SARS-CoV-2 Spike IgG antibodies via molecular mimicry. Anti-Spike IgG antibodies in the saliva correlated with enhanced abundance of Streptococcus salivarius 1month after anti-SARS-CoV-2 vaccination. Several human commensal bacteria, including S.salivarius, were recognized by SARS-CoV-2-neutralizing monoclonal antibodies and induced cross-reactive anti-Spike antibodies in mice, facilitating SARS-CoV-2 clearance. A specific S.salivarius protein, RSSL-01370, contains regions with homology to the Spike receptor-binding domain, and immunization of mice with RSSL-01370 elicited anti-Spike IgG antibodies in the serum. Additionally, oral S.salivarius supplementation enhanced salivary anti-Spike antibodies in vaccinated individuals. Altogether, these data show that distinct species of the human microbiota can express molecular mimics of SARS-CoV-2 Spike protein, potentially enhancing protective immunity.

Identification of Contamination Sources and Assessment of Risk Factors Associated with the Occurrence of Escherichia coli O157:H7 on Small-scale Cow-calf Operations in Oklahoma and Louisiana

Escherichia coli O157:H7 is a human pathogen that exists as part of the commensal microflora of cattle and is shed in animal feces. Little is known about the effect of management practices on its occurrence and transmission on small-scale cow-calf operations. Identification of risk factors associated with farm practices could help implement effective measures to control E. coli O157:H7. This study quantified the risk of E. coli O157:H7 occurrence associated with cow-calf farm practices using risk modeling. Management practices of small-scale cow-calf operations in OK and LA were assessed through survey-based research. Fecal, water, sediments and water-trough-swab samples were collected to determine the incidence of E. coli O157:H7, and potential on-farm contamination sources and risk factors identified. Association between the occurrence of pathogen and farm practices was determined using two risk assessment models (I and II). Model I determined the association of E. coli O157:H7 occurrence with water source, water container, feed, cattle breed, and herd density, while Model II determined its association with farm cleanliness. For both models, logistic regression was followed using a two-step approach, univariable and multivariable analysis. In OK and LA, E. coli O157:H7 was present in 5.8% and 8.8% fecal, 4.4% and 9.4% water, 10.3% and 9.6% sediments, and 1.5% and 10.6% water-trough-swab samples, respectively. In Model I, univariable analysis identified water container and feed, whereas multivariable analysis identified feed as a significant risk factor. In Model II, the univariable analysis found cleanliness of cattle-contact areas, such as, alleyways, water-trough, chute and equipment, to be a significant risk factor. In multivariable analysis, only the cleanliness of water-trough was identified to be a significant risk factor. Results from the study could aid in the development of on-farm best management practices for the reduction of E. coli O157:H7.

A Fluorogenic Disaccharide Substrate for α-Mannosidases Enables High-Throughput Screening and Identification of an Inhibitor of the GH92 Virulence Factor from Streptococcus pneumoniae.

Trimming of host glycans is a mechanism that is broadly employed by both commensal and pathogenic microflora to enable colonization. Host glycan trimming by the opportunistic Gram-positive bacterium Streptococcus pneumoniae has been demonstrated to be an important mechanism of virulence. While S. pneumoniae employs a multitude of glycan processing enzymes, the exo-mannosidase SpGH92 has been shown to be an important virulence factor. Accordingly, SpGH92 is hypothesized to be a target for much-needed new treatments of S. pneumoniae infection. Here we report the synthesis of 4-methylumbelliferyl α-d-mannopyranosyl-(1→2)-β-d-mannopyranoside (Manα1,2Manβ-4MU) as a fluorogenic disaccharide substrate and development of an assay for SpGH92 that overcomes its requirement for +1 binding site occupancy. We miniaturize our in vitro assay and apply it to a high-throughput screen of >65 000 compounds, identifying a single inhibitory chemotype, LIPS-343. We further show that Manα1,2Manβ-4MU is also a substrate of the human Golgi-localized α-mannosidase MAN1A1, suggesting that this substrate should be useful for assessing the activity of this and other mammalian α-mannosidases.

Understanding the Probiotic Bacterial Responses Against Various Stresses in Food Matrix and Gastrointestinal Tract: A Review.

Probiotic bacteria are known to have ability to tolerate inhospitable conditions experienced during food preparation, food storage, and gastrointestinal tract of consumer. As probiotics are living cells, they are adversely affected by the harsh environment of the carrier matrix as well as low pH, bile salts, oxidative stress, osmotic pressure, and commensal microflora of the host. To overcome the unfavorable environments, many probiotics switch on the cell-mediated protection mechanisms, which helps them to survive, acclimatize and remain operational in the harsh circumstances. In this review, we provide comprehensive understanding on the different stresses experienced by the probiotic when added in carrier food as well as during human gastrointestinal tract transit. Under such situation how these health beneficial bacteria protect themselves by activation of several defense systems and get adapted to the lethal environments.

Severity of acute lung injury in aspiration pneumonia model mice transplanted with human oral microflora

AbstractObjectivesWhen the microflora balance becomes disturbed, referred to as “dysbiosis,” immune homeostasis is altered, triggering various diseases. In the oral cavity, it is also becoming evident that dysbiosis can act as a stimulus for various systemic diseases. Aspiration pneumonia occurs when oral microflora enters the lungs of elderly individuals. Aspiration pneumonia is highly lethal and intractable; thus, a detailed understanding of the interaction between the microflora and lung immunity is essential to establish the optimal treatment.MethodsHuman oral microflora‐associated mice (HOMA) were created by transplanting human oral commensal microflora into germ‐free mice. Then, the effects of oral microflora were analyzed on lung immunity and systemic conditions of acute lung injury and acute respiratory distress syndrome (ALI/ARDS).ResultsThe microflora in HOMA was in a state of dysbiosis. Furthermore, the accumulation of neutrophils in the lungs during septic conditions was more significant in HOMA. Serum tumor necrosis factor alpha (TNF‐α) increased considerably in HOMA during ALI/ARDS. Simultaneously, the tissue distribution of lung macrophages in HOMA decreased more significantly in alveolar macrophages than in tissue macrophages. Finally, we found that microbial compositions in the lungs during ALI/ARDS were only a single or a small number of species, as in aspiration pneumonia in humans.ConclusionSystemic inflammation and lung tissue damage were observed more significantly in HOMA during ALI/ARDS, suggesting that dysbiosis has a synergistic effect with septic shock, resulting in severe injury. Thus, oral and systemic dysbiosis may be a potential target for treating aspiration pneumonia in the elderly.

Selection of the isolate of <i>Staphylococcus hominis</i> for bacteriotherapy in patients with atopic dermatitis

Introduction<i>Staphylococcus aureus</i> plays a significant role in the development of the clinical picture in patients with atopic dermatitis. The use of commensal microflora can be a promising direction in treatment of atopic dermatitis.AimThe aim of this study is the selection of the optimal safe isolate of <i>S. hominis</i> for bacteriotherapy in patients with atopic dermatitis.Material and methodsSensitivity of isolates of<i> S. hominis</i> ssp.<i> hominis</i> to antibacterial drugs was determined by the disk-diffusion method on Mueller–Hinton agar (HiMedia, India). The ability to form a biofilm was determined by measuring the amount of dye absorption by the biofilm on a microplate reader MR-96A (Mindray, China) at a wavelength of 495 nm. Antagonism in vitro was determined by the method of perpendicular strokes on the blood agar. In total, 24 adult volunteers (aged 18 to 60 years) were screened and included in the study. The results were calculated according to the zone of <i>S. aureus</i> growth retardation under the influence of metabolic products of<i> S. hominis</i> ssp. <i>hominis</i>.Results and DiscussionAs a result of the study of 8 isolates of <i>S. hominis</i> ssp. <i>hominis</i>, which were obtained from the swabs taken from healthy skin of 24 people, one isolate of <i>S. hominis</i> ssp. <i>hominis</i> Hom-2 met all criteria of safety – Hom-2 demonstrated sensitivity to the studied antibiotics and formed a biofilm of low density (OD 0.15), and effectiveness (morphological and cultural properties, antagonistic effect on <i>S. aureus</i>).ConclusionsIn this work, an isolate of <i>S. hominis</i> ssp. <i>hominis</i> Hom-2 met all criteria of safety and efficacy and will be used in the further study of bacteriotherapy in patients with atopic dermatitis.

Aryl polyenes expressed by Uropathogenic Escherichia colicontribute to pathogenesis in a mouse model with an aberrant macrophage polarization

Abstract Uropathogenic Escherichia coli (UPEC) is a causative agent of urinary tract infections (UTIs), and one of the most common causes of pyelonephritis. Interestingly, UPEC is often found as a non-pathobiont in the gut flora. The transition from gut flora to pathogen for UPEC is dependent upon a flexible tropism, and a number of virulence factors that aid in UPEC’s colonization and invasion of the urinary tract. We recently demonstrated a role for the E. coli aryl polyenes (APEs) as a potential UPEC fitness factor. The current hypothesis is that APEs contribute to UPEC virulence in the host system. APEs are encoded by a biosynthetic gene cluster (BGC) family identified among many gram-negative bacteria. The products of this BGC family are lipids comprised of an aryl head group and conjugated double bond system, which are structurally reminiscent of established virulence factors found in gram-positives. In addition to the structural mimicry, UPEC APE expression conferred resistance to reactive oxygen species and enhanced biofilm formation. In a UTI mouse model, infection with UPEC that constitutively expressed APEs (UPEC APE+) increased pathogenicity. Transcriptomic analyses of in vitro co-incubation experiments indicates that UPEC APE+exposure influences the macrophage gene transcription profile differently as compared to UPEC WT. Taken together, our findings suggest that APE expression aids in bacterial virulence and immune modulation during infection. Therefore, targeting the biosynthetic gene product APE may be a viable therapeutic approach to reduce fitness of pathogenic populations while leaving commensal gut microflora unharmed and minimize tissue damage. NIAID RO1AI153173 Cleveland Clinic Foundation

Combined Ferromagnetic Nanoparticles for Effective Periodontal Biofilm Eradication in Rat Model.

The critical challenge for periodontitis therapy is thoroughly eliminating the dental plaque biofilm, particularly penetrating the deep periodontal tissue. Regular therapeutic strategies are insufficient to penetrate the plaque without disturbing the commensal microflora of the oral cavity. Here, we constructed a Fe3O4 magnetic nanoparticle loading minocycline (FPM NPs) to penetrate the biofilm physically and effectively eliminate periodontal biofilm. In order to penetrate and remove the biofilm effectively, Fe3O4 magnetic nanoparticles were modified with minocycline using a co-precipitation method. The particle size and dispersion of the nanoparticles were characterized by transmission electron microscopy, scanning electron microscopy, and dynamic light scattering. The antibacterial effects were examined to verify the magnetic targeting of FPM NPs. Confocal laser scanning microscopy was employed to check the effect of FPM + MF and develop the best FPM NPs treatment strategy. Additionally, the therapeutic effect of FPM NPs was investigated in periodontitis rat models. The expression of IL-1β, IL-6, and TNF-α in periodontal tissues was measured by qRT-PCR and Western blot. The multifunctional nanoparticles exhibited intense anti-biofilm activity and good biocompatibility. The magnetic forces could pull FMP NPs against the biofilm mass and kill bacteria deep in the biofilms both in vivo and in vitro. The integrity of the bacterial biofilm is disrupted under the motivation of the magnetic field, allowing for improved drug penetration and antibacterial performance. The periodontal inflammation recovered well after FPM NPs treatment in rat models. Furthermore, FPM NPs could be monitored in real-time and have magnetic targeting potentials. FPM NPs exhibit good chemical stability and biocompatibility. The novel nanoparticle presents a new approach for treating periodontitis and provides experimental support for using magnetic-targeted nanoparticles in clinic applications.

The conjunctival fungal microflora of horses in a North Queensland tropical environment and their in vitro susceptibilities to antifungal agents

Fungi are ubiquitous in the environment and part of the commensal microflora on the conjunctiva of equine eyes. North Queensland, being tropical, presents an ideal environment for fungi growth. When the cornea is injured, fungi can invade the corneal stroma, resulting in keratomycosis. The objectives of this study were to determine the fungal species specific to the eyes of horses in the Townsville region; to investigate the potential risk factors associated with the presence of fungi; and to test their susceptibility to antifungals to create an empirical guide for treatment. The eyes of forty ophthalmologically normal horses from James Cook University were sampled throughout the summer months of December 2017, January 2018, and January and February 2020. Cultured fungi were identified morphologically, and their identity confirmed by comparing partial 18sRNA DNA sequences with the NCBI nucleotide database. Minimum inhibitory concentration testing of common antifungal medications was performed. Sixty-one out of eighty conjunctival samples grew fungi, and 21 different fungi genera were isolated. The most common genera were Aspergillus (18%, 26/141), Curvularia (14%,20/141), Rhodotorula (12%,17/141) and Penicillium (12%,17/141). No significant association was found between age or environmental factors and fungal culture status. Most fungi were highly susceptible to voriconazole and ketoconazole but resistant to fluconazole and amphotericin B. This adds to the body of evidence on which species of fungi are present as normal ocular microflora of horses living in tropical regions of Australia, and an avenue for treating them.

Optimization and evaluation of a multiplex PCR assay for detection of Staphylococcus aureus and its major virulence genes for assessing food safety.

Staphylococcus aureus is a natural commensal microflora of humans which causes opportunistic infections due to its large arsenal of exotoxins, invasion, immune evasion, and antibiotic resistance mechanisms. The primary goal of this study is to develop a multiplex PCR (mPCR) assay for simultaneous detection of Staphylococcus aureus (nuc) and its virulence genes coding for prominent exotoxins namely alpha hemolysin (hla), enterotoxins A (sea), enterotoxin B (seb), toxic shock syndrome toxin (tsst-1), and the gene coding for methicillin resistance (mecA). A competitive internal amplification control (IAC) was included in the assay to exclude the false negative outcomes. Highly specific primer pairs were designed for the target genes using in silico resources. At the outset, monoplex PCRs were standardized using reference S. aureus strains. Primer specificity to the target genes was authenticated through restriction digestion analysis of amplified PCR products. Multiplex PCR was optimized in increments of one gene starting with nuc and IAC amplified simultaneously using one pair of primers (nuc) in a competitive manner. The mPCR assay was found to be highly sensitive with a detection limit of ~10 CFUs per reaction for pure cultures. Multiplex PCR assay was further evaluated on the retail and processed food samples to test the prevalence of S. aureus and study their exotoxin profiles. Of the 57 samples examined, 13 samples (22.80%) were found to be contaminated with S. aureus whose DNA was extracted after a 6-h enrichment period. Among these, a high percentage of hemolytic and enterotoxin A positive strains were encountered. The mPCR assay developed in this study would be a useful tool for rapid and reliable monitoring of S. aureus for food quality testing and from clinical infections.

Probiotics Mechanism of Action on Immune Cells and Beneficial Effects on Human Health.

Immune cells and commensal microbes in the human intestine constantly communicate with and react to each other in a stable environment in order to maintain healthy immune activities. Immune system-microbiota cross-talk relies on a complex network of pathways that sustain the balance between immune tolerance and immunogenicity. Probiotic bacteria can interact and stimulate intestinal immune cells and commensal microflora to modulate specific immune functions and immune homeostasis. Growing evidence shows that probiotic bacteria present important health-promoting and immunomodulatory properties. Thus, the use of probiotics might represent a promising approach for improving immune system activities. So far, few studies have been reported on the beneficial immune modulatory effect of probiotics. However, many others, which are mainly focused on their metabolic/nutritional properties, have been published. Therefore, the mechanisms behind the interaction between host immune cells and probiotics have only been partially described. The present review aims to collect and summarize the most recent scientific results and the resulting implications of how probiotic bacteria and immune cells interact to improve immune functions. Hence, a description of the currently known immunomodulatory mechanisms of probiotic bacteria in improving the host immune system is provided.

Diagnosis of bacteriospermia and its impact on spermogram parameters in adolescents with varicocele.

Infectious etiology is the cause of about 15% of cases of male infertility. And if sexually transmitted infections are easily diagnosed, the role of asymptomatic bacteriospermia in the formation of infertility in men, and especially in adolescents against the background of the existing pathology of the reproductive sphere (varicocele), remains insufficiently studied. A microbiological study in the ejaculate of adolescents revealed the following types of bacteria: Escherichia coli, Enterococcus faecalis, Corynebacterium glucuronolyticum, Corynebacterium minitissimum, Streptococcus anginosus, Staphylococcus epidermidis, Staphylococcus haemolyticus. Bacteria in the ejaculate were also detected during semen analysis and electron microscopic examination of spermatozoa. With abundant growth of microorganisms in a monoculture or an association of two microorganisms present in a moderate amount, in all cases, violations of sperm motility, an increase in the viscosity of the ejaculate, the presence of leukocytes in the seminal fluid were detected, and damage to the chromatin, acrosome and mitochondria was recorded at the ultrastructural level, which may indicate active infection. When bacterial flora was detected in a small and moderate amount (<10 CFU/ml), no pathological changes in the ejaculate were observed. The microflora of the ejaculate of the examined adolescents is represented by gram-positive microflora. Simultaneous study of the ejaculate sample by bacteriological seeding, the performance of spermogram and EMIS allowed to increase the detection of bacteriospermia. Opportunistic pathogens with abundant growth or their various combinations can serve as a factor in the development of pathospermia. It is possible to distinguish an active infection from commensal microflora or sample contamination not only by the presence of bacteria in the ejaculate and their quantitative accounting, but also by the degree of damage to the function of spermatozoa and pathological changes in the parameters of the ejaculate, by combining diagnostic methods. Most often, in the presence of bacteria in the ejaculate, asthenozoospermia is diagnosed.

Гормональная и бактериальная регуляция фенотипических изменений врожденных лимфоидных клеток (ILC) у больных рассеянным склерозом и здоровых доноров

Multiple sclerosis (MS) is an autoimmune neurodegenerative disease in which the immune system attacks myelin basic protein of nerve axons. Recently, there has been growing interest in studying the role of a newly described population of innate immunity cells – innate lymphoid cells (ILCs) in the pathogenesis of the disease. At the same time, it was found that during pregnancy there is a weakening of Th1-mediated autoimmune pathologies manifestations, including MS. In this work, we studied phenotypic characteristics of ILC cells in MS patients in comparison with healthy donors after 48 h incubation with pregnancy hormone estriol (E3) and commensal microflora cells. To activate ILC, strains of Ecsherichia coli K12 and Lactobacillus plantarum 8R-A3 were used. ILC phenotype was assessed by flow cytometry using monoclonal antibody staining. It has been established that E3 and bacterial factors are able to regulate the maturation of ILC subtypes in different ways. In particular, MS patients’ cells are more susceptible to hormonal modulation, while those of healthy donors are more susceptible to bacterial modulation. In general, the studied factors influence the phenotypic changes in ILC cells, leading to the transition from one type to another, both in healthy donors and in MS.