Rs531564 polymorphism in microRNA-214 regulates interleukin-6R expression in anal fissure patients to affect the risk of anal abscess formation

BACKGROUND

Anal abscess is an important complication of anal fissure (AF), whereas interleukin-6R (IL-6R) has been implicated in the development of abscess. In this study, we aimed to explore the possible molecular mechanisms underlying the regulatory effects of miRNAs on IL-6R and other inflammatory factors related to the induction of anal abscess in AF.

METHODS

Bioinformatics analysis, luciferase assay, real-time polymerase chain reaction, and Western blot analysis were performed to identify the possible regulatory relationships between IL-6R and miR-124/miR-125a by comparing the differentiated expression of miR-125a, miR-124, tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and IL-4 among different groups of AF patients.

RESULTS

IL-6R messenger RNA (mRNA) was identified as a target gene of miR-124 because the luciferase activity in cells cotransfected with wild-type IL-6R and miR-124 mimics was significantly reduced. In addition, the expression of IL-6R mRNA and protein was significantly inhibited in the presence of miR-124 or an IL-6R inhibitor, confirming the presence of a negative regulatory relationship between miR-124 and IL-6R. Moreover, miR-124 and inflammatory factors were differentially expressed in AF patients carrying different genotypes of rs531564 polymorphism.

CONCLUSIONS

miR-124 and inflammatory factors TNF-α, IFN-γ, and IL-4 may be used as indicators of anal abscess development in AF patients. In addition, miR-124 polymorphism rs531564 is involved with the pathogenesis of anal abscess in AF patients, and the presence of rs531564 may increase the incidence of anal abscess via upregulating the expression of IL-6R, TNF-α, IFN-γ, and IL-4.

GHIP in Streptococcus pneumoniae is involved in antibacterial resistance and elicits a strong innate immune response through TLR2 and JNK/p38MAPK

Interaction between pneumococcal virulence factors and innate immune receptors triggers host responses via specific signaling pathways after infection. By generating a deficient mutant, we show here that, compared with the wild-type parent strain, glycosyl hydrolase 25 relating to invasion protein (GHIP) mutant strain was impaired in rapid dissemination into vessels and caused less severe inflammation in mice lungs. Further study demonstrated that the lack of this protein in Streptococcus pneumoniae caused an increased susceptibility to whole blood or neutrophils, while this impairment could be recovered by supplementing recombinant GHIP (rGHIP). Additionally, secreted GHIP could be detected in culture medium, and purified protein was able to induce the release of tumor necrosis factor α and interleukin 6 from peritoneal macrophages. Further investigations revealed that the induction of interleukin 6 by this virulence factor depended on the phosphorylation of c-Jun N-terminal kinase and p38 mitogen activated protein kinase and Toll-like receptor 2. Taken together, GHIP, a novel pneumococcal virulence factor, appeared to play a critical role in bacterial survival and the induction of host innate immune response during pneumococcal infection.

What is different about serotype 1 pneumococci?

Serotype 1 Streptococcus pneumoniae is among the most commonly isolated serotype in invasive pneumococcal disease but is rarely found causing asymptomatic nasopharyngeal colonization. Compared to infection by other serotypes, infection caused by serotype 1 is more likely to be identified in young patients without comorbidities but is generally associated with a lower mortality. Empyema and extrapulmonary manifestations are common. Outbreaks of serotype 1 disease have been reported in closed communities and epidemics are particularly common in sub-Saharan Africa. The serotype 1 capsular polysaccharide is a zwitterionic structure that enables it to function as a T-cell dependent antigen under some circumstances, in contrast to other pneumococcal capsular polysaccharides that are T-cell independent antigens. There are also differences in the key virulence factor pneumolysin in some serotype 1 isolates. The clinical significance of these differences remains to be determined.

The modulation of adaptive immune responses by bacterial zwitterionic polysaccharides

The detection of pathogen-derived molecules as foreign particles by adaptive immune cells triggers T and B lymphocytes to mount protective cellular and humoral responses, respectively. Recent immunological advances elucidated that proteins and some lipids are the principle biological molecules that induce protective T cell responses during microbial infections. Polysaccharides are important components of microbial pathogens and many vaccines. However, research concerning the activation of the adaptive immune system by polysaccharides gained interest only recently. Traditionally, polysaccharides were considered to be T cell-independent antigens that did not directly activate T cells or induce protective immune responses. Here, we review several recent advances in “carbohydrate immunobiology”. A group of bacterial polysaccharides that are known as “zwitterionic polysaccharides (ZPSs)” were recently identified as potent immune modulators. The immunomodulatory effect of ZPSs required antigen processing and presentation by antigen presenting cells, the activation of CD4 T cells and subpopulations of CD8 T cells and the modulation of host cytokine responses. In this review, we also discuss the potential use of these unique immunomodulatory ZPSs in new vaccination strategies against chronic inflammatory conditions, autoimmunity, infectious diseases, allergies and asthmatic conditions.

Total synthesis of the Bacteroides fragilis zwitterionic polysaccharide A1 repeating unit

Nearly all bacteria capsular polysaccharides are T-cell-independent antigens that do not promote immunoglobulin class switching from IgM to IgG nor memory responses. In contrast, zwitterionic polysaccharides activate T-cell-dependent immune responses by major histocompatability complex class II presentation, a mechanism previously believed to be reserved for peptidic antigens. The best studied zwitterionic polysaccharide, polysaccharide A1 (PS A1) is found on the capsule of the commensal bacteria Bacteroides fragilis . Its potent immunomodulatory properties have been linked to postoperative intra-abdominal abscess formation. Here, we report the synthesis of the PS A1 tetrasaccharide repeating unit (2) as a tool to investigate the biological role of this polysaccharide. A modular synthetic strategy originating from the reducing end of the PS A1 repeating unit was unsuccessful and illustrated the limitations of glycosylation reactions between highly armed glycosylating agents and poor nucleophiles. Thus, a [3 + 1] glycosylation relying on trisaccharide 5 and pyruvalated galactose 6 was used to complete the first total synthesis of the PS A1 repeating unit (2).