HLA-B27 modulates intracellular growth of Salmonella pathogenicity island 2 mutants and production of cytokines in infected monocytic U937 cells

The Interleukine-17 Cytokine Family: Role in Development and Progression of Spondyloarthritis, Current and Potential Therapeutic Inhibitors

Spondyloarthritis (SpA) encompasses a group of chronic inflammatory rheumatic diseases with a predilection for the spinal and sacroiliac joints, which include axial spondyloarthritis, psoriatic arthritis, reactive arthritis, arthritis associated with chronic inflammatory bowel disease, and undifferentiated spondyloarthritis. The prevalence of SpA in the population varies from 0.5 to 2%, most commonly affecting young people. Spondyloarthritis pathogenesis is related to the hyperproduction of proinflammatory cytokines (TNFα, IL-17A, IL-23, etc.). IL-17A plays a key role in the pathogenesis of spondyloarthritis (inflammation maintenance, syndesmophites formation and radiographic progression, enthesites and anterior uveitis development, etc.). Targeted anti-IL17 therapies have established themselves as the most efficient therapies in SpA treatment. The present review summarizes literature data on the role of the IL-17 family in the pathogenesis of SpA and analyzes existing therapeutic strategies for IL-17 suppression with monoclonal antibodies and Janus kinase inhibitors. We also consider alternative targeted strategies, such as the use of other small-molecule inhibitors, therapeutic nucleic acids, or affibodies. We discuss advantages and pitfalls of these approaches and the future prospects of each method.

Environmental Risks for Spondyloarthropathies

Spondyloarthropathies, also known as spondyloarthritis, encompasses a spectrum of diseases classified by it's axial and peripheral musculoskeletal manifestations. Extra-articular features are common in SpA making these systemic rheumatologic diseases involve the skin, eye, gut, and other organ systems.Research has identified risk factors for the development of spondyloarthritis, particularly regarding genetic susceptibility and the strong association with HLA-B27. Multiple studies have elucidated clinical risk factors associated with SpA disease activity and severity. In this review, we aim to explore the environmental risk factors for spondyloarthritis.

Genetic Susceptibility to Enteric Fever in Experimentally Challenged Human Volunteers

Infections with Salmonella enterica serovars Typhi and Paratyphi A cause an estimated 14 million cases of enteric fever annually. Here, the controlled nature of challenge studies is exploited to identify genetic variants associated with enteric fever susceptibility. Human challenge participants were genotyped by Illumina OmniExpress-24 BeadChip array (n = 176) and/or transcriptionally profiled by RNA sequencing (n = 174). While the study was underpowered to detect any single nucleotide polymorphisms (SNPs) significant at the whole-genome level, two SNPs within CAPN14 and MIATNB were identified with P < 10-5 for association with development of symptoms or bacteremia following oral S. Typhi or S. Paratyphi A challenge. Imputation of classical human leukocyte antigen (HLA) types from genomic and transcriptomic data identified HLA-B*27:05, previously associated with nontyphoidal Salmonella-induced reactive arthritis, as the HLA type most strongly associated with enteric fever susceptibility (P = 0.011). Gene sets relating to the unfolded protein response/heat shock and endoplasmic reticulum-associated protein degradation were overrepresented in HLA-B*27:05+ participants following challenge. Furthermore, intracellular replication of S. Typhi is higher in C1R cells transfected with HLA-B*27:05 (P = 0.02). These data suggest that activation of the unfolded protein response by HLA-B*27:05 misfolding may create an intracellular environment conducive to S. Typhi replication, increasing susceptibility to enteric fever.

Analysis of In Vivo Transcriptome of Intracellular Bacterial Pathogen Salmonella enterica serovar Typhmurium Isolated from Mouse Spleen

Salmonella&nbsp;enterica serovar Typhimurium (S. Typhimurium) is an important intracellular pathogen that poses a health threat to humans. This study tries to clarify the mechanism of Salmonella survival and reproduction in the host. In this study, high-throughput sequencing analysis was performed on RNA extracted from the strains isolated from infected mouse spleens and an S. Typhimurium reference strain (ATCC 14028) based on the BGISEQ-500 platform. A total of 1340 significant differentially expressed genes (DEGs) were screened. Functional annotation revealed DEGs associated with regulation, metabolism, transport and binding, pathogenesis, and motility. Through data mining and literature retrieval, 26 of the 58 upregulated DEGs (FPKM > 10) were not reported to be related to the adaptation to intracellular survival and were classified as candidate key genes (CKGs) for survival and proliferation in vivo. Our data contribute to our understanding of the mechanisms used by Salmonella to regulate virulence gene expression whilst replicating inside mammalian cells.

Treatment of reactive arthritis with biological agents: a review

The pathogenesis of reactive arthritis (ReA) has not been fully elucidated. In recent years, many researchers have confirmed that multiple cytokines are involved in the occurrence and development of ReA. Although ReA is self-limiting, it is still incurable for some patients who have no or a weak response to traditional drugs, such as non-steroidal anti-inflammatory agents, glucocorticoids and immunosuppressive agents. This is called refractory reactive arthritis. Currently, there is insufficient evidences for the treatment of refractory ReA with biological agents, though biological agents against cytokines have been developed over the past few years. This review summarizes the current development of clinical treatments of ReA with biological agents, which provides future investigations on refractory ReA with more evidence and references.

Reactive Arthritis: Update

Purpose of Review

The aim of this paper is to provide an overview about reactive arthritis, with an update regarding pathophysiology and therapeutic approach of the disease, outlining the clinical features and diagnostic approach, based on recent literature review.

Recent Findings

Reactive arthritis is considered to be part of the spectrum of the spondyloarthritis. Its epidemiology is changing worldwide due to several reasons, among them are as follows: different diagnosis approach and clinical presentations, different grades of infection, microbiome changes, etc. The understanding of pathophysiological models is challenging, but recent studies contribute to elucidate the major factors involved in the development of the disease. The management of ReA depends on the triggering agent and the phase of disease, whether it is acute or chronic.

Summary

The association between the microbiome changes and spondyloarthropathies (ReA) is becoming increasingly evident. The results regarding the biologic treatment on refectory ReA are promising.

Microbes, helminths, and rheumatic diseases

There has been a progressive interest on modifications of the human defense system following insults occurring in the interface between our body and the external environment, as they may provoke or worsen disease states. Studies suggest that billions of germs, which compose the gut microbiota influence one's innate and adaptive immune responses at the intestinal level, but these microorganisms may also impact rheumatic diseases. The microbiota of the skin, respiratory, and urinary tracts may also be relevant in rheumatology. Evidence indicates that changes in the gut microbiome alter the pathogenesis of immune-mediated diseases such as rheumatoid arthritis and ankylosing spondylitis but also of other disorders like atherosclerosis and osteoarthritis. Therapeutic strategies to modify the microbiota, including probiotics and fecal microbiota transplantation, have been received with skepticism, which, in turn, has drawn attention back to previously developed interventions such as antibiotics. Helminths adapted to humans over the evolution process, but their role in disease modulation, particularly immune-mediated diseases, remains to be understood. The present review focuses on data concerning modifications of the immune system induced by interactions with microbes and pluricellular organisms, namely helminths, and their impact on rheumatic diseases. Practical aspects, including specific microbiota-targeted therapies, are also discussed.

Development of high-throughput genotyping method of all 18 HR HPV based on the MALDI-TOF MS platform and compared with the Roche Cobas 4800 HPV assay using clinical specimens

Background

To develop a new 18 high-risk human papillomavirus (HR HPV) detection and genotyping assay, which is important to evaluate the risk degree of HR HPV for causing cancers.

Methods

All 18 HR HPV and β-globin relative DNA fragments were synthesized and cloned to a plasmid pUC57 to obtain their recombinant plasmids. Based on the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) platform, each of the 18 HR HPV genotypes were investigated using their constructed recombinant plasmids. The new 18 HR HPV genotyping assay was tested using 356 clinical specimens and the results were compared to ones detected by the Roche Cobas 4800 HPV assay (Cobas). The discrepant results between two assays were resolved by sequencing and genotyping methods.

Results

The new 18 HR HPV MALDI-TOF MS genotyping assay was developed using HPV recombination plasmids. The sensitivity was 10³ to 10² copies/reaction for the all 18 HR HPV. This new developed HR HPV genotyping test was used to detect the clinical specimens. When the results on clinical samples detected by the new MALDI-TOF MS HPV test were compared with ones detected by the Roche Cobas 4800 HPV assay in terms of 14 HR HPV, the concordance was 80.1% (kappa coefficient, 0.60; 95% confidence interval [CI], 0.52–0.69). The discrepant results were resolved by sequencing and genotyping and suggests that the developed HR HPV assay is more sensitive and specific.

Conclusions

The new developed 18 HR HPV detection method based on MALDI-TOF MS platform is a high-throughput assay for the all 18 HR HPV genotypes and a powerful complement to current detection methods.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-6036-z) contains supplementary material, which is available to authorized users.

The role of the gut and microbes in the pathogenesis of spondyloarthritis

The intestinal microbiota is firmly implicated not only in the pathogenesis of inflammatory bowel disease (IBD) but increasingly also in the development of inflammation at extraintestinal tissue sites. Significant clinical, genetic, immunological, and microbiological overlap exists between IBD and spondyloarthritis (SpA), which indicates that pathophysiological mechanisms are shared between these diseases and may center on the intestinal microbiota. Recently, culture-independent techniques have enabled the microbiota in health and disease to be described in increasing detail. Moreover, functional studies have identified myriad host effector and regulatory pathways that shape or are shaped by this microbial community. We consider the complex relationship between SpA pathogenesis and gut microbes, with a discussion of how manipulation of the gut microbiota itself may be a promising future target for SpA therapy.

The role of intracellular organisms in the pathogenesis of inflammatory arthritis

Inflammatory arthritis is a condition which is characterised by recurrent episodes of joint pain and swelling. It encompasses a spectrum of disorders ranging from rheumatoid arthritis to ankylosing spondylitis. In these conditions, for reasons that are poorly understood, the immune system raises an inflammatory response within the joint space. In some cases, autoantigens have been identified (e.g., anticitrullinated peptides in rheumatoid arthritis), but the absence of these, in the seronegative arthritides, for example, raises question as to the underlying pathogenesis. Interest has, therefore, turned to host-pathogen interactions and whether aberrant immune responses to these could explain the development of arthritis. This has been most widely studied in reactive arthritis (ReA), where an infectious episode precedes the development of the joint symptoms. In this review, we present the evidence for the role of host-bacterial interactions in the pathogenesis of joint inflammation with particular emphasis on ReA. We discuss a range of possible mechanisms including molecular mimicry, persistent low grade infections, and abnormal host responses to common bacterial causes of reactive arthritis as well as discussing some of the clinical challenges that we face in making the diagnosis and in treatment of persistent symptoms.

Altered regulation of ELAVL1/HuR in HLA-B27-expressing U937 monocytic cells

OBJECTIVE

To investigate the role of HLA-B27 expression in the regulation of RNA binding protein (RBP) Embryonic Lethal Abnormal Vision (ELAV) L1/Human antigen R (HuR) expression in Salmonella-infected or LPS-stimulated human monocytic cells, since HuR is a critical regulator of the post-transcriptional fate of many genes (e.g. TNFα) important in inflammatory response.

METHODS

U937 monocytic cells were stably transfected with pSV2neo resistant vector (mock), wild type HLA-B27, or mutated HLA-B27 with amino acid substitutions in the B pocket. Cells were differentiated, infected with Salmonella enteritidis or stimulated with lipopolysaccharide. The expression levels of HuR protein and cleavage products (CP1 and CP2) were detected by Western blotting and flow cytometry. Specific inhibitors were used to study the role of PKR and p38 in HuR expression and generation of CPs. TNFα and IL-10 secretion after p38 and PKR inhibition were measured by ELISA.

RESULTS

Full length HuR is overexpressed and HuR cleavage is disturbed in U937 monocytic cells expressing HLA-B27 heavy chains (HC). Increased full length HuR expression, disturbed cleavage and reduced dependence on PKR after infection correlate with the expression of glutamic acid 45 in the B pocket that is linked to the misfolding of HLA-B27.

CONCLUSION

Results show that the expression of HLA-B27 HCs modulates the intracellular environment of U937 monocyte/macrophages by altering HuR regulation. This phenomenon is at least partly dependent on the misfolding feature of the B27 molecule. Since HuR is an important regulator of multiple genes involved in inflammatory response observations offer an explanation how HLA-B27 may modulate inflammatory response.

Evidence supporting a role for dormant bacteria in the pathogenesis of spondylarthritis

Spondylarthritis is still viewed as a reaction to infectious agents, as opposed to an infection by persistent bacteria, for several reasons: (a) an infection is considered proven only when the organism can be cultured; (b) no studies have identified dormant bacteria in the tissues targeted by spondylarthritis; (c) the bacterial persistence hypothesis has no therapeutic implications at the time being, since antibiotics are effective neither on dormant bacteria nor on the manifestations of spondylarthritis; and (d) the high prevalence of borderline disorders combining features of spondylarthritis and of psoriatic arthritis, or even rheumatoid arthritis (RA), would indicate a role for dormant bacteria in these last two diseases. However, recent data on dormant bacteria have rekindled interest in the bacterial persistence hypothesis. Dormant bacteria cannot be cultured, because they express only a small group of genes, known as the regulon, which includes genes for transcription factors that block the expression of the usual bacterial genes. Certain forms of cell stress, such as molecule misfolding, promote the entry of bacteria into a state of dormancy, which induces the low-level release by the host cells of cytokines such as TNF. Whether HLA-B27 misfolding facilitates the persistence of dormant bacteria within spondylarthritis tissue targets remains to be determined. If it does, then treatments that reactivate dormant bacteria might make these organisms susceptible to appropriate antibiotics and might therefore serve as useful adjuncts to nonsteroidal anti-inflammatory drugs and TNFα antagonists. TNFα antagonists rarely reactivate dormant bacteria, with the exception of Mycobacterium tuberculosis, which, together with metastatic cells, is the most extensively studied latency model to date.