Low molecular weight proteins of outer membrane of Salmonella typhimurium are immunogenic in Salmonella induced reactive arthritis revealed by proteomics

Diagnostic considerations in the clinical management of sudden swelling of the knee: a case report and review of the literature

BACKGROUND

Reactive arthritis and septic arthritis rarely present concomitantly in the same joint and patient. Reactive arthritis presenting after coronavirus disease 2019 is also exceedingly rare, with less than 30 cases reported thus far. Less common pathogens such as Clostridium difficile have been reported to cause reactive arthritis, especially in patients with a positive human leukocyte antigen B27, and therefore should be considered in diagnostic algorithms. The aim of this case report is to highlight the difficulties and precautions in discerning and diagnosing patients presenting with sudden swelling of the knee.

CASE PRESENTATION

We report the case of a 70-year-old Caucasian male with a recent history of coronavirus disease 2019 upper respiratory infection and diarrhea and negating trauma, who presented with a swollen and painful knee. Pain and swelling worsened and inflammatory parameters increased after an intraarticular corticosteroid injection. The patient was therefore treated with arthroscopic lavage and intravenous antibiotics for suspected septic arthritis. Synovial fluid and synovium samples were taken and sent for microbiological analysis. Synovial fluid cytology showed increased leukocytes at 10,980 × 106/L, while polymerase chain reaction and cultures came back sterile. Clostridium difficile toxin was later detected from a stool sample and the patient was treated with oral vancomycin. The patient was tested for the presence of human leukocyte antigen B27, which was positive. We present a review of the literature about the challenges of distinguishing septic from reactive arthritis, and about the mechanisms that predispose certain patients to this rheumatological disease.

CONCLUSIONS

It is still a challenge to differentiate between septic and reactive arthritis of the knee, and it is even more challenging to identify the exact cause of reactive arthritis. This case report of a human leukocyte antigen-B27-positive patient highlights the necessity of contemplating different, less common causes of a swollen knee joint as a differential diagnosis of an apparent septic infection, especially in the coronavirus disease 2019 era. Treating the patient for septic arthritis prevented any possible complications of such a condition, while treating the C. difficile infection contributed to the substantial relief of symptoms.

Salmonella Typhimurium Adhesin OmpV Activates Host Immunity To Confer Protection against Systemic and Gastrointestinal Infection in Mice

Salmonella enterica Typhimurium is a rod-shaped Gram-negative bacterium that mostly enters the human body through contaminated food. It causes a gastrointestinal disorder called salmonellosis in humans and typhoid-like systemic disease in mice. OmpV, an outer membrane protein of S. Typhimurium, helps in adhesion and invasion of bacteria to intestinal epithelial cells and thus plays a vital role in the pathogenesis of S. Typhimurium. In this study, we have shown that intraperitoneal immunization with OmpV is able to induce high IgG production and protection against systemic disease. Further, oral immunization with OmpV-incorporated proteoliposome (OmpV-proteoliposome [PL]) induces production of high IgA antibody levels and protection against gastrointestinal infection. Furthermore, we have shown that OmpV induces Th1 bias in systemic immunization with purified OmpV, but both Th1 and Th2 polarization in oral immunization with OmpV-proteoliposome (PL). Additionally, we have shown that OmpV activates innate immune cells, such as monocytes, macrophages, and intestinal epithelial cells, in a Toll-like receptor 2 (TLR2)-dependent manner. Interestingly, OmpV is recognized by the TLR1/2 heterodimer in monocytes, but by both TLR1/2 and TLR2/6 heterodimers in macrophages and intestinal epithelial cells. Further, downstream signaling involves MyD88, interleukin-1 receptor-associated kinase (IRAK)-1, mitogen-activated protein kinase (MAPK) (both p38 and Jun N-terminal protein kinase (JNK)), and transcription factors NF-κB and AP-1. Due to its ability to efficiently activate both the innate and adaptive immune systems and protective efficacy, OmpV can be a potential vaccine candidate against S. Typhimurium infection. Further, the fact that OmpV can be recognized by both TLR1/2 and TLR2/6 heterodimers increases its potential to act as good adjuvant in other vaccine formulations.

OmpW is positively regulated by iron via Fur, and negatively regulated by SoxS contribution to oxidative stress resistance in Escherichia coli

Iron plays a central role at the interface of pathogen and host. The ability to sequester iron from a host not only reduces host immune defenses but also promotes pathogen virulence, leading to the occurrence of infectious disease. Recently, outer membrane protein OmpW was shown to protect bacteria against harsh environmental conditions and to play a role in infectious disease. The expression of this versatile protein is controlled by iron, but the underlying mechanism of iron regulation has not been elucidated. In this study, the relation between OmpW expression and iron was investigated. Our results demonstrated that expression of OmpW is responsive to iron. Iron uptake analysis showed that an ompW mutant strain has a strong requirement for iron as compared to wild type and the ompW complemented strain. Moreover, ferric uptake regulation protein Fur, an iron binding transcriptional factor, was downregulated under iron limitation conditions and had a similar expression profile to OmpW in the presence or absence of iron. Based on these results, we suggest that iron regulates OmpW by binding to Fur. Furthermore, SoxS, a transcriptional factor involved in oxidative stress, was found to negatively regulate OmpW. We found that downregulating or knocking out OmpW results in bacterial resistance to oxidative stress. These findings provide new insight into the regulation of OmpW expression by iron, and may represent a new mechanism contributing to iron-mediated infectious disease.

Differential functional patterns of memory CD4+ and CD8+ T-cells from volunteers immunized with Ty21a typhoid vaccine observed using a recombinant Escherichia coli system expressing S. Typhi proteins

It is widely accepted that CD4⁺ and CD8⁺ T-cells play a significant role in protection against Salmonella enterica serovar Typhi (S. Typhi), the causative agent of the typhoid fever. However, the antigen specificity of these T-cells remains largely unknown. Previously, we demonstrated the feasibility of using a recombinant Escherichia coli (E. coli) expression system to uncover the antigen specificity of CD4⁺ and CD8⁺ T cells. Here, we expanded these studies to include the evaluation of 12 additional S. Typhi proteins: 4 outer membrane proteins (OmpH, OmpL, OmpR, OmpX), 3 Vi-polysaccharide biosynthesis proteins (TviA, TviB, TviE), 3 cold shock proteins (CspA, CspB, CspC), and 2 conserved hypothetical proteins (Chp 1 and Chp2), all selected based on the bioinformatic analyses of the content of putative T-cell epitopes. CD4⁺ and CD8⁺ T cells from 15 adult volunteers, obtained before and 42 days after immunization with oral live attenuated Ty21a vaccine, were assessed for their functionality (i.e., production of cytokines and cytotoxic expression markers in response to stimulation with selected antigens) as measured by flow cytometry. Although volunteers differed on their T-cell antigen specificity, we observed T-cell immune responses against all S. Typhi proteins evaluated. These responses included 9 proteins, OmpH, OmpR, TviA, TviE, CspA, CspB, CspC, Chp 1 and Chp 2, which have not been previously reported to elicit T-cell responses. Interestingly, we also observed that, regardless of the protein, the functional patterns of the memory T-cells were different between CD4⁺ and CD8⁺ T cells. In sum, these studies demonstrated the feasibility of using bioinformatic analysis and the E. coli expressing system described here to uncover novel immunogenic T-cell proteins that could serve as potential targets for the production of protein-based vaccines.

Tolerogenic vaccine composited with islet-derived multipeptides and cyclosporin A induces pTreg and prevents Type 1 diabetes in murine model

Regulatory T cells (Tregs) play a crucial role in the control of the initiation and progression of type 1 diabetes (T1D). Various immunological interventions including those to ex vivo expansion Tregs transfer, in vivo induction of peripherally derived Treg (pTreg) have been considered as promising approaches for T1D therapy. In this study, we developed a novel tolerogenic vaccine using four autoantigenic peptides of islet-derived with cyclosporine A (CsA) as the pTreg inducer, designated as GAD-IN+CsA. This vaccine immunized into prediabetic NOD mice subcutaneously could induce IL-10 and TGF-β expressing pTregs and lead to suppressing autoreactive T cells responses, resulting in the prevention of T1D in these animals. Furthermore, we demonstrated that CsA with autoantigenic peptides modulates dendritic cells (DCs) to become immature IL-10^hiCD40^lo DCs. Such modulated DCs could foster naïve CD4⁺CD25⁻ T cell into Tregs when presenting antigen peptides in vitro. This novel approach offers an alternative strategy to induce pTregs to treat T1D.

Evolving patterns of reactive arthritis

OBJECTIVE

To characterize rheumatologists' perspectives on evolving trends of reactive arthritis (ReA).

METHODS

After ethics approval, 548 members of the Canadian Rheumatology Association were surveyed with 37 questions covering their demographic information, subspecialty, level of experience, practice setting and opinions on prevalence, treatment, and causes of ReA. Results were analyzed with descriptive statistics.

RESULTS

Ninety-seven responded to the survey (18% response rate); 66 fully completed it. Nearly half of respondents believed that the incidence of ReA is declining and causes of ReA may be changing. Physicians reported that most of the ReA cases in their practices were caused by an unknown organism, sexually transmitted, or gastrointestinal infection. Full triad ReA increased the chance of recurrence according to their impressions. Common investigations in ReA included inflammatory markers, HLA-B27, chlamydia and gonorrhea testing, stool cultures, synovial fluid analyses, SI joint imaging. ReA treatment included NSAIDs, intra-articular corticosteroid injections, and DMARDs. Two-thirds said they used TNF alpha inhibitors in chronic ReA occasionally or more frequently.

CONCLUSION

ReA may be decreasing in frequency and severity in Canada. Changes could be due to less food borne illness, cleaner water, or more rapid treatment of sexually transmitted infections. The cause is often unknown in clinical practice.Key Points• Reactive arthritis (ReA) is likely decreasing in prevalence and severity.• Patients with classic trial of arthritis, urethritis, and conjunctivitis are more likely to have recurrent and/or chronic ReA.• The causal organisms are often not detected and seem to be changing over time.

Proteomic Analysis of Outer Membrane Proteins from Salmonella Enteritidis Strains with Different Sensitivity to Human Serum

Differential analysis of outer membrane composition of S. Enteritidis strains, resistant to 50% normal human serum (NHS) was performed in order to find factors influencing the resistance to higher concentrations of NHS. Ten S. Enteritidis clinical strains, resistant to 50% NHS, all producing very long lipopolysaccharide, were subjected to the challenge of 75% NHS. Five extreme strains: two resistant and three sensitive to 75% NHS, were chosen for the further analysis of outer membrane proteins composition. Substantial differences were found in the levels of particular outer membrane proteins between resistant and sensitive strains, i.e. outer membrane protease E (PgtE) was present mainly in resistant strains, while sensitive strains possessed a high level of flagellar hook-associated protein 2 (FliD) and significantly higher levels of outer membrane protein A (OmpA).

Contribution of the outer membrane protein OmpW in Escherichia coli to complement resistance from binding to factor H

The serum complement system is essential for innate immune defense against invading pathogenic bacteria. Some of the 8-stranded β-barrel outer membrane proteins confer bacterial resistance to the innate host immunity. We have previously demonstrated that OmpW, also an 8-stranded β-barrel protein that was identified a decade ago, protects bacteria against host phagocytosis. In this study, we investigated the complement resistance of OmpW. Our results indicate that the upregulation of OmpW is associated with increased survival when bacteria are exposed to normal human sera (NHS). Mutant bacteria lacking OmpW in NHS exhibited significantly lower survival rates in comparison to wild-type and ompW complemented bacteria. Furthermore, the bacterial survival significantly decreased in NHS that was supplemented with EGTA-Mg(2+) compared to that in NHS supplemented with EDTA. These results suggest that OmpW confer resistance to alternative complement pathway-mediated killing. Moreover, the binding of OmpW to factor H, a major inhibitor of alternative pathway, was found, indicating that OmpW recruitment of factor H is a mechanism for bacterial evasion of complement attack.

Recombinant Salmonella typhimurium outer membrane protein A is recognized by synovial fluid CD8 cells and stimulates synovial fluid mononuclear cells to produce interleukin (IL)-17/IL-23 in patients with reactive arthritis and undifferentiated spondyloarthropathy

In developing countries, one-third of patients with reactive arthritis (ReA) and undifferentiated spondyloarthropathy (uSpA) are triggered by Salmonella typhimurium. Synovial fluid mononuclear cells (SFMCs) of patients with ReA and uSpA proliferate to low molecular weight fractions (lmwf) of outer membrane proteins (Omp) of S. typhimurium. To characterize further the immunity of Omp of Salmonella, cellular immune response to two recombinant proteins of lmwf, OmpA and OmpD of S. typhimurium (rOmpA/D-sal) was assessed in 30 patients with ReA/uSpA. Using flow cytometry, 17 of 30 patients' SF CD8(+) T cells showed significant intracellular interferon (IFN)-γ to Omp crude lysate of S. typhimurium. Of these 17, 11 showed significantly more CD8(+) CD69(+) IFN-γ T cells to rOmpA-sal, whereas only four showed reactivity to rOmpD-sal. The mean stimulation index was significantly greater in rOmpA-sal than rOmpD-sal [3·0 (1·5-6·5) versus 1·5 (1·0-2·75), P < 0·005]. Similarly, using enzyme-linked immunospot (ELISPOT) in these 17 patients, the mean spots of IFN-γ-producing SFMCs were significantly greater in rOmpA-sal than rOmpD-sal [44·9 (3·5-130·7) versus 19·25 (6-41), P < 0·05]. SFMCs stimulated by rOmpA-sal produced significantly more proinflammatory cytokines than rOmpD-sal: IFN-γ [1·44 (0·39-20·42) versus 0·72 (0·048-9·15) ng/ml, P < 0·05], interleukin (IL)-17 [28·60 (6·15-510·86) versus 11·84 (6·83-252·62) pg/ml, P < 0·05], IL-23 [70·19 (15-1161·16) versus 28·25 (> 15-241·52) pg/ml, P < 0·05] and IL-6 [59·78 (2·03-273·36) versus 10·17 (0·004-190·19) ng/ml, P < 0·05]. The rOmpA-sal-specific CD8(+) T cell response correlated with duration of current synovitis (r = 0·53, P < 0·05). Thus, OmpA of S. typhimurium is a target of SF CD8(+) T cells and drives SFMC to produce increased cytokines of the IL-17/IL-23 axis which contribute to the pathogenesis of Salmonella-triggered ReA.

Linocin and OmpW Are Involved in Attachment of the Cystic Fibrosis-Associated Pathogen Burkholderia cepacia Complex to Lung Epithelial Cells and Protect Mice against Infection

Members of the Burkholderia cepacia complex (Bcc) cause chronic opportunistic lung infections in people with cystic fibrosis (CF), resulting in a gradual lung function decline and, ultimately, patient death. The Bcc is a complex of 20 species and is rarely eradicated once a patient is colonized; therefore, vaccination may represent a better therapeutic option. We developed a new proteomics approach to identify bacterial proteins that are involved in the attachment of Bcc bacteria to lung epithelial cells. Fourteen proteins were reproducibly identified by two-dimensional gel electrophoresis from four Bcc strains representative of two Bcc species: Burkholderia cenocepacia, the most virulent, and B. multivorans, the most frequently acquired. Seven proteins were identified in both species, but only two were common to all four strains, linocin and OmpW. Both proteins were selected based on previously reported data on these proteins in other species. Escherichia coli strains expressing recombinant linocin and OmpW showed enhanced attachment (4.2- and 3.9-fold) to lung cells compared to the control, confirming that both proteins are involved in host cell attachment. Immunoproteomic analysis using serum from Bcc-colonized CF patients confirmed that both proteins elicit potent humoral responses in vivo Mice immunized with either recombinant linocin or OmpW were protected from B. cenocepacia and B. multivorans challenge. Both antigens induced potent antigen-specific antibody responses and stimulated strong cytokine responses. In conclusion, our approach identified adhesins that induced excellent protection against two Bcc species and are promising vaccine candidates for a multisubunit vaccine. Furthermore, this study highlights the potential of our proteomics approach to identify potent antigens against other difficult pathogens.

The intestinal microbiome in spondyloarthritis

PURPOSE OF REVIEW

Microbial dysbiosis in the gut is emerging as a common component in various inflammatory disorders including spondyloarthritis (SpA). The depth of this influence has begun to be realized with next-generation sequencing of the gut microbiome providing unbiased assessment of previously uncharted bacterial populations.

RECENT FINDINGS

Decreased numbers of Firmicutes, a major phyla of gut commensals, especially the species Faecalibacterium prausnitzii and Clostridium leptum have been found in various inflammatory disorders including SpA and inflammatory bowel disease (IBD), and could be an important link between SpA and gut inflammation. Multiple studies in ankylosing spondylitis, psoriatic arthritis, juvenile SpA, and animal models of SpA are revealing common bacterial associations among these diseases as well as IBD.

SUMMARY

We are beginning to appreciate the complex relationship between the gut microbiome and host immune regulation and dysregulation in health and disease. Potentially important differences have been revealed in SpA, but cause and effect relationships remain far from established. Many critical questions remain to be answered before we can apply new knowledge to improve therapeutics in SpA.

Influence of heat-labile serum components in the presence of OmpA on the outer membrane of Salmonella gallinarum

Salmonella gallinarum is the causative agent of fowl typhoid. Being a Gram-negative bacteria, its outer membrane proteins (OMP) can be regulated by different microenvironments. S. gallinarum was cultured under the following conditions: nutrient broth (NB), NB supplemented with serum from specific pathogen-free birds (NBS) and NB with serum incubated at 56 °C prior to incubation with the bacteria (NBSD); OMP were subsequently extracted. Several changes were observed in the apparent expression of OMP, mainly a decrease in an OMP with a size of 30 kDa, approximately, under the NBS condition. In contrast, the same event was not observed in NB and NBSD when using one- and two-dimensional polyacrylamide gels (SDS-PAGE). Using the OMP with a size of 30 kDa, approximately, as antigen in indirect ELISA, we were able to differentiate serum from healthy and vaccinated birds, as well as birds infected with S. gallinarum and S. enteritidis. The amino-terminal of this protein was sequenced, showing 100 % identity with OmpA of S. typhimurium. Subsequently, we designed primers to amplify the gene by PCR. The partial sequence of the amplified gene showed 100 % identity with OmpA of S. gallinarum. (1) Heat-labile serum components influence the presence of OmpA in the OM of S. gallinarum; (2) by the way of ELISA, OmpA allows to specifically differentiate healthy from diseased birds.

Identification of DLD, by immunoproteomic analysis and evaluation as a potential vaccine antigen against three Vibrio species in Epinephelus coioides

Vibrio spp. represent a serious threat to the culture of Epinephelus coioides (Orange-spotted Grouper) in Southeast Asia. In this study we used two-dimensional electrophoresis (2-DE) and Western blotting to identify common immunogenic proteins of Vibrio alginolyticus, Vibrio harveyi and Vibrio parahaemolyticus. Membranes were probed with orange-spotted grouper anti-V. alginolyticus sera and accordingly 60, 58 and 48 immunogenic protein spots were detected. By matching analysis for the three Western blotting membranes, 6 cross immunogenic spots for the three Vibrio species were identified. They were Outer membrane protein W (OmpW), dihydrolipoamide dehydrogenase (DLD), succinate dehydrogenase flavoprotein subunit(SDHA), elongation factor Ts(Ts), peptide ABC transporter periplasmic peptide-binding protein and phosphoenolpyruvate carboxykinase(PEPCK). One of the proteins, DLD, was used to evaluate the cross protective function for E. coioides with a bacterial immunization and challenge method. The relative percent survival rate of E. coioides against V. alginolyticus, V. harveyi and V. parahaemolyticus was 90%, 86% and 80%, respectively. This work may provide potential cross protective vaccine candidate antigens for three Vibrio species, and DLD may be considered as an effective cross-protective immunogen against three Vibrio species.

Complete proteome of a quinolone-resistant Salmonella Typhimurium phage type DT104B clinical strain

Salmonellosis is one of the most common and widely distributed foodborne diseases. The emergence of Salmonella strains that are resistant to a variety of antimicrobials is a serious global public health concern. Salmonella enterica serovar Typhimurium definitive phage type 104 (DT104) is one of these emerging epidemic multidrug resistant strains. Here we collate information from the diverse and comprehensive range of experiments on Salmonella proteomes that have been published. We then present a new study of the proteome of the quinolone-resistant Se20 strain (phage type DT104B), recovered after ciprofloxacin treatment and compared it to the proteome of reference strain SL1344. A total of 186 and 219 protein spots were recovered from Se20 and SL1344 protein extracts, respectively, after two-dimensional gel electrophoresis. The signatures of 94% of the protein spots were successfully identified through matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS). Three antimicrobial resistance related proteins, whose genes were previously detected by polymerase chain reaction (PCR), were identified in the clinical strain. The presence of these proteins, dihydropteroate synthase type-2 (sul2 gene), aminoglycoside resistance protein A (strA gene) and aminoglycoside 6'-N-acetyltransferase type Ib-cr4 (aac(6')-Ib-cr4 gene), was confirmed in the DT104B clinical strain. The aac(6')-Ib-cr4 gene is responsible for plasmid-mediated aminoglycoside and quinolone resistance. This is a preliminary analysis of the proteome of these two S. Typhimurium strains and further work is being developed to better understand how antimicrobial resistance is developing in this pathogen.

RNA-seq analysis of the influence of anaerobiosis and FNR on Shigella flexneri

Background

Shigella flexneri is an important human pathogen that has to adapt to the anaerobic environment in the gastrointestinal tract to cause dysentery. To define the influence of anaerobiosis on the virulence of Shigella, we performed deep RNA sequencing to identify transcriptomic differences that are induced by anaerobiosis and modulated by the anaerobic Fumarate and Nitrate Reduction regulator, FNR.

Results

We found that 528 chromosomal genes were differentially expressed in response to anaerobic conditions; of these, 228 genes were also influenced by FNR. Genes that were up-regulated in anaerobic conditions are involved in carbon transport and metabolism (e.g. ptsG, manX, murQ, cysP, cra), DNA topology and regulation (e.g. ygiP, stpA, hns), host interactions (e.g. yciD, nmpC, slyB, gapA, shf, msbB) and survival within the gastrointestinal tract (e.g. shiA, ospI, adiY, cysP). Interestingly, there was a marked effect of available oxygen on genes involved in Type III secretion system (T3SS), which is required for host cell invasion and pathogenesis. These genes, located on the large Shigella virulence plasmid, were down regulated in anaerobiosis in an FNR-dependent manner. We also confirmed anaerobic induction of csrB and csrC small RNAs in an FNR-independent manner.

Conclusions

Anaerobiosis promotes survival and adaption strategies of Shigella, while modulating virulence plasmid genes involved in T3SS-mediated host cell invasion. The influence of FNR on this process is more extensive than previously appreciated, although aside from the virulence plasmid, this transcriptional regulator does not govern expression of genes on other horizontally acquired sequences on the chromosome such as pathogenicity islands.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-438) contains supplementary material, which is available to authorized users.

Gene polymorphism analysis of Yersinia enterocolitica outer membrane protein A and putative outer membrane protein A family protein

Background

Yersinia enterocolitica outer membrane protein A (OmpA) is one of the major outer membrane proteins with high immunogenicity. We performed the polymorphism analysis for the outer membrane protein A and putative outer membrane protein A (p-ompA) family protein gene of 318 Y. enterocolitica strains.

Results

The data showed all the pathogenic strains and biotype 1A strains harboring ystB gene carried both ompA and p-ompA genes; parts of the biotype 1A strains not harboring ystB gene carried either ompA or p-ompA gene. In non-pathogenic strains (biotype 1A), distribution of the two genes and ystB were highly correlated, showing genetic polymorphism. The pathogenic and non-pathogenic, highly and weakly pathogenic strains were divided into different groups based on sequence analysis of two genes. Although the variations of the sequences, the translated proteins and predicted secondary or tertiary structures of OmpA and P-OmpA were similar.

Conclusions

OmpA and p-ompA gene were highly conserved for pathogenic Y. enterocolitica. The distributions of two genes were correlated with ystB for biotype 1A strains. The polymorphism analysis results of the two genes probably due to different bio-serotypes of the strains, and reflected the dissemination of different bio-serotype clones of Y. enterocolitica.

Developing top down proteomics to maximize proteome and sequence coverage from cells and tissues

Mass spectrometry based proteomics generally seeks to identify and characterize protein molecules with high accuracy and throughput. Recent speed and quality improvements to the independent steps of integrated platforms have removed many limitations to the robust implementation of top down proteomics (TDP) for proteins below 70 kDa. Improved intact protein separations coupled to high-performance instruments have increased the quality and number of protein and proteoform identifications. To date, TDP applications have shown >1000 protein identifications, expanding to an average of ∼3-4 more proteoforms for each protein detected. In the near future, increased fractionation power, new mass spectrometers and improvements in proteoform scoring will combine to accelerate the application and impact of TDP to this century's biomedical problems.

Outer membrane protein OmpW of Escherichia coli is required for resistance to phagocytosis

Eight-stranded β-barrel outer membrane proteins can confer bacterial virulence via resistance to host innate defenses. This resistance function of OmpW, which was recently identified as an eight-stranded β-barrel protein, was investigated in this study. Our results demonstrated that upregulation of OmpW correlated with increased bacterial survival during phagocytosis. Bacterial mutants harboring a deletion of ompW exhibited a significantly increased phagocytosis rate. Both observations suggest that the OmpW protein protects bacteria against host phagocytosis. In addition, expression of ompW is regulated by iron, which implies that the resistance provided by OmpW may be an important factor in iron-related infectious diseases. Furthermore, OmpW has been identified as a protective antigen that protects mice against bacterial infection and is therefore a promising target for vaccine development against infectious diseases.

Proteomics indicates modulation of tubulin polymerization by L-menthol inhibiting human epithelial colorectal adenocarcinoma cell proliferation

Menthol is a naturally occurring cyclic monoterpene used in oral hygiene products, confectionary, pharmaceuticals, cosmetics, pesticides, and as a flavoring agent. In the present study, we analyzed the differentially expressing proteome in L-menthol-treated Caco-2 cell line as it was found to inhibit cell proliferation. Interestingly, free tubulin proteins were observed to be limited after menthol treatment. Semiquantitative RT-PCR with α-tubulin primers showed no change in the level of RNA expression in menthol-treated cell line. However, tubulin polymerization assay with menthol indicated a trend similar to taxol in promoting microtubule assembly. Further, physical counting of apoptotic nuclei and active caspase-3 assays confirmed onset of apoptosis though the rate was slower as compared with that of taxol treatment. This study is the first report of a monoterpene L-menthol modulating tubulin polymerization and apoptosis to inhibit cancer cell proliferation.

Bacterial agents in spondyloarthritis: a destiny from diversity?

The spondyloarthritides (SpAs) are a group of diseases that share clinical, radiographic and laboratory features; these arthritides also display a tendency for family aggregation. Given the intimate relationship that these types of arthritis share, it suggests that the SpAs might share a common aetiology. Of all the SpAs, the role of bacteria is most clearly defined in reactive arthritis. Tremendous recent insights into the pathophysiology of reactive arthritis have been made, demonstrating that the causative bacteria play a much more complex role than previously thought. The bacteria that are proven to cause reactive arthritis, one of the five types of SpA, will be reviewed and their role in the pathophysiology of reactive arthritis will be examined. The speculative data suggesting links between various other bacteria and the other types of SpAs will be critically analysed. Although these data are not definitive, when viewed using the paradigm that the SpAs might actually represent a common end point from several diverse starting points, they are provocative, suggesting that bacteria might, indeed, be aetiological for the entire group of SpAs.

Evidence of cellular immune response to outer membrane protein of Salmonella typhimurium in patients with enthesitis-related arthritis subtype of juvenile idiopathic arthritis

OBJECTIVE

enthesitis-related arthritis subtype of juvenile idiopathic arthritis (JIA-ERA) clinically resembles reactive arthritis (ReA). In patients with ReA the immune response is targeted at the outer membrane protein (OMP) of Salmonella typhimurium. We studied the immune response in JIA-ERA to S. typhimurium OMP.

METHODS

synovial fluid mononuclear cells (SFMC) and peripheral blood mononuclear cells (PBMC) were isolated from blood and SF of patients with JIA-ERA. Lymphocyte transformation test was done with S. typhimurium OMP and crude bacterial lysates of Yersinia enterocolitica, Shigella flexneri, and S. typhimurium. IgG and IgA ELISA were performed in serum and SF using S. typhimurium OMP as antigen and compared with sera from healthy controls.

RESULTS

in PBMC samples (n = 25) an antigen-specific proliferative response was seen in 13 patients and a cross-reactive response in 6. Among these 19 patients, 12 showed response to OMP. In SFMC (n = 15) antigen-specific responses were seen in 3 patients and cross-reactive responses in 9. Among these 12 patients, 11 showed response to OMP. The IgG and IgA anti-OMP antibody concentrations in serum and SF were similar in patients and controls.

CONCLUSION

in JIA-ERA, OMP is the major antigenic target recognized by both SFMC and PBMC. Response to OMP is independent of specific bacterial response, suggesting that OMP is the immunodominant antigen. In these patients, absence of significant humoral response suggests response to OMP is mainly T cell mediated.

Reactive arthritis: a review

This review article summarizes the available literature on adolescent reactive arthritis. A review of the pathophysiology, diagnosis, and treatment guidelines will be helpful to better diagnose and treat reactive arthritis.

Bacterial membrane proteomics

About one quarter to one third of all bacterial genes encode proteins of the inner or outer bacterial membrane. These proteins perform essential physiological functions, such as the import or export of metabolites, the homeostasis of metal ions, the extrusion of toxic substances or antibiotics, and the generation or conversion of energy. The last years have witnessed completion of a plethora of whole-genome sequences of bacteria important for biotechnology or medicine, which is the foundation for proteome and other functional genome analyses. In this review, we discuss the challenges in membrane proteome analysis, starting from sample preparation and leading to MS-data analysis and quantification. The current state of available proteomics technologies as well as their advantages and disadvantages will be described with a focus on shotgun proteomics. Then, we will briefly introduce the most abundant proteins and protein families present in bacterial membranes before bacterial membrane proteomics studies of the last years will be presented. It will be shown how these works enlarged our knowledge about the physiological adaptations that take place in bacteria during fine chemical production, bioremediation, protein overexpression, and during infections. Furthermore, several examples from literature demonstrate the suitability of membrane proteomics for the identification of antigens and different pathogenic strains, as well as the elucidation of membrane protein structure and function.

Th1/Th17 cytokine profiles in patients with reactive arthritis/undifferentiated spondyloarthropathy

OBJECTIVE

Data on synovial fluid (SF) cytokine concentrations in patients with reactive arthritis (ReA) or undifferentiated spondyloarthropathy (uSpA) are limited and contradictory. We measured levels of several proinflammatory and immunoregulatory cytokines in SF and sera from patients with ReA/uSpA.

METHODS

Interleukin 17 (IL-17), IL-6, interferon-g (IFN-g), and IL-12p40, and immunoregulatory cytokines IL-10 and transforming growth factor-beta (TGF-beta) were assayed using ELISA in SF specimens from 51 patients with ReA/uSpA (ReA 21, uSpA 30), 40 patients with rheumatoid arthritis (RA), and 11 patients with osteoarthritis (OA). IL-17, IL-6, IFN-g, and IL-10 levels were also measured in paired sera samples from patients with ReA/uSpA.

RESULTS

SF concentrations of IL-17, IL-6, TGF-beta, and IFN-g were significantly higher in patients with ReA/uSpA as compared to RA patients (for IL-17 median 46 pg/ml, range < 7.8-220 vs median < 7.8 pg/ml, range < 7.8-136, p < 0.05; for TGF-beta median 4.2 ng/ml, range 1.32-12 vs median 3.01 ng/ml, range 0.6-9.6, p < 0.01; for IL-6 median 58 ng/ml, range 2-540 vs median 34.5 ng/ml, range < 0.009-220, p < 0.05; for IFN-g median 290 pg/ml, range < 9.4-1600 vs median 100 pg/ml, range < 9.4-490, p < 0.05). SF levels of IL-10 were comparable but the ratio of IFN-g/IL-10 was significantly higher in ReA/uSpA patients than RA patients (median 3.18, range 0.06-200 for ReA/uSpA vs median 1.0, range 0.03-26.9 for RA; p < 0.05). IL-17, IL-6, IL-10, and IFN-g SF levels were significantly higher than paired serum levels in ReA/uSpA patients (p < 0.01 for IL-17, p < 0.0001 for IL-6, p < 0.0001 for IL-10, and p < 0.001 for IFN-g).

CONCLUSION

Increased IL-17, IL-6, TGF-beta, and IFN-g concentrations in ReA/uSpA than in RA suggest that Th1 and Th17 cells could be the major agents in inflammation in ReA/uSpA.