Possible Role of Staphylococcal Enterotoxin B in the Pathogenesis of Autoimmune Diseases

Autoimmunity: A New Focus on Nasal Polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) has long been considered a benign, chronic inflammatory, and hyperplastic disease. Recent studies have shown that autoimmune-related mechanisms are involved in the pathology of nasal polyps. Activated plasma cells, eosinophils, basophils, innate type 2 lymphocytes, mast cells, and proinflammatory cytokine in polyp tissue indicate the mobilization of innate and adaptive immune pathways during polyp formation. The discovery of a series of autoantibodies further supports the autoimmune nature of nasal polyps. Local homeostasis dysregulation, infection, and chronic inflammation may trigger autoimmunity through several mechanisms, including autoantigens overproduction, microbial translocation, molecular mimicry, superantigens, activation or inhibition of receptors, bystander activation, dysregulation of Toll-Like Receptors (TLRs), epitope spreading, autoantigens complementarity. In this paper, we elaborated on the microbiome-mediated mechanism, abnormal host immunity, and genetic changes to update the role of autoimmunity in the pathogenesis of chronic rhinosinusitis with nasal polyps.

An Unusual Case of Seronegative Cryoglobulinemic Glomerulonephritis with Dominant Organized IgA Deposits Associated with Staphylococcal Infection: Casual or Causal Relationship?

Introduction

Cryoglobulinemia refers to the presence of cryoglobulins (CGs) in the serum, encompassing a group of diseases caused by the type of circulating GC. Cryoglobulinemic glomerulonephritis (CryoGN) is the principal manifestation of renal involvement. The diagnosis may be challenging because the hallmark of cryoglobulinemia is the detection of CG in the serum. However, cases of CryoGN without serological evidence of CGs are not uncommon in clinical practice, often diagnosed by anatomopathological findings in the renal biopsy.

Case Presentation

We report the case of an 86-year-old male who developed renal impairment, nephritic syndrome, and nephrotic-range proteinuria, without serological evidence of CGs, associated with staphylococcal bacteremia without apparent focus. Renal biopsy and pathological examination showed a membranoproliferative glomerulonephritis pattern with CD61-negative pseudothrombi. Immunofluorescence microscopy showed atypical IgA-dominant deposits. Electron microscopy revealed amorphous subendothelial and mesangial deposits and organized electrodense deposits within capillary loops (pseudothrombi) with microtubular substructure measuring 20-40 nm in thickness. These findings were consistent with seronegative CryoGN and microtubular organized atypical IgA-dominant deposits.

Discussion

In this report, we discuss the clinical, analytical, and histopathological findings of a rare case of CryoGN without serological evidence of CGs. Regarding the etiology that triggered the glomerular disease in our patient, we conducted an exhaustive study in order to determine the underlying cause of CryoGN. At the time of biopsy, the patient had an active staphylococcal bacteremia. There are reports that postulate that staphylococcal antigens drive activation of immune system and in consequence, could cause this rare form of IgA-dominant glomerulonephritis with cryoglobulinemic features. After ruling out other causes of cryoglobulinemia, we discuss a plausible causal relationship of the staphylococcal infection in the pathogenesis of CryoGN in our patient.

Anti-staphylococcal responses and their relationship with HLA-DR-DQ polymorphism in granulomatosis with polyangiitis: a preliminary evidence of association with disease outcome

Chronic nasal carriage of Staphylococcus aureus (S. aureus) is a risk factor for relapse of granulomatosis with polyangiitis (GPA), and genetic susceptibility to infections and autoimmune diseases is majorly affected by HLA genes. Previous studies have shown the association of HLA Class-II genes with GPA susceptibility. Here, we aim to assess immune responses of GPA patients against S. aureus antigens in relation to the HLA-DR-DQ genes polymorphism to determine the disease outcome. A total of 45 GPA patients and 128 healthy controls during 2010-2012 were included in this case-control study. HLA-DRB1/DQB1 allele typing was performed by polymerase chain reaction-sequence-specific primer (PCR-SSP) method. Immune responses against S. aureus antigens were investigated in 20 active vs. remitting GPA (after 6 months of cyclophosphamide and glucocorticoids) patients by Western blot. Statistical analysis was performed using χ² test and Fisher's exact test. We observed a significant association of DRB1*08, DRB1*16 and DQB1*04 alleles with GPA susceptibility, whereas DRB1*15, DRB1*10 and DQB1*05 alleles were suggested as protective alleles. Among S. aureus antigens, active GPA patients' sera reacted more strongly with 34 and 24 kDa antigens of S. aureus than remitting and healthy control  sera. Furthermore, we observed that the lack of DQB1*06 allele confers complete remission even in the presence of anti-S. aureus antibodies against 24 kDa protein. Our findings suggest that the presence of DQB1*06 allele and S. aureus infection may prolong active disease. Further, our study indicates the potential of using anti-staphylococcal medications for achieving remission in patients having HLA-DQB1*06 allele.

Reagentless detection of staphylococcal enterotoxin B via electrochemical interrogation of conformational changes

An electrochemical biosensor for staphylococcal enterotoxin B (SEB) detection has been designed on the basis of electrochemical interrogation of conformational changes. Ferrocene-labeled hairpin probe (Fc-HP) and SEB aptamer are introduced for the construction of the platform. Without SEB, the rigid construction of DNA duplex that included SEB aptamer and Fc-HP prevented Fc getting access to the electrode surface, keeping the "eT-off" state in the detection system. In the presence of SEB, the interaction between SEB and the aptamer could trigger the disruption of DNA duplex and the restoration of hairpin structure, accompanied by the increase of Fc oxidation current. The decreasing distance between the redox probe and electrode upon the nucleic acid reconfiguration substantially increased the efficiency of eT, which resulted in the enhanced Fc signal. The proposed strategy presented a wide linear detection range from 0.005 to 100 ng mL^-1 with a detection limit down to 3 pg mL^-1 (S/N = 3). To investigate the applicability and reliability of the method in real food samples such as milk samples, we compared the results between this method and the commercial ELISA kit. The relative percentage error between the two assays ranged from -6.42% to 6.31%, indicating that there was no obvious difference between the results.

Attomolar analyte sensing techniques (AttoSens): a review on a decade of progress on chemical and biosensing nanoplatforms

Detecting the ultra-low abundance of analytes in real-life samples, such as biological fluids, water, soil, and food, requires the design and development of high-performance biosensing modalities. The breakthrough efforts from the scientific community have led to the realization of sensing technologies that measure the analyte's ultra-trace level, with relevant sensitivity, selectivity, response time, and sampling efficiency, referred to as Attomolar Analyte Sensing Techniques (AttoSens) in this review. In an AttoSens platform, 1 aM detection corresponds to the quantification of 60 target analyte molecules in 100 μL of sample volume. Herein, we review the approaches listed for various sensor probe design, and their sensing strategies that paved the way for the detection of attomolar (aM: 10^-18 M) concentration of analytes. A summary of the technological advances made by the diverse AttoSens trends from the past decade is presented.

Genetic diversity of Staphylococcus aureus influences disease phenotype of systemic lupus erythematosus

OBJECTIVE

We investigated the genetic diversity, molecular epidemiology and evolutionary dynamics of Staphylococcus aureus (SA) isolated from SLE patients by means of phylogenetic analysis.

METHODS

Consecutive SLE patients (ACR 1997 criteria) were enrolled: clinical/laboratory data were collected and nasal swab for SA identification was performed. On the basis of the translation elongation factor (tuf) gene, a phylogenetic analysis was performed to investigate relationships and to assess significant clades. Selective pressure analysis was used to investigate the evolution of the SA tuf gene. The gene sequences from non-SLE individuals, downloaded from the GenBank database, were compared through phylogenetic analysis with the tuf gene from SLE patients.

RESULTS

We enrolled 118 patients [M/F 10/108; median (interquartile range (IQR)) age 45.5 (13.2) years; median (IQR) disease duration 120 (144) months]. Twenty-four patients (20.3%) were SA carriers (SA+), three of them MRSA. SA+ SLE showed significantly higher SLEDAI-2k values [SA+: median (IQR) 2 (3.75); SA-: 0 (2); P = 0.04]. The phylogenetic analysis, restricted to 21 non-MRSA SA+, revealed a statistically supported larger clade (A, n = 17) and a smaller one (B, n = 4). Patients located in clade A showed a significantly higher prevalence of joint involvement (88.2%) in comparison with clade B (50.0%, P < 0.0001) and SA- (62.7%, P < 0.0001). Haematological manifestations were significantly more frequent in clade A (64.7%) compared with B (50.0%, P = 0.004).

CONCLUSION

We suggest a possible role of SA nasal carriage status in SLE disease activity. Moreover, our findings support the hypothesis that bacterial genetic variants may be associated with specific disease features.

IL-33 and Superantigenic Activation of Human Lung Mast Cells Induce the Release of Angiogenic and Lymphangiogenic Factors

Human lung mast cells (HLMCs) express the high-affinity receptor FcεRI for IgE and are strategically located in different compartments of human lung, where they play a role in several inflammatory disorders and cancer. Immunoglobulin superantigens (e.g., protein A of Staphylococcus aureus and protein L of Peptostreptococcus magnus) bind to the variable regions of either the heavy (V_H3) or light chain (κ) of IgE. IL-33 is a cytokine expressed by epithelial cells that exerts pleiotropic functions in the lung. The present study investigated whether immunoglobulin superantigens protein A and protein L and IL-33 caused the release of inflammatory (histamine), angiogenic (VEGF-A) and lymphangiogenic (VEGF-C) factors from HLMCs. The results show that protein A and protein L induced the rapid (30 min) release of preformed histamine from HLMCs. By contrast, IL-33 did not induce the release of histamine from lung mast cells. Prolonged incubation (12 h) of HLMCs with superantigens and IL-33 induced the release of VEGF-A and VEGF-C. Preincubation with IL-33 potentiated the superantigenic release of histamine, angiogenic and lymphangiogenic factors from HLMCs. Our results suggest that IL-33 might enhance the inflammatory, angiogenic and lymphangiogenic activities of lung mast cells in pulmonary disorders.

Molecular docking analysis of Enterotoxin I from Staphylococcus aureus with Nafcillin analogues

Staphylococcal enterotoxins (SEs) are liked with food poisoning and other related infections. Nafcillin is an antibiotic used to treat S. aureus. Therefore, it is of interest to study the molecular interactions of 25 nafcillin analogues with enterotoxin I using molecular docking analysis. The analysis shows optimal interaction features of Nafcillin analogues with Enterotoxin I from Staphylococcus aureus for further consideration.

Parsonage Turner syndrome caused by Staphylococcus aureus spondylodiscitis

Parsonage Turner syndrome (otherwise known as PTS, neuralgic amyotrophy or acute brachial neuritis) is a rare, but clinically significant cause of atraumatic shoulder girdle pain and weakness. Diagnosis is primarily clinical and can be challenging due to its heterogeneous presentation. A case of PTS following systemic infection from Staphylococcus aureus spondylodiscitis is presented. Timely consideration of the diagnosis prevented unnecessary investigation and allowed effective rehabilitation. This is the first case of PTS preceded by S. aureus infection. PTS should be considered in those presenting with acute, atraumatic shoulder dysfunction after systemic infection.

Staphylococcus aureus Nasal Carriage and Autoimmune Diseases: From Pathogenic Mechanisms to Disease Susceptibility and Phenotype

The role of infective agents in autoimmune diseases (ADs) development has been historically investigated, but in the last years has been strongly reconsidered due to the interest in the link between the microbiome and ADs. Together with the gut, the skin microbiome is characterized by the presence of several microorganisms, potentially influencing innate and adaptive immune response. S. aureus is one of the most important components of the skin microbiome that can colonize anterior nares without clinical manifestations. Data from the literature demonstrates a significantly higher prevalence of nasal colonization in ADs patients in comparison with healthy subjects, suggesting a possible role in terms of disease development and phenotypes. Thus, in the present narrative review we focused on the mechanisms by which S. aureus could influence the immune response and on its relationship with ADs, in particular granulomatosis with polyangiitis, rheumatoid arthritis, and systemic lupus erythematosus.

Frequency of superantigen encoding genes of Staphylococcus aureus isolates collected from multiple sclerosis (MS) patients and nasal carriers

BACKGROUND

Bacterial superantigens are potent T cell activators that can have acute or chronic effects on the central nervous system.

OBJECTIVES

In this study, the role of enterotoxins, exfoliative toxins and toxic shock syndrome toxin of Staphylococcus aureus was investigated in MS patients and healthy nasal carriers.

METHODS

Three-hundred fifty nasal swabs were collected from healthy nasal carriers (n = 210) and MS (n = 140) patients. Staphylococcus aureus superantigens were detected by multiplex PCR. Antimicrobial susceptibility pattern was performed using disk diffusion method.

RESULTS

The highest rates of nasal colonization were seen in MS patients (46.42%). The rates of nasal colonization in the healthcare workers were 30.95%. The most commonly detected superantigens were SEA (31.5%), SEB (17.7%) and ETA (16.9%). The Staphylococcus aureus isolates had the highest levels of resistance against erythromycin (57.7%), clindamycin (55.4%) and co-trimoxazole (43.1%). All isolates were susceptible to vancomycin, linezolid, and mupirocin.

CONCLUSION

Our results revealed that the frequency of superantigen producing Staphylococcus aureus isolates is high in the MS patients. As well as these isolates are sensitive to mupirocin. Thus it is better to use of mupirocin for nasal decolonization of Staphylococcus aureus in the MS patients.

Telmisartan Protects a Microglia Cell Line from LPS Injury Beyond AT1 Receptor Blockade or PPARγ Activation

The Angiotensin II Receptor Blocker (ARB) Telmisartan reduces inflammation through Angiotensin II AT1 receptor blockade and peroxisome proliferator-activated receptor gamma (PPARγ) activation. However, in a mouse microglia-like BV2 cell line, imitating primary microglia responses with high fidelity and devoid of AT1 receptor gene expression or PPARγ activation, Telmisartan reduced gene expression of pro-injury factors, enhanced that of anti-inflammatory genes, and prevented LPS-induced increase in inflammatory markers. Using global gene expression profiling and pathways analysis, we revealed that Telmisartan normalized the expression of hundreds of genes upregulated by LPS and linked with inflammation, apoptosis and neurodegenerative disorders, while downregulating the expression of genes associated with oncological, neurodegenerative and viral diseases. The PPARγ full agonist Pioglitazone had no neuroprotective effects. Surprisingly, the PPARγ antagonists GW9662 and T0070907 were neuroprotective and enhanced Telmisartan effects. GW9226 alone significantly reduced LPS toxic effects and enhanced Telmisartan neuroprotection, including downregulation of pro-inflammatory TLR2 gene expression. Telmisartan and GW9662 effects on LPS injury negatively correlated with pro-inflammatory factors and upstream regulators, including TLR2, and positively with known neuroprotective factors and upstream regulators. Gene Set Enrichment Analysis (GSEA) of the Telmisartan and GW9662 data revealed negative correlations with sets of genes associated with neurodegenerative and metabolic disorders and toxic treatments in cultured systems, while demonstrating positive correlations with gene sets associated with neuroprotection and kinase inhibition. Our results strongly suggest that novel neuroprotective effects of Telmisartan and GW9662, beyond AT1 receptor blockade or PPARγ activation, include downregulation of the TLR2 signaling pathway, findings that may have translational relevance.

Staphylococcal Infection-Related Glomerulonephritis With Cryoglobulinemic Features

Introduction

Staphylococcal infection–related glomerulonephritis (GN) has been shown to represent a unique form of infection-related GN that contains IgA-dominant deposits and is often seen concurrently with the bacterial infection. Biopsies commonly reveal an endocapillary proliferative and/or exudative or mesangial proliferative GN. Rare cases have been reported to show cryoglobulin-like features, including hyaline pseudothrombi and wireloop deposits; however, detailed characterization of these cases is lacking.

Methods

The pathology archives from the University of Utah and Sharp Memorial Hospital were reviewed from January 2016 to September 2017 in search of cases with GN containing IgA-dominant deposits and features of cryoglobulinemia.

Results

Of 1965 native kidney biopsies, 5 showed IgA-dominant GN with cryoglobulinemic features. All patients had active staphylococcal infections at the time of biopsy. All presented with acute kidney injury (serum creatinine range: 1.7−6 mg/dl), and all had proteinuria and hematuria. All biopsies showed exudative GN, and 4 biopsies had focal crescents. All had focally prominent hyaline pseudothrombi with or without wireloop deposits, and all showed co-dominant staining for IgA and C3 on immunofluorescence microscopy. Serologic testing for cryoglobulinemia was performed in 3 patients and was transiently positive in 1 patient. Four patients required hemodialysis at last follow-up, whereas 1 patient returned to baseline kidney function.

Conclusion

IgA-dominant GN with cryoglobulinemic features is an uncommon but severe form of glomerular injury in patients with staphylococcal infections. Four of 5 patients had crescentic glomerular injuries, all of whom required hemodialysis at last follow-up. Patients with IgA-dominant GN with features of cryoglobulinemia should be evaluated for active staphylococcal infection.

Interleukin-26 (IL-26) is a novel anti-microbial peptide produced by T cells in response to staphylococcal enterotoxin

Anti-microbial peptides are produced at outer and inner surfaces by epithelia and innate immune cells in response to bacterial infection. Staphylococcus aureus is an enterotoxin producing, Gram-positive pathogen, which is a major cause of soft tissue infections and life-threatening bacteremia and sepsis. Here we show that (i) skin T cells in chronic wounds infected with S. aureus express interleukin-26 (IL-26) in situ, (ii) staphylococcal enterotoxins (SE) trigger IL-26 expression in T cell lines and primary skin T cells, and (iii) IL-26 triggers death and inhibits biofilm formation and growth of S. aureus. Thus, we provide novel evidence that IL-26 is an anti-microbial peptide produced by T cells in response to SE. Accordingly, we propose that IL-26 producing T cells take part in the innate immune response to SE producing S. aureus and thus play a novel role in the primary innate immune defense in addition to their classical role in adaptive immunity.

Basis of Virulence in Enterotoxin-Mediated Staphylococcal Food Poisoning

The Staphylococcus aureus enterotoxins are a superfamily of secreted virulence factors that share structural and functional similarities and possess potent superantigenic activity causing disruptions in adaptive immunity. The enterotoxins can be separated into two groups; the classical (SEA-SEE) and the newer (SEG-SElY and counting) enterotoxin groups. Many members from both these groups contribute to the pathogenesis of several serious human diseases, including toxic shock syndrome, pneumonia, and sepsis-related infections. Additionally, many members demonstrate emetic activity and are frequently responsible for food poisoning outbreaks. Due to their robust tolerance to denaturing, the enterotoxins retain activity in food contaminated previously with S. aureus. The genes encoding the enterotoxins are found mostly on a variety of different mobile genetic elements. Therefore, the presence of enterotoxins can vary widely among different S. aureus isolates. Additionally, the enterotoxins are regulated by multiple, and often overlapping, regulatory pathways, which are influenced by environmental factors. In this review, we also will focus on the newer enterotoxins (SEG-SElY), which matter for the role of S. aureus as an enteropathogen, and summarize our current knowledge on their prevalence in recent food poisoning outbreaks. Finally, we will review the current literature regarding the key elements that govern the complex regulation of enterotoxins, the molecular mechanisms underlying their enterotoxigenic, superantigenic, and immunomodulatory functions, and discuss how these activities may collectively contribute to the overall manifestation of staphylococcal food poisoning.

Monoclonal antibodies protect from Staphylococcal Enterotoxin K (SEK) induced toxic shock and sepsis by USA300 Staphylococcus aureus

Staphylococcus aureus is a leading infectious cause of life-threatening disease in humans, yet there is currently no vaccine to combat this bacterium. The pathogenesis of S. aureus is mediated by a diverse array of protein toxins including a large family of secreted pyrogenic superantigens. Neutralization of superantigens, including SEB and TSST-1, has proven to be protective in several animal models of toxic shock and sepsis. We demonstrate, for the first time, that a far more prevalent staphylococcal superantigen, SEK, can also induce lethal shock in mice. Additionally, we describe monoclonal antibodies (mAbs) that inhibit SEK-induced mitogenicity as well as protect against SEK-induced lethality, and enhance survival from S. aureus septicemia in murine models. MAb-4G3 (IgG2b), mAb-5G2 (IgG1), and mAb-9H2 (IgG1), all inhibit SEK-induced proliferation and cytokine production of human immune cells. We then demonstrate that passive immunization with a combination of mAb-4G3 and mAb-5G4, 2 mAbs that do not compete for epitope(s) on SEK, significantly enhance survival in a murine model of SEK-induced toxic shock (p = 0.006). In the setting of sepsis, passive immunization with this combination of mAbs also significantly enhances survival in mice after challenge with CA-MRSA strain USA300 (p = 0.03). Furthermore, septic mice that received mAb treatment in conjunction with vancomycin exhibit less morbidity than mice treated with vancomycin alone. Taken together, these findings suggest that the contribution of SEK to S. aureus pathogenesis may be greater than previously appreciated, and that adjunctive therapy with passive immunotherapy against SEs may be beneficial.