Streptococcal infection and autoimmune diseases.

Excessive activation of immune cells by environmental factors, such as infection or individual genetic risk, causes various autoimmune diseases. Streptococcus species are gram-positive bacteria that colonize the nasopharynx, respiratory tract, gastrointestinal tract, genitourinary tract, and skin. Group A Streptococcus (GAS) species cause various symptoms, ranging from mild infections, such as tonsillitis and pharyngitis, to serious infections, such as necrotizing fasciitis and streptococcal toxic shock syndrome. The contribution of GAS infections to several autoimmune diseases, including acute rheumatic fever, vasculitis, and neuropsychiatric disorders, has been studied. In this review, we focus on the association between streptococcal infections and autoimmune diseases, and discuss current research on the mechanisms underlying the initiation and progression of autoimmune diseases.

Bone Development and Regeneration 2.0.

Bone is an important tissue which is a structural body component, carrying out the roles of mechanical stress response and organ/tissue protection [...].

Association of anti-TPM4 autoantibodies with vasculopathic cutaneous manifestations in juvenile dermatomyositis.

OBJECTIVES: AECAs are detected in multiple forms of vasculitis or vasculopathy, including JDM. High levels of tropomyosin alpha-4 chain (TPM4) gene expression in cutaneous lesions and TPM4 protein expression in some endothelial cells (ECs) have been proven. Furthermore, the presence of autoantibodies to tropomyosin proteins have been discovered in DM. We therefore investigated whether anti-TPM4 autoantibodies are an AECA in JDM and are correlated with clinical features of JDM. METHODS: The expression of TPM4 protein in cultured normal human dermal microvascular ECs was investigated by Western blotting. Plasma samples from 63 children with JDM, 50 children with polyarticular JIA (pJIA) and 40 healthy children (HC) were tested for the presence of anti-TPM4 autoantibodies using an ELISA. Clinical features were compared between JDM patients with and without anti-TPM4 autoantibodies. RESULTS: Autoantibodies to TPM4 were detected in the plasma of 30% of JDM, 2% of pJIA (P < 0.0001) and 0% of HC (P < 0.0001). In JDM, anti-TPM4 autoantibodies were associated with the presence of cutaneous ulcers (53%; P = 0.02), shawl sign rash (47%; P = 0.03), mucous membrane lesions (84%; P = 0.04) and subcutaneous edema (42%; P < 0.05). Anti-TPM4 autoantibodies significantly correlated with the use of intravenous steroids and IVIG therapy in JDM (both P = 0.01). The total number of medications received was higher in patients with anti-TPM4 autoantibodies (P = 0.02). CONCLUSION: Anti-TPM4 autoantibodies are detected frequently in children with JDM and are novel myositis-associated autoantibodies. Their presence correlates with vasculopathic and other cutaneous manifestations of JDM that may be indicative of more refractory disease.

Association of anti-HSC70 autoantibodies with cutaneous ulceration and severe disease in juvenile dermatomyositis.

OBJECTIVES: JDM is an inflammatory myopathy characterized by prominent vasculopathy. AECAs are frequently detected in inflammatory and autoimmune diseases. We sought to determine whether AECAs correlate with clinical features of JDM, and thus serve as biomarkers to guide therapy or predict outcome. METHODS: Plasma samples from 63 patients with JDM, 49 patients with polyarticular JIA and 40 juvenile healthy controls were used to detect anti-heat shock cognate 71 kDa protein (HSC70) autoantibodies, a newly identified AECA, in ELISA assays. Clinical features were compared between JDM patients with and without anti-HSC70 autoantibodies. RESULTS: Anti-HSC70 autoantibodies were detected in 35% of patients with JDM, in 0% of patients with JIA (P < 0.0001) and in 0% of healthy donors (P < 0.0001). Both the presence of cutaneous ulcers (59% vs 17%, P < 0.002) and the use of wheelchairs and/or assistive devices (64% vs 27%, P < 0.007) were strongly associated with anti-HSC70 autoantibodies in JDM. High scores on the severity of myositis damage measures at the time of measurement of anti-HSC70 autoantibodies and an increased number of hospitalizations were also associated with anti-HSC70 autoantibodies. Intravenous immunoglobulin therapy was used more often in anti-HSC70 autoantibody-positive patients. CONCLUSION: Anti-HCS70 autoantibodies are detected frequently in children with JDM and are novel myositis-associated autoantibodies correlating with disease severity.

Physiologic Mechanical Stress Directly Induces Bone Formation by Activating Glucose Transporter 1 (Glut 1) in Osteoblasts, Inducing Signaling via NAD+-Dependent Deacetylase (Sirtuin 1) and Runt-Related Transcription Factor 2 (Runx2).

Mechanical stress is an important factor affecting bone tissue homeostasis. We focused on the interactions among mechanical stress, glucose uptake via glucose transporter 1 (Glut1), and the cellular energy sensor sirtuin 1 (SIRT1) in osteoblast energy metabolism, since it has been recognized that SIRT1, an NAD+-dependent deacetylase, may function as a master regulator of the mechanical stress response as well as of cellular energy metabolism (glucose metabolism). In addition, it has already been demonstrated that SIRT1 regulates the activity of the osteogenic transcription factor runt-related transcription factor 2 (Runx2). The effects of mechanical loading on cellular activities and the expressions of Glut1, SIRT1, and Runx2 were evaluated in osteoblasts and chondrocytes in a 3D cell-collagen sponge construct. Compressive mechanical loading increased osteoblast activity. Mechanical loading also significantly increased the expression of Glut1, significantly decreased the expression of SIRT1, and significantly increased the expression of Runx2 in osteoblasts in comparison with non-loaded osteoblasts. Incubation with a Glut1 inhibitor blocked mechanical stress-induced changes in SIRT1 and Runx2 in osteoblasts. In contrast with osteoblasts, the expressions of Glut1, SIRT1, and Runx2 in chondrocytes were not affected by loading. Our present study indicated that mechanical stress induced the upregulation of Glut1 following the downregulation of SIRT1 and the upregulation of Runx2 in osteoblasts but not in chondrocytes. Since SIRT1 is known to negatively regulate Runx2 activity, a mechanical stress-induced downregulation of SIRT1 may lead to the upregulation of Runx2, resulting in osteoblast differentiation. Incubation with a Glut1 inhibitor the blocked mechanical stress-induced downregulation of SIRT1 following the upregulation of Runx2, suggesting that Glut1 is necessary to mediate the responses of SIRT1 and Runx2 to mechanical loading in osteoblasts.

Effects of Different Exercise Conditions on Antioxidant Potential and Mental Assessment.

Exercise increases oxidative stress, leading the body to strengthen its antioxidant defenses, thus reducing the incidence of major diseases. As these associations are relatively unclear for ordinary levels of exercise for reduced stress, this study evaluated the effects of different exercise conditions on diacron-reactive oxygen metabolites (d-ROMs), biological antioxidant potential (BAP), and subjective mood. Forty-nine students (22.4 ± 2.6 years) were assessed using the Profile of Mood States (POMS) before and after exercising for 60 min. Participants were divided into two groups: Group A engaged in compulsory sports and Group B in freely chosen sports. d-ROMs and BAP were measured, and their modified ratio was calculated as an index of antioxidant potential. Physiological evaluation showed significant improvements in BAP and the BAP/d-ROMs ratio, irrespective of exercise condition (p < 0.001, p < 0.01). Comparison between the exercise conditions revealed a significant difference in the modified ratio (p < 0.02). In mood assessment, scores on emotion-related scales without vigor improved significantly under both exercise conditions (p < 0.001). Mental changes were evident after exercise, and potential antioxidant capacity was higher in freely chosen sports (p < 0.03). Assessment of antioxidant status before and after exercise may provide an objective index of mental and physical conditioning.

A novel, self-assembled artificial cartilage-hydroxyapatite conjugate for combined articular cartilage and subchondral bone repair: histopathological analysis of cartilage tissue engineering in rat knee joints.

PURPOSE: We previously created a self-assembled cartilage-like complex in vitro from only three cartilage components, hyaluronic acid (HA), aggrecan (AG) and type II collagen, without other materials such as cross-linking agents. Based on this self-organized AG/HA/collagen complex, we have created three novel types of biphasic cartilage and bone-like scaffolds combined with hydroxyapatite (HAP) for osteochondral tissue engineering. These scaffolds have been developed from self-assembled cartilage component molecules and HAP at the nanometer scale by manipulating the intermolecular relations. PATIENTS AND METHODS: The surface structure of each self-organized biphasic cartilage and bone-like scaffold was evaluated by scanning electron microscopy, whereas the viscoelasticity was also analyzed in vitro. Three types of artificial cartilage-HAP conjugates were implanted into an osteochondral defect in rat knee joints, and bone and cartilage tissues of the implanted site were examined 4 and 8 weeks after implantation. The tissues were examined histopathologically to evaluate the effects of the implantation on the articular cartilage and subchondral bone tissues. RESULTS: Our in vitro and in vivo data reveal that the self-organized biphasic cartilage and bone-like scaffold conjugated with HAP are superior to the scaffold with no HAP in both cartilage regeneration and subchondral bone regeneration. CONCLUSION: Our present study indicates that the self-organized biphasic cartilage and bone-like scaffold, which is conjugated with an HAP layer, may have potential not only to repair articular cartilage defects but also to ameliorate the degeneration of subchondral bone in the diseases with osteochondral defect.

SPACIA1/SAAL1 Deletion Results in a Moderate Delay in Collagen-Induced Arthritis Activity, along with mRNA Decay of Cyclin-dependent Kinase 6 Gene.

This study was performed to elucidate the molecular function of the synoviocyte proliferation-associated in collagen-induced arthritis (CIA) 1/serum amyloid A-like 1 (SPACIA1/SAAL1) in mice CIA, an animal model of rheumatoid arthritis (RA), and human RA-synovial fibroblasts (RASFs). SPACIA1/SAAL1-deficient mice were generated and used to create mouse models of CIA in mild or severe disease conditions. Cell cycle-related genes, whose expression levels were affected by SPACIA1/SAAL1 small interfering RNA (siRNA), were screened. Transcriptional and post-transcriptional effects of SPACIA1/SAAL1 siRNA on cyclin-dependent kinase (cdk) 6 gene expression were investigated in human RASFs. SPACIA1/SAAL1-deficient mice showed later onset and slower progression of CIA than wild-type mice in severe disease conditions, but not in mild conditions. Expression levels of cdk6, but not cdk4, which are D-type cyclin partners, were downregulated by SPACIA1/SAAL1 siRNA at the post-transcriptional level. The exacerbation of CIA depends on SPACIA1/SAAL1 expression, although CIA also progresses slowly in the absence of SPACIA1/SAAL1. The CDK6, expression of which is up-regulated by the SPACIA1/SAAL1 expression, might be a critical factor in the exacerbation of CIA.

Multiple target autoantigens on endothelial cells identified in juvenile dermatomyositis using proteomics.

Objective: Although generally classified within the group of inflammatory myopathies, JDM displays many pathological features of vasculitis. Previous work has shown that AECA are abundant in other forms of vasculitis. We therefore investigated whether such antibodies might also be detected in JDM. Methods: We screened plasma from children with JDM for the presence of AECA by western blotting and 2D gel electrophoresis (2DE) using proteins extracted from human aortic endothelial cells as the substrate. We performed mass spectrometry to identify candidate antigens from 2DE gels and used ELISA to confirm the presence of specific antibodies. Results: We identified 22 candidate target autoantigens for AECA probed with JDM plasma. Interestingly, 17 of these 22 target antigens were proteins associated with antigen processing and protein trafficking. ELISA confirmed the presence of antibodies to heat shock cognate 71 kDa protein in JDM plasma, particularly in children with active, untreated disease. Conclusion: Children with JDM express antibodies to autoantigens in endothelial cells. The clinical and pathological significance of such autoantibodies require further investigation.

T cells upon activation promote endothelin 1 production in monocytes via IFN-γ and TNF-α.

Endothelin 1 (ET-1), mainly produced from vascular endothelial cells, induces vasoconstriction in physiological conditions. The endothelin receptor antagonist is among the most effective agents for pulmonary hypertension. However, little is known about the production source of ET-1 in inflammation and immunity. Here, we studied whether T cell-mediated ET-1 production system exists and operates independent of the production system in vascular endothelial cells. ET-1 production was readily detectable in the culture supernatant of human PBMCs and murine spleen cells stimulated with anti-CD3 antibody. Immunocytostaining showed that ET-1-producing cells emerged only in PBMCs stimulated with anti-CD3 antibody. Using the Transwell system, both murine and human monocytes sorted with magnetic beads in the inner chamber produced ET-1 when T cells were activated with antigen or anti-CD3 antibody in the outer chamber. This ET-1 production was inhibited by anti-IFN-γ and/or TNF-α antibody. Furthermore, monocytes purified from ETflox/flox;Tie2-Cre( + ) mice, which conditionally lack ET-1 in hematopoietic stem cells and vascular endothelial cells, did not produce ET-1 even when stimulated by antigen-specific T cell activation. This study demonstrates the existence of an immune-mediated ET-1 production induced by T cells upon activation through IFN-γ and TNF-α.

The NAD-Dependent Deacetylase Sirtuin-1 Regulates the Expression of Osteogenic Transcriptional Activator Runt-Related Transcription Factor 2 (Runx2) and Production of Matrix Metalloproteinase (MMP)-13 in Chondrocytes in Osteoarthritis.

Aging is one of the major pathologic factors associated with osteoarthritis (OA). Recently, numerous reports have demonstrated the impact of sirtuin-1 (Sirt1), which is the NAD-dependent deacetylase, on human aging. It has been demonstrated that Sirt1 induces osteogenic and chondrogenic differentiation of mesenchymal stem cells. However, the role of Sirt1 in the OA chondrocytes still remains unknown. We postulated that Sirt1 regulates a hypertrophic chondrocyte lineage and degeneration of articular cartilage through the activation of osteogenic transcriptional activator Runx2 and matrix metalloproteinase (MMP)-13 in OA chondrocytes. To verify whether sirtuin-1 (Sirt1) regulates chondrocyte activity in OA, we studied expressions of Sirt1, Runx2 and production of MMP-13, and their associations in human OA chondrocytes. The expression of Sirt1 was ubiquitously observed in osteoarthritic chondrocytes; in contrast, Runx2 expressed in the osteophyte region in patients with OA and OA model mice. OA relating catabolic factor IL-1ßincreased the expression of Runx2 in OA chondrocytes. OA chondrocytes, which were pretreated with Sirt1 inhibitor, inhibited the IL-1ß-induced expression of Runx2 compared to the control. Since the Runx2 is a promotor of MMP-13 expression, Sirt1 inactivation may inhibit the Runx2 expression and the resultant down-regulation of MMP-13 production in chondrocytes. Our findings suggest thatSirt1 may regulate the expression of Runx2, which is the osteogenic transcription factor, and the production of MMP-13 from chondrocytes in OA. Since Sirt1 activity is known to be affected by several stresses, including inflammation and oxidative stress, as well as aging, SIRT may be involved in the development of OA.

Cutaneous manifestations of patients with relapsing polychondritis: an association with extracutaneous complications.

The aim of this study was to determine the prognostic characteristics of patients with relapsing polychondritis (RP) accompanying cutaneous manifestations in Japan. We analyzed a cohort of 239 patients with RP in view of cutaneous and extracutaneous complications. Thirty three cases (14%) developed cutaneous manifestations and 23 cases had both cutaneous and extracutaneous manifestations. Five RP patients developed myelodysplastic syndrome (MDS) and all of the five patients had cutaneous manifestations, including Sweet's syndrome. Only one patient died of MDS among the five patients, suggesting rather better prognosis as compared with ordinary MDS. Five RP patients developed Behcet's disease and all the five patients had cutaneous manifestations. Death rate of the RP patients with cutaneous manifestations (15%) was slightly higher than that of whole Japanese RP patient cohort (9.2%). RP patients with cutaneous manifestations had a slightly higher death rate, than those without cutaneous manifestations. MDS of RP patients had a rather better prognostic impact in Japan. Further studies are needed to elucidate the pathophysiology of RP, which brings about development of extracutaneous manifestations, especially MDS and Behcet's disease.

Age-related Decrease of Sirtuin 2 Protein in Human Peripheral Blood Mononuclear Cells.

Sirtuin 2, which is mainly present in cytoplasm, plays an important role in mammalian development, caloric restriction, metabolic regulation cellular antioxidant potential and the regulation of aging. We found that the protein level of sirtuin 2 in human peripheral blood mononuclear cells (PBMCs) decreases with an advance in donor age in men and women. Our data suggest that sirtuin 2 level in PBMCs decreases with age in both men and women and may have a potential as a useful biomarker monitoring health conditions and aging.

Secretion of inflammatory factors from chondrocytes by layilin signaling.

Layilin (LAYN) is thought to be involved in reorganization of cytoskeleton structures, interacting with merlin, radixin, and talin. Also, LAYN is known to be one of the receptors for hyaluronic acid (HA). In rheumatoid arthritis (RA), inflammatory cytokines like tumor necrosis factor α (TNF-α) have been known to play pathological roles. HA with low molecular weight is speculated to exacerbate inflammation in RA. In this context, differences of quantity and functions of HA receptors would affect the severity of inflammation in RA. Chondrocytes, which play critical roles in maintaining articular cartilage and are affected in RA, express at least kinds of HA receptors like CD44 and LAYN. However, roles and regulation of LAYN in articular chondrocytes have been poorly understood. To clarify regulation of LAYN in chondrocytes, we here investigated whether TNF-α affected expression levels of LAYN in human articular chondrocytes. Next, to clarify LAYN-specific roles in chondrocytes, we investigated whether binding of antibodies to the extracellular domain of LAYN affected secretion of inflammatory cytokines using a chondrosarcoma cell line. As a result, we found that TNF-α up-regulated expression levels of LAYN in the chondrocytes. Further, the LAYN signaling was found to enhance secretion of inflammatory factors, IL-8 and complement5 (C5)/C5a, from the cells. Our results indicate that LAYN would be involved in the enhancement of inflammation and degradation of cartilage in joint diseases such as RA and OA.

The DNA repair enzyme apurinic/apyrimidinic endonuclease (Apex nuclease) 2 has the potential to protect against down-regulation of chondrocyte activity in osteoarthritis.

Apurinic/apyrimidinic endonuclease 2 (Apex 2) plays a critical role in DNA repair caused by oxidative damage in a variety of human somatic cells. We speculated that chondrocyte Apex 2 may protect against the catabolic process of articular cartilage in osteoarthritis (OA). Higher levels of Apex 2 expression were histologically observed in severely compared with mildly degenerated OA cartilage from STR/OrtCrlj mice, an experimental model which spontaneously develops OA. The immunopositivity of Apex 2 was significantly correlated with the degree of cartilage degeneration. Moreover, the OA-related catabolic factor interleukin-1ß induced the expression of Apex 2 in chondrocytes, while Apex 2 silencing using small interfering RNA reduced chondrocyte activity in vitro. The expression of Apex 2 in chondrocytes therefore appears to be associated with the degeneration of articular cartilage and could be induced by an OA-related catabolic factor to protect against the catabolic process of articular cartilage. Our findings suggest that Apex 2 may have the potential to prevent the catabolic stress-mediated down-regulation of chondrocyte activity in OA.

Serum level of soluble triggering receptor expressed on myeloid cells-1 as a biomarker of disease activity in relapsing polychondritis.

OBJECTIVES: We aimed to identify a serum biomarker for evaluating the disease activity of relapsing polychondritis (RP). METHODS: We measured and compared serum levels of 28 biomarkers potentially associated with this disease, including soluble triggering receptor expressed on myeloid cells-1 (sTREM-1), high-sensitivity C-reactive protein (hs-CRP), and cartilage oligomeric matrix protein (COMP), in 15 RP patients and 16 healthy donors (HDs). We divided the 15 RP patients into active RP (n = 8) and inactive RP (n = 7) groups, depending on the extent of the disease, and compared candidate markers between groups. The localization of membrane-bound TREM-1 in the affected tissue was examined by immunohistochemistry. RESULTS: Serum levels of sTREM-1, interferon-γ, chemokine (C-C motif) ligand 4, vascular endothelial growth factor, and matrix metalloproteinases-3 were significantly higher in RP patients than HDs. Among these markers, sTREM-1 had the highest sensitivity and specificity (86.7 and 86.7 %, respectively). Furthermore, the serum level of sTREM-1 was significantly higher in active RP patients than inactive RP patients (p = 0.0403), but this was not true for hs-CRP or COMP. TREM-1 was expressed on endothelial cells in RP lesions. CONCLUSIONS: The serum level of sTREM-1 may be a useful marker of disease activity in RP.

Protein profiles of peripheral blood mononuclear cells as a candidate biomarker for Behçet's disease.

OBJECTIVES: To investigate the pathophysiology of Behçet's disease (BD) and find biomarkers for the disease, we analysed protein profiles of peripheral blood mononuclear cells (PBMCs). METHODS: Proteins, extracted from PBMCs, were comprehensively analysed in 16 patients with BD, 16 patients with rheumatoid arthritis (RA), 12 patients with Crohn's disease (CD), and 16 healthy control subjects (HC) by 2-dimensional differential gel electrophoResis (2D-DIGE). Differently expressed proteins were identified by mass spectrometry. RESULTS: 563 protein spots were detected. We completely discriminated between the BD and HC groups, between the BD and RA groups, and between the BD and CD groups by multivariate analysis of intensity of 23, 35, and 1 spots, respectively. The spots contributing to the differences included proteins related to cytoskeleton, transcription/translation, T cell activation, bone turnover, regulating apoptosis, and microbial infection. Intensity of 3 spots (tyrosine-protein phosphatase non-receptor type 4, threonine synthase-like 2, and ß-actin) provided area under the receiver operating characteristic curves (AUROC) of 0.889 for discrimination between the BD group and the non-BD groups. Informatively, intensity of the above 1 spot completely discriminated the CD group from the other groups (AUROC 1.000). This spot, identified as ß-actin, had different pI from the above ß-actin-spot probably due to different post-translational modification. CONCLUSIONS: PBMC protein profiles, especially the profile of the 3 spots, would be candidate biomarkers for BD. The latter ß-actin subtype would be useful for discriminating inflammatory bowel diseases from BD and other diseases. The identified proteins may play important roles in the pathophysiology of BD.

Positive feedback loop via astrocytes causes chronic inflammation in virus-associated myelopathy.

Human T-lymphotropic virus type 1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a rare neurodegenerative disease characterized by chronic inflammation in the spinal cord. We hypothesized that a positive feedback loop driven by chemokines may be responsible for the chronic inflammation in HAM/TSP. We aimed to determine the identity of these chemokines, where they are produced, and how they drive chronic inflammation in HAM/TSP. We found that patients with HAM/TSP have extraordinarily high levels of the chemokine CXCL10 (also known as IP-10) and an abundance of cells expressing the CXCL10-binding receptor CXCR3 in the cerebrospinal fluid. Histological analysis revealed that astrocytes are the main producers of CXCL10 in the spinal cords of patients with HAM/TSP. Co-culture of human astrocytoma cells with CD4+ T cells from patients with HAM/TSP revealed that astrocytes produce CXCL10 in response to IFN-γ secreted by CD4+ T cells. Chemotaxis assays results suggest that CXCL10 induces migration of peripheral blood mononuclear cells to the central nervous system and that anti-CXCL10 neutralizing antibody can disrupt this migration. In short, we inferred that human T-lymphotropic virus type 1-infected cells in the central nervous system produce IFN-γ that induces astrocytes to secrete CXCL10, which recruits more infected cells to the area via CXCR3, constituting a T helper type 1-centric positive feedback loop that results in chronic inflammation.