Monoclonal ribosomal P autoantibody inhibits the expression and release of IL-12, TNF-α and iNOS in activated RAW macrophage cell line

Arbutin Improves Functional Recovery and Attenuates Glial Activation in Lysolecethin-Induced Demyelination Model in Rat Optic Chiasm

Neuroinflammation, glial activation, and oxidative injury are the main pathological mechanisms of demyelination in multiple sclerosis (MS). Arbutin, a natural polyphenol compound, possesses antioxidant, anti-inflammatory, and neuroprotective properties whose therapeutic potential has not been studied in the experimental animal models of MS. In the present study, the efficiency of arbutin on lysolecthin (LPC)-induced local demyelination model was investigated. Demyelination was induced by micro-injection of 2 μl LPC (1%) into the rat optic chiasm and the treated group received daily injection of arbutin (50 mg/kg, i.p) during 2 weeks. Visual-evoked potential (VEP) recordings were used to functionally assess the visual pathway. Gene expression analysis was done to evaluate the arbutin effect on the inflammatory, stress oxidative-related mediators, and myelin markers. The myelin-specific staining was performed to assess demyelination and GFAP staining as an astrocyte marker. We found that arbutin significantly reduced P1-latency of VEPs waves and demyelination at 7 and 14 days post-demyelination. Arbutin decreased inflammatory cytokines (IL-1B, IL-17, TNF-α) and iNOS mRNA expression level. In addition, the expression level of anti-inflammatory cytokine (IL-10) and antioxidant mediators (Nrf-2 and HO-1) was enhanced by arbutin treatment. Arbutin increased MBP and Olig2 expression levels in demyelination context. Finally, arbutin attenuated GFAP as an astrocyte marker. Finally, this study demonstrates that arbutin improves functional recovery and myelin repair in the demyelinated optic chiasm through attenuation of inflammation, astrocyte activation, and oxidative stress. These findings might open new promising avenues for treating demyelinating disorders such as multiple sclerosis. Graphical abstract.

Personalized therapy design for systemic lupus erythematosus based on the analysis of protein-protein interaction networks

We analyzed protein expression data for Lupus patients, which have been obtained from publicly available databases. A combination of systems biology and statistical thermodynamics approaches was used to extract topological properties of the associated protein-protein interaction networks for each of the 291 patients whose samples were used to provide the molecular data. We have concluded that among the many proteins that appear to play critical roles in this pathology, most of them are either ribosomal proteins, ubiquitination pathway proteins or heat shock proteins. We propose some of the proteins identified in this study to be considered for drug targeting.

Anti-ribosomal P antibodies are associated with elevated circulating IFNα and IL-10 levels in systemic lupus erythematosus patients

OBJECTIVE

The objective of this paper is to analyze the relationship of anti-protein ribosomal P (RibP) antibodies with circulating levels of IFNα, TNFα, IFNγ, IL-17 and IL-10 in SLE. Disease activity and other systemic lupus erythematosus (SLE) features were also analyzed.

METHODS

Anti-RibP and other SLE-related antinuclear antibodies (ANA) were determined by fluoro-enzyme immunoassay in the sera of 107 SLE patients. Circulating cytokines were quantified by flow cytometry (IFNα, IL-10 and IL-17) or ELISA (TNFα and IFNγ).

RESULTS

Anti-RibP-positive patients (14.9%) displayed significantly higher serum levels of IFNα (p = 0.023) and IL-10 (p = 0.016) than their negative counterparts. This cytokine upregulation was independent of the presence of other ANA even though, in our patient cohort, anti-dsDNA was found to be associated with anti-RibP (OR, CI 95%: 6.03, 1.32-27.93, p = 0.021) and to correlate with IL-10 levels (r = 0.204, p = 0.036). In fact, patients positive for anti-RibP but negative for anti-dsDNA exhibited the highest amounts of both IL-10 and IFN-α that were not related to disease activity since these patients showed lower SLEDAI than patients also positive for anti-dsDNA (p = 0.018). Anti-RibP positivity was also associated with early diagnosis, hypocomplementemia and leukopenia.

CONCLUSIONS

Presence of anti-RibP was found to be related to increased serum IFNα and IL-10 levels independently of both antibody status and disease activity.

Genome-wide association study in Asian populations identifies variants in ETS1 and WDFY4 associated with systemic lupus erythematosus

Systemic lupus erythematosus is a complex and potentially fatal autoimmune disease, characterized by autoantibody production and multi-organ damage. By a genome-wide association study (320 patients and 1,500 controls) and subsequent replication altogether involving a total of 3,300 Asian SLE patients from Hong Kong, Mainland China, and Thailand, as well as 4,200 ethnically and geographically matched controls, genetic variants in ETS1 and WDFY4 were found to be associated with SLE (ETS1: rs1128334, P = 2.33×10⁻¹¹, OR = 1.29; WDFY4: rs7097397, P = 8.15×10⁻¹², OR = 1.30). ETS1 encodes for a transcription factor known to be involved in a wide range of immune functions, including Th17 cell development and terminal differentiation of B lymphocytes. SNP rs1128334 is located in the 3′-UTR of ETS1, and allelic expression analysis from peripheral blood mononuclear cells showed significantly lower expression level from the risk allele. WDFY4 is a conserved protein with unknown function, but is predominantly expressed in primary and secondary immune tissues, and rs7097397 in WDFY4 changes an arginine residue to glutamine (R1816Q) in this protein. Our study also confirmed association of the HLA locus, STAT4, TNFSF4, BLK, BANK1, IRF5, and TNFAIP3 with SLE in Asians. These new genetic findings may help us to gain a better understanding of the disease and the functions of the genes involved.

In this study, we first conducted a genome-wide association study in a Hong Kong Chinese population, followed by replication in three other cohorts from Mainland China and a cohort from Thailand, which totaled 3,300 Asian patients and 4,200 ethnically and geographically matched controls. We identified novel variants in ETS1 and WDFY4 associated with SLE with genome-wide significance and confirmed the association of HLA locus, STAT4, BLK, IRF5, BANK1, TNFSF, and IRF5 with the disease. ETS1 encodes a critical transcription factor involved in Th17 and B cell development. Allelic expression study showed a significantly lower expression of ETS1 from the risk allele, which provided functional support to the genetic findings. WDFY4 is a huge protein with unknown function but is predominantly expressed in primary and secondary immune tissues, and a nonsynonymous SNP in this gene was found to be highly associated with SLE susceptibility. Our findings shed new light on the function of these genes as well as the mechanism of this devastating disease.

Anti-ribosomal phosphoprotein autoantibody triggers interleukin-10 overproduction via phosphatidylinositol 3-kinase-dependent signalling pathways in lipopolysaccharide-activated macrophages

Anti-ribosomal phosphoprotein autoantibodies have been shown to be significantly associated with multiple manifestations of systemic lupus erythematosus (SLE). High levels of interleukin-10 (IL-10) have been demonstrated to contribute to lupus susceptibility and severity. In this study, we investigated the molecular mechanisms of anti-ribosomal phosphoprotein monoclonal antibody (anti-P mAb)-induced autoimmune responses. Anti-P mAb promoted IL-10 overproduction in a dose- and time-dependent manner in both lipopolysaccharide (LPS)-activated RAW 264.7 cells and primary human macrophages. Anti-P mAb enhanced phosphorylation of Akt (PKB; protein kinase B), extracellular signal regulated kinase 1/2 (ERK1/2) and c-Jun NH2-terminal kinase 1/2 (JNK1/2), while phosphorylation of p38 remained unaltered. Furthermore, anti-P mAb decreased glycogen synthase kinase 3 (GSK3) activity and reduced the phosphorylation of I kappaB alpha in LPS-activated macrophages. The Syk, phosphatidylinositol 3-kinase (PI3K), protein kinase C (PKC), JNK and ERK signalling pathways involved in anti-P mAb-triggered IL-10 secretion were also confirmed using various pharmacological inhibitors. In addition, nuclear factor (NF)-kappaB had negative regulatory effects on anti-P mAb-triggered IL-10 secretion. Using reporter plasmids containing the nuclear factor binding sites of NF-kappaB, cAMP-enhanced activation protein 1 (AP-1), serum response element (SRE) or cyclic AMP response element (CRE), treatment of anti-P mAb led to activation of the corresponding factors that bind to the AP-1 site, SRE and CRE in the LPS-activated macrophages. Furthermore, by transfection with reporter plasmids bearing various lengths of the IL-10 promoter, the AP-1 binding site, SRE and CRE were shown to be required for anti-P mAb-induced effects. Collectively, our results provide a molecular model for anti-P mAb-induced IL-10 overproduction in LPS-activated macrophages, which may play a role in the pathogenesis of SLE.

Are anti-ribosomal P protein antibodies relevant in systemic lupus erythematosus?

Systemic lupus erythematosus (SLE) is a prototypal auto-immune disorder characterized with multiple organ involvement resulting in disability and increased mortality. Immune regulatory disturbances cumulate in activation of B cells and consequent auto-antibody production. Antigens for these auto-antibodies can be nuclear components and cytoplasmic elements. Anti-P antibodies react against acidic phosphorylated ribosomal proteins P0, P1, and P2 (with molecular mass of 38, 19, and 17 kDa, respectively) and are located on the S60 subunit of ribosomes. Ribosomal P proteins share a common 22-amino acid sequence that is present in the carboxyl-terminal. Anti-P antibodies can be detected in approx 15 to 20% of patients with lupus by several immunoassays, most frequently by enzyme-linked immunosorbent assay (ELISA) and/or Western blotting. However, no standardized assay is available. Auto-antibodies against eukaryotic P proteins appear highly specific for SLE; therefore, they can be used as diagnostic marker for the disease. Furthermore, association has been described with particular manifestations of lupus, especially with neuropsychiatric, renal, and hepatic involvements. Anti-P positivity and the titer of anti-P antibodies also fluctuate with clinical disease activity. Despite several lines of evidence, results are conflicting regarding the existence of such associations. Discrepancies can be explained by different study set-up or study population; it also can be attributed to the different sensitivity of tests used for the detection of anti-P antibody.

Fcgamma receptors mediate internalization of anti-Ro and anti-La autoantibodies from Sjögren's syndrome and apoptosis in human salivary gland cell line A-253

BACKGROUND

The presence of serum anti-Ro and anti-La autoantibodies directed against the ribonucleoproteins Ro and La has been associated with Sjögren's syndrome (SS), an autoimmune rheumatic disease that targets salivary and lachrymal glands. There is increasing evidence of the direct involvement of autoantibodies in the pathogenesis of tissue injury and correlation of their presence with clinical manifestations in SS. The focus of this work was to explore the cellular apoptotic pathway triggered by binding and penetration of anti-Ro and anti-La autoantibodies in human salivary gland cell line A-253 and to identify the membrane receptors through which anti-Ro and anti-La could exert their effect.

METHODS

Anti-Ro and anti-La autoantibodies were purified from IgG fractions, obtained from eleven healthy volunteers and patients with primary Sjögren's syndrome, using Sepharose 4B-Ro and Sepharose 4B-La affinity columns. Flow cytometry, RT-PCR, western blot and confocal microscopy analysis were used to visualize the FCgammaRI, FCgammaRII and FCgammaRIII receptors on the A-253 cell membrane. DNA laddering and western blot analysis of caspases activation were studied to evaluate in A-253 cells treated with anti-Ro and anti-La autoantibodies.

RESULTS

The results yeilded the evidence of the presence of members of the Fcgamma receptors (FcgammaRs) family on the cell membrane of the human salivary gland cell line A-253. Furthermore, we demonstrated that, in the A-253 cell line, anti-Ro and anti-La autoantibodies can access the cells probably through Fcgamma receptors, and trigger apoptotis.

CONCLUSIONS

We conclude that anti-Ro and anti-La autoantibodies have pathogenic effects that could depend on binding to Fcgamma receptors.

Studies on the cell-immunosuppressive mechanism of Oridonin from Isodon serra

Distinct effects of Oridonin and Lasiodonin, which were extracted from Isodon serra was compared by the ratio of IC(50) versus EC(50), the therapeutic index. After choosing the more effective one, Oridonin, its immunosuppressive effect and mechanism were investigated using BALB/c mouse splenic lymphocytes both in vitro and in vivo. When murine splenic lymphocytes was incubated with Oridonin, the novel extract effectively suppress the overproduction of the cell stimulated by Concanavalin A in a dose and time-dependent manner. This inhibitive activity was mainly due to interfering DNA replication in G(1) stages and regulating cell cycle and minorly due to decreasing the CD4(+)/CD8(+) lymphocytes level, according to Flow cytometry analyses (FCAS) results. Xylene-induced mouse tumescence model result suggested that Oridonin depressed the murine ear-swelling extent and the level of Interleukin-2 in the blood serum of experimental animals. The exciting results of enzyme-linked immunosorbent assay (ELISA) indicated that Oridonin could inhibit the secretion of Interleukin-2, Interferon-gamma, Interleukin-12p40 and Tumor necrosis factor-alpha in murine splenic lymphocytes. Moreover, the results of reverse transcriptase-polymerase chain reaction (RT-PCR) confirmed that the inhibition was through decreasing the expression level of these cytokines mRNA. Consequently, the results of our research showed that Oridonin suppressed overproduction of murine splenic lymphocytes through interference of DNA replication, regulation of cell cycle and inhibition of cytokine secretion both at protein and mRNA level.

To smell autoimmunity: Anti-P-ribosomal autoantibodies, depression, and the olfactory system

Central Nervous System involvement in Systemic Lupus Erythematosus (CNS-SLE) is very common and ranges between 25%-70% of the patients. The CNS involvement is listed in the ARA criteria for SLE diagnosis. CNS-SLE is associated with more than 20 different autoantibodies. Yet, remarkable among them are the anti-P-ribosomal antibodies (anti-PR). These autoantibodies directed mainly against the carboxy 22 amino acids of the PO, P1 P2 ribosomal phosphoproteins. They are capable of penetrating lived cells and inducing apoptotic changes as well as leading to inhibition of specific cytokine secretion. The titer of the autoantibodies correlate with disease activity, kidney involvement and hepatitis. In this review, the mechanisms involved in CNS involvement and its relationship with anti-P ribosomal antibodies will be described.

Increased nitric oxide levels and nitric oxide synthase isoform expression in the cerebellum of the taiep rat during its severe demyelination stage

We have previously reported progressive reactive astrocytes in the cerebellum of taiep rats, one of the most regions affected by demyelination, and activation of cerebellar glial cells in vitro. Based on the hypothesis that activated glial cells produce high levels of reactive nitrogen intermediates, we assessed the production of nitric oxide (NO) and the expression of the three NO synthases (NOS) in the cerebellum of 6-month-old taiep rats. A significant 40% increase of NO levels was measured in taiep rats when compared with controls. The protein and mRNA levels of the three NOS isoforms were also significantly increased. In contrast to controls, immunostaining assays against nNOS or iNOS showed an increased number of immunoreactive glial cells in the granular layer (nNOS) and Purkinje layer (iNOS) of cerebellum of taiep rats. Microglia-macrophages and both CD4- and CD8-immunoreactive cells were observed in cerebellar white matter of taiep rats only, thus suggesting other possible cell sources of those NOSs. Differences in the cellular location for eNOS immunoreactivity were not observed. The enhanced levels of NO, NOS proteins, mRNAs, and NOS immunoreactivities in glial cells and microglia strongly suggest glial activation together with the professional immune cells can aggravate the demyelination of aged taiep rats.

Clinical and biological aspects of anti-P-ribosomal protein autoantibodies

Among the many clinical manifestations of systemic lupus erythematosus (SLE), central nervous system (CNS) involvement is of a prognostic importance. In this respect, anti-ribosomal P protein antibodies were shown by many to occur in association with SLE neuropsychiatric manifestations, mainly psychosis. The prevalence of anti-P antibodies was strongly related to disease activity wherein disease remission was associated with the disappearance of these antibodies. In addition to its association with CNS involvement, the occurrence of liver and kidney disease in SLE patients with anti-P antibodies was widely reported. Anti-P antibodies are able to bind T cells, monocytes, neurons and hepatocytes thereby enhancing the production of pro-inflammatory cytokines and both CNS and liver damage. Similar to the ability of anti-dsDNA antibodies, anti-P antibodies were shown to penetrate into living cells, leading to cell dysfunctions such as cell apoptosis. These biological aspects may play an important role in the pathogenesis of SLE.