Immunoglobulin G amplifies the production of regulatory rheumatoid factor in vitro through idiotype-anti-idiotype interactions.

Immunoglobulin G can inhibit antibody response. The mechanism of immunosuppression by immunoglobulins remains unknown. Recently, we found a new factor of immunoregulation referred to as regulatory rheumatoid factor (regRF). RegRF prevents autoimmunity and reduces experimental autoimmune reactions. RegRF comprises a population of anti-idiotypic antibodies that have a unique paratope specific to the antigen-binding sites of the antibodies, and a shared paratope specific to neoepitopes of IgG Fc fragments. Given the specificity of regRF, we can anticipate that IgG would be able to induce regRF production, and consequently that the immunosuppressive effect of IgG may be mediated by regRF. We found that IgG induces regRF production in a culture of B lymphocytes obtained from the red bone marrow of intact rats. IgG does not expose neoepitopes recognized by the shared paratope of regRF, and does not acquire them in culture. Therefore, the stimulation of regRF production induced by IgG is not a result of the interaction between the shared paratope of regRF and the neoepitopes of IgG. Fc fragments of IgG are unable to stimulate regRF production. Fab fragments inhibit spontaneous regRF production. F(ab´)2 fragments stimulate regRF production in lymphocyte culture. We theorize that IgG activates regRF-producing lymphocytes through idiotype-anti-idiotype interactions.

Rheumatoid factor as predictor of response to treatment with anti-TNF alpha drugs in patients with rheumatoid arthritis: Results of a cohort study.

We determined whether rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibody (ACPA) can predict remission or severe disability in rheumatoid arthritis (RA) patients treated with anti-tumor necrosis factor (TNF) alpha drugs.We performed a cohort study based on the clinical data from a referral center for the treatment of RA in Bogotá, Colombia, were included patients aged ≥18 years with diagnosis of RA with an active disease and for whom a treatment scheme was begun with anti-TNF alpha medication, with a minimum follow-up time of 12 months. Disease activity of Rheumatoid Arthritis was assessed through measurement of RF, ACPA, disease activity score (DAS28), and health assessment questionnaire (HAQ). We calculated the incidence rates (IRs) for remission and severe disability. We also calculated the incidence rate ratio (IRR) for each outcome by adjusting for possible confounders using the Poisson regression method. The hypothesis was tested with a P value of <.05. Statistical analysis was performed in Stata 15.We included 400 patients receiving an anti-TNF alpha agent. Median age was 60 years, and 322 patients were women (80.5%). RF was positive in 357 patients (89%), ACPA in 348 patients (87%), and co-positivity in 324 patients (81%). Median follow-up was 41 months (range, 12-79 months). The IR for remission was 23 per 100 person-years in RF-negative patients and 16 per 100 person-years in RF-positive patients. The adjusted IRR (age sex, treatment, and ACPA) was 1.51 (95%CI, 1.05-2.18). The IR for severe disability was 10.8 per 100 person-years in the RF-positive cohort and 2.3 per 100 person-years in the RF-negative cohort. The IRR adjusted for these factors was 4.37 (95%CI, 1.6-12). Co-positivity had a similar behavior to RF. No differences were recorded in the rates of remission or disability in ACPA-positive and ACPA-negative patients.Our findings suggest that remission is less frequent and severe disability more frequent in RF-positive patients treated with anti-TNF alpha agents than in RF-negative patients.

The Role of Neutrophil Proteases in LPS-Induced Production of Regulatory Rheumatoid Factor that Suppresses Autoimmunity.

BACKGROUND: We recently identified a regulatory rheumatoid factor (regRF), the production of which is associated with autoimmune disease resistance and remission. In studies of regRF in the blood of healthy rats, spontaneous increases in the regRF level were noted. We suggest that in the normal state, a mechanism exists for maintaining the activity of the pool of regRF-producing lymphocytes at a level that makes it possible to control the expansion of autoreactive lymphocytes. OBJECTIVE: The purpose of this study was to test the hypothesis that the endogenous stimulator of regRF production is Fc fragments of IgG that are formed upon exposure to the proteases of neutrophils. RESULTS: Injection of Salmonella typhi LPS caused neutrophilic leukocytosis in the rats, followed by elevated level of regRF. Neutrophils were obtained from LPS-treated rats and then treated with LPS in vitro to degranulate them to form pre-split IgG that exposes antigenic determinants for regRF. A condition required for Fc fragments to be formed by neutrophils is that the pre-split IgG must be treated with a thiol reducing agent. Antigenic determinants for regRF were retained by Fc fragments of IgG. CONCLUSION: Thus, the pre-split IgG and Fc fragments of IgG formed by LPS-activated neutrophils are the potential physiological activators of regRF production.

Aging-dependent decline of IL-10 producing B cells coincides with production of antinuclear antibodies but not rheumatoid factors.

Aging is associated with development of autoimmunity. Loss of B cell tolerance in the elderly is suggested by an increased prevalence of anti-nuclear antibodies (ANAs) and rheumatoid factors (RFs). Accumulating evidence indicates that B cells also impact autoimmunity via secretion of cytokines. So far, few studies have directly assessed the effect of aging on the latter B cell function. Here, we determined if and how human aging influences the production of cytokines by B cells. In a cross-sectional study, we found that absolute numbers of circulating B cells were similar in 31 young (ages 19-39) and 73 old (age ≥ 60) individuals. Numbers of transitional B cells (CD19(+)CD27(-)CD38(High)CD24(High)) were decreased in old individuals, whereas numbers of naive and memory B cell subsets were comparable in young and old individuals. Short-term in vitro stimulation of whole blood samples revealed that numbers of B cells capable of producing TNF-α were similar in young and old individuals. In contrast, B cells capable of IL-10 production were decreased in old subjects. This decline of IL-10(+) B cells was observed in old individuals that were ANA positive, and in those that were negative for both ANAs and RFs. However, IL-10(+) B cells were remarkably well retained in the circulation of old subjects that were RF positive. Thus, pro-inflammatory TNF-α(+) B cells are retained in the elderly, whereas IL-10(+) B cells generally decline. In addition, our findings indicate that IL-10(+) B cells may differentially impact the development of ANAs and RFs in the elderly.

Disease-modifying anti-rheumatic drugs improve autonomic neuropathy in arthritis: DIANA study.

Autonomic neuropathy (AN) is a risk predictor for sudden cardiac death in rheumatoid arthritis (RA) and ankylosing spondylitis (AS). However, the impact of most commonly employed disease-modifying anti-rheumatic drug (DMARD) therapy on autonomic neuropathy in rheumatic diseases is not known. Hence, we investigated the efficacy of DMARDs on autonomic neuropathy in RA and AS. We performed autonomic function assessment in 60 patients in this open-label, 12-week pilot study including 42 patients with RA, 18 with AS, and 30 aged-matched healthy subjects. The methodology included assessment of cardiovascular autonomic reflex tests according to Ewing. Parasympathetic dysfunction was established by performing three tests: heart rate response to deep breathing, standing, and Valsalva tests. Sympathetic dysfunction was examined by applying two tests: blood pressure response to standing and handgrip tests. Sudomotor function was assessed by Sudoscan. Cardiovascular reflex tests were impaired significantly among the patients as compared to healthy subjects (p < 0.05). Autonomic neuropathy was more pronounced in biologic-naive RA and AS patients. After treatment with combination synthetic DMARDs, parasympathetic, and sudomotor dysfunction significantly (p < 0.05) improved in RA and AS. Biologic DMARDs significantly improved parasympathetic, sympathetic and peripheral sympathetic autonomic neuropathy (p < 0.05) in biologic-naive RA and AS patients. In conclusion, synthetic DMARDs improved parasympathetic and sudomotor dysfunction in both DMARD-naive RA and AS patients. However, biologic DMARDs improved parasympathetic, sympathetic and sudomotor dysfunction to a greater extent than synthetic DMARDs in both RA and AS patients.

Elevated serum resistin in juvenile idiopathic arthritis: relation to categories and disease activity.

BACKGROUND: Juvenile Idiopathic Arthritis (JIA) is one of the more common chronic diseases of childhood that often persists into adulthood and can result in significant long-term morbidity, including physical disability. The aim of the present study was to assess the serum level of resistin in JIA patients and compare its levels according to the categories, clinical manifestations and disease activity. METHODS: Sixty-eight JIA patients and 33 age and sex matched control children were included in the present study. All patients included in this study were subjected to full history taking, clinical examination. Juvenile arthritis disease activity score in 27 joints (JADAS-27) was calculated and Childhood Health Assessment Questionnaire (CHAQ) was used to measure the functional status. Serum resistin levels were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: The mean serum resistin was significantly higher in the JIA patients (4.01 ± 2.46 ng/ml) compared to the control (2.08 ± 1.23 ng/ml) (p<0.001) especially those with systemic-onset. Its level was significantly higher in those receiving steroids and those with a positive antinuclear antibody. Resistin significantly correlated with the JADAS27 (r 0.26, p 0.035) and CHAQ (r 0.4, p 0.001). The JIA patients were 50 females and 18 males; however, the level of resistin was insignificantly different according to the gender although there was a tendency to be higher in females. CONCLUSION: Our results reinforce the proposition of an important role for resistin in JIA and may be considered an interesting biomarker for disease activity especially those with systemic onset.

Rheumatoid arthritis: from autoimmunity to synovitis and joint destruction.

Rheumatoid arthritis is an autoimmune disease characterized by the production of two known antibodies - rheumatoid factor and anti-citrullinated peptide antibody (ACPA) - against common autoantigens that are widely expressed within and outside the joints. The interactions between genes and environment are crucial in all stages of the disease, involving namely genes from major histocompatibility complex locus, and antigens such as tobacco or microbes (e.g. Porphyromonas gingivalis). T and B cells are activated as soon as the earliest phases of the disease, rheumatoid arthritis appearing as a Th1 and Th17 disease. Inflammatory cytokines have a considerable importance in the hierarchy of the processes involved in RA. The joint destruction seen in RA is caused not only by cytokine imbalances, but also by specific effects of the Wnt system and osteoprotegerin on osteoclasts and by matrix production dysregulation responsible for cartilage damage. Both innate and adaptative immunity demonstrated their respective cornerstone position in rheumatoid arthritis, since targeted treatments has been efficiently developed against TNF-α, IL-6 receptor, IL-1ß, CD20 B cells and T-cell/Dendritic cell interactions.

IL-17 patterns in synovium, serum and synovial fluid from treatment-naïve, early rheumatoid arthritis patients.

BACKGROUND: There are actually becoming controversial data regarding the profiles of interleukin-17 (IL-17) in different pathogenical stages of rheumatoid arthritis (RA). OBJECTIVES: To assessing the IL-17 patterns in synovium, serum and synovial fluid from treatment-naïve early RA patients and to identifying potential correlations with disease activity markers and with synovial histopathological profile. MATERIALS AND METHODS: Serum samples from 30 treatment-naïve early RA patients were evaluated for C-reactive protein (CRP), erythrocytes sedimentation rate (ESR), rheumatoid factor (RF), anti-cyclic citrullinated peptide antibodies (anti-CCP). IL-17A levels were also assessed in serum and synovial fluid (SF). Disease activity score (DAS28) calculation was done for all patients. Control serum and SF samples were obtained from 29 patients with osteoarthritis (OA); control synovium specimens were obtained from eight patients with OA and during surgery for knee tear ligaments. Histopathological (Hp) score, immunohistochemical reactivity for IL-17 were also assessed in synovium of early RA patients and controls. Dependencies between serum and synovial profile of IL-17A and the other parameters were statistically tested. RESULTS: In early RA patients, strong correlations of serum and SF IL-17A levels were found with ESR, CRP, RF, anti-CCP, Hp score and IL-17 synovial immunoreactivity; a good correlation was noted with DAS28 score. Also, strong correlation was noted between serum and SF IL-17A levels. CONCLUSIONS: In early stages of untreated RA, simultaneous IL-17 assessment of serum, SF and synovium might be valuable in defining activity and predictive patterns, given that synovium is highly suggestive for an disease aggressivity and might express specific therapeutically targets.

Role of PIR-B in autoimmune glomerulonephritis.

PIR-B, an inhibitory receptor expressed on murine B cells and myeloid cells, regulates humoral and cellular immune responses via its constitutive binding to the ligand, MHC class I molecules, on the same cells (cis) or on different cells (trans). Although it has been speculated that PIR-B is important for maintaining peripheral tolerance, PIR-B single deficiency does not cause overt autoimmune diseases. Recently, however, the combination of its deficiency with the Fas lpr mutation was found to result in augmented production of autoantibodies such as IgG rheumatoid factor and anti-DNA IgG, leading to glomerulonephritis in mice. Although the precise molecular mechanism for the overall scenario is unclear, PIR-B was found to suppress TLR9-mediated production of naturally autoreactive antibodies by innate B cells or B-1 cells by inhibiting the activation of Bruton's tyrosine kinase. Thus, PIR-B is an important regulator of innate immunity mediated by TLR9 in B-1 cells, which can otherwise provoke autoimmunity when overactivated.

Outcomes in recent-onset inflammatory polyarthritis differ according to initial titers, persistence over time, and specificity of the autoantibodies.

OBJECTIVE: To prospectively evaluate the predictive value of initial titers and subsequent variations of 3 rheumatoid arthritis­associated antibodies for outcomes at 30 months in patients with recent-onset polyarthritis. METHODS: IgM rheumatoid factor (RF), anti-Sa (citrullinated vimentin) antibodies, anti­ cyclic citrullinated peptide 2 (anti­CCP-2) antibodies, modified Health Assessment Questionnaire score, Disease Activity Score in 28 joints, and Sharp/van der Heijde radiologic scores were determined at baseline and at 18 and 30 months in a cohort of consecutive HLA­DR-typed treated patients with recent-onset polyarthritis aiming at remission. RESULTS: At inclusion, 113 (44.7%), 58 (22.9%), and 97 (38.3%) of 253 recent-onset polyarthritis patients were positive for RF, anti-Sa, and anti­CCP-2, respectively; at 30 months, 85 (33.6%), 31 (12.4%), and 100 (39.5%) patients were similarly positive. A low titer of any particular antibody was associated with higher risks for seroreversion. Similar to their persistent absence, reversion of RF and anti­CCP-2 was associated with low risks for severity. Patients who acquired RF or anti­CCP-2 after inclusion trended toward a poor prognosis. Relative to RF and anti­CCP-2 antibodies, only the presence of anti-Sa at inclusion, especially at higher titers and even when it subsequently disappeared, significantly predicted more rapid radiographic damage and lower remission rates at 30 months. CONCLUSION: In treated recent-onset polyarthritis, anti­CCP-2 prevalence is stable or increases slightly, whereas anti-Sa and RF frequently disappear. Subsequent reversion and conversion of RF and anti­CCP-2 blur the prognostic significance of initial RF and anti­CCP-2 positivity. Of the 3 antibodies, only anti-Sa, even if it disappears afterward, independently predicts severe outcomes.

Autologous stromal vascular fraction cells: a tool for facilitating tolerance in rheumatic disease.

Since the days of Medawar, the goal of therapeutic tolerogenesis has been a "Holy Grail" for immunologists. While knowledge of cellular and molecular mechanisms of this process has been increasing at an exponential rate, clinical progress has been minimal. To provide a mechanistic background of tolerogenesis, we overview common processes in the naturally occurring examples of: pregnancy, cancer, oral tolerance and anterior chamber associated immune deviation. The case is made that an easily accessible byproduct of plastic surgery, the adipose stromal vascular fraction, contains elements directly capable of promoting tolerogenesis such as T regulatory cells and inhibitory macrophages. The high content of mesenchymal and hematopoietic stem cells from this source provides the possibility of trophic/regenerative potential, which would augment tolerogenic processes by decreasing ongoing inflammation. We discuss the application of this autologous cell source in the context of rheumatoid arthritis, concluding with some practical examples of its applications.

[Incidence of serum rheumatoid factors in elder non-rheumatic individuals].

With the aging of the Japanese population, an increase in the number of elderly patients with rheumatoid arthritis (RA) has been noted in recent years. Although rheumatoid factor (RF) is found in a high proportion of RA patients, it is also known to be present in non-rheumatoid patients. However, no studies have investigated the rate of RF positivity in elderly non-rheumatoid individuals. In this study, we examined the rate of RF positivity in such individuals and the association between smoking and RF production. The subjects were 25 men (aged 67 to 87 years, with a mean of 74.0) and 24 women (aged 60 to 86 years, with a mean of 70.7). Of these subjects, nine (18.4%), including seven men, were RF-positive. A significant positive correlation was observed between age and RF values (n=49, p<0.05). Of 23 subjects with a smoking habit, eight (34.8%) were RF-positive. In contrast, only one (3.8%) of 26 nonsmokers was RF-positive. This difference in the rate of RF positivity was significant (p<0.01). In addition, a significant positive correlation was noted between the duration of smoking and rate of RF positivity (p<0.05), particularly in men (p<0.01). These results suggest that smoking is closely involved in RF production in the elderly.

Autoantibodies in silicosis patients and in silica-exposed individuals.

The aim of this study was to evaluate the prevalence of autoantibodies in silica-exposed patients with and without silicosis and without any known rheumatic disease. We studied 61 males exposed to silica for a mean time of 12.2 +/- 10.2 years of exposure. A total of 72.1% (44/61) of them presented with pulmonary silicosis. As control group we included 62 healthy males. In all samples we screened for rheumatoid factor (latex agglutination), antinuclear antibodies (indirect immunofluorescence), anti Scl-70 (ELISA) and ANCA (indirect immunofluorescence technique). One patient (1.6%) of the silica group had weakly positive ANA (titer 1:80, centromeric pattern); one (1.6%) had atypical ANCA and seven patients (11.4%) presented positive rheumatoid factor (values range from 8 to 32 UI/ml). One control patient had a positive RF and none of them had positive ANA or ANCA. All patients and controls were negative for anti-Scl-70. The finding of positive RF was higher in the silica-exposed patients (p = 0.032; Fisher). All patients with positive RF had pulmonary silicosis. In the silica-exposed group we could not find a relationship between the presence of RF and age (p = 0.21; Mann-Whitney), smoking habits (p = 0.25; Fisher) but a positive relationship was found with exposure time to silica dust (p = 0.005; Mann-Whitney). We conclude that there was 11.4% prevalence of low titer RF in the silica-exposed patients without known rheumatic disease. RF was more common in patients with longer exposure to silica dust and appeared only in those with silicosis. The presence of ANA, Scl-70 and ANCA was the same as in the control population.

Different properties of ACPA and IgM-RF derived from a large dataset: further evidence of two distinct autoantibody systems.

INTRODUCTION: The aim of this study was to examine seroconversion and the relationship with age and inflammation of autoantibodies in a large group of patients attending an outpatient rheumatology clinic. METHODS: Levels of antibodies to citrullinated proteins/peptides (ACPAs) and IgM rheumatoid factor (IgM-RF) were determined in 22,427 samples collected from 18,658 patients. The diagnosis was derived from a diagnosis registration system. The degree of seroconversion in repeated samples and the correlation of levels with age and inflammatory markers were determined for ACPA and IgM-RF in rheumatoid arthritis (RA) and non-RA patients. RESULTS: Seventy-one percent of RA patients (n = 1,524) were ACPA-positive and 53% were IgM-RF-positive; in non-RA patients (n = 2,245), the corresponding values were 2% and 4%, respectively. In patients with at least two samples (n = 3,769), ACPA status was more stable than IgM-RF status in RA patients. ACPA- or IgM-RF-negative non-RA patients seldom became positive. ACPA positivity was unrelated to age in both RA and non-RA patients. IgM-RF positivity was unrelated to age in RA patients; however, it increased with age in non-RA patients. The correlation between autoantibody levels and inflammatory markers was low in general and was somewhat higher for IgM-RF than for ACPA. CONCLUSIONS: ACPA status is more stable in time and with increasing age than IgM-RF status, further establishing its role as a disease-specific marker. ACPA and IgM-RF levels are only moderately correlated with markers of inflammation.

Ongoing somatic hypermutation of the rearranged VH but not of the V-lambda gene in EBV-transformed rheumatoid factor-producing lymphoblastoid cell line.

Epstein-Barr virus (EBV) transforms human peripheral B cells into lymphoblastoid cell lines (LCLs) that secrete specific antibodies. In contrast to peripheral blood B cells, LCLs express the activation-induced cytidine deaminase (AID) gene, a key enzyme in the generation of somatic hypermutation (SHM) in immunoglobulin variable genes. We have previously studied an LCL that secretes a rheumatoid factor (RF: an IgM(lambda) anti-IgG antibody) and identified the accumulation of SHM at a frequency of 1.5 x 10(-3)mut/bp in the rearranged variable region heavy chain gene (VH) of its RF sub-culture (i.e., RF-2004). The aim of the present work was to find out whether SHM was initiated as an early event following EBV transformation. Our results show that already the earliest RF-culture (RF-1983) mutates its VH at a somewhat higher frequency of 1.9 x 10(-3). Overall, we detected 17 point mutations in the RF-2004 culture and in 26 cellular clones derived from the RF-1983 and RF-2004 cultures. Most of the mutations were due to C to T or G to A transitions, with preferential targeting to WRCH/DGYW hotspot motifs, indicating that they were due to the initial phase of AID-directed mutations. A genealogical tree demonstrates that mutations were accumulated in a stepwise manner with 1-2 mutations per cell division. However, no mutations were found in the rearranged V-lambda (Vlambda) gene in the same RF-cultures and their subclones (i.e., <1.2 x 10(-4)mut/bp). To our knowledge this is the first reported clonal cell line that generates SHM in the VH, but not in the Vlambda. It may be due to abrogation of a cis-regulatory element(s) in the Vlambda or to a lack of a specific trans-acting factor which differentially direct the SHM machinery to this gene. Out of the 17 point mutations detected in both cell lines there were, 1 stop codon, 3 mutations which obliterated the binding of the RF antibody to its IgG antigen and 1 or 2 mutations which enhanced antigen-binding affinity. These results show that the evolutionary developed germline encoded antibody combining site is highly sensitive to amino acid replacements. Our combined findings that the RF cells accumulate in a stepwise manner up to 1-2 point mutations/sequence per cell division and the generation of high percentage of functionally deleterious mutations, are in accord with the 'multiphase-recycling model' of SHM, which states that B cells in the germinal center are subjected to multiple rounds of somatic mutations interchanged with periods of antigenic selection.

B cells in rheumatoid arthritis.

Though its etiology remains unknown thus far, the role that autoimmune processes play in rheumatoid arthritis (RA) pathogenesis has been widely proven. Given the easier accessibility of humoral components, the first feature of this contribution to be recognized has been the occurrence of the so-called rheumatoid factor in a large proportion of RA patients. This antibody recognizes the Fc portion of human IgG. By investigating RA pathologic processes and also through experimental models where immune complexes play a fundamental role, many other autoantibodies have then come to our knowledge to be associated with the disease. Their presence and persistence implies that clones of autoreactive B cells survive and proliferate in RA patients under a continuous stimulation. Whether this is a mechanism of disease initiation or just an epiphenomenon is still unclear but no doubt exists that autoantibodies represent a very useful tool in both diagnostic and prognostic terms. Being much more than simple autoantibody producers, B cells are able to secrete many important cytokines and to efficiently present antigens to T lymphocytes in the synovial environment. All of these functions are essential in the development of RA, and lately have claimed attention as B cell depletion has become a common and effective strategy of treatment in RA.

Effects of low-dosage simvastatin on rheumatoid arthritis through reduction of Th1/Th2 and CD4/CD8 ratios.

The objective of this study was to assess both the anti-inflammatory and immunomodulatory effects of low-dosage simvastatin on rheumatoid arthritis (RA). In each patient, simvastatin at 10 mg/day was administered for 12 weeks. The other treatments were unchanged at least 3 months before simvastatin administration to the end of the study. Patients were assessed for the improvement in clinical, laboratory, and immunological parameters of RA and for adverse events. Twenty-four patients with RA were enrolled. Clinical symptoms, including patient's assessment of pain and disease activity on visual analog scale (VAS), the swollen joint and tender joint counts, and handgrip strength significantly improved. Physician's assessment of disease activity on VAS, a period of morning stiffness and modified health assessment questionnaire showed a tendency of improving after administration of low-dosage of simvastatin. Of special interest was that the median levels of erythrocytes sedimentation rate, C-reactive protein, and rheumatoid factor were significantly decreased from 54.0 mm/h to 45.5 mm/h, from 1.50 mg/dl to 0.85 mg/dl, and from 57.0 IU/ml to 28.0 IU/ml, respectively, after administration of simvastatin. ACR20 and ACR50 responses were achieved in 62% and 38%, respectively, of simvastatin-treated patients for 12 weeks. Immunological assessment in peripheral blood revealed that the Th1/Th2 and CD4/CD8 ratios were significantly reduced by simvastatin. No adverse events were reported during simvastatin treatment. Immunomodulation through the alteration of Th1/Th2 and CD4/CD8 ratios may be a pharmacological mechanism in the anti-rheumatic effect of low-dosage simvastatin. Although it is necessary to evaluate the long-term effects of statins, low-dosage statins appear to be good as additional therapeutic agents.

IgM plays an important role in induction of collagen-induced arthritis.

IgM is one major type of B cell receptor (BCR) expressed on most of the B cells from immature to mature stages. During normal B cell ontogeny, signals transduced through the IgM BCR play an important role in regulating B cell maturation and survival at multiple checkpoints. In addition, IgM BCR is also required for antigen-dependent differentiation and activation of B cells. However, whether IgM BCR-mediated signalling is important for the pathogenesis of autoimmune diseases remains elusive. Using IgM-deficient mice, we examined the effect of absence of IgM on the development of collagen-induced arthritis (CIA), an animal model of rheumatoid arthritis (RA). Compared to their wild-type littermates, IgM-deficient mice were either resistant to arthritis induction or developed significantly less severe arthritis. There was a significant decrease of autoantibody production in IgM-deficient mice, particularly IgG2a antibodies, which is believed to be pathogenic in CIA. Thus, although IgM(-/-) mice have relatively normal B cell development with IgD BCR replacing IgM BCR, the absence of IgM-mediated signals has a profound impact on the development of CIA, indicating that IgM plays an important role in the development and pathogenesis of autoimmune arthritis and IgM-mediated signalling is critical in the generation of pathogenic autoreactive antibodies.

Rheumatoid factor induction in murine models of liver injury.

Alcoholic liver disease and hepatitis C are associated with the production of autoantibodies such as rheumatoid factors (RF), which bind to IgG and can aid in host defence, but are also associated with pathological conditions such as rheumatoid arthritis. Because little is known about the role of RF in liver disease, we characterized the RF production that either occurred spontaneously in response to alcohol consumption or was induced by injection of an Escherichia coli glycolipoprotein in C57Bl/6 mice. Whereas severe liver damage was induced by carbon tetrachloride (CCl(4)), minimal damage was caused by chronic alcohol consumption. Liver damage was monitored by measurements of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Circulating RF was induced in response to chronic alcohol consumption; the latter probably involved Toll-like receptor ligation. In contrast, CCl(4)-induced damage was not associated with RF induction. However, concurrent treatment with an E. coli glycolipoprotein macromolecule that induced RF, protected against CCL(4)-induced liver damage as measured by a highly significant decrease (P = 0.008) at 4 weeks in AST and ALT. RF induced by E. coli glycolipoprotein correlated with 'protection' from liver damage, indicating that the RF autoimmune response does not necessarily exacerbate liver disease.

Agonistic antibodies to Fas induce a breach in the endothelial lining of the liver and a breakdown in B cell tolerance.

Liver disease can be associated with a breakdown in self-tolerance and the production of autoantibodies such as rheumatoid factors (RF), which bind to IgG. Here we investigated whether primary, non-infectious liver damage was sufficient to induce autoantibody production. We established a model of targeted liver damage induced by weekly sublethal injections of pro-apoptotic anti-Fas (CD95) antibodies. Liver damage, monitored by measurements of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, was minimal 1 week after anti-Fas injection. However, the sublethal Fas stimulation was sufficient to trigger significant haemorrhage in the liver, as assessed by Evans Blue dye leakage into the organ 5 h after anti-Fas antibody injection. We observed an induction of RF in response to the weekly injections of sublethal anti-Fas antibodies but not of isotype control antibodies, indicating a breakdown of self-tolerance induced by Fas engagement. RF induction was unlikely to be due to direct activation of B cells, as splenocytes stimulated with anti-Fas antibodies in vitro did not produce RF. These studies show that sublethal damage to the liver by Fas engagement leads to liver haemorrhage and is sufficient to trigger the breakdown of self-tolerance.