Impaired ATM activation in B cells is associated with bone resorption in rheumatoid arthritis

Patients with rheumatoid arthritis (RA) may display atypical CD21^-/lo B cells in their blood, but the implication of this observation remains unclear. We report here that the group of patients with RA and elevated frequencies of CD21^-/lo B cells shows decreased ataxia telangiectasia-mutated (ATM) expression and activation in B cells compared with other patients with RA and healthy donor controls. In agreement with ATM involvement in the regulation of V(D)J recombination, patients with RA who show defective ATM function displayed a skewed B cell receptor (BCR) Igκ repertoire, which resembled that of patients with ataxia telangiectasia (AT). This repertoire was characterized by increased Jκ1 and decreased upstream Vκ gene segment usage, suggesting improper secondary recombination processes and selection. In addition, altered ATM function in B cells was associated with decreased osteoprotegerin and increased receptor activator of nuclear factor κB ligand (RANKL) production. These changes favor bone loss and correlated with a higher prevalence of erosive disease in patients with RA who show impaired ATM function. Using a humanized mouse model, we also show that ATM inhibition in vivo induces an altered Igκ repertoire and RANKL production by immature B cells in the bone marrow, leading to decreased bone density. We conclude that dysregulated ATM function in B cells promotes bone erosion and the emergence of circulating CD21^-/lo B cells, thereby contributing to RA pathophysiology.

IL-10 signaling in CD4+ T cells is critical for the pathogenesis of collagen-induced arthritis

INTRODUCTION

IL-10 is a very important anti-inflammatory cytokine. However, the role of this cytokine in T cells in the pathogenesis of collagen-induced arthritis is unclear. The purpose of this study was to define the role of IL-10 signaling in T cells in the pathogenesis of collagen-induced arthritis.

METHODS

IL-10 receptor dominant-negative transgenic (Tg) and control mice were immunized with bovine type II collagen to induce arthritis. The severity of arthritis was monitored and examined histologically. T-cell activation and cytokine production were analyzed using flow cytometry. T-cell proliferation was examined by [3H]thymidine incorporation. Antigen-specific antibodies in serum were measured by ELISA. Foxp3 expression in CD4+ regulatory T cells (Tregs) was determined by intracellular staining or Foxp3-RFP reporter mice. The suppressive function of Foxp3+ CD4+ Tregs was determined in vitro by performing a T-cell proliferation assay. The level of IL-17 mRNA in joints was measured by real-time PCR. A two-tailed nonparametric paired test (Wilcoxon signed-rank test) was used to calculate the arthritis and histological scores. Student's paired or unpaired t-test was used for all other statistical analyses (InStat version 2.03 software; GraphPad Software, San Diego, CA, USA).

RESULTS

Blocking IL-10 signaling in T cells rendered mice, especially female mice, highly susceptible to collagen-induced arthritis. T-cell activation and proliferation were enhanced and produced more IFN-γ. The suppressive function of CD4+ Foxp3+ regulatory T cells was significantly impaired in Tg mice because of the reduced ability of Tregs from Tg mice to maintain their levels of Foxp3. This was further confirmed by transferring Foxp3-RFP cells from Tg or wild-type (Wt) mice into a congenic Wt host. The higher level of IL-17 mRNA was detected in inflammatory joints of Tg mice, probably due to the recruitment of IL-17+ γδ T cells into the arthritic joints.

CONCLUSION

IL-10 signaling in T cells is critical for dampening the pathogenesis of collagen-induced arthritis by maintaining the function of Tregs and the recruitment of IL-17+ γδ T cells.

From T to B and back again: positive feedback in systemic autoimmune disease

Systemic lupus erythematosus, a prototypical systemic autoimmune disease, is the result of a series of interactions within the immune system that ultimately lead to the loss of self-tolerance to nuclear autoantigens. Here, we present an integrated model that explains how self-tolerance is initially lost and how the loss of tolerance is then amplified and maintained as a chronic autoimmune state. Key to this model are the self-reinforcing interactions of T and B cells, which we suggest lead to perpetuation of autoimmunity as well as its spread to multiple autoantigen targets.

Safety and immunogenicity of an outer surface protein A vaccine in subjects with previous Lyme disease

The safety and immunogenicity of a recombinant outer surface protein A (OspA) Lyme vaccine in patients previously diagnosed with Lyme disease was assessed in a dose-ranging, prospective study. Thirty healthy volunteers were consecutively assigned to receive three doses of 3, 10, or 30 micrograms of OspA vaccine at 0, 1, and 2 months. Subjects were seen 3 days after each vaccine dose and 1 month after completion of the three-dose schedule. Local side effects included soreness, induration, swelling, and redness. Transient systemic side effects occurred in 21 subjects, the majority of which (81%) were characterized as mild. Solicited symptoms included migratory mild arthralgias that lasted 24 h in 3 subjects. Side effects were not more evident after the second or third dose. Of the patients, 93% developed high-titer OspA antibodies. Thus, an OspA vaccine may be safe and immunogenic in patients with a history of Lyme disease.

T cells with gamma/delta T cell receptors (TCR) of intestinal type are preferentially expanded in TCR-alpha-deficient lpr mice

Fas-mediated apoptosis is essential for activation-induced cell death of alpha/beta T cells, but it is not clear what role, if any, it plays in regulating other components of the immune system. To study the role of Fas in gamma/delta T cell development, Fas-deficient lpr mice were bred with T cell receptor alpha gene-ablated (TCR-alpha-/-) mice to generate mice deficient in one or both genes. The TCR-alpha-/-, lpr/lpr mice had a nearly 10-fold increase in total lymph node cell (LNC) number compared with Fas-intact TCR-alpha-/- mice, because of expansion of TCR-gamma/delta+ and TCR-beta+ cells. In Fas-intact TCR-alpha-/- mice, approximately one third of the LNCs expressed TCR-gamma/delta. These were evenly divided between the CD4-, CD8-alpha+ and the CD4-, CD8- subsets, and rarely expressed the B220 epitope of CD45. In contrast, in TCR-alpha-/-, lpr/lpr mice, TCR-gamma/delta+ cells comprised half of the LNCs and were primarily CD4-, CD8-, and B220+. Moreover, Fas deficiency in TCR-alpha-/- mice caused a preferential expansion of gamma/delta T cells expressing variable region genes characteristic of intestinal intraepithelial lymphocytes. These results demonstrate a role for Fas in regulating the gamma/delta T cell contribution to peripheral lymph nodes. This mechanism may be most important in limiting the access of activated intestinal intraepithelial lymphocytes to the peripheral lymphoid system.

Molecular structure and function of autoantigens in systemic sclerosis

Autoantibodies in systemic sclerosis target a limited set of nuclear proteins, principally those of the nucleolus and RNA transcription complexes. These antibodies have proved helpful in diagnosis of this disease, and have been used extensively as probes of nuclear structure and function. Despite these advances, the events that initially trigger autoantibody production in systemic sclerosis are not yet known. While these ANA are not known to disrupt cellular processes by entering living cells, or to cause tissue injury (in contrast to SLE, where autoantibodies may mediate tissue damage), it seems likely that they do not merely represent epiphenomena of the disease. Rather, it is logical to assume that their origin is in some manner tied to etiology of systemic sclerosis, since they segregate by syndrome within the spectrum of this disease (for example, anti-kinetochore antibodies occur in limited cutaneous disease, and anti-topoisomerase I and anti-RNA polymerase antibodies occur in diffuse disease), and since they are distinct from the ANA found in other connective tissue diseases in their selectivity for the nucleolus and RNA polymerases.

Immunoglobulin synthesis and generalized autoimmunity in mice congenitally deficient in alpha beta(+) T cells

Through cognate B-cell-T-cell interactions and provision of cytokines, CD4+ T-cell antigen receptor (TCR) alpha beta+ T cells regulate immunoglobulin isotype synthesis. Murine IgG1 and IgE secretion is therefore substantially T-cell-dependent, whereas IgM and IgG3 secretion is not. Here we report that in the absence of alpha beta T cells, B cells expand, differentiate and secrete copious amounts of antibodies of 'T-dependent' isotypes. Moreover, the antibodies are reactive towards self-antigens, as in patients with systemic lupus erythematosus, so autoantibodies of 'T-dependent' type can develop without the help of CD4+ alpha beta T cells. This phenotype is not evident in mice or humans that are congenitally deficient in specific alpha beta T-cell functions, but bears comparison with B-cell hyperactivity and autoimmunity in transplant rejection and in immunodeficiencies such as AIDS.

A human IgM M-protein in a patient with unknown bleeding disorder binds to beta-galactosyl and beta-glucosyl residues

In a patient with an unknown bleeding disorder and an IgM lambda paraproteinemia, we demonstrated by thin-layer chromatography immunostaining and enzyme-linked immunosorbent assay that this protein specifically bound to a number of glycolipids and glycoproteins which have terminal beta-galactosyl or beta-glucosyl residues. Binding to galactosylceramide or glucosylceramide was inhibited by both galactosylceramide and glucosylceramide. From these studies, it is apparent that the M-protein recognized both beta-galactosyl and beta-glucosyl residues. This M-protein was also shown to prolong the partial thromboplastin time of normal plasma. Thus, this case represents an example of anti-carbohydrate specificity of an IgM M-protein in association with a spontaneous bleeding disorder.

Linked sets of antinuclear antibodies: what do they mean?

Among the many antinuclear antibodies found among patients with systemic lupus erythematosus, a subset predominates in terms of frequency of occurrence and titer. These antibodies include anti-DNA, antihistone, anti-U1 RNP, anti-Sm and anti-Ro and they tend to occur in linked sets which correspond to their autoantigenic epitopes on the nucleosome, the U1 snRNP, and the Ro particle. This pattern of occurrence suggests that these nucleoprotein structures elicit at least some of the autoimmune responses in this disease.

Autoantigenic histone epitopes: a comparison between procainamide- and hydralazine-induced lupus

Using the technique of immunoblotting, we assessed the ability of sera from 19 patients with drug-induced lupus to bind individual histones and specific histone fragments. The pattern of histone epitopes bound by sera from 9 patients with procainamide-induced lupus was very similar to that described previously in spontaneous systemic lupus erythematosus. In contrast, sera from 10 patients with hydralazine-induced lupus bound a broader array of individual histones and recognized a different set of histone epitopes. We conclude that these 2 drugs induce antihistone antibodies through somewhat different mechanisms, which possibly involve differences in their ability to structurally alter chromatin.

Patterns of autoimmunity to nucleoproteins in patients with systemic lupus erythematosus

The ANAs described above can be accounted for on the basis of an immune response to just three nucleoprotein structures--the nucleosome, the U1 snRNP, and the Ro particle. When these nucleoproteins are looked at in turn, the following picture emerges. The nucleosome is identified by both anti-histone and anti-DNA antibodies. Anti-histone H1 and anti-histone H2B antibodies predominate and tend to occur together. They, as well as the anti-DNA antibodies with which they appear to be linked, recognize external features of the intact nucleosome. The U1 snRNP is recognized by both anti-U1 RNP and anti-Sm antibodies. Most so-called anti-U1 RNP antisera actually contain several linked sets of different antibodies that are directed against various polypeptides (68K, A, and C) found on the U1 snRNP. Anti-Sm antibodies are linked to the occurrence of anti-U1 RNP antibodies. The Ro particle is recognized by both anti-La and anti-Ro antibodies, and almost all sera that contain anti-La antibodies also contain anti-Ro antibodies. Thus, it appears that these three nucleoprotein particles become direct focal points for autoimmune responses in SLE. It is difficult to explain such focused responses on the basis of a general defect in immune regulation or spontaneous B-lymphocyte hyperactivity. Rather it appears that these nucleoproteins themselves are directly involved in determining which B-lymphocyte clones become activated. Thus, the simplest rationalization for the patterns with which these autoantibodies occur is to invoke the possibility that the particles themselves are directly triggering autoimmune responses.

Clinical manifestations of Lyme disease

Lyme disease typically begins with a unique skin lesion, erythema chronicum migrans (ECM) (stage 1). Patients with this lesion may also have headache, meningeal irritation, mild encephalopathy, multiple annular secondary lesions, malar or urticarial rash, generalized lymphadenopathy and splenomegaly, migratory musculoskeletal pain, hepatitis, sore throat, non-productive cough, conjunctivitis, periorbital edema, or testicular swelling. After a few weeks to months (stage 2), about 15% of patients develop frank neurologic abnormalities, including meningitis, encephalitis, cranial neuritis (including bilateral facial palsy), motor or sensory radiculoneuritis, mononeuritis multiplex, or myelitis. At this time, about 8% of patients develop cardiac involvement--AV block, acute myopericarditis, cardiomegaly, or pancarditis. Throughout this stage, many patients continue to experience migratory musculoskeletal pain in joints, tendons, bursae, muscle, or bone. Months to years after disease onset (stage 3), about 60% of patients develop frank arthritis, which may be intermittent or chronic. Recently evidence suggests that Lyme disease may also be associated with chronic neurologic or skin involvement. Thus, Lyme disease occurs in stages with different clinical manifestations at each stage, but the course of the illness in each patient is highly variable.

Antigens of Borrelia burgdorferi recognized during Lyme disease. Appearance of a new immunoglobulin M response and expansion of the immunoglobulin G response late in the illness

Using immunoblots, we identified proteins of Borrelia burgdorferi bound by IgM and IgG antibodies during Lyme disease. In 12 patients with early disease alone, both the IgM and IgG responses were restricted primarily to a 41-kD antigen. This limited response disappeared within several months. In contrast, among six patients with prolonged illness, the IgM response to the 41-kD protein sometimes persisted for months to years, and late in the illness during arthritis, a new IgM response sometimes developed to a 34-kD component of the organism. The IgG response in these patients appeared in a characteristic sequential pattern over months to years to as many as 11 spirochetal antigens. The appearance of a new IgM response and the expansion of the IgG response late in the illness, and the lack of such responses in patients with early disease alone, suggest that B. burgdorferi remains alive throughout the illness.

Antibody response in Lyme disease: evaluation of diagnostic tests

The antibody response to the Ixodes dammini spirochete was determined in 41 serial serum samples from 12 patients with Lyme disease. By enzyme-linked immunosorbent assay (ELISA), 11 of the 12 patients had higher titers of specific IgM antibody (greater than 1:200) during early disease than did 40 control subjects. Specific IgM antibody titers, which correlated with total amounts of IgM antibody (P less than .001), sometimes remained elevated throughout the illness. During neuritis, nine of 10 patients had higher specific IgG antibody titers (greater than 1:200) than did controls, and when arthritis was present, all had such titers, which remained elevated after months of remission. In the ELISA, antibody responses determined by single or serial dilutions were similar, but the ELISA was more sensitive and specific than was immunofluorescence. Adsorption of sera with Borrelia hermsii generally resulted in a fourfold decrease in titers of cross-reactive antibodies, but the titers of sera from patients with Lyme disease were also reduced. Currently, the ELISA, without adsorption, is the best diagnostic test for Lyme disease.

Recovery of Lyme disease spirochetes from patients

Since the summer of 1982, we have cultured patient specimens for Lyme disease spirochetes. Of 118 patients cultured, four specimens yielded spirochetes: two from blood, one from a skin biopsy specimen of erythema chronicum migrans (ECM), and one from cerebrospinal fluid. All four isolates appeared identical when examined with a monoclonal antibody. However, attempts to recover the spirochete from synovium or synovial fluid were unsuccessful. In addition, the organism could not be visualized in skin or synovial biopsy specimens using the avidin-biotin peroxidase complex detection system. Thus, the current yield in culturing spirochetes from patients is quite low, and it is not yet known whether the organism is still alive later in the disease when arthritis is present.

The antibody response in Lyme disease

We determined the antibody response against the Ixodes dammini spirochete in Lyme disease patients by indirect immunofluorescence and an enzyme-linked immunosorbent assay (ELISA). The specific IgM response became maximal three to six weeks after disease onset, and then declined, although titers sometimes remained elevated during later disease. Specific IgM levels correlated directly with total serum IgM. The specific IgG response, often delayed initially, was nearly always present during neuritis and arthritis, and frequently remained elevated after months of remission. Although results obtained by indirect immunofluorescence and the ELISA were similar, the ELISA was more sensitive and specific. Cross-reactive antibodies from patients with other spirochetal infections were blocked by absorption of sera with Borrelia hermsii, but titers of Lyme disease sera were also decreased. To further characterize the specificity of the humoral immune response against the I. dammini spirochete, 35S-methionine-labeled spirochetal antigens were identified by immunoprecipitation with sera from Lyme arthritis patients. These polypeptides had molecular weights of 62, 60, 47, 37, 22, 18, and 15 kDa, and were not recognized by control sera. We conclude that the ELISA, without absorption, is the best method to assay the humoral immune response in Lyme disease, and we have identified methionine-containing spirochetal polypeptides that may be important in Lyme arthritis.

Treatment of the early manifestations of Lyme disease

During 1980 and 1981, we compared antibiotic regimens in 108 adult patients with early Lyme disease. Erythema chronicum migrans and its associated symptoms resolved faster in penicillin- or tetracycline-treated patients than in those given erythromycin (mean duration, 5.4 and 5.7 versus 9.2 days, F = 3.38, p less than 0.05). None of 39 patients given tetracycline developed major late complications (meningoencephalitis, myocarditis, or recurrent attacks of arthritis) compared with 3 of 40 penicillin-treated patients and 4 of 29 given erythromycin (chi square with 2 degrees of freedom = 5.33, p = 0.07). In 1982, all 49 adult patients were given tetracycline; again, none of them developed major complications. However, with all three antibiotic agents nearly half of the patients had minor late symptoms such as headache, musculoskeletal pain, and lethargy. These complications correlated significantly with the initial severity of illness. For patients with early Lyme disease, tetracycline appears to be the most effective drug, then penicillin, and finally erythromycin.

The early clinical manifestations of Lyme disease

Lyme disease, caused by a tick-transmitted spirochete, typically begins with a unique skin lesion, erythema chronicum migrans. Of 314 patients with this skin lesion, almost half developed multiple annular secondary lesions; some patients had evanescent red blotches or circles, malar or urticarial rash, conjunctivitis, periorbital edema, or diffuse erythema. Skin manifestations were often accompanied by malaise and fatigue, headache, fever and chills, generalized achiness, and regional lymphadenopathy. In addition, patients sometimes had evidence of meningeal irritation, mild encephalopathy, migratory musculoskeletal pain, hepatitis, generalized lymphadenopathy and splenomegaly, sore throat, nonproductive cough, or testicular swelling. These signs and symptoms were typically intermittent and changing during a period of several weeks. The commonest nonspecific laboratory abnormalities were a high sedimentation rate, an elevated serum IgM level, or an increased aspartate transaminase level. Early Lyme disease can be diagnosed by its dermatologic manifestations, rapidly changing system involvement, and if necessary, by serologic testing.

The spirochetal etiology of Lyme disease

We recovered a newly recognized spirochete from the blood, skin lesions (erythema chronicum migrans [ECM]), or cerebrospinal fluid of 3 of 56 patients with Lyme disease and from 21 of 110 nymphal or adult lxodes dammini ticks in Connecticut. These isolates and the original one from l. dammini appeared to have the same morphologic and immunologic features. In patients, specific IgM antibody titers usually reached a peak between the third and sixth week after the onset of disease; specific IgG antibody titers rose slowly and were generally highest months later when arthritis was present. Among 40 patients who had early disease only (ECM alone), 90 per cent had an elevated IgM titer (greater than or equal to 1:128) between the ECM phase and convalescence. Among 95 patients with later manifestations (involvement of the nervous system, heart, or joints), 94 per cent had elevated titers of IgG (greater than or equal to 1:128). In contrast, none of 80 control subjects had elevated IgG titers, and only three control patients with infectious mononucleosis had elevated IgM titers. We conclude that the I. dammini spirochete is the causative agent of Lyme disease.