Are the B cells cast with the leading part in the Sjogren's syndrome scenario?

The autoimmune exocrinopathy Sjögren's syndrome (SS) is characterized by mononuclear cell (MNC) infiltrates of exocrine glands and overactivity of B lymphocytes. Although T cells have long been perceived as the prime effectors, increasing evidence indicates that the key role is rather served by B cells. Among related abnormalities are rheumatoid factor (RF), anti-SSA/Ro, and anti-SSB/La antibodies (Ab). Also, supporting this view is our finding of an increase in the number of circulating naïve mature B (Bm) cells, with a reciprocal decrease in that of memory B cells. Furthermore, a ratio of Bm2-plus-Bm2' cells to early Bm5-plus-late Bm5 above 5 is diagnostic. This variation partly reflects the migration of active memory B cells into the exocrine glands of the patients, as well as into their skin. More recently, the B-cell-activating factor of the TNF family (BAFF) has been endorsed with a pivotal role in B-cell survival and hence implicated in the pathogenesis of autoimmunity. In practice, B cells have turned quite attractive as a target for biotherapy. For example, treatment with anti-CD20 Ab has afforded some benefits in this disease, while BAFF blockers are still on the way, but should expand our armamentarium for treating SS. With such B-cell-directed biotherapies in mind, we delineate herein the distinguishing traits of B lymphocytes in SS.

Updating the physiology, exploration and disease relevance of complement factor H.

The factor H (FH) protein (also known as beta1H globulin) is the main regulator of the complement alternative pathway. It exhibits multivalent binding sites to the complement component C3b, and polyanions and one binding site to sialic acid and cell surfaces. These multiple binding sites confer to FH a decay-accelerating factor activity in the fluid phase as well as at the cell surface. A defect in FH activity or a FH protein deficiency triggers chronic inflammation and tissue injury, leading to various disorders impacting the kidney or the eye. In contrast, some pathogens, as well as cancer cells, develop various strategies to bind FH and thereby subvert a complement attack. We focus on the functions of FH, and review the main pathological conditions in which FH is involved. Since the pathogenesis is elusive, appropriate FH dosage in biological fluids and FH gene analysis may help in improving understanding of such diseases.

Is the blood B-cell subset profile diagnostic for Sjogren syndrome?

OBJECTIVE: To evaluate the relevance of the blood B-cell subset profile for the diagnosis of Sjögren syndrome. METHODS: The distribution of mature blood B cells from Bm1 through Bm5 was determined in 161 patients, of whom 25 fulfilled the American-European Consensus Group criteria for primary SS (pSS), and 136 served as disease controls. RESULTS: The percentage of Bm2 and Bm2' cells was increased in the patients with pSS compared with 54 patients with rheumatoid arthritis (RA) and 18 with systemic lupus erythematosus (SLE) (p<0.001 for the two comparisons). In contrast, those of early Bm5 (eBm5) and Bm5 were decreased in patients with pSS, compared with patients with RA and with SLE (p<0.001 for the two comparisons). The receiver operating characteristic curves allowed for an optimising cut-off value of Bm2+Bm2' cells at 71.1% for 88.0% sensitivity and 83.1% specificity, that of eBm5+Bm5 cells at < or =13.5% for 84.0% sensitivity and 83.1% specificity, and, consequently, that of Bm2+Bm2'/eBm5+Bm5 at > or =5 for 88.0% sensitivity and 84.6% specificity. CONCLUSION: Given its presentation as a signature for pSS, relative to RA and SLE, such a distribution of B-cell subsets might provide a useful diagnostic tool.

[B lymphocytes in Sjögren's syndrome]. / Les lymphocytes B dans le syndrome de Gougerot-Sjögren.

INTRODUCTION: Sjögren's syndrome (SS) is an autoimmune epithelitis hallmarked by a disruption of epithelial cells, the subsequent lymphocytic infiltration of lachrymal and salivary glands (SGs), and their ensuing dryness. One may posit that SS is triggered by viruses, and/or modulated by sex steroid hormones, and there is indeed a consensus that its aetiology is multifactorial, with genetic factors interacting with environmental agents. CURRENT KNOWLEDGE AND KEY POINTS: T-cells have long occupied central stage of the debate on the type of lymphocytes involved in the pathogenesis of SS. The relevance of B cells has, however, been emphasized over the past five years and new insights into their functions revealed. Furthermore, increased levels of the B-cell activating factor (BAFF) may be responsible for quantitative and qualitative anomalies of B-cells found in SS such as emergence of self reactive B-cells. This review reports compelling evidence that B-cells are involved in the pathophysiology of SS. PROSPECTS: Since SS may thus be conceived as a model for B-cell-induced autoimmunity, it is no surprise that B-cell ablative-treatment has proven to be relatively effective in SS.

The binding of some human antiendothelial cell antibodies induces endothelial cell apoptosis.

The pathogenic role of antiendothelial cell antibodies (AECA) remains unclear. They are frequently associated with antibodies to anionic phospholipids (PL), such as phosphatidylserine (PS), which is difficult to reconcile with the distribution of PL molecular species within the plasma membrane. Since it is already known that PS is transferred to the outer face of the membrane as a preclude to apoptosis, the possibility exists that apoptosis is initiated by AECA. AECA-positive/anti-PL antibody-negative sera from eight patients with systemic sclerosis (SS) and 21 control patients were evaluated. Endothelial cells (EC) were incubated with AECA and the exposure of PS was established through the binding of annexin V. Hypoploid cell enumeration, DNA fragmentation, and optical and ultrastructural analyses of EC were used to confirm apoptosis. Incubation of EC with AECA derived from six of eight patients with SS led to the expression of PS on the surface of the cells. This phenomenon was significantly more frequent in SS (P < 0.04) than in control diseases. The redistribution of plasma membrane PS preceded other events associated with apoptosis: hypoploidy, DNA fragmentation, and morphology characteristic for apoptosis. Apoptosis-inducing AECA did not recognize the Fas receptor. We conclude that AECA may be pathogenic by inducing apoptosis.

Modulation of autoimmunity by the latest interleukins (with special emphasis on IL-32).

Interleukins (IL) and other cytokines display a number of overlapping abilities to stimulate cells of various lineages and differentiation stages. Most notably, IL-1, tumor necrosis factor (TNF)-alpha, IL-6, IL-15, IL-17, IL-18, IL-21, IL-25, IL-25, IL-31 and IL-32 contribute in concert to pathophysiological events. These include cell death, inflammation, allergy and autoimmunity. Up-regulation of either T helper (TH)1 or TH2 cells is pathogenic, and these subsets downregulate each other. The expression of chemokines/cytokines by endothelial cells is also crucial to autoimmunity by trafficking inflammatory T cells into the central-nervous system. IL-32 (previously termed NK transcript 4), is the newest inflammatory cytokine produced by mitogen-activated lymphocytes, interferon-gamma activated epithelial cells and IL-12, IL-18 and IL-32-activated NK cells. This induces TNF-alpha, IL-1beta, IL-6 and 2 C-X-C chemokine family members involved in several autoimmune diseases. In addition, IL-32 activates arachidonic acid metabolism in peripheral blood mononuclear cells by stimulating the release of prostaglandins. Discovery of this supplementary inflammatory cytokine further complicates the network of inflammation.

B-cell: a logical target for treatment of rheumatoid arthritis.

The interest for B-cells in rheumatoid arthritis (RA) is currently being revived. They are involved in the development and activation of lymphoid architecture by regulating dentritic cell and T-cell function through cytokine production. Receptor editing an revising are also essential in B-cells and aid in preventing autoimmunity. Abnormalities in the subset distribution and a default in any task assigned to the B-cells may favor autoimmunity. Beneficied responses to B-cell depletion in RA by anti-CD20 monoclonal antibody rituximab illustrate the importance of B-lymphocytes in the pathogenesis of this disease. A new avenue has thus been opened, whereby B-lymphocytes return as a significant contributor to autoimmune disorders.

BAFF and rheumatic autoimmune disorders: implications for disease management and therapy.

Interest in B-cells has been revived due to the description of new functions. Supporting a role for B-cells in the genesis of autoimmune diseases is the fact that the B-cell activating factor of the TNF ligand family (BAFF) is essential in their physiology. However, in each disease, this is restricted to a subgroup of patients. Based on experiments in mice, and validated in humans, this new cytokine has been highlighted. Excessive production of BAFF alters immune tolerance by rescuing self-binding B-cells. Overexpression in mice leads to autoimmune manifestation, and BAFF levels are elevated in the serum of autoimmune patients. Similar abnormalities occur in chronic lymphocytic leukemia. Recent works suggest that antagonizing the protein (or competing for its receptors) is relevant to the treatment. Advances in our understanding of the BAFF system offers the opportunity to improve our therapeutic approach.

B cell-ablative therapy: where are we now?

Based on their multifaceted functions, B cells participate in several pathological settings such as lymphoproliferative disorders, autoimmune diseases and graft rejection. B cell-ablative therapy has thus emerged as a mainstay in these diseases. A number of anti-B cell antibodies (Abs) have been generated, among which anti-CD20 Abs appear to be efficient. Rituximab (RTX) is one of these anti-CD20 monoclonal Abs. Originally approved for the treatment of non-Hodgkin lymphoma, RTX is now being administered in other malignant proliferations, applied to an increasing number of autoimmune diseases and required to prevent rejection of a graft. Although this medication is remarkably safe, a handful of laboratory tests have been proposed to monitor RTX-treated patients. The efficacy in different diseases, and the emergence of new anti-CD20 Abs raise many questions. Thus, their detailed understanding can lead to a better issue for inhibition of immune responses.

Role of B-cell antigen receptor-associated molecules and lipid rafts in CD5-induced apoptosis of B CLL cells.

A total of 40 patients with B-CLL were investigated for CD5-triggered apoptosis and categorized as 20 resistant (group I) and 20 sensitive patients (group II). The densities of surface IgM (sIgM) and CD5 were lower in group I than group II, as were the percentages of CD79b+, CD38+, and Zap70-expressing B cells. CD5 signaling was mediated through the BCR in group II B cells, as established by coimmunoprecipitation of CD5 and CD79a and tyrosine phosphorylation of CD79a. Following colocalization of CD5 and sIgM in membrane lipid rafts (LRs), Syk became associated with these molecules, whereas SHP-1 was uncoupled from CD5. Nonresponsiveness to CD5 cross-linking in group I was ascribed to three possible abnormalities, and defined as three subgroups of patients. In subgroups Ia and Ib, CD5 and sIgM colocalized within the LRs. SHP-1 remained attached to the BCR in subgroup Ia, but not in subgroup Ib, where signal transduction was associated with an excess of truncated CD79b. In subgroup Ic, CD5 and sIgM segregated into different LRs, resulting in no signaling of apoptosis.

The ananti-alpha-actinin test completes ananti-DNA determination in systemic lupus erythematosus.

In murine systemic lupus erythematosus (SLE) models, nephritogenic anti-dsDNA IgG has been shown to cross-react with a kidney antigen, alpha-actinin, and to be critical in renal pathogenesis. In humans, studies of anti-alpha-actinin antibodies (Abs) are scarce, and these antibodies remain to be evaluated. We have thus far tested sera from patients with SLE (n = 103), rheumatoid arthritis (RA, n = 93), and primary Sjögren syndrome (pSS, n = 34), and from healthy subjects (n = 160), for the presence of anti-alpha-actinin and anti-DNA Abs. The latter were tested using several methods [IIF on Crithidia luciliae (Crit) and ELISA using dsDNA]. Anti-alpha-actinin Abs were confirmed by Western blot. Sera from 23 of 103 SLE patients, 3 of 93 RA patients, 1 of 33 pSS patients, and 1 of 160 controls scored positive for anti-alpha-actinin Abs. In SLE, the positivity was significantly associated with anti-dsDNA reactivity (22 of 23): 19 of 23 sera were alpha-actinin-positive/dsDNA-positive and 13 were alpha-actinin-positive/Crit-positive. Few cases were alpha-actinin-positive/dsDNA-negative: 1 SLE, 3 RA, and 1 control. Furthermore, anti-alpha-actinin Abs have been detected at high level before or at the early stage of lupus nephritis when compared with active and inactive SLE without kidney manifestations.

CD5-induced apoptosis of B cells in some patients with chronic lymphocytic leukemia.

Although B chronic lymphocytic leukemia (B-CLL) is characterized by prolonged survival of CD5(+) B cells in vivo, these cells apoptose spontaneously in vitro. The effect of CD5 ligation on apoptosis was studied in 27 newly diagnosed patients with B-CLL, in relation to the expression of surface IgM (sIgM), CD79b, CD38, CD72 and CD19. B cells from 15 patients (group I) were resistant to anti-CD5-induced apoptosis, whereas apoptosis above spontaneous levels was seen in the remaining 12 studied (group II). Group II was then subdivided on the basis of differences in the time required to reach maximum apoptosis: whilst B cells from seven patients underwent apoptosis by 18 h, those from the remaining five needed 36 h to apoptose. The expression of sIgM, CD5, CD79b and CD38 was higher in group II than group I, suggesting that signaling for apoptosis might operate via CD79, and that CD38 expression was required. As shown by flow cytometry and confirmed by Western blotting, apoptosis was associated with a decrease in the ratios of Bcl-2/Bax and Bcl(XL)/Bax, due to an increase in the level of Bax, but no change in that of Bcl-2. This heterogeneous apoptotic response to CD5 ligation offers an explanation for the incomplete success of anti-CD5 monoclonal therapy, and might help identify patients who would respond to such treatment.

Differential effects of anti-Fc gamma RIIIb autoantibodies on polymorphonuclear neutrophil apoptosis and function.

Anti-Fc gamma receptor IIIb (Fc gammaRIIIb) human autoantibodies (Ab) have been classified previously into three groups, based on the results of an indirect immunofluorescence (IIF) test and an enzyme-linked immunosorbent assay (ELISA): IIF+/ELISA+ (group A), IIF+/ELISA- (group B), and IIF-/ELISA+ (group C) sera. In this study, differential effects between IIF+ autoAb, recognizing cell-bound Fc gammaR, and those ELISA+, recognizing only cell-free Fc gammaR, were studied on polymorphonuclear neutrophils (PMN). Neither group A nor B autoAb was cytotoxic, although both prolonged the survival of PMN by delaying spontaneous apoptosis. By the same extent, the PMN-binding antisera stimulated the appearance of a CD11b(dim) population, following a 12-h incubation. This event was associated with a lowered expression of beta2 integrin molecules, resulting in altered PMN function. Treatment with groups A and B autoAb reduced adhesiveness and respiratory burst. This impairment of the responses was more pronounced when the cells originated from donors NA1+ NA1+ rather than donors NA2+ NA2+. From our observations, the influences of anti-Fc gammaRIIIb autoAb on PMN survival, as well as function and subsequent dysregulation of the inflammatory response, have proven somewhat dependent on their target antigens, as determined by IIF coupled with ELISA and Fc gammaRIIIb polymorphism.

Clinical relevance of elevated serum thrombomodulin and soluble E-selectin in patients with Wegener's granulomatosis and other systemic vasculitides.

PURPOSE: Vascular injury plays an important pathophysiological role in vasculitis. Soluble serum thrombomodulin (sTM), a promising marker of endothelial cell injury, is released into the circulating blood following cell damage and was therefore investigated as a parameter of disease activity in patients with Wegener's granulomatosis (WG) and various other vasculitides. PATIENTS AND METHODS: One hundred and ninety-seven sera of 102 patients with histologically proven WG of different disease activity and 41 sera of patients with other vasculitides at their active stage were investigated (12 Takayasu arteritis [TA], 7 giant cell arteritis [GCA], 10 polyarteritis nodosa [PAN], 12 Behcet's disease [BD]). The sera were examined for the levels of sTM and sE-selectin (CD62E) by enzyme-linked immunosorbent assay (ELISA) and for the presence of classical anti-neutrophil cytoplasmic antibodies (cANCA) by indirect immunofluorescence (IIF). The disease activity was evaluated according to the clinical symptoms and organ involvement. RESULTS: A significant increase of sTM levels compared with control values (26 +/- 2 ng/ml) was found in active WG, TA, GCA, PAN, and BD: limited active WG: 63 +/- ng/ml; generalized active WG: 119 +/- 15 ng/ml; limited WG, partial remission: 60 +/- 5 ng/ml; generalized WG, partial remission: 75 +/- 7 ng/ml; active TA: 36 +/-; active GCA: 36 +/- 4 ng/ml, active PAN: 33 +/- 2 ng/ml, active BD: 40 +/- 4 ng/ml. Limited and generalized WG in complete remission did not have elevated levels of sTM. sTM values closely reflected relapses and therapy-induced remissions of WG. Elevated cANCA titers were correlated as well with the disease activity in WG but more weakly than sTM levels. In contrast, sE-selectin values were not significantly correlated with the disease activity and the course of disease. CONCLUSIONS: sTM is a promising serological marker of disease activity and progression in active limited and generalized WG and other vasculitides reflecting the degree of endothelial cell damage. sTM might prove to be a clinically useful marker for therapeutic considerations.

Antiendothelial cell antibodies: useful markers of systemic sclerosis.

BACKGROUND: Systemic sclerosis (SS) encompasses a wide spectrum of clinical presentations. Antiendothelial cell antibodies (AECA) in patients with primary Raynaud's phenomenon (PRP), limited SS (lSSc), or diffuse SS (dSSc) may help to determine the long-term prognosis of the disease. METHODS: Twenty-seven normal controls, 13 patients with PRP, 36 with lSSc, and 31 with dSSc were included in the study. Sera were examined for the presence of AECA, using a cellular enzyme-linked immunosorbent assay (ELISA). Angiotensin-converting enzyme (ACE) activity, plasma von Willebrand factor antigen (vWfAg), and thrombomodulin (Tm) concentrations were also evaluated. The medical records of 50 of the lSSc and dSSc patients were reviewed and the organ system involvement noted. RESULTS: Antiendothelial cell antibodies were present in 3 patients with PRP, 16 patients with lSSc, and 26 patients with dSSc. These autoantibodies were mainly of the IgG isotype. There was no difference in ACE activity between patients and controls. In contrast, vWfAg and Tm concentrations were higher in patients with PRP relative to controls, and higher in patients with lSSc compared with those with PRP. The presence of AECA was associated with digital scars and ulcers (P < 0.004 and P < 0.003, respectively), severe RP (P < 0.01), grade 3 tortuosity of vessels (P < 0.0004), and lung involvement (P < 0.02). CONCLUSION: The significant trend for AECA to increase with disease severity across the three groups of patients studies suggests that the AECA test can identify subsets of SSc with differing prognoses.

Folic acid deficiency and neutrophil dysfunction.

Polymorphonuclear leukocyte functions were studied in 92 patients with protein-calorie malnutrition. Serum folic acid levels were higher than 3 ng/ml in 38 patients and 3 ng/ml or less in 54 patients. Significant differences were found between these two groups of patients with regard to phagocytosis (81.5 +/- 1.9 versus 69.2 +/- 2.0 percent, p less than 0.001) and bactericidal ability (90.6 +/- 1.1 versus 84.5 +/- 2.3 percent, p less than 0.05). Correction of folic acid deficiency in 22 patients was associated with recovery of normal phagocytosis (p less than 0.001) but not bactericidal function. Adding folic acid to the serum of eight patients also restored normal phagocytic function (p less than 0.001). A correlation was found in vivo and in vitro between changes over time in folic acid levels and in phagocytosis.

Distinguishing features of anti-beta2 glycoprotein I antibodies between patients with leprosy and the antiphospholipid syndrome.

Anticardiolipin (ACA), anti-beta2 glycoprotein I (beta2GPI), and antiprothrombin antibodies of IgG and IgM classes were quantitated by enzyme-linked immunosorbent assays in 176 untreated leprosy patients across the histopathological spectrum. Positivity rates ranged from 21% (IgG ACA) to 30% (IgM anti-prothrombin) versus 4% in healthy controls (p <10(-2) to 10(-3)). Levels of IgM anti-beta2GPI and IgG ACA were significantly higher in lepromatous leprosy and multibacillary patient subgroups. IgG3 was the most common subclass reactive to both beta2GPI and prothrombin in selected high-titer leprosy sera, unlike antibodies from patients with the antiphospholipid syndrome (APS) largely restricted to IgG2. In leprosy patients, but not in the APS control group, there was no statistical correlation between ACA and anti-beta2GPI antibody levels. Likewise, a large fraction of anti-beta2GPI positive sera (36/45 and 28/44 for IgG and IgM, respectively) were unreactive in the standard ACA assay. Most assayed anti-beta2GPI antibodies from leprosy patients showed (i) ability to recognize both human and bovine beta2GPI immobilized on non-irradiated polystyrene plates, (ii) concentration-dependent inhibition of binding by cardiolipin, and (iii) relatively high avidity binding to fluid-phase beta2GPI, thereby differing from those found in APS. Finally, the location of the major epitopic region on the beta2GPI molecule targeted by autoantibodies was different in leprosy and APS, as assessed by direct binding to domain I- and V-deleted mutants and competition with the mouse monoclonal antibody 8C3, directed at domain I. Thus, leprosy-related antiphospholipid antibodies comprise persistent IgG and IgM anti-beta2GPI that differ from APS-related ones with respect to IgG subclass, avidity and epitope specificity, possibly reflecting distinct pathophysiological significance.

Oxidation of beta2-glycoprotein I (beta2GPI) by the hydroxyl radical alters phospholipid binding and modulates recognition by anti-beta2GPI autoantibodies.

We investigated whether beta2-glycoprotein I (beta2GPI), the key antigen in the antiphospholipid syndrome, is susceptible to oxidative modifications by the hydroxyl radical (*OH) that may influence its lipid-binding and antigenic properties. The effects on human and bovine beta2GPI of *OH free radicals generated by gamma-radiolysis of water with 137Cs were studied. Radiolytic *OH caused a dose-dependent loss of tryptophan, production of dityrosine and carbonyl groups. dimerization and/or extensive aggregation of beta2GPI. It ensued a reduction in affinity binding to cardiolipin liposomes and loss of beta2GPI-dependent autoantibody binding to immobilized cardiolipin. Patient anti-beta2GPI antibodies (n = 20) segregated into two groups based on the effect in the beta2GPI-ELISA of beta2GPI pretreatment with *OH: enhancement (group A, n = 10) or suppression (group B, n = 10) of IgG binding. The avidities of group A antibodies for fluid-phase beta2GPI were low but increased in a dose-dependent manner upon beta2GPI irradiation, in relation to protein crosslinking. Distinguishing features of group B antibodies included higher avidities for fluid-phase beta2GPI that was no longer recognized after *OH treatment, and negative anticardiolipin tests suggesting epitope location near the phospholipid binding site. The *OH scavengers thiourea and mannitol efficiently protected against all above changes. Therefore, oxidative modifications of beta2GPI via *OH attack of susceptible amino acids alter phospholipid binding, and modulate recognition by autoantibodies depending on their epitope specificities. These findings may be of clinical relevance for the generation and/or reactivity of anti-beta2GPI antibodies.

The majority of Fc gamma RIII-positive gamma delta T cells do not express HLA-DR in patients with primary Sjögren's syndrome.

The percentages of circulating gamma delta T cells and the proportions of these expressing Fc gamma RIII (CD16) or HLA-DR in patients with primary Sjögren's syndrome (pSS) and controls were determined using monoclonal antibodies and flow cytometry. There was no significant difference in the percentages of gamma delta T cells in the pSS patients compared with controls. There was, however, a significant increase in the proportions of both CD16+ and HLA-DR+ gamma delta T cells in pSS patients. A 3-colour immunofluorescence technique demonstrated that these two markers were mutually exclusive and therefore may identify either subpopulations of gamma delta T cells or different stages of the activation process.