A comparison of genome-scans performed in multicase families with systemic lupus erythematosus from different population groups

Systemic lupus erythematosus is a disease of unknown etiology. Multiple genetic factors are believed to be involved in its pathogenesis. In addition, and due to genetic heterogeneity, these factors and/or their combinations may be different in different ethnic groups, while some might be shared between populations. We have performed genome scans in multicase families from three different population groups, two from Northern Europe, with a high degree of homogeneity, and the third from a recently admixed population of Mexican Mestizos. Although our family material is relatively small, the results presented here show that using family sets from well defined populations are sufficient to detect susceptibility loci for SLE. Our results also reveal the chromosomal regions most likely to contain susceptibility genes for SLE.

The G20210A polymorphism in the 3'-untranslated region of the prothrombin gene in Mexican mestizo patients with primary antiphospholipid syndrome

In an effort to identify alleles associated with an increased risk of venous thrombosis in patients with primary antiphospholipid syndrome, we studied the G20210A polymorphism (the G-->A mutation at nucleotide position 20210) in the 3'-untranslated region of the prothrombin gene in a group of 14 patients with primary antiphospholipid syndrome. We did not find any patient with the mutated gene. Since the prothrombin mutation is more prevalent in white populations, this finding may be related with the genetic composition of the Mexican mestizos, in whom the white component is low. The polymorphism of the prothrombin gene in Mexican mestizo patients with antiphospholipid syndrome does not seem to be related to the thrombophilia observed in these patients.

Serum anti-beta2-glycoprotein-I and anticardiolipin antibodies during thrombosis in systemic lupus erythematosus patients

PURPOSE

Antibodies to beta2-glycoprotein-I are more strongly associated with clinical antiphospholipid syndrome than are anticardiolipin antibodies. We previously found a decrease in anticardiolipin antibodies at the time of thrombosis in 6 patients with systemic lupus erythematosus (SLE). We therefore sought to determine the prevalence and levels of antibodies to beta2-glycoprotein-I and to cardiolipin before, during, and after thrombosis in patients with SLE, and to compare them with patients who did not have thrombosis.

METHODS

We studied 24 patients with SLE who had at least one episode of thrombosis and 102 patients with SLE without thrombosis. Serum anticardiolipin antibodies were measured by conventional enzyme-linked immunosorbent assay (ELISA) using newborn calf serum as the blocking agent. Serum anti-beta2-glycoprotein-I antibodies were measured by ELISA on nonirradiated plates, using purified human beta2-glycoprotein-I without phospholipid.

RESULTS

All patients with thrombosis had anti-beta2-glycoprotein-I antibodies, compared with only 17% of controls (P <0.0001). We observed a significant decrease in serum anti-beta2-glycoprotein-I levels at the time of thrombosis, as compared with previous and subsequent samples. The prevalence and levels of IgG and IgM anticardiolipin antibodies were similar in patients with and without thrombosis. A decrease in IgG or IgM anticardiolipin titers occurred during thrombosis in 6 patients. Anticoagulant, corticosteroid, and immunosuppressive treatments did not appear to affect anti-beta2-glycoprotein-I levels at the time of thrombosis.

CONCLUSION

Anti-beta2-glycoprotein-I antibodies are strongly associated with thrombosis in patients with SLE. The decrease of anti-beta2-glycoprotein-I levels at the time of thrombosis may indicate a pathogenic role. This antibody may also be a marker of predisposition for thrombosis in these patients.

Immunogenetics of mixed connective tissue disease in a Mexican Mestizo population

OBJECTIVE

The aim of this study was to determine the HLA antigens in Mexican Mestizo patients with mixed connective tissue disease (MCTD).

METHODS

We studied 30 patients with MCTD and 99 healthy controls. HLA-A, -B, and -DQ antigens were typed by microlymphocytotoxicity assays. DRB1, DQA1 and DQB1 alleles were oligotyped.

RESULTS

HLA-A2 and HLA-B35 were the most frequent MHC class I alleles in MCTD patients, although they were not statistically more frequent than in the controls. According to serological tests, the most frequent DQ allele in the patients was DQ1, which was statistically increased when compared with controls (p = 0.0051). By oligotyping, the DR1 allele and the DQB1*0501 specificities were significantly increased in the patients vs. controls (p = 0.032 and 0.027, respectively).

CONCLUSION

The elevated levels of DQ1 found in Mexican MCTD patients, although weak, may indicate a particular genetic susceptibility, since there are previous reports of associations of other alleles (such as DR4) with MCTD in other populations. The increase in DQB1*0501 may account for the increase in DQ1. DQB1*0501 has also been reported in black patients with anti-RNP autoantibodies, compared with black patients without anti-RNP or anti-Sm.

Differential oncogene and TNF-alpha mRNA expression in bone marrow cells from systemic lupus erythematosus patients

The aim of the study was to investigate the bone marrow expression of genes involved in cell growth and apoptosis in patients with systemic lupus erythematosus (SLE). Spontaneous expression of bcl-2, bax, c-myc. c-fos, c-jun, p53, Fas and tumour necrosis factor (TNF)-alpha by bone marrow cells was measured using either semiquantitative or quantitative reverse transcription polymerase chain reaction in SLE patients (n = 8) and in eight normal control subjects. The expression of bcl-2 was found to be higher in SLE patients than in controls. Bone marrow cells from SLE patients showed significant down-regulation of bax, c-myc, c-fos and p53 (P < or = 0.05), as compared to normal controls. In both SLE patients and controls the expression of c-jun and Fas was very low or undetectable. Finally, TNF-alpha gene expression was higher in bone marrow samples from SLE patients than in those of controls (P= 0.01). The abnormal expression of genes regulating cell growth and apoptosis in bone marrow cells from SLE patients may help explain the presence of autoreactive cells in secondary lymphoid organs and peripheral blood of SLE patients.

Penetration of anti-DNA antibodies into immature live cells

Several data suggest that immature lymphoid cells are more prone to penetration and therefore are affected more by antibodies than their mature counterparts. In this study, we examined the penetration of monoclonal anti-DNA antibodies in several models of immature cells. Results confirm that most anti-DNA antibodies penetrate larger proportions of immature cells than normal adult cells. It was also proven that anti-DNA antibodies induce larger fractions of immature cells to undergo apoptosis than mature cells; however, there is not a numerical association between penetration and apoptosis. Additionally, the penetration and induction of apoptosis of several anti-DNA monoclonal antibodies into U937 and NIH-3T3 cells followed a rather heterogeneous pattern. When mature and immature cells were stimulated polyclonally, it was shown that polyreactive antibodies might act as an accessory signal to induce apoptosis in immature cells. This process could contribute to the edition of the immune repertoire. We propose that naturally occurring polyreactive antinuclear antibodies, through penetration and deletion of self-reacting cells, could participate, either as a unique or secondary signal, in the mechanism of self tolerance. If these polyreactive antibodies undergo affinity maturation, it is possible they may develop into pathogenic antibodies.

Role of IL-10 in the abnormalities of early cell activation events of lymphocytes from patients with systemic lupus erythematosus

Lymphocytes from patients with systemic lupus erythematosus (SLE) exhibit abnormalities in early cell activation events as well as increased production of IL-10. We explored the possible role of IL-10 on defective cell activation events of SLE lymphocytes and first studied the in vitro effect of IL-10 on peripheral blood mononuclear cells (PBMNC) from healthy subjects. After 5 days of culture in the presence of exogenous IL-10, these cells demonstrated abnormal expression of CD69 as well as high intracellular pH and defective activation of the Na+/H+ anti-porter by PMA. We then investigated the effect of IL-10 blockade on PBMNC from SLE patients. SLE PBMNC cultured for 5 days with a blocking anti-IL-10 monoclonal antibody (mAb) partially corrected abnormalities in CD69 expression and intracellular pH; however, in 1/5 patients studied, no significant positive effect was observed. The effect of the anti-IL-10 mAb was apparently not related to protection against activation-induced cell death. We conclude that IL-10 in normal PBMNC induce some of the defects in early cell activation events seen in SLE lymphocytes. Accordingly, the blockade of IL-10 partially corrects these abnormalities in SLE cells. Our data further support the importance of IL-10 in immune dysfunction seen in SLE.

Immunochemical determination of DNA in immune complexes present in the circulation of patients with systemic lupus erythematosus

The presence of DNA antigen in circulating immune complexes formed with anti-DNA antibodies of IgG class was determined in sera of 138 SLE patients and 23 healthy donors, employing monoclonal anti-dsDNA antibodies in a quantitative dot blot assay. About half of the SLE patients had elevated amounts of DNA antigen in the immune complexes (presumably as nucleosomes). The number of patients with the SLE manifestations was not higher in the group with the high amount of DNA in immune complexes. Elevated levels of DNA in immune complexes was found only in sera of SLE patients with the active, as well as quiescent form, of the disease and not in sera of healthy donors. The presence of increased amounts of DNA antigen in circulating immune complexes could indicate the presence of SLE pathology even if no manifestations of SLE are found. The level of the circulating anti-DNA antibodies was not correlated with the amount of DNA in immune complexes.

Penetrating anti-DNA monoclonal antibodies induce activation of human peripheral blood mononuclear cells

Different studies have shown that some autoantibodies are able to penetrate into living cells and that this phenomenon has functional consequences, including apoptosis. We have explored the effect of anti-DNA antibodies (Ab) on the in vitro activation of peripheral blood mononuclear cells (PBMNC) and found that a human polyclonal anti-DNA, IgG, which efficiently penetrated living cells, was able to induce the expression of different cell activation antigens in vitro such as CD69, CD71 or CD98 by PBMNC from normal individuals. However, the cell activation phenotype induced by anti-DNA Ab was considered anomalous since the expression of some activation antigens was not up-regulated, and others showed aberrant behaviour (such as down-regulation of ICAM-1 expression). Similar results were obtained using different murine anti-DNA monoclonal antibodies (mAb). In addition, mAb that showed an efficient ability to penetrate living cells tended to have a greater effect on PBMNC activation. Anti-DNA Ab were also able to induce a noticeable expression of CD95/Fas. These data indicate that penetrating anti-DNA Ab are able to induce an anomalous activation state in vitro in a significant fraction of PBMNC. We believe this effect may occur in vivoand could have an important function in the pathogenesis of the immune dysregulation seen in SLE.

Autoantibodies in systemic lupus erythematosus

Cationic germ line gene-encoded anti-DNA antibodies appear to cause inflammatory lesions via deposition and in situ formation of immune complexes, but also perhaps through apoptosis of glomerular mesangial cells. Somatic mutation is not critical for the expression of the electrical net charge of anti-DNA. In one transgenic mouse model, the nephrogenicity of anti-DNA was dependent on the expression of interleukin alpha by epidermal cells. Anti-P autoantibodies are present in the serum of healthy children but are masked by IgG antibodies. Some anti-P antibodies appear to be a subset of antilymphocyte autoantibodies. It was confirmed that anti-Ro/SS-A antibodies react with structurally unrelated conformational epitopes. The combined results of immunofluorescence and enzyme-linked immunosorbent assay in the detection of antineutrophil cytoplasmic antibody has a 99.5% specificity for vasculitis among patients with connective tissue diseases. Antinucleosome antibodies are highly prevalent in patients with systemic lupus erythematosus and show an inverse correlation with nucleosome plasma levels. Transfected T-cell receptor alpha chains specific for nucleosomal autoepitopes from a Th clone that accelerates lupus nephritis, recognized the nucleosomal epitopes presented by antigen presenting cell-bearing 1-A molecules, as well as human DR molecules, via the classical major histocompatibility complex class II groove. IgG antibodies against (beta 2 -glycoprotein (GP)-1 are significantly associated with thrombosis in patients with antiphospholipid syndrome, with a specificity and sensitivity that ranges from 85% to 98% and 32% to 54%, respectively. The lupus anticoagulant activity, or the lack of it, of anti-beta 2-glycoprotein-1 appears to reside on the epitope specificity. Beta 2-glycoprotein-1 binds to apoptotic cells; in turn, anti-beta 2-glycoprotein-1 facilitate apoptotic cell clearance by macrophages. The recently described anti-A2/RA33 autoantibody appears to recognize an epitope capable of distinguishing patients with lupus or with rheumatoid arthritis from those with mixed connective tissue disease.

Hidden anti-phospholipid antibodies in normal human sera circulate as immune complexes whose antigen can be removed by heat, acid, hypermolar buffers or phospholipase treatments

Heat treatment of normal human serum reveals otherwise masked anti-cardiolipin antibodies (aCL). We studied the mechanism of masking and the nature of the inhibitor of these aCL IgG. Other forms of treatment, besides heating for 30 min at 56 degrees C, can also unmask hidden aCL IgG. These include acid pH, hypermolar buffers and phospholipase digestion. When unmasked, these aCL recognize other anionic and zwitterionic phospholipids, but do not react with DNA, cell antigens or IgG. Using thin layer chromatography we demonstrate that the heat-labile inhibitor(s) of these aCL are phosphatidylserine, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine. These antibodies are not beta2-glycoprotein-I dependent and actually compete with this protein for phospholipid binding. The hidden antibodies are comprised of two populations of IgG autoantibodies: one reactive with cardiolipin, phosphatidylserine, phosphatidylinositol, phosphatidylglycerol, phosphatidylethanolamine and sphingomyelin, and the other reactive almost exclusively with phosphatidylcholine and phosphorylcholine on enzyme-linked immunosorbent assay plates or when exposed by bromelain on the erythrocyte surface. Our data suggest that hidden aCL are natural oligoreactive IgG anti-phospholipid autoantibodies that circulate masked by their antigen.

Oral manifestations in patients with Sjögren's syndrome

OBJECTIVE

To investigate oral signs and symptoms in patients with Sjögren's syndrome (SS), and to compare results with a group of healthy individuals. METHODS. Each individual completed a questionnaire designed to investigate his/her perception of oral health and dryness, as well as a list of signs and symptoms associated with xerostomia. An oral clinical evaluation was performed.

RESULTS

A total of 81 subjects were studied, 21 with primary SS, 29 with secondary SS, and 31 healthy individuals. Patients with SS considered that their oral health was poor. Oral dryness was perceived as intense. Symptoms most commonly expressed were: sensitivity to acids (68%), difficulty eating dry foods (66%), and sensitivity to spicy foods (58%). Dryness of the lips (76%) and the tongue (68%) were also among the most frequent complaints. Oral findings of patients with SS included cervical or atypical caries in 83%, fissured erythematous tongue in 70%, and oral candidiasis in 74%. Significant differences were found when results obtained from patients with SS were compared with the healthy group.

CONCLUSION

The oral health of this group of patients with SS was deficient. Adequate management of dry mouth was not achieved, mainly for the modifiable components such as dental decay and oral candidiasis. Therefore. treatment and prevention plans are mandatory. These measures might help to reduce the discomfort associated with oral dryness and to reduce dental loss.

Oral candidiasis and Sjögren's syndrome

OBJECTIVE

To determine the prevalence of oral candidiasis (OC) in patients with Sjögren's syndrome (SS), to identify oral signs and symptoms associated with OC, and to compare them with a healthy group.

METHODS

Patients with primary SS, and with SS associated with autoimmune disease were identified according to established criteria. Each individual had: (1) a questionnaire, (2) an oral clinical evaluation, (3) a set of microbiological tests: tongue smear, culture of tongue smear, and saliva sample. Diagnosis of OC was established with 2 positive results and the presence of any sign or symptom.

RESULTS

A total of 81 subjects were studied, 21 with primary SS, 29 secondary SS, and 31 healthy subjects. We diagnosed OC in 74% of patients with SS, which was statistically significant compared to the healthy group (23%) p < 0.001. Frequent symptoms associated with OC were increased sensitivity to spicy foods (58%) and unpleasant metallic taste (40%). Common signs of OC were erythematous lesion on the dorsum of the tongue (68%) and angular cheilitis (24%).

CONCLUSION

Prevalence of OC was high in patients with SS. The frequency of signs and symptoms associated with OC may explain some of the clinical manifestations. If chronic erythematous OC is found in patients with SS an oral assessment at every appointment may help provide appropriate treatment.

A bioactive 60-kilodalton prolactin species is preferentially secreted in cultures of mitogen-stimulated and nonstimulated peripheral blood mononuclear cells from subjects with systemic lupus erythematosus

We have evaluated the production of PRL by human peripheral mononuclear cells (PBMNC) from normal subjects and patients with systemic lupus erythematosus (SLE). Conditioned medium prepared from basal and Con-A-stimulated PBMNC was assessed for the presence of PRL-like by its ability to stimulate growth of PRL-responsive Nb2 rat lymphoma cells. In the presence or absence of Con-A, SLE PBMNC secrete significantly higher (P < 0.001) amounts of bioactive PRL-like species than normal cells. Growth of Nb2 cells by conditioned medium was inhibited with specific antiserum to human PRL. Western blotting using a polyclonal antibody to human PRL revealed a single 60-kDa PRL-like species in both normal and SLE PBMNC extracts, the immunoreactivity of which was preferentially found in SLE subjects. With the use of reverse transcription-PCR an expected 633-bp band was observed, and its similarity to pituitary PRL was further confirmed by Southern blot analysis with human PRL complementary DNA as a probe. We conclude that a high molecular mass PRL-like species is synthesized and secreted by PBMNC, and patients with SLE have an increased secretion of lymphocyte-derived PRL-like material.

Autoantibodies in systemic lupus erythematosus

Research on pathogenic and nonpathogenic anti-DNA antibodies has shown that the charge and affinity for double-stranded DNA may not be adequate predictors of their pathogenicity. In turn, anti-DNA-induced renal damage could be caused by differences in fine specificities. Penetration of anti-double-stranded DNA monoclonal antibodies into live cells appears to require DNA or a DNA-like membrane receptor. Anti-U1 ribonucleoproteins penetrate live cells and induce apoptosis. HLA-DRB1*1501 or HLA-DRB1*1503, DQA1*0102, and DQB1*0602 haplotypes were increased in patients with systemic lupus erythematosus with anti-ribosomal protein P (anti-P) antibodies, particularly in whites, blacks, and Mexican-Americans. Anti-Ro/Sjögren's syndrome antigen A antibodies had a strong predictive diagnostic value for systemic lupus erythematosus among patients positive for antinuclear antibodies and negative for double-stranded DNA but had no utility among those positive for both antinuclear antibodies and anti-DNA antibodies. True antiphospholipid murine monoclonal antibodies display an unusual number of cationic residues in the H-chain CD3 region, whereas anti-beta 2-glycoprotein-I monoclonal antibodies lack them. The association of IgG anti-beta 2-glycoprotein-I with a history of thrombosis in systemic lupus erythematosus has been largely confirmed. Apoptotic thymocytes bind antiphospholipid antibodies in a beta 2-glycoprotein-I-dependent manner and may constitute a source of immunogen in autoimmune disease.

Prevalence of 13 autoantibodies and of the 16/6 and related pathogenic idiotypes in 465 patients with systemic lupus erythematosus and their relationship with disease activity

With a cross sectional study of 465 consecutive systemic lupus erythematosus (SLE) patients tested for 13 autoantibodies (Aab) and two idiotypes we determined the prevalence of Aab according to disease activity, both general and at particular organ systems. Seventy seven percent of SLE sera had at least one Aab and 56% had it at high titres. Pathogenic idiotypes had a prevalence of less than 10% and 166 sera had Aab to 5 or more antigens and 9 sera had Aab against all 13 antigens tested. Patients with active disease had increased prevalence of Aab to DNP, ssDNA, ENA, mitochondria and histones when considered at 5 s.d. above the mean of normal controls. The higher positivity of Aab in patients with active disease was confirmed in logistic regression analysis adjusted by age, disease duration, and intensity of treatment. A trend was observed of increased prevalence and titres of Aab from inactive disease without treatment, to inactive disease but still being treated, to active disease. Only 22% of patients with active disease had no Aab and the higher the number of Aab the higher the frequency of active disease. Patients with active arthritis, and to a lesser degree those with active mucocutaneous involvement, had higher prevalence and titres of most autoantibodies than patients with disease activity at other organ systems. Active renal disease associated only with anti-dsDNA, whereas active CNS disease associated with anti-mitochondrial Aab. Our findings support the vision of SLE as an immune dysregulation leading to polyclonal B cell activation with resulting production of multiple Aab. Their profiles seem influenced by genetical, hormonal and environmental factors and, in turn, they contribute to the clinical picture in each patient. Disease activity influences the presence of some, but not all, Aab and some of them may remain present in some patients, even in remission.

Vasculitis in systemic lupus erythematosus

We studied the frequency, location, clinical and histopathological features, associated manifestations, and prognosis of vasculitides in a cohort of 667 SLE patients. Exclusion of patients with previous vasculitis or insufficient information left 540 patients, 194 of whom has vasculitis (incidence density: 0.053 new cases/person/year, cumulative incidence of 0.051 at one year, 0.232 at 5 years and 0.411 at 10 years). Vasculitis was confirmed by biopsy in 46 cases, by arteriography in five, and by both in three. A single episode of vasculitis occurred in 119 and two or more in 75 patients. Vasculitis was cutaneous in 160, visceral in 24, both in 10. In the first episode of cutaneous vasculitides, 111 had punctuate lesions, 32 palpable purpura, 6 urticaria, 6 ulcers, 8 papules, 5 erythematous plaques or macules confirmed with biopsy, 2 erythema with necrosis, and 1 panniculitis (plus small vessel vasculitis). Of 29 with visceral vasculitis in the first episode, 19 had mononeuritis multiplex, 5 digital necrosis, 3 large artery vasculitis of limbs, one mesenteric, and one coronary, more than one type could appear simultaneously or in subsequent episodes. Patients with vasculitis had longer disease duration and followup, younger age of onset of SLE, and were more frequently males than those without. Lupus manifestations associated with vasculitis in univariate logistic regression included myocarditis, psychosis, Raynaud's phenomenon, serositis, leukopenia, lymphopenia and pleuritis. Vasculitis also associated with the antiphospholipid syndrome. The strength of this association increased when patients with vasculitis confirmed by biopsy and/or arteriography were considered separately. Visceral vasculitis associated with increased mortality when controlled for age of onset and nephropathy.

Relationship of anticardiolipin antibodies and antiphospholipid syndrome to HLA-DR7 in Mexican patients with systemic lupus erythematosus (SLE)

We studied IgG and IgM anticardiolipin antibodies (aCL) by an ELISA method in 80 Mexican systemic lupus erythematosus (SLE) patients and 378 of their first degree relatives. Sixty five percent of SLE patients and 16% of their relatives were positive for aCL. We also determined allele and haplotype frequencies of Major Histocompatibility Complex (MHC) genes (classes I, II and III) in both patients and relatives. MHC allele and haplotype frequencies of aCL positive and negative individuals were compared to those of normal ethnically matched controls. SLE patients with aCL had statistically significant increased corrected frequencies of HLA-DR3 (pC = 0.04, RR = 2.78); DR7 (pC = 0.005), RR = 3.42) and DQ2 (pC = 0.003, RR = 2.58) antigens. Their first degree relatives positive for aCL also had increased frequency of HLA-DR7 but it did not remain significant after correcting the P value. On the other hand, SLE patients negative for aCL had a moderate increased frequency of DR3 and DQ2 but not of DR7. These results suggest that DR7 associates with the presence of aCL. The distribution of MHC alleles in SLE patients positive for aCL resembles that found in their aCL positive first degree relatives. Since the presence of the antibody is not sufficient to predict a clinical outcome, we studied those patients with reliable clinical data regarding the presence of the antiphospholipid syndrome (aPLS). SLE patients with aPLS had significantly increased frequency of DR7 (pC = 0.004), as did those with probable aPLS (pC = 0.05), while the frequency of DR7 in SLE patients in the doubtful or negative aPLS categories was no different from normal controls. These data support a possible role of DR7 in the development of aCL in SLE patients and their relatives and suggest a contribution of this class II MHC antigen to the development of aPLS within SLE.