Hyperuricemia is an independent risk factor for renal pathological damage and poor prognosis in lupus nephritis patients.

OBJECTIVE: To explore the correlation between hyperuricemia and renal damage in patients with lupus nephritis (LN).
 Methods: The data for clinical features, laboratory and renal pathological examination were collected from 177 renal biopsy-proven LN patients with or without hyperuricemia and were retrospectively analyzed to determine the correlation between serum uric acid and renal damage.
 Results: LN patients with hyperuricemia group had higher rate of hypertension and higher level of blood urea nitrogen and serum creatinine while lower estimated glomerular filtration rate (eGFR) and lower positive rate of anti-U1RNP antibody (P<0.05). In the LN patients with hyperuricemia group, renal pathological scores, including acitive index, chronic index and tubulointerstitial lesions, were higher than those in the LN patients without hyperuricemia group (P<0.05). The level of serum uric acid was positively correlated with serum creatinine, renal pathological classification and renal pathological scores while negatively correlated with eGFR (P<0.05).
 Conclusion: LN patients with hyperuricemia are associated with more serious renal damage. Hyperuricemia is an important predictor for poor prognosis in patients with LN.

Association between anti-U1 ribonucleoprotein antibodies and inflammatory mediators in cerebrospinal fluid of patients with neuropsychiatric systemic lupus erythematosus.

OBJECTIVE: We investigated possible associations between neurotoxic inflammatory mediators (IMs) and anti-U1RNP antibodies (Abs) in cerebrospinal fluid (CSF) of neuropsychiatric systemic lupus erythematosus (NPSLE). METHODS: Serum and CSF anti-U1RNP Abs were detected using an RNA-immunoprecipitation assay and CSF anti-U1RNP Ab levels were measured by ELISA. IFN-α, MCP-1 and IL-8 levels in CSF were determined by quantitative multiplex cytokine analysis. IM levels were compared among anti-U1RNP-positive and anti-U1RNP-negative NPSLE as well as other rheumatic disease controls (controls). RESULTS: Anti-U1RNP Abs were detected in serum (58%) and in CSF (18%) of 82 NPSLE patients. CSF MCP-1 levels were higher in NPSLE than in controls. CSF IFN-α level was higher in CSF anti-U1RNP Ab-positive than in -negative patients or controls. When limited to serum anti-U1RNP Ab-positive patients, however, levels of all three IMs in CSF were higher in CSF anti-U1RNP Ab-positive than in -negative patients. Anti-U1RNP Ab levels in CSF correlated with CSF MCP-1, but not IFN-α and IL-8 levels. CONCLUSIONS: CSF anti-U1RNP Ab positivity is associated with increased level of CSF IFN-α. MCP-1 levels correlated with CSF anti-U1RNP Ab levels, whereas the increased CSF MCP-1 was not specific to CSF anti-U1RNP Ab-positive NPSLE.

Altered posttranslational modification on U1 small nuclear ribonucleoprotein 68k in systemic autoimmune diseases detected by 2D Western blot.

Anti-ribonucleoprotein (anti-RNP) antibodies are one of the representative autoantibodies detectable in patients with systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD). Generally, posttranslational modifications (PTMs) on autoantigens are proposed to be involved in the production of autoantibodies. In this study, we tried to detect the alteration in PTMs on a U1 small nuclear RNP 68k subunit (U1-68k), a major antigen of anti-RNP antibodies. Peripheral blood mononuclear cells (PBMCs) were obtained from patients with MCTD, SLE, and rheumatoid arthritis (RA), and from healthy donors. U1-68ks in the PBMCs were detected by 2D Western blot (WB), where extracted nuclear proteins were separated by 2DE, followed by the detection of U1-68k using WB. More than 20 PTM isoforms were detected with different molecular weights of 65.0 , 66.5, and 68.0kDa, and different pIs between 6.0 and 8.5. Importantly, the relative intensity of the spot with 66.5 kDa and pI 7.5 was significantly increased in the MCTD and SLE groups compared to the RA and healthy groups. Further, this U1-68k isoform, in particular, in its RS domain, was found to have significantly decreased phosphorylation compared to the other isoforms. The PTM alternation may be one of the steps to generate the anti-RNP antibodies.

Juvenile onset Systemic Lupus Erythematosus thyroid dysfunction: a subgroup with mild disease?

The aim of this study was to evaluate the frequency of thyroid dysfunction and thyroid antibodies in patients with juvenile onset Systemic Lupus Erythematosus (JOSLE) and its association with clinical and immunological features. Seventy-seven patients with JOSLE, 64 females, median age 19 years, were consecutively enrolled from March to December 2007. Clinical data related to thyroid dysfunction and lupus were obtained by chart review and patient interview. Serum levels of TSH, free T4, anti-thyroglobulin (TgAb), anti-thyroperoxidase (TPOAb), TRAb and lupus related autoantibodies were analyzed by standard techniques. Nine patients were diagnosed as hypothyroidism and 4 hyperthyroidism. 28% JOSLE patients had moderate/high titer of thyroid antibodies: 23% TgAb, 2.6% TPOAb and 3.9% TRAb. JOSLE patients with positive thyroid autoantibodies had higher frequency of anti-U1RNP antibodies than patients without these antibodies (40.9 vs. 14.5%, OR:0.25, CI:0.08-0.76, p = 0.017). Furthermore, renal/neurological/hematological involvement was less frequently observed in patients with hypothyroidism (55.6 vs. 87.5%, OR:0.18, CI:0.04-0.81, p = 0.035) and with thyroid antibodies (68.4 vs. 90.9%, OR:0.22, CI:0.06-0.82, p = 0.027) than in patients without these alterations. No association with PTPN22 polymorphism was found. In conclusion, JOSLE patients have high prevalence of subclinical hypothyroidism. The novel association of anti-thyroid antibodies with anti-U1RNP antibodies in JOSLE seems to identify a subgroup of patients with less life-threatening organ involvement.

Longitudinal study of interleukin-10, tumor necrosis factor-alpha, anti-U1-snRNP antibody levels and disease activity in patients with mixed connective tissue disease.

OBJECTIVE: To investigate the levels and relationship between IL-10, TNF-alpha, anti-U1snRNP antibodies and disease activity in longitudinally collected serum samples from patients with mixed connective tissue disease (MCTD). METHODS: Six patients followed for 17-138 months were investigated with ELISA for estimation of cytokine levels and antibodies to the different epitopes of the U1snRNP. Disease activity was assessed by systemic lupus activity measure (SLAM). RESULTS: IL-10 and TNF-alpha levels fluctuated with time in at least half of the patients. Three patients had increased IL-10 levels and two had increased TNF-alpha in all samples. There was no correlation between cytokine levels and disease activity or clinical manifestations. All patients had increased levels of antibodies to the main components of the U1snRNP. Both antibody levels and disease activity decreased with time. A correlation between TNF-alpha and U1snRNP antibody levels were observed in five patients. CONCLUSIONS: Increased and fluctuating levels of IL-10 or TNF-alpha without correlation to disease activity were observed in MCTD patients. In some patients increased cytokine levels were observed over several years irrespective of disease activity indicating that they could be constitutively increased in these individuals.

Dual posttranscriptional targets of retinoic acid-induced gene expression.

Retinoic acid-induced differentiation of the pre-osteoblastic cell line, UMR 201, is associated with a marked increase in the proficiency of posttranscriptional nuclear processing of alkaline phosphatase mRNA. In this study we attempted to correlate the posttranscriptional actions of retinoic acid with changes in phosphorylation, or abundance of spliceosome components, or both. Treatment with retinoic acid for periods of < or = 4 h resulted in dephosphorylation of nuclear U1 70K protein without affecting its abundance. Peptide mapping showed that U1 70K dephosphorylation was related to the disappearance of one specific phosphopeptide out of four major U1 70K phosphopeptides. A twofold decrease in mRNA expression of an isoform of alternative splicing factor that inhibits splicing was also observed over the same period. Tumor necrosis factor-alpha, which enhances the posttranscriptional action of retinoic acid, reduced U1 70K mRNA expression, while an inhibition of retinoic acid action by transforming growth factor-beta was associated with a marked increase in U1 70K mRNA levels. Our results draw attention to the complex interactions between short- and long-term alterations in the abundance and functional status of U1 70K, as well as SR proteins by growth and/or differentiation factors in the regulation of spliceosome formation and function.

'Autoantibody dominance' pattern following idiotypic manipulation of naive mice by immunization with anti-U1RNP antibodies.

OBJECTIVE: To study the immune response and clinical findings in mice immunized with different epitope-specific anti-U1RNP antibodies purified from the sera of mixed connective tissue disease (MCTD) patients with various clinical manifestations. METHODS: BALB/c mice were immunized with anti-U1RNP-IgG preparations from 3 patients with MCTD. Group 1 was immunized with U1 70 kD A-positive IgG, group 2 with U1 70 kD-negative, U1A, U1C, B-B'-positive IgG and group 3 with U1 70 kD, U1A, U1C-positive IgG. The induced autoantibody response in the mice was studied by ELISA and immunoblots and the clinical findings of MCTD in humans were assessed. RESULTS: Immunoblot assays showed that mice immunized with different human anti-U1RNP antibodies developed predominantly autoantibodies directed against U1 68-70 kD epitope. This 'autoantibody dominance' pattern was not associated with clinical findings. CONCLUSIONS: The restricted murine autoimmune response may provide clues to the diversified autoantibody production in autoimmune diseases and explain in part the changing patterns of clinical findings in individuals with MCTD.

The penetration of autoantibodies into cells may induce tolerance to self by apoptosis of autoreactive lymphocytes and cause autoimmune disease by dysregulation and/or cell damage.

Autoantibodies to intracellular constituents often occur naturally. This would be difficult to understand were they unable to penetrate live cells, as was once generally accepted; however, they can and in so doing may alter cell functions, cause damage and even kill cells by apoptosis. Different autoantibodies have different effects and in this paper, further to our previous report on the penetration of anti-DNA, the penetration of anti-RNP, which may be a possible cause of apoptosis, is demonstrated. Penetration of lymphocytes by autoantibodies may play a role in the causation of autoimmune disease, influencing immune regulation and causing cell damage either directly or through nucleosomal DNA release as a result of apoptosis. This, in turn, could also further promote antigen-driven production of anti-DNA. In addition, by causing apoptosis of autoreactive cell clones, natural autoantibodies could influence tolerance during development and also later in life, thus, paradoxically, helping prevent autoimmune disease.

IgM anti-A and D SnRNP proteins and IgM anti-dsDNA are closely associated in SLE sera.

U1RNP and Sm precipitins occur in systemic lupus erythematosus (SLE) and in overlap syndromes, while precipitins to Ro/SSA and La/SSB occur in SLE and its variants as well as Sjögren's syndrome. In studying IgM and IgG antibodies to these polypeptides by Western blot, we found the expected frequency of antibodies to the A protein of the U1RNP specificity and the D protein of the Sm specificity in sera with precipitins to U1RNP and Sm, but also found the frequent occurrence of both IgM and IgG anti-A and D in SLE sera with no precipitins, and in sera with anti-Ro/SSA and/or anti-La/SSB precipitins, but not in sera from patients with rheumatoid arthritis, polymyositis, scleroderma, or normals. We have studied the sera which bind the A and D polypeptides on Western blot to test their ability to bind native U1RNP (which contain the A and D proteins) in ELISA. The results indicate that most anti-Ro/SSA alone, anti-Ro/SSA, and anti-La/SSB sera as well as SLE sera with no precipitins react preferentially with the denatured A and D proteins. Further study of sera with IgM anti-A and D in Western blot reveals that these sera also frequently contain anti-double-stranded DNA antibodies. These results show that the anti-A and D responses, especially IgM anti-A and D, occur not only in patients with precipitating antibodies to SnRNPs, but in almost half of patients across the lupus spectrum. The extended prevalence of antibodies to the denatured A and D proteins in Western blot is associated with the cross-reaction of antibodies to dsDNA.