KL-6 is a long-term disease-activity biomarker for interstitial lung disease associated with polymyositis/dermatomyositis, but is not a short-term disease-activity biomarker.

Objectives: We aimed to evaluate the usefulness of serum KL-6 for interstitial lung disease (ILD) with polymyositis/dermatomyositis (PM/DM). Methods: All consecutive and previously untreated adult patients with PM/DM who were admitted to our hospital from 2010 to 2015 were included. The associations between serum KL-6 levels and clinical information were retrospectively analyzed. Results: Baseline serum KL-6 levels were significantly higher in patients with ILD than in those without (n = 41 and 15, respectively; p < .001). In the 14 patients whose ILD improved within 4 weeks post-treatment, their serum KL-6 levels did not significantly decrease at 2 weeks, 4 weeks, or 3 months post-treatment (p = 1.00, 1.00, and .83, respectively). Conversely, their serum KL-6 levels significantly decreased at 6, 9, and 12 months post-treatment (p = .01 in all comparisons). In the 12 patients whose ILD remained unchanged or deteriorated in 4 weeks post-treatment, only the difference between their serum KL-6 levels at 3 and 12 months was significant (p = .003). Conclusions: The present study validated the serum KL-6 as a diagnostic marker for ILD in PM/DM. However, serum KL-6 is not a short-term disease-activity biomarker for ILD with PM/DM, but it is a long-term disease-activity biomarker.

Sildenafil attenuates the fibrotic phenotype of skin fibroblasts in patients with systemic sclerosis.

Systemic sclerosis (SSc) is a multi-organ fibrotic disease that affects the skin and various internal organs. Therapeutic strategies for tissue fibrosis have not been established; however, aberrantly activated fibroblasts in affected lesions are key targets for modulating fibrosis. Recently, increased intracellular cyclic GMP (cGMP) levels were demonstrated to improve fibrosis levels in various diseases. The purpose of this study was to assess the anti-fibrotic properties of cGMP in cultured fibroblasts from patients with SSc. The phosphodiesterase (PDE) 5 inhibitor sildenafil increased the intracellular cGMP levels in skin fibroblasts in a dose-dependent manner. Sildenafil treatment also significantly decreased the expression of several pro-fibrotic factors that were upregulated by TGF-ß1 treatment in SSc skin fibroblasts. These inhibitory effects occurred via non-canonical TGF-ß signaling. Our findings revealed that sildenafil might be a novel strategy to treat tissue fibrosis and vasculopathy in SSc.

Cytokine profiles in polymyositis and dermatomyositis complicated by rapidly progressive or chronic interstitial lung disease.

OBJECTIVE: PM and DM are often complicated by interstitial lung disease (ILD). In this study we aimed to evaluate various serum cytokines in patients with PM/DM with ILD so as to clarify the differences in pathophysiology between anti-melanoma differentiation-associated gene 5 antibody-associated ILD (anti-MDA5-ILD) and anti-aminoacyl tRNA synthetase antibody-associated ILD (anti-ARS-ILD). METHODS: We evaluated the serum cytokine profiles of 38 patients with PM/DM and compared the cytokine profiles of the non-ILD and ILD subsets as well as the anti-MDA5-ILD and anti-ARS-ILD subsets. RESULTS: The myositis intention-to-treat activity index score, which indicates whole disease activity, significantly correlated with serum IL-6, IL-8, TNF-α and IP-10. These cytokine levels were significantly higher in the ILD subset than the non-ILD subset and were lower in the ILD subset following treatment. By multivariate analysis, TNF-α was the most significant cytokine [P = 0.0006, odds ratio (OR) 1.4, CI 1.1, 2.2] associated with PM/DM with ILD. IL-8 levels were significantly higher in anti-MDA5-ILD than in anti-ARS-ILD, although IL-6, TNF-α and IP-10 levels were high in both subsets. IL-8 was the most significant cytokine (P = 0.0006, OR 1.5, CI 1.1, 3.0) associated with anti-MDA5-ILD by multivariate analysis. Moreover, the ratio of IL-4 to IFN-γ was lower in anti-MDA5-ILD than in anti-ARS-ILD. CONCLUSION: IL-6, IL-8, TNF-α and IP-10 are associated with global disease activity in PM/DM. These cytokine levels were high, especially in the ILD subset. Serum IL-8 levels and the balance between IL-4 and IFN-γ may contribute to the differences in pathophysiology between anti-ARS-ILD and anti-MDA5-ILD.

Ghrelin attenuates collagen production in lesional fibroblasts from patients with systemic sclerosis.

Systemic sclerosis (SSc) is a connective tissue disease characterized by thickening of the skin and tissue fibrosis of the internal organs. Ghrelin is primarily described as a gut hormone, and many studies currently indicate that ghrelin has protective effects in different organs, including the heart, pancreas, lung and liver, resulting from its anti-fibrotic properties. We found decreased levels of ghrelin in the plasma from patients with SSc compared with those from healthy controls. In skin fibroblast cultures, recombinant ghrelin diminished the production of collagen type I. In addition, the mRNA levels of COL1A2 and TGFB genes were significantly decreased by the stimulation of ghrelin. We showed that ghrelin may exert anti-fibrotic effects in the skin fibroblasts from patients with SSc. Because the plasma levels of ghrelin are low in SSc, the administration of ghrelin could be a new strategy for the treatment of SSc.

Urinary free light chain is a potential biomarker for ISN/RPS class III/IV lupus nephritis.

OBJECTIVES: To evaluate the use of urinary free light chains (FLCs) as a biomarker for proliferative LN and the potential association between the intensity of plasma cell infiltration of the kidney and urinary FLC levels in LN. METHODS: Forty-three SLE patients were consecutively enrolled in the study. These patients were divided into an International Society of Nephrology and Renal Pathology Society (ISN/RPS) class III/IV LN subset (n = 18) and an ISN/RPS class I/II/V (class non-III/IV) LN subset (n = 25). The expression of κ-LCs, λ-LCs, CD19 and CD138 in kidney specimens was also evaluated with immunohistochemical staining. To measure FLC levels before and after treatment, an additional six patients with class III/IV LN were consecutively enrolled. RESULTS: Urinary FLCs were significantly higher in the class III/IV LN subset than in the class non-III/IV LN subset. Urinary λ-FLC levels were significantly correlated with the urinary protein-creatinine ratio in the class III/IV LN subset (rs = 0.67, P < 0.01). Moreover, the LC-secreting CD19(-)/CD138(+) cell counts in the kidney specimens were higher in the class III/IV LN subset than in the class non-III/IV LN subset. Total urinary FLC levels were correlated with the numbers of CD138(+) cells in the kidney (r = 0.71, P = 0.03). Following treatment, urinary λ-FLCs could not be detected in any of the patients. CONCLUSION: The intensity of plasma cell infiltration of the kidney is associated with urinary FLC levels. Urinary FLCs are potentially useful biomarkers in ISN/RPS class III/IV LN or proliferative LN.

Brief report: Association of HLA-DRB1*0101/*0405 with susceptibility to anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis in the Japanese population.

OBJECTIVE: The complication of interstitial lung disease (ILD) in polymyositis/dermatomyositis (PM/DM) is associated with anti-aminoacyl-transfer RNA synthetase (anti-aaRS) antibody or anti-melanoma differentiation-associated gene 5 (anti-MDA-5) antibody positivity. Anti-MDA-5 antibody is associated with clinically amyopathic DM and fatal outcome due to rapidly progressive ILD in Asian populations. The association between genetic factors and anti-MDA-5 antibody-positive DM is unclear. This study was undertaken to investigate the HLA-DRB1 genotype in patients with anti-MDA-5 antibody-positive DM. METHODS: We examined genetic differences among 17 patients with anti-MDA-5 antibody-positive DM, 33 patients with anti-aaRS antibody-positive PM/DM, 33 patients with PM/DM without anti-aaRS antibody or ILD, and 265 healthy controls. RESULTS: The frequencies of HLA-DRB1*0101 and DRB1*0405 were 29% and 71%, respectively, in patients with anti-MDA-5 antibody-positive DM, which were higher than the frequencies in healthy controls (10% and 25%, respectively). Among the 17 patients with anti-MDA-5 antibody-positive DM, 16 (94%) harbored either the DRB1*0101 or DRB1*0405 allele. The combined frequency of the DRB1*0101 allele and the DRB1*0405 allele was significantly higher in patients with anti-MDA-5 antibody-positive DM than in patients with PM/DM without anti-aaRS antibody or ILD, with an odds ratio (OR) of 42.7 (95% confidence interval [95% CI] 4.9-370.2) (P = 1.1 × 10(-5)), or in patients with anti-aaRS antibody-positive PM/DM (OR 13.3 [95% CI 1.6-112.6], P = 4.5 × 10(-3)). CONCLUSION: Our findings indicate that HLA-DRB1*0101/*0405 is associated with susceptibility to anti-MDA-5 antibody-positive DM in the Japanese population.

A case of Takayasu arteritis complicated with acute pericarditis at initial presentation.

Takayasu arteritis (TAK) is a rare, large-vessel vasculitis, frequently presenting at approximately 20 years of age. Patients with TAK without characteristic clinical findings are sometimes left undiagnosed and are followed by a fever of unknown origin; delayed diagnosis may lead to irreversible ischaemia and organ damage. Here, we report a case of an 18-year-old woman with TAK complicated by acute pericarditis at initial presentation. She was diagnosed with idiopathic acute pericarditis and treated with non-steroidal anti-inflammatory drugs (NSAIDs). However, the patient's fever and pain in the chest and upper back persisted. On admission to our hospital, magnetic resonance angiography and ultrasonography revealed wall thickening in the common carotid artery, subclavian artery, and aorta, along with vascular narrowing in the celiac, superior mesenteric, and bilateral renal arteries. The patient was diagnosed with TAK and treated with glucocorticoids, including methylprednisolone pulse therapy, and azathioprine. The treatment improved the patient's signs and symptoms, and pericardial effusion decreased. Acute pericarditis is a rare manifestation of TAK, but it is important to differentiate diseases, including TAK in patients with acute pericarditis who fail to respond to 2-3 weeks of conventional therapy with NSAIDs.

Anti-MDA5 antibody, ferritin and IL-18 are useful for the evaluation of response to treatment in interstitial lung disease with anti-MDA5 antibody-positive dermatomyositis.

OBJECTIVE: The aim of this study was to investigate the precise clinical characteristics and to analyse the association between the anti-MDA5 antibody (anti-MDA5ab) titre and disease status in patients with anti-MDA5ab-positive DM. METHODS: Twenty-seven patients who presented with DM and were positive for the anti-MDA5ab were enrolled. The association between the clinical manifestations and the clinical parameters, including the anti-MDA5ab, was analysed. RESULTS: The complication of rapidly progressive interstitial lung disease (RP-ILD) occurred in 20 (74%) patients. The frequencies of fatal outcome, relapse and malignancy were 33, 4 and 4%, respectively. Remarkably, a fatal outcome occurred within the first 6 months. Compared with six non-RP-ILD patients, elderly age at onset, severely involved pulmonary function and high levels of serum ferritin were present in 20 RP-ILD patients with anti-MDA5ab. Alveolar-arterial oxygen difference (AaDO(2)) ≥32 mmHg and ferritin ≥828 ng/ml at admission were poor prognostic factors in RP-ILD patients with anti-MDA5ab-positive DM. The median value of the anti-MDA5ab titre on admission was higher in patients who later died than in those who survived. The efficacy of treatment was indicated by the anti-MDA5ab, ferritin and IL-18 concentrations. The decline index of the anti-MDA5ab titre after treatment was lower in the subset of patients who died than in the subset of patients who lived. Sustained high levels of anti-MDA5ab, ferritin and IL-18 were present in the patients who died. CONCLUSION: Anti-MDA5ab titre and ferritin and IL-18 concentrations are useful for the evaluation of the response to treatment and the status of ILD in patients with anti-MAD5ab-positive DM.

NR2-reactive antibody decreases cell viability through augmentation of Ca(2+) influx in systemic lupus erythematosus.

OBJECTIVE: Anti-N-methyl-D-aspartate (anti-NMDA) receptor subunit NR2-reactive antibody may play a crucial role in neuronal manifestations of systemic lupus erythematosus (SLE). However, how NR2-reactive antibody acts as a critical modulator of the NMDA receptor is unknown. This study was undertaken to investigate the biologic function of NR2-reactive antibody in patients with SLE. METHODS: The study included 14 patients with SLE, 9 of whom had NR2-reactive antibody. We analyzed the effects of NR2-reactive antibody on cell viability and intracellular Ca(2+) level. We also investigated the efficacy of zinc as a modulator of the intracellular Ca(2+) level in the presence of NR2-reactive antibody. RESULTS: There was a significant inverse correlation between the NR2-reactive antibody titer and cell viability (R(2) = 0.67, P < 0.0001; n = 23), and there was a significant association between the NR2-reactive antibody titer and the intracellular Ca(2+) level in NR1/NR2a-transfected HEK 293 cells (R(2) = 0.69, P < 0.0001). Intracellular Ca(2+) levels were significantly higher in cells incubated with IgG derived from NR2-reactive antibody-positive SLE patients than in those incubated with IgG derived from NR2-reactive antibody-negative SLE patients (P = 0.0002). The addition of zinc decreased the intracellular Ca(2+) level in a dose-dependent manner. NR2-reactive antibody-positive SLE IgG weakened the efficacy of zinc as a negative modulator of the intracellular Ca(2+) level. CONCLUSION: Our findings indicate that NR2-reactive antibody decreases cell viability by Ca(2+) influx in SLE through inhibition of the binding capacity of zinc.

Anti-NR2A antibody as a predictor for neuropsychiatric systemic lupus erythematosus.

OBJECTIVE: The aim of this study is to establish a detection method for anti-N-methyl-d-aspartate receptor subunit 2A (NR2A) antibody and to evaluate the relationship between anti-NR2A antibody and various organ involvement in SLE. METHODS: Serum anti-NR2A antibody was measured by ELISA using a peptide with a core of either DWEYS or DWDYS as autoantigen. Additionally, clinical characteristics were compared between 27 anti-NR2A antibody-positive (P group) and 80 antibody-negative (N group) SLE patients using DWDYS peptide. RESULTS: The optical density (OD) values of anti-NR2A antibody using DWDYS and DWEYS peptides correlated significantly (r = 0.94, P < 0.0001). The median OD value was significantly higher (P < 0.0001) with DWDYS. Additionally, the SLEDAI was significantly higher (P = 0.023) in the P group. The frequency of neuropsychiatric SLE (NPSLE) was significantly higher (P = 0.0002) in the P group, although the frequencies of serositis and nephritis were not statistically significant. Significant correlations were found between anti-NR2A antibody and leucocyte count (r(s) = -0.31, P = 0.001) and haemoglobin (r(s) = -0.42, P < 0.0001), although no correlation was found between anti-NR2A antibody and the titre of anti-dsDNA antibody. NPSLE was the most significant independent variable (P = 0.0008) associated with anti-NR2A antibody positivity, as estimated by multiple linear regression analysis. CONCLUSION: Serum anti-NR2A antibody can be associated with the complication of NPSLE and may indicate the involvement of non-nervous tissue. The use of peptides that include DWDYS is preferable to detect anti-NR2A antibody in ELISA.

Tumour necrosis factor inhibitor-induced myositis in a patient with ulcerative colitis.

Tumour necrosis factor (TNF) inhibitors are known to induce autoimmune diseases, such as lupus-like syndrome; in rare cases, TNF inhibitor-induced myositis has been reported. This report documents the case of a male patient with ulcerative colitis (UC) complicated by TNF inhibitor-induced myositis. After UC diagnosis and treatment with azathioprine and infliximab, he was evaluated for a recent 5-month history of muscle weakness and pain. Laboratory tests revealed elevated muscle enzymes, such as serum creatine kinase (CK) and aldolase. He also tested positive for anti-nuclear antibodies and anti-double stranded DNA antibodies. High-intensity signals in his quadriceps on magnetic resonance image (MRI) and fibrillation potentials in his proximal muscles on electromyography were demonstrated. Muscle biopsy revealed the endomysial infiltration of mononuclear cells surrounding myofibers. Eventually, the patient fulfilled the classification criteria for idiopathic inflammatory myopathies. Although an adverse drug reaction of infliximab had been speculated, his muscle involvements did not improve in 6 weeks from the last administration of infliximab; therefore, treatment with prednisolone was initiated. Subsequently, his muscle symptoms ameliorated, and his serum CK levels returned to normal. Repeat MRI revealed a complete resolution of the signal intensity, and he reported no symptoms of UC or myositis while prednisolone was tapered without resumption of infliximab. Clinicians should consider the diagnosis of drug-induced myositis if muscle symptoms develop in patients treated with TNF inhibitors.

Interleukin-18 is a key mediator in dermatomyositis: potential contribution to development of interstitial lung disease.

OBJECTIVE: To determine whether IL-18 is involved in the inflammation of DM and PM. METHODS: Thirty-three patients with DM were enrolled in this study, including 25 with interstitial lung disease (ILD). In addition, 16 patients with PM were enrolled, including 6 with ILD. All patients were admitted to our hospital as a result of their condition requiring treatment, and clinical laboratory data including serum IL-18 were recorded on admission. RESULTS: Serum IL-18 was significantly (P < 0.0001) higher in both DM and PM patients than in healthy controls (n = 30). Serum ferritin and IL-18 were significantly (P = 0.003 and 0.0044, respectively) higher in DM than in PM patients. Additionally, ferritin and IL-18 were significantly (P = 0.023 and 0.034, respectively) higher in DM patients with ILD than in DM patients without ILD. Significant positive correlations were found between creatine kinase (CK) and ferritin (r(s) = 0.39, P = 0.024); CK and IL-18 (r(s) = 0.48, P = 0.005); and IL-18 and ferritin (r(s) = 0.54, P = 0.0012) in the DM group as a whole. These findings were different for the DM plus ILD subgroup: significant positive correlations were found between CK and ferritin (r(s) = 0.40, P = 0.047); CK and IL-18 (r(s) = 0.63, P = 0.0008); and IL-18 and ferritin (r(s) = 0.41, P = 0.042). CONCLUSION: Serum IL-18 was strikingly elevated in patients with DM and was associated particularly with disease activity and ILD complication in DM.

Interferon-induced helicase (IFIH1) polymorphism with systemic lupus erythematosus and dermatomyositis/polymyositis.

The aim of the present study was to evaluate whether the interferon-induced helicase (IFIH1) Ala946Thr (rs1990760 A>G) polymorphism is associated with susceptibility to systemic lupus erythematosus (SLE) and dermatomyositis (DM) or polymyositis (PM) in the Japanese population. The study population consisted of 243 SLE patients, 125 DM/PM patients, and 268 healthy controls from Japan. A Taqman single nucleotide polymorphism genotyping assay was designed for rs1990760 by Applied Biosystems. There were no significant differences between SLE and DM/PM patients and healthy controls regarding the frequency of each genotype and allele. However, the frequency of the AA genotype and the A allele tended to be higher in PM patients with interstitial lung disease (ILD). Additionally, when comparing the AA and AG + GG genotypes at rs1990760, the AA genotype was significantly more frequent in PM patients with ILD than in healthy controls [odds ratio, 3.23 (95% confidence interval, 1.06-9.81); P = 0.04] or in PM patients without ILD [odds ratio, 5.40 (95% confidence interval, 1.37-21.26); P = 0.027]. Our observations suggest that the G allele protects against the onset of ILD and that the AA genotype is a risk factor for lung injury in PM patients.

Clinical usefulness of anti-M-type phospholipase-A-receptor antibodies in patients with membranous nephropathy and the comparison of three quantification methods.

Associations between anti-M-type phospholipase A2 receptor (PLA2R) antibodies and disease activity and prognosis have been suggested in primary membranous nephropathy (MN); however, more evidence is needed. We aimed to establish a clinically useful method to measure anti-PLA2R antibodies. We developed a western blot assay and a cell-based enzyme-linked immunosorbent assay (ELISA). Anti-PLA2R antibodies were evaluated retrospectively using these assays and the commercial solid-phase ELISA. Anti-PLA2R antibodies were detected in 12, 6, and 12 out of 23 Japanese patients with biopsy-proven primary MN using the western blot, the cell-based ELISA, and the solid-phase ELISA, respectively. The samples of the lupus MN patients tested negative. The levels of proteinuria correlated moderately with the titres of anti-PLA2R antibodies measured by the three methods (r = 0.39-0.47). Anti-PLA2R antibodies were significantly associated with physicians' decisions on immunosuppressive treatment without prior knowledge of anti-PLA2R antibody positivity (p < .01). In the longitudinal analysis, the titres of anti-PLA2R antibodies measured by the solid-phase ELISA declined significantly following treatment (p = .03). In conclusion, these results suggest the usefulness of anti-PLA2R antibody as a diagnostic, prognostic, and surrogate biomarker in primary MN. The three methods proved to be reliable for measuring anti-PLA2R antibody titres, but their performances differ.

Regional overdistension during prone positioning in a patient with acute respiratory failure who was ventilated with a low tidal volume: a case report.

BACKGROUND: Prone positioning may provide a uniform distribution of transpulmonary pressure and contribute to prevent ventilator-induced lung injury. However, despite moderate positive end-expiratory pressure and low tidal volumes, there is still a risk of regional overdistension. CASE PRESENTATION: A man with refractory hypoxemia was mechanically ventilated with prone positioning. Although prone positioning with a plateau pressure of 18 cmH2O and a positive end-expiratory pressure of 8 cmH2O promptly improved oxygenation, regional ventilation monitoring using electrical impedance tomography initially detected decreased distribution in the dorsal region but increased in the ventral, suggesting overdistension. CONCLUSIONS: Our experience indicates monitoring regional ventilation distribution is useful for decreasing the risk of overdistension during prone positioning.

Clinical Manifestations and Myositis-Specific Autoantibodies Associated with Physical Dysfunction after Treatment in Polymyositis and Dermatomyositis: An Observational Study of Physical Dysfunction with Myositis in Japan.

OBJECTIVE: The physical function of PM/DM patients after remission induction therapy remains unknown adequately. The aim of our study was to evaluate the present status of physical dysfunction and to clarify the clinical manifestations and myositis-specific autoantibodies (MSAs) associated with physical dysfunction after treatment in PM/DM. METHODS: We obtained clinical data including the age at disease onset, gender, disease duration, laboratory data prior to initial treatment, and the specific treatment administered. We evaluated disease activity and physical dysfunction after treatment using the core set provided by the International Myositis Assessment and Clinical Studies Group. RESULTS: 57% of the 77 enrolled patients with PM/DM had troubles in daily living after treatment. At the enrolment, disease activity evaluated by physicians was only revealed in 20% of patients. In a multivariate analysis, the age at disease onset, female gender, and CK levels before treatment were significantly associated with the severity of physical dysfunction after treatment. Anti-SRP positivity was associated with more severe physical dysfunction after treatment than anti-ARS or anti-MDA5. CONCLUSIONS: Half of the PM/DM patients showed physical dysfunction after treatment. Age at disease onset, gender, CK level before treatment, and anti-SRP were significant predictors associated with physical dysfunction after treatment in PM/DM.

IL-6, IL-8, and IL-10 are associated with hyperferritinemia in rapidly progressive interstitial lung disease with polymyositis/dermatomyositis.

OBJECTIVE: Hyperferritinemia is frequently accompanied by rapidly progressive (RP) interstitial lung disease (ILD) with polymyositis (PM)/dermatomyositis (DM). To clarify the mechanism of RP-ILD with hyperferritinemia, we investigated the associations between serum ferritin levels and various cytokines in patients with PM/DM. METHODS: This retrospective study included 38 patients admitted to our hospital with PM/DM. Levels of serum ferritin and cytokines (IL-1ß, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-13, IL-17, IL-18, TNF-α, IFN-α, IFN-γ, and IP-10) were measured. Disease activity was evaluated using the tool proposed by the International Myositis Assessment and Clinical Studies Group. We analyzed the associations between disease activity and levels of serum ferritin and cytokines. RESULTS: The levels of serum ferritin, IL-8, IL-10, IL-18, and TNF-α, were significantly correlated with disease activity. In a multivariate analysis, IL-6 (t = 3.6, P = 0.0010), IL-8 (t = 4.8, P < 0.0001), and IL-10 (t = 5.7, P < 0.0001) significantly contributed to serum ferritin levels. The levels of serum ferritin, IL-6, IL-8, and IL-10, were higher in the RP-ILD subset than in the non-ILD subset or the chronic ILD subset. CONCLUSION: IL-6, IL-8, and IL-10 are significant contributors to hyperferritinemia in PM/DM. The regulation of these cytokines might offer a possible treatment strategy for RP-ILD with PM/DM.

Frequency of class III and IV nephritis in systemic lupus erythematosus without clinical renal involvement: an analysis of predictive measures.

OBJECTIVE: To determine the frequency of International Society of Nephrology/Renal Pathology Society (ISN/RPS) class III or IV lupus nephritis in patients with systemic lupus erythematosus (SLE) without clinical renal involvement. METHODS: We investigated the renal pathology of 195 patients with SLE, including 86 patients without clinical renal involvement. RESULTS: Lupus nephritis other than class I was found in 58% of the patients without clinical renal involvement, and class III and IV nephritis was found in 15% of these patients. To reveal the predictive measures involved in class III or IV lupus nephritis, we explored the clinical measures in patients with SLE who did not have clinical renal involvement. Anti-dsDNA antibody titers were significantly higher (p = 0.0266) and C3 values were significantly lower (p = 0.0073) in patients with class III or IV lupus nephritis than in patients without class III or IV lupus nephritis. The sensitivity and specificity values were 77% and 73%, respectively, for cutoff levels of both 40 IU/ml for anti-dsDNA antibodies and 55 mg/dl for C3 (OR 8.8, p = 0.0011). CONCLUSION: The frequency of nephritis, including ISN/RPS class III and IV, was unexpectedly high in SLE patients without clinical renal involvement. ISN/RPS class III or IV lupus nephritis could be hidden in patients with SLE who present both a high titer of anti-dsDNA antibody and a low concentration of C3, even when they have clinically normal urinary findings and renal function.