Clinical and ultrasound features of difficult-to-treat rheumatoid arthritis: A multicenter RA ultrasound cohort study

OBJECTIVE

The optimal strategy for difficult-to-treat (D2T) rheumatoid arthritis (RA) has not been identified, and the ultrasound characteristics of D2T RA have not been reported. We investigated the clinical characteristics and factors contributing to the outcome in D2T RA in a multicentre RA ultrasound observational cohort.

METHOD

We reviewed 307 Japanese patients diagnosed with RA who underwent treatment with biological and targeted synthetic disease-modifying anti-rheumatic drugs (b/tsDMARDs). We compared the differences in patient characteristics between the D2T RA and non-D2T RA groups. We examined the factors contributing to a good response [defined as b/tsDMARD continuation and Clinical Disease Activity Index (CDAI) ≤ 10 at 12 months] in the D2T RA patient group.

RESULTS

Forty-three patients (14%) were categorized as D2T RA and the remaining 264 (86%) as non-D2T RA at baseline. The grey-scale (GS) score, disease duration, and CDAI at the initiation of treatment were significantly higher in the D2T RA group than in the non-D2T RA group. In contrast, the power Doppler (PD) score was not significantly different between the two groups. Of the 43 D2T RA patients, 20 achieved a good response. The introduction of CTLA4-Ig (n = 5) was significantly associated with a good response in analysis based on inverse probability weighting with propensity score. GS and PD scores at baseline were not significantly associated with therapeutic response at 12 months in D2T RA patients.

CONCLUSIONS

Patients with D2T RA had high clinical and ultrasound activity and poor responses to treatment with b/tsDMARDs. CTLA4-Ig was associated with a good response at 12 months in D2T RA patients.

Ultrasound efficacy of targeted-synthetic disease-modifying anti-rheumatic drug treatment in rheumatoid arthritis: a multicenter prospective cohort study in Japan

OBJECTIVE

This study investigated the effectiveness of treatment with Janus kinase (JAK) inhibitors in rheumatoid arthritis (RA) assessed by ultrasonography (US) activity, and the influence of patient characteristics and previous treatments.

METHOD

This prospective study assessed 60 treatment initiations among 53 Japanese patients diagnosed with RA who underwent treatment with JAK inhibitors during June 2013 to February 2020. Of the 53 patients, seven patients were enrolled in duplicate because they were treated with two different JAK inhibitors at different periods. For each case, the improvement rate on the power Doppler (PD) score was assessed at 6 month follow-up. Median improvement rate of PD score was used to classify cases as either US responders or non-responders, and patient characteristics were compared between the two groups.

RESULTS

All indicators of clinical disease activity and US activity showed a significant improvement at 3 months compared with baseline. Although the JAK inhibitor-cycler group and the interleukin-6 (IL-6) inhibitor inadequate response (IR) group tended to show a later improvement for US activity, all indicators of clinical disease activity and US activity showed a significant improvement at 6 months compared with baseline for both groups. Multivariate analysis showed that concomitant methotrexate use and an IR to the previous biologic or targeted-synthetic disease-modifying anti-rheumatic drug (b/tsDMARD) treatment were independently and significantly associated with US responders.

CONCLUSION

Use of a JAK inhibitor in combination with methotrexate and an absence of IR to any previous b/tsDMARDs demonstrated superior effectiveness for patients with RA.

POS1353 SERUM PROTEOMICS REVEALS INSULIN-LIKE GROWTH FACTOR BINDING PROTEINS-1 AS BIOMARKERS FOR IDIOPATHIC MULTICENTRIC CASTLEMAN’S DISEASE

Background:

Castleman’s disease (CD) is a lymphoproliferative disorder1 and presents as two distinct clinical entities: the localized form, unicentric CD (UCD) and the multicentric form, multicentric CD (MCD)2. MCD without human herpesvirus-8 (HHV-8) infection is defined idiopathic MCD (iMCD)3 and most MCDs in Japan are iMCDs. TAFRO syndrome is a group of disease that present with T: thrombocytopenia, A: anasarca, F: fever, R: reticulin fibrosis/renal dysfunction, O: organomegaly4. iMCD-TAFRO is present in the TAFRO syndrome and it is thought that pathology of lymph node biopsy shows an MCD-like appearance, and some clinical features overlap with MCD5. That do not belong to any of the above categories is classified as iMCD-not otherwise specified (iMCD-NOS). No biomarkers stratifying iMCD-NOS and iMCD-TAFRO have been identified, and no biomarkers defining treatment response have been identified for iMCD.

Objectives:

We will identify biomarkers that discriminate iMCD-NOS and iMCD-TAFRO or predict the treatment responsiveness.

Methods:

We performed a comprehensive analysis of serum proteins using the L-Series Human Antibody Array L-507 on the 4 iMCD-NOS and 2 iMCD-TAFRO patients from which pre- and post-tocilizumab treatment samples were obtained. An analysis by L-507 identified insulin-like growth factor binding proteins-1 (IGFBP-1) as a protein with a high rate of reduction post treatment. Sera from 28 healthy controls, 8 patients with iMCD-NOS, and 6 patients with iMCD-TAFRO were used to validate IGFBP-1 by ELISA. The mean ages of healthy controls, iMCD-NOS, and iMCD-TAFRO used in the validation ELISA were 50, 56, and 47 years, respectively, with no significant differences among the groups. The ratio of male to female was almost 1:1.

Results:

The 4 patients who responded well to treatment with tocilizumab all had a high rate of IGFBP-1 reduction by L-507 serum protein arrays. In ELISA, serum IGFBP-1 was significantly higher (p=0.0016) before the introduction of treatment in iMCD patients than healthy controls. In addition, serum IGFBP-1 level of iMCD-TAFRO was significantly higher than iMCD-NOS (p=0.024). Furthermore, post-treatment serum IGFBP-1 was decreased in many cases.

Conclusion:

Serum IGFBP-1 may play a particularly important role in the pathogenesis of iMCD-TAFRO and may be useful in discriminating between iMCD-NOS and iMCD-TAFRO. In the future, we will accumulate more cases, compare it with other inflammatory diseases, and examine the difference in response to treatment.

References:

[1]CASTLEMAN, et al. 1954. CASE records of the Massachusetts General Hospital Weekly Clinicopathological Exercises: Case 40011. N Engl J Med, 250, 26-30.

[2]WATERSTON, et al. 2004. Fifty years of multicentric Castleman’s disease. Acta Oncol, 43, 698-704.

[3]FAJGENBAUM D, et al. 2014. HHV-8-negative, idiopathic multicentric castleman disease (iMCD): A description of clinical features and therapeutic options through a systematic literature review. Blood (ASH Annual Meeting Abstracts), 124, 4861.

[5]TAKAI K, et al. 2010. Thrombocytopenia with mild bone marrow fibrosis accompanied by fever, pleural effusion, ascites and hepatosplenomegaly [in Japanese]. Rinsho Ketsueki, 51, 320-325.

[6]IWAKI N, et al. 2016. Clinicopathologic analysis of TAFRO syndrome demonstrates a distinct subtype of HHV-8-negative multicentric Castleman disease. Am J Hematol, 91, 220-226.

Disclosure of Interests:

None declared

POS0718 CLINICAL CHARACTERISTICS ASSOCIATED WITH GLANDULAR INVOLVEMENT EVALUATED BY SALIVARY GLAND ULTRASONOGRAPHY IN SJÖGREN’S SYNDROME

Background:

Sjögren’s syndrome (SS) is a systemic autoimmune disease characterized by periductal lymphocytic infiltration of the salivary and lacrimal glands, which results in reduced secretory functions and oral and ocular dryness (1). In addition, patients often have extraglandular manifestations, such as interstitial pneumonia and interstitial nephritis, and the appearance of autoantibodies such as anti-Ro/SS-A and La/SS-B antibodies. Salivary gland ultrasonography (SGUS) is typically used to evaluate the findings of salivary glands; thus, we can evaluate the severity of salivary gland disorders due to SS using SGUS in real time (2).

Objectives:

To identify clinical indices, including disease activity, associated with glandular involvement evaluated using SGUS in patients with SS.

Methods:

We enrolled patients with SS (n=115) and non-SS sicca subjects (n=90) who visited Nagasaki University Hospital between 1995 and 2019. The patients’ SS classifications were based on the 2002 American–European Consensus Group (AECG) SS classification criteria (3). The non-SS sicca subjects exhibited sicca symptoms but did not fulfill the AECG SS classification criteria. SGUS and clinical indices such as age, sex, the focus score (FS), sicca symptoms, the Saxon test results, Schirmer’s test results, anti-SS-A/Ro antibody positivity, anti-SS-B/La antibody positivity, anti-centromere antibody (ACA) positivity, serum immunoglobulin G levels, and the clinical European League Against Rheumatism SS disease activity index were examined. The ultrasonography (US) score was calculated based on SGUS imaging (hypoechoic area, hyperechoic band, and irregular border) (4).

Results:

The US score was significantly higher in patients with SS than that in non-SS sicca subjects. In addition, we found significant correlations between the US score and FS in patients with SS. Multivariate analysis revealed the FS, Saxon test positivity, and ACA positivity as the variables independently associated with the US score in patients with SS. These results were the same in the primary SS patient group (n=96). Patients with ACA positivity had significantly higher US scores compared to those in patients with ACA negativity, whereas the FS was not significantly high. In addition, patients with ACA positivity had significantly greater positivity of hyperechoic bands than that in patients with ACA negativity.

Conclusion:

This study indicated that ACA positivity, which is not reflected in sialadenitis of SS, is associated with the US score in patients with SS. These results suggest that US findings of patients with ACA positivity might show specific changes in salivary glands, such as fibrosis, and not only sialadenitis (5).

References:

[1]Ramos-Casals M, Tzioufas AG, Font J. Primary Sjogren’s syndrome: new clinical and therapeutic concepts. Ann Rheum Dis. 2005;64(3):347-54.

[2]van Ginkel MS, Glaudemans A, van der Vegt B, Mossel E, Kroese FGM, Bootsma H, et al. Imaging in Primary Sjogren’s Syndrome. J Clin Med. 2020;9(8).

[3]Vitali C, Bombardieri S, Jonsson R, Moutsopoulos HM, Alexander EL, Carsons SE, et al. Classification criteria for Sjogren’s syndrome: a revised version of the European criteria proposed by the American-European Consensus Group. Ann Rheum Dis. 2002;61(6):554-8.

[4]Takagi Y, Nakamura H, Sumi M, Shimizu T, Hirai Y, Horai Y, et al. Combined classification system based on ACR/EULAR and ultrasonographic scores for improving the diagnosis of Sjogren’s syndrome. PLoS One. 2018;13(4):e0195113.

[5]Nakamura H, Kawakami A, Hayashi T, Iwamoto N, Okada A, Tamai M, et al. Anti-centromere antibody-seropositive Sjögren’s syndrome differs from conventional subgroup in clinical and pathological study. BMC Musculoskelet Disord. 2010;11:140.

Disclosure of Interests:

None declared

Discrepancy between clinical and ultrasound remissions in rheumatoid arthritis: a multicentre ultrasound cohort study in Japan

Objectives: Using multicentre ultrasound (US) cohort data among patients with rheumatoid arthritis (RA), we aimed to identify baseline factors that permit differentiation between two patient cohorts achieving US remission and clinical remission, and to determine the factors contributing to the discrepancy.Method: We reviewed 248 Japanese patients diagnosed with RA who underwent treatment with biological disease-modifying anti-rheumatic drugs at 13 centres. We performed US assessments of the synovia of 22 joints. We assessed the percentages of patients with clinical remission and US remission, defined as total power Doppler scores of 0 at 12 months.Results: The 87 patients who achieved US remission were divided into a group that achieved both clinical and US remission (n = 53) and a group that achieved US remission only (n = 34). Baseline factors that were significantly and independently associated with clinical remission at 12 months among patients who also achieved US remission included short disease duration, the presence of concomitant methotrexate use, and low patient global assessment score (p < 0.05, p < 0.05, and p < 0.005, respectively).Conclusions: RA patients with baseline high patient global assessment scores and long disease duration at baseline were unlikely to achieve clinical remission even after achieving US remission. Objective joint assessments using US provide additional information of potential importance for the management of RA.

IL-15 is a biomarker involved in the development of rapidly progressive interstitial lung disease complicated with polymyositis/dermatomyositis

BACKGROUND

Polymyositis/dermatomyositis (PM/DM) is an autoimmune disease that is sometimes complicated with rapidly progressive interstitial lung disease (RPILD). However, serum and lung biomarkers that can predict RPILD development remain unclear.

OBJECTIVES

To determine potential serum and lung biomarkers that can predict RPILD development in patients with PM/DM-ILD.

METHODS

In total, 49 patients with PM/DM-ILD were enrolled. We measured the serum levels of 41 cytokines/chemokines, ferritin and anti-MDA5 antibody, compared them between the RPILD (n = 23) and non-RPILD (n = 26) groups, and ranked them by their importance through random forest analysis. To distinguish the two groups, we determined biomarker combinations by logistic regression analysis. We also measured the bronchoalveolar lavage fluid (BALF) levels of 41 cytokines/chemokines. Using immunohistochemistry, we examined IL-15 expression in lung tissues. The IL-15 production was also investigated using A549 and BEAS-2B cells.

RESULTS

The RPILD group had significantly higher IL-15, IL-1RA, IL-6, CXCL10, VCAM-1, anti-MDA5 antibody and ferritin serum levels than the non-RPILD group, but it had a significantly low CCL22 level. Meanwhile, anti-MDA5 antibody, IL-15, CXCL8, CCL22, IL-1RA and ferritin were the best combination to distinguish the two groups. IL-15 and CCL22 were also predictive marker for RPILD development in anti-MDA5 antibody-positive patients. Additionally, the RPILD group had significantly high IL-15 levels in BALF. The lung tissues expressed IL-15, which increased after cytokine stimulation in the A549 cells.

CONCLUSION

This study identified a combination of biomarkers predicting PM/DM-RPILD progression, and IL-15 is an important cytokine for predicting RPILD development and reflecting ILD severity.

Significance of anti-Ro/SSA antibodies in the response and retention of abatacept in patients with rheumatoid arthritis: a multicentre cohort study

Objective: To determine whether the positivity of baseline anti-Ro/Sjögren's syndrome antigen A (SSA) antibodies influences the response to abatacept, we compared therapeutic responses between anti-Ro/SSA antibody-negative and -positive patients with rheumatoid arthritis (RA) using a multicentre RA ultrasonography prospective cohort. Method: We reviewed Japanese patients with RA who started abatacept as the first biological disease-modifying anti-rheumatic drug between June 2013 and April 2018. We assessed 28-joint Disease Activity Score-erythrocyte sedimentation rate (DAS28-ESR) change between baseline and 6 or 12 months after treatment in RA patients treated with abatacept, and European League Against Rheumatism (EULAR) response at 6 and 12 months. The Global OMERACT-EULAR Synovitis Score (GLOESS) was calculated at baseline and at 6 and 12 months. Results: Overall, 51 patients were enrolled and divided into anti-Ro/SSA antibody-negative and -positive groups of 35 and 16, respectively. Median age at baseline was significantly higher in the anti-Ro/SSA antibody-negative group (p = 0.04). The retention rate and percentage of EULAR good responders at 12 months were significantly higher in the anti-Ro/SSA antibody-negative group (both p = 0.02). Anti-Ro/SSA antibody-negative patients exhibited larger decreases in both DAS28-ESR and DAS28-C-reactive protein at 12 months than anti-Ro/SSA antibody-positive patients (p = 0.02 and 0.04, respectively). GLOESS decreased significantly at 6 months in anti-Ro/SSA antibody-negative patients (p = 0.03). Multivariate analyses showed that anti-Ro/SSA antibody positivity was an independent factor associated with change in the DAS28-ESR at 6 months (p < 0.05). Conclusion: Anti-Ro/SSA antibody positivity predicts a poor response to abatacept and low retention rate.

Characterization of H7N9 avian influenza viruses isolated from duck meat products

Avian influenza H7N9 viruses have caused five epidemic waves of human infections since the first human cases were reported in 2013. In 2016, the initial low pathogenic avian influenza (LPAI) H7N9 viruses became highly pathogenic, acquiring multi-basic amino acids at the haemagglutinin cleavage site. These highly pathogenic avian influenza (HPAI) H7N9 viruses have been detected in poultry and humans in China, causing concerns of a serious threat to global public health. In Japan, both HPAI and LPAI H7N9 viruses were isolated from duck meat products carried illegally and relinquished voluntarily at the border by passengers on flights from China to Japan between 2016 and 2017. Some of the LPAI and HPAI H7N9 viruses detected at the border in Japan were characterized previously in chickens and ducks; however, their pathogenicity and replicative ability in mammals remain unknown. In this study, we assessed the biological features of two HPAI H7N9 virus isolates [A/duck/Japan/AQ-HE29-22/2017 (HE29-22) and A/duck/Japan/AQ-HE29-52/2017 (HE29-52); both of these viruses were isolated from duck meat at the border)] and an LPAI H7N9 virus isolate [A/duck/Japan/AQ-HE28-3/2016 (HE28-3)] in mice and ferrets. In mice, HE29-52 was more pathogenic than HE29-22 and HE28-3. In ferrets, the two HPAI virus isolates replicated more efficiently in the lower respiratory tract of the animals than did the LPAI virus isolate. Our results indicate that HPAI H7N9 viruses with the potential to cause severe diseases in mammals have been illegally introduced to Japan.

Complete renal response at 12 months after induction therapy is associated with renal relapse-free rate in lupus nephritis: a single-center, retrospective cohort study

Background

Lupus nephritis (LN) is a major risk factor for overall morbidity and mortality in systemic lupus erythematosus (SLE).

Methods

We retrospectively analyzed cases of proliferative and membranous LN patients who underwent a renal biopsy at our hospital in 1993–2016. We analyzed the association between complete renal response (CR) rates at 12 months after induction therapy and predictive factors for CR and their association with renal flares.

Results

Of the 95 cases analyzed, we were able to track the therapeutic responses of 81 patients at 12 months after their induction therapy. The median follow-up duration after renal biopsy was 51 months (interquartile range: 16.5–154.5 months). The Cox proportional hazards model showed that, compared to not attaining CR at 12 months, the attainment of CR at 12 months was correlated with being free from renal flares. The multivariate logistic analysis revealed that the predictive factors for CR at 12 months were the anti-La/SSB antibodies (U/ml) (odds ratio (OR) 1.22, 95% confidence interval (CI) 1.01–1.63, p = 0.0220), blood urea nitrogen (BUN) (OR 0.68, 95% CI 0.44–0.90, p = 0.00048) and serum β2 microglobulin (MG) (OR 0.26, 95% CI 0.06–0.74, p = 0.00098) levels.

Conclusions

Among LN patients, being free from renal flares was associated with attaining CR at 12 months after induction therapy. Anti-La/SSB antibodies were a positive predictive factor, and BUN and serum β2MG levels were negative predictive factors of CR at 12 months.

Repeated detection of H7N9 avian influenza viruses in raw poultry meat illegally brought to Japan by international flight passengers

H7N9 highly and low pathogenic avian influenza viruses (HPAIV and LPAIV, respectively) have been isolated from duck meat products that were brought illegally into Japan by flight passengers in their hand luggage. These H7N9 virus isolates were phylogenetically closely related to those prevailing in China. Antigenic analysis revealed that the hemagglutinin of the H7N9 HPAIV isolate was slightly different from those of the H7N9 LPAIV and older H7 strains. These meat products contaminated with AIVs repeatedly brought into Japan lead to increased risks of poultry and public health. Continuous border disease control based on the detection and culling of infected poultry and meat products is, thus, essential for the prevention of introduction and spread of AIVs.

Device for the removal of button batteries

OBJECTIVE

There is an increasing number of accidents by erroneous ingestion of button batteries in recent years; the batteries arouse the interest of infants because of their attractive shape and luster. The batteries remaining in the gastrointestinal tract and discharging electric current over a long period of time may induce ulceration or perforation, thus must be carefully considered the selection of appropriate treatment.

METHODS

We remove erroneously ingested button batteries with two tubes with ferrite magnets nearly the same size as the button batteries themselves.

PATIENTS

Four cases of erroneous ingestion of button batteries.

RESULTS

We easily removed button batteries from the stomach within 5 minutes in all cases with two magnet-attached tubes.

CONCLUSION

We present this battery removal device together with a literature review, because it seems convenient and useful.

Air contamination of a closed anesthesia circuit

Closed-circuit anesthesia (CCA) has certain advantages such as decreased cost, decreased anesthetic gas pollution, improved inhalational gas humidity and temperature in comparison to conventional inhalational anesthesia using a high fresh gas flow, i.e. more than 2 L x min(-1), with a semi-closed breathing circuit. The main disadvantage of CCA is the possibility of hypoxic anesthetic gas delivery. This potentially lethal situation is caused by an insufficient oxygen flow rate for the body metabolism or by the accumulation of inactive gas, usually nitrogen, within the breathing circuit in spite of a sufficient oxygen concentration in the fresh gas supply to the breathing circuit. In the latter case, the accumulation of inactive gas may also lead an increased risk of awareness because of its dilution effect on the concentrations of inhalational anesthetics. We herein present a case of air contamination of the breathing circuit through a sampling line of an anesthetic gas monitor. The air caused a decrease in the oxygen concentration during closed circuit anesthesia.

Diadenosine polyphosphates directly relax porcine coronary arterial smooth muscle

By use of front-surface fluorometry and fura-2-loaded medial strips of the porcine coronary artery, cytosolic Ca++ concentration ([Ca++]i) and force development were monitored simultaneously to determine the mechanisms of vasorelaxation induced by the diadenosine polyphosphates (APnA) diadenosine 5',5'''-P1, P4-tetraphosphate (AP4A) and diadenosine 5',5'''-P1,P5-pentaphosphate (AP5A). APnA concentration-dependently inhibited the sustained elevations of [Ca++]i and force induced by U-46619, a thromboxane A2 analog, in the presence of extracellular Ca++. APnA shifted the [Ca++]i-force relation curves of contractions induced by various concentrations of high K+ to the right. The AP4A-induced decreases in [Ca++]i and force were largely attenuated by tetrabutylammonium. The AP4A-induced decreases in force were attenuated by 4-aminopyridine and charybdotoxin. The AP5A-induced decreases in [Ca++]i and force were attenuated by tetrabutylammonium, 4-aminopyridine and charybdotoxin. In the absence of extracellular Ca++, APnA did not inhibit the transient elevations of [Ca++]i induced by histamine or caffeine. Both AP4A and AP5A increased intracellular cAMP content. We thus conclude that AP4A and AP5A relax the porcine coronary artery by decreasing [Ca++]i, possibly through the activation of K+ channels, but not through inhibition of intracellular Ca++ release and by decreasing the Ca++ sensitivity of the contractile machinery. These effects were considered to be mediated by cAMP.

Relationship of low-density lipoprotein particle size to plasma lipoproteins, obesity, and insulin resistance in Japanese men

OBJECTIVE

To determine the clinical characteristics of patients with small low-density lipoprotein (LDL) particles among Japanese men with mild glucose intolerance and to investigate the relationship of LDL particle size to the levels of other plasma lipoproteins, obesity, insulin resistance, and blood pressure (BP).

RESEARCH DESIGN AND METHODS

The subjects were 40 men with impaired glucose tolerance or diabetes treated by diet alone, and 40 healthy men matched for age and body mass index (BMI) were used as control subjects. LDL particle size was measured using gradient gel electrophoresis.

RESULTS

Of the 40 patients with glucose intolerance, 19 had small LDL (particle size < 25.5 nm) compared with only 4 of the 40 control subjects. In the patients with small LDL, the plasma levels of cholesterol, triglycerides, and apolipoprotein B, the fasting serum immunoreactive insulin, and the waist-to-hip ratio were all higher than in the patients with normal LDL (particle size > or = 25.5 nm), while the high-density lipoprotein cholesterol level was lower. However, there were no significant differences in BMI, BP, or insulin sensitivity in a euglycemic clamp study between the small-LDL and normal-LDL subgroups.

CONCLUSIONS

Japanese men with glucose intolerance frequently have small LDL, and this abnormality is associated with other dyslipoproteinemias and increased waist-to-hip ratio.

Insulin resistance in a patient with diabetes mellitus associated with Turner's syndrome

We evaluated insulin resistance and assessed the effect of gliclazide on insulin resistance in a patient with diabetes mellitus associated with Turner's syndrome. Insulin-induced glucose metabolism markedly decreased compared with 12 healthy subjects. The insulin dose-response curve of this patient shifted to the right and down, and recovered somewhat after the administration of gliclazide. This patient had exhibited marked insulin resistance, which seemed to be caused by a defect at the receptor and/or post-receptor levels. Gliclazide reduced her insulin resistance, which suggests that this agent is suitable for treating the insulin resistance in diabetic patients with Turner's syndrome.

Complement C6 and C7 polymorphisms in Japanese patients with chronic glomerulonephritis

C6 and C7 types were studied in 158 Japanese patients with different types of chronic glomerulonephritis: 75 patients with IgA nephropathy (IgA-N); 49 patients with idiopathic membranous nephropathy (IMN), and 34 patients with minimal-change nephrotic syndrome (MCNS). There were significant differences in the C6 and C7 allele and phenotype frequencies between the patient groups and controls. A strong association was found between IgA-N and C7 5 phenotype (p less than 0.001, RR = 12.71), and between MCNS and C7 5 phenotype (p less than 0.001, RR = 14.20). A significant association between MCNS and C6 B2 phenotype (p less than 0.05, RR = 2.42) was also found. In the IMN patient group, a significant association with C7 4 phenotype (p less than 0.05, RR = 2.42) was observed. Thus, C6 and C7 phenotypes may be causative factors in the development of chronic glomerulonephritis.