A unique case of polymyositis with anti-signal recognition particle antibody complicated by subacute interstitial lung disease and subluxing arthropathy, resembling anti-synthetase syndrome

Abstract BackgroundAutoimmune necrotizing myopathy with anti-signal recognition particle antibodies (ANM-SRP) is considered as a refractory myositis; some patients respond poorly to conventional immunosuppression，required the treatment of B lymphocyte clearance. We aimed to identify the factors related to refractory ANM-SRP.Results48 patients with ANM-SRP were included to identify the factors related to refractory ANM-SRP. We monitored the clinical symptoms and image changes over 12 months. Refractory ANM-SRP appeared in 32.5% patients, who showed no or minimal improvement after 12 months with steroid therapy. The clinical risk factors for refractory patients were male (19.57, 1.49-256.53), severe muscle weakness (7.51, 41.03-54.88) and concurrent interstitial lung disease (39.70, 3.04-518.38). The fatty infiltration rate of thigh muscles over 3 months was more severe (P=0.022) in refractory patients. Muscles of all patients underwent routine histology, enzyme histochemistry and immunohistochemistry staining. The first antibodies used for immunohistochemistry include anti-B cell activating factor (BAFF) and BAFF receptor (BAFF-R) antibodies. Immunohistochemical staining and western bolt showed that the expression of BAFF and BAFF-R in muscles of the patients were higher than that of the normal controls. The positive BAFF-R cells (P=0.036) and CD19 positive lymphocytes (P=0.002) in refractory patients were higher than in patients with good clinical response to therapy.ConclusionThe expression of BAFF and BAFF-R in muscles of ANM-SRP were upregulated. Male, severe muscle weakness, concurrent interstitial lung disease, quick development of muscle fatty infiltration and more BAFF-R and B-lymphocytes infiltration in muscle indicate a poor response to immunosuppressive therapy.

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Interstitial lung disease is not rare in immune-mediated necrotizing myopathy with anti-signal recognition particle antibodies

BMC Pulmonary Medicine ◽

10.1186/s12890-021-01802-1 ◽

2022 ◽

Vol 22 (1) ◽

Author(s):

Yongpeng Ge ◽

Hanbo Yang ◽

Xinyue Xiao ◽

Lin Liang ◽

Xin Lu ◽

...

Keyword(s):

Interstitial Lung Disease ◽

Lung Disease ◽

Pulmonary Function Tests ◽

Signal Recognition Particle ◽

Ground Glass Opacity ◽

Signal Recognition ◽

High Resolution Computed Tomography ◽

Necrotizing Myopathy ◽

Immune Mediated ◽

Long Term Follow Up

Abstract Objectives The purpose was to clarify the characteristics of interstitial lung disease (ILD) in immune-mediated necrotizing myopathy (IMNM) patients with anti-signal recognition particle (SRP) antibodies. Methods Medical records of IMNM patients with anti-SRP antibodies were reviewed retrospectively. Results A total of 60 patients were identified. Twenty-seven (45.0%) patients were diagnosed with ILD based on lung imaging: nonspecific interstitial pneumonia (NSIP) in 17 patients (63.0%) and organizing pneumonia in 9 patients (33.3%). Reticulation pattern was identified in 17 patients (63.0%) whereas 10 cases (37.0%) showed ground glass opacity and patchy shadows by high-resolution computed tomography (HRCT). Pulmonary function tests (PFTs) were available in 18 patients, 6 (33.3%) and 10 (55.6%) patients were included in the mild and moderate group, respectively. The average age at the time of ILD onset was significantly older than those without ILD (48.6 ± 14.4 years vs. 41.2 ± 15.4 years, p < 0.05), and the frequency of dysphagia in the ILD group was higher than the group without ILD (p < 0.05). Long-term follow-up was available on 9 patients. PFTs were stable in 8 (88.9%), and the HRCT remained stable in 6 (66.7%) patients. Conclusions ILD is not rare in IMNM patients with anti-SRP antibodies, most being characterized as mild to moderate in severity. NSIP is the principal radiologic pattern, and ILD typically remains stable following treatment.

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Factors associated with refractory autoimmune necrotizing myopathy with anti-signal recognition particle antibodies

10.21203/rs.2.23941/v2 ◽

2020 ◽

Author(s):

Yawen Zhao ◽

Wei Zhang ◽

Yilin Liu ◽

Zhaoxia Wang ◽

Yun Yuan

Keyword(s):

Interstitial Lung Disease ◽

Lung Disease ◽

B Cell ◽

Muscle Weakness ◽

Fatty Infiltration ◽

Signal Recognition Particle ◽

Poor Response ◽

Signal Recognition ◽

Factors Associated ◽

Necrotizing Myopathy

Abstract Background: Autoimmune necrotizing myopathy with anti-signal recognition particle antibodies (ANM-SRP) is regarded as refractory myositis, whereby some patients respond poorly to conventional immunosuppression and require B cell depletion treatment. This study aimed to evaluate factors associated with refractory ANM-SRP.Results: Clinical and pathological data from 48 patients with ANM-SRP were collected. We followed up clinical symptoms and image changes over 12 months. Univariate and multivariate analyses were undertaken to determine the associations between variables of interest and poor response to therapy. Refractory ANM-SRP appeared in 32.5% of patients who showed no or minimal improvement after 12 months of steroid therapy. The clinical risk factors for refractory patients were being male (OR, 19.57; P<0.001), severe muscle weakness (OR, 7.51; P<0.001) and concurrent interstitial lung disease (OR, 39.70; P<0.001). The imaging refractory-related factor was the fatty infiltration rate of thigh muscles over 3 months (P=0.022) and the pathological factor associated with refractory ANM-SRP was the high expression of B cell activating factor receptor (BAFF-R) in muscle (P=0.036).Conclusion: Being male, severe muscle weakness, concurrent interstitial lung disease, quick development of muscle fatty infiltration and more BAFF-R and B lymphocyte infiltration in muscle indicate a poor response to immunosuppressive therapy in patients with ANM-SRP.

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