A comparative study on the clinical and magnetic resonance imaging features between seronegative and seropositive rheumatoid arthritis.

OBJECTIVES: Seronegative rheumatoid arthritis (SNRA) is less common and less known compared with seropositive rheumatoid arthritis (SPRA). The aim of this study was to characterise the clinical and magnetic resonance imaging (MRI) features of SNRA and investigate the associated factors of structural damage. METHODS: We retrospectively collected newly diagnosed RA patients who had MRI data of the hands at baseline. The clinical and MRI features and treatment responses during the 12-month follow-up were compared between SNRA and SPRA. The associated factors of the erosion rate were analysed. RESULTS: A total of 310 RA patients were included in this study. Compared with SPRA, SNRA had a higher level of inflammation (p-values were all <0.001), a higher incidence of low bone mineral density (p=0.009), but a lower erosion score (p<0.001) and a lower probability of interstitial lung disease (ILD) (p=0.019). The main eroded bones were different between SNRA (the scaphoid and the lunate) and SPRA (the capitate and the hamate). In the multivariate analysis, synovitis score, the levels of IL-6 and TNF-α, and hyperglobulinaemia were positively associated with the erosion rate of SNRA (p-values were all <0.05). During the 12-month follow-up, the treatment response between the two groups was comparable (p-values were all >0.05). CONCLUSIONS: SNRA had more severe inflammation but milder erosion compared with SPRA. SNRA with severe inflammation or hyperglobulinaemia needs the same powerful therapy of SPRA to prevent erosion progression.

The landscape of T and B lymphocytes interaction and synergistic effects of Th1 and Th2 type response in the involved tissue of IgG4-RD revealed by single cell transcriptome analysis.

OBJECTIVES: To investigate the landscape of T-B cell interaction, immune receptor profiles and effects of different types of immune responses in the involved tissues of IgG4-RD. METHODS: Single cell RNA sequencing, bulk sample RNA sequencing, immune receptor repertoire analysis (both BCR and TCR), multi-color flow cytometry, and in-vitro assays with model cells (e.g. EBV-immortalized B cells from IgG4-RD patient) and histologic methods were applied to investigate the immunopathological features of IgG4-RD from multiple aspects. RESULTS: Ectopic germinal center formation was observed in IgG4-RD patients at advanced disease stage, and a large part of B cells in involved tissue were germinal center B cell-like. Germinal center reaction in IgG4-RD led to the irregularities of both TCR and BCR clones in the involved tissues, and limited clonal overlaps among different samples. Enhanced Th1- and Th2-type responses were observed in involved tissues of IgG4-RD and patients with both increased Th1- and Th2-type response related cell subsets possessed more severe inflammatory indices. Analyses to the origin of IGHG4 transcripts in IgG4-RD indicated that IgG4 could be switched from IgM directly, or from other IgG subclasses. In vitro assays with EBV-immortalized B cells, fibroblasts and epithelial cells revealed the effects of Th1-type and Th2-type responses on germinal center reaction, ectopic expression of MHC-II molecules, and formation of tertiary lymphoid structures. CONCLUSIONS: Synergistic effects of Th1- and Th2-type responses were involved in the pathogenesis of IgG4-RD via their influences on both acute inflammatory processes and the chronicity and complexity of IgG4-RD.

Clinical features of rheumatic patients infected with COVID-19 in Wuhan, China.

OBJECTIVE: The clinical features of rheumatic patients with coronavirus disease 2019 (COVID-19) have not been reported. This study aimed to describe the clinical features of COVID-19 in rheumatic patients and provide information for handling this situation in clinical practice. METHODS: This is a retrospective case series study. Deidentified data, including gender, age, laboratory and radiological results, symptoms, signs, and medication history, were collected from 2326 patients diagnosed with COVID-19, including 21 cases in combination with rheumatic disease, in Tongji Hospital between 13 January and 15 March 2020. RESULTS: Length of hospital stay and mortality rate were similar between rheumatic and non-rheumatic groups, while the presence of respiratory failure was more common in rheumatic cases (38% vs 10%, p<0.001). Symptoms of fever, fatigue and diarrhoea were seen in 76%, 43% and 23% of patients, respectively. There were four rheumatic patients who experienced a flare of rheumatic disease during hospital stay, with symptoms of muscle aches, back pain, joint pain or rash. While lymphocytopaenia was seen in 57% of rheumatic patients, only one patient (5%) presented with leucopenia in rheumatic cases. Rheumatic patients presented with similar radiological features of ground-glass opacity and consolidation. Patients with pre-existing interstitial lung disease showed massive fibrous stripes and crazy-paving signs at an early stage. Five rheumatic cases used hydroxychloroquine before the diagnosis of COVID-19 and none progressed to critically ill stage. CONCLUSIONS: Respiratory failure was more common in rheumatic patients infected with COVID-19. Differential diagnosis between COVID-19 and a flare of rheumatic disease should be considered. TRIAL REGISTRATION NUMBER: ChiCTR2000030795.

Machine-learning-based models assist the prediction of pulmonary embolism in autoimmune diseases: A retrospective, multicenter study.

BACKGROUND: Pulmonary embolism (PE) is a severe and acute cardiovascular syndrome with high mortality among patients with autoimmune inflammatory rheumatic diseases (AIIRDs). Accurate prediction and timely intervention play a pivotal role in enhancing survival rates. However, there is a notable scarcity of practical early prediction and risk assessment systems of PE in patients with AIIRD. METHODS: In the training cohort, 60 AIIRD with PE cases and 180 age-, gender-, and disease-matched AIIRD non-PE cases were identified from 7254 AIIRD cases in Tongji Hospital from 2014 to 2022. Univariable logistic regression (LR) and least absolute shrinkage and selection operator (LASSO) were used to select the clinical features for further training with machine learning (ML) methods, including random forest (RF), support vector machines (SVM), neural network (NN), logistic regression (LR), gradient boosted decision tree (GBDT), classification and regression trees (CART), and C5.0 models. The performances of these models were subsequently validated using a multicenter validation cohort. RESULTS: In the training cohort, 24 and 13 clinical features were selected by univariable LR and LASSO strategies, respectively. The five ML models (RF, SVM, NN, LR, and GBDT) showed promising performances, with an area under the receiver operating characteristic (ROC) curve (AUC) of 0.962-1.000 in the training cohort and 0.969-0.999 in the validation cohort. CART and C5.0 models achieved AUCs of 0.850 and 0.932, respectively, in the training cohort. Using D-dimer as a pre-screening index, the refined C5.0 model achieved an AUC exceeding 0.948 in the training cohort and an AUC above 0.925 in the validation cohort. These results markedly outperformed the use of D-dimer levels alone. CONCLUSION: ML-based models are proven to be precise for predicting the onset of PE in patients with AIIRD exhibiting clinical suspicion of PE. TRIAL REGISTRATION: Chictr.org.cn: ChiCTR2200059599.

Expression of USP25 associates with fibrosis, inflammation and metabolism changes in IgG4-related disease.

IgG4-related disease (IgG4-RD) has complex clinical manifestations ranging from fibrosis and inflammation to deregulated metabolism. The molecular mechanisms underpinning these phenotypes are unclear. In this study, by using IgG4-RD patient peripheral blood mononuclear cells (PBMCs), IgG4-RD cell lines and Usp25 knockout mice, we show that ubiquitin-specific protease 25 (USP25) engages in multiple pathways to regulate fibrotic and inflammatory pathways that are characteristic to IgG4-RD. Reduced USP25 expression in IgG4-RD leads to increased SMAD3 activation, which contributes to fibrosis and induces inflammation through the IL-1ß inflammatory axis. Mechanistically, USP25 prevents ubiquitination of RAC1, thus, downregulation of USP25 leads to ubiquitination and degradation of RAC1. Decreased RAC1 levels result in reduced aldolase A release from the actin cytoskeleton, which then lowers glycolysis. The expression of LYN, a component of the B cell receptor signalosome is also reduced in USP25-deficient B cells, which might result in B cell activation deficiency. Altogether, our results indicate a potential anti-inflammatory and anti-fibrotic role for USP25 and make USP25 a promising diagnostic marker and potential therapeutic target in IgG4-RD.

Clinical characteristics of SLE patients infected with Epstein-Barr virus and potential associated risk factors.

OBJECTIVE: To investigate the clinical features and potential associated risk factors of Epstein-Barr virus (EBV) DNA positivity in systemic lupus erythematosus (SLE) patients. METHODS: A total of 121 newly diagnosed SLE patients who had never used immunosuppressive drugs (treatment-naïve) and 191 previously treated SLE patients from January 2017 to January 2020 were enrolled in this study. And 115 age- and sex-matched non-rheumatic disease controls were also included. RESULTS: A significantly higher incidence of EBV DNA positivity and higher viral DNA copies in peripheral blood mononuclear cells were observed among treatment-naïve and previously treated SLE patients compared with controls. The positivity rate of EBV DNA was further increased in previously treated SLE patients compared with that in treatment-naïve patients. EBV DNA-positive treatment-naïve SLE patients presented lower incidence of hemolytic anemia and more affected organ number than EBV DNA-negative patients. EBV DNA-positive treated SLE patients showed older age, longer immunosuppressive duration, higher IgG level, and higher Th/Ts ratio than EBV DNA-negative patients. Patients responding well to treatment with decreased SLE disease activity index scores had a transformation of EBV DNA from positive to negative in treated SLE patients. Multivariate logistic regression analysis showed that older age, higher IgG level, and longer immunosuppressive duration were associated risk factors for EBV DNA positivity in SLE patients, while higher TNF-α level was a protective factor. CONCLUSION: Older age, higher IgG level, and longer immunosuppressive duration are associated with the positivity of EBV DNA in SLE patients. A seroconversion of EBV DNA indicates an association between EBV positivity and therapy response, while larger number cases are needed to confirm. Key Points • Older age, higher IgG level, and longer immunosuppressive duration are associated with EBV DNA positivity in SLE patients. • A seroconversion of EBV DNA might be an indicator to reflect the SLE therapy -response.

Update on classification, diagnosis, and management of immunoglobulin G4-related disease.

ABSTRACT: Immunoglobulin G4-related disease (IgG4-RD) is a newly recognized chronic fibro-inflammatory autoimmune disease, and its recognition has been constantly increasing worldwide over the last few years. A correct and timely recognition, as well as appropriate intervention, is crucial for the treatment of IgG4-RD. For certain subtypes of IgG4-RD, organ-specific criteria are formulated to make the diagnosis more accurate. New biomarkers have emerged in the recent years to aid the disease diagnosis, its prognosis prediction, as well as therapy response monitoring. Although recurrence is very common in IgG4-RD, glucocorticoid is still the first-line treatment for the majority of patients. The factors that affect the likelihood of disease relapse are multifaceted. The selection strategy of various steroid-sparing agents is still being explored. Besides, when patients have special sites involvement leading to severe clinical conditions, surgical operation or interventional therapy should also be considered. An update on classification, diagnosis, and management of IgG4-RD is provided in the current study to fully elucidate the recommended clinical practice of this mysterious disease.

Potential roles of non-lymphocytic cells in the pathogenesis of IgG4-related disease.

Studies have confirmed the involvement of a variety of lymphocyte subsets, including type 2 helper T lymphocytes (Th2) and IgG4+ B lymphocytes, in the pathogenesis of IgG4-related disease (IgG4-RD). Those lymphocytes contribute to the major pathogenetic features of IgG4-RD. However, they are not the only cellular components in the immunoinflammatory environment of this mysterious disease entity. Recent studies have suggested that various non-lymphocytic components, including macrophages and fibroblasts, may also play an important role in the pathogenetic process of IgG4-RD in terms of contributing to the chronic and complex progress of the disease. Therefore, the potential role of non-lymphocyte in the pathogenesis of IgG4-RD is worth discussing.

Efficacy of plasma exchange on top of standard immunosuppressive therapy in adult autoimmune inflammatory rheumatic diseases-associated macrophage activation syndrome, a single center real-world analysis.

BACKGROUND: There is a lack of documented real-world evidence about the efficacy of current therapeutics for autoimmune inflammatory rheumatic diseases (AIIRD)-associated adult macrophage activation syndrome (MAS). OBJECTIVE: To analyze the efficacy of different treatments, especially plasma exchange (PE), in AIIRD-associated MAS. METHODS: Among 5775 patients with AIIRD in Tongji Hospital from 2014 to 2020, 62 AIIRD-associated MAS cases were collected. Unadjusted logistic regression, least absolute shrinkage and selection operator (LASSO), and inverse probability of treatment weight (IPTW) analyses were used to characterize the clinical features and potential factors related to the prognosis. Paired t-test was used to compared the changes of inflammatory indicators before and after PE treatment. RESULTS: The baseline data was defined as the data collected at the onset of MAS, and all of the 62 patients were diagnosed as AIIRD before MAS onset. The prevalance rate of MAS in AIIRD was 1.1%, and the most common types of AIIRD were systemic lupus erythematosus (45.2%) and adult-onset Still's disease (33.9%). All 62 MAS patients received glucocorticoids, 87.1% patients used at least one immunosuppressive agent, and 54.8% received PE. LASSO regression indicates a positive effect of PE on the basis of variables. After PE treatment, serum levels of multiple inflammatory cytokines were rapidly reduced, accompanied by improvements in clinical symptoms and laboratory indecies including ferritin, lactate dehydrogenase, and C-reactive protein. LASSO regression indicates that PE treatment was associated with a marked reduction of mortality (from 53.6% to 11.8%), with a hazard ratio (HR) of 0.148 (p < 0.001) after adjustment for confounding factors using IPTW analysis. CONCLUSION: With the background therapy of glucocorticoids and immunosuppressive agents, PE is an effective approach to rapidly clear inflammatory cytokines and reduce mortality of AIIRD-associated MAS. CLINICAL IMPLICATION: This study provided real-world information on the efficacy of PE in AIIRD-associated MAS.

Proteomic characteristics of saliva in patients with different subgroups of IgG4-RD.

Background: Immunoglobulin G4-related disease (IgG4-RD) is a newly defined disease entity, with great heterogeneity among IgG4-RD subgroups with different organ involvement patterns. Identification of the proteomic characteristics of IgG4-RD subgroups will be critical for the understanding of the pathogenic mechanisms of IgG4-RD. Method: In this study, we performed proteomic analysis using Tandem Mass Tags (TMT) technology with "high field" mass analyzer with improved resolution and sequencing speed to investigate the proteomic profile of saliva and plasma samples from ten untreated IgG4-RD patients and five healthy controls (HCs). Differentially expressed proteins (DEPs) were identified by "t test" function in R package. Functional enrichment analysis was used to investigate pathways enriched in IgG4-RD samples. Results: Most salivary DEPs identified in IgG4-RD patients compared with HCs were mainly enriched in neutrophil mediated GO bioprocess. Within the comparisons between four IgG4-RD subgroups, more DEPs were identified in the comparison of Mikulicz group and Head and neck group. Among four subgroups of IgG4-RD, Head and neck group showed the most distinctive proteomic expression pattern when compared with HCs. Moreover, "Neutrophil mediated process" related GO bioprocess was commonly identified between comparisons of Mikulicz group and Head and neck group, Head and neck group and Retroperitoneal aorta group, Head and neck group and HCs, IgG4-RD patients with saliva gland involvement and those without saliva gland involvement. Key DEPs that involved in this GO bioprocess were identified. Besides, we performed proteomic analysis for plasma samples between ten IgG4-RD and five HCs and there were several DEPs identified overlapped in saliva and plasma. Conclusion: We identified multiple processes/factors and several signaling pathways in saliva that may be involved in the IgG4-RD pathogenesis.

Structural Lesion Progression of the Sacroiliac Joint and Clinical Features in axSpA During TNFi Reduction: A Retrospective Cohort Study.

Objective: In the clinic, some patients with axial spondyloarthritis (axSpA) have to reduce tumor necrosis factor inhibitor (TNFi) for various reasons. However, there are few studies about how to balance the relapse and TNFi reduction. Here we retrospectively analyzed the structural progression of the sacroiliac joint (SIJ) and clinical features in axSpA during TNFi reduction. Methods: A total of 108 patients with axSpA who followed up for 2 years and completed at least baseline, 12-month, and 24-month MRI scans of SIJ were divided into the tapering group (n = 63) and withdrawal group (n = 45) according to whether TNFi was stopped. We divided 2 years into five intervals, calculating the average dose quotient (DQ) for each of 540 intervals from 108 patients. By using generalized estimation equations with inverse probability of treatment weighting, we investigated the unbiased effects of average DQ on structural progression and treatment response. Results: The disease activity (such as Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Ankylosing Spondylitis Disease Activity Score (ASDAS)-CRP, and ASDAS-ESR) and relapse rate were lower in the tapering group at 12 and 24 months (p < 0.05). Δerosion (ß = -0.0100, p = 0.00026) and Δthe Spondyloarthritis Research Consortium of Canada (SPARCC; ß = -0.0959, p < 0.0001) were negatively correlated with average DQ. The average DQ 30 (74.8%, 80.0%) or 41.6 (76.5%, 83%) was best to discriminate the status of treatment response or the status of bone marrow edema, but considering operability, the average DQ 25 (78.0%, 63.3%) was also acceptable especially for patients with HLA-B27 negative and non-severe fat metaplasia. Conclusion: Complete TNFi withdrawal was not recommended. Our study provided a referable strategy (tapering then maintained the average DQ over 30 or even 25) for patients who need TNFi reduction. Higher dose usage of TNFi was associated with a slower erosion progression of SIJ.

Intratracheal Poly(I:C) Exposure Accelerates the Immunological Disorder of Salivary Glands in Sjogren's-Like NOD/ShiLtJ Mice.

Evidences have suggested that Sjogren's syndrome (SS) is associated with viral infection. The aim of this study was to investigate the involvement of respiratory viral poly(I:C) in the pathogenesis of SS and potential mechanisms using a SS-like NOD/ShiLtJ (NOD) mouse model. 5-week female NOD mice were intratracheally administered poly(I:C) every other day for 5 times to mimic viral infection. Pilocarpine induced saliva secretion was determined every 8 days. Submandibular glands (SMG) and lungs were harvested for the detection of pathological changes. We found that intratracheal administration of poly(I:C) significantly advanced and enhanced the reduction of saliva flow rate in NOD mice. Furthermore, poly(I:C) treatment aggravated the histopathological lesions and inflammatory cells infiltration in SMG. Accompanied by elevated expression of IFN cytokines and IL-33, Th1 activation was enhanced in SMG of poly(I:C)-treated NOD mice, but Th17 cells activation was unchanged among the groups. In addition, intratracheal poly(I:C) exposure promoted the expression of IL-33 and increased T cells proportion in the lung, which were consistent with the change in SMG. Therefore, intratracheal poly(I:C) exposure aggravated the immunological and function disorder of SMG in NOD mice.

An Autocrine Circuit of IL-33 in Keratinocytes Is Involved in the Progression of Psoriasis.

IL-33 is constitutively expressed in the skin. Psoriasis is a common skin inflammatory disease. The roles of IL-33 in psoriasis have not been well-elucidated. We identified that keratinocytes (KCs) are the predominant cells expressing IL-33 and its receptor, suppression of tumorigenicity 2, in the skin. KCs actively released IL-33 on psoriasis inflammatory stimuli and induced psoriasis-related cytokine, chemokine, and inflammatory molecules genes transcription in KCs in an autocrine manner. IL-33‒specific deficiency in KCs ameliorated imiquimod-induced psoriatic dermatitis. In addition, intradermal injection of recombinant IL-33 alone induced psoriasis-like dermatitis, which is attributed to the transcriptional upregulation of genes enriched in IL-17, TNF, and chemokine signaling pathway in KCs on recombinant IL-33 stimulation. Our data demonstrate that the autocrine circuit of IL-33 in KCs promotes the progression of psoriatic skin inflammation, and IL-33 is a potential therapeutic target for psoriasis.

COVID-19 infection in patients with connective tissue disease: A multicity study in Hubei province, China.

Novel Coronavirus disease 2019 (COVID-19) has spread rapidly around the world. Individuals with immune dysregulation and/or on immunosuppressive therapy, such as rheumatic patients, are considered at greater risk for infections. However, the risks of patients with each subcategory of rheumatic diseases have not been reported. Here, we identified 100 rheumatic patients from 18,786 COVID-19 patients hospitalized in 23 centers affiliated to Hubei COVID-19 Rheumatology Alliance between January 1 and April 1, 2020. Demographic information, medical history, length of hospital stay, classification of disease severity, symptoms and signs, laboratory tests, disease outcome, computed tomography, and treatments information were collected. Compared to gout and ankylosing spondylitis (AS) patients, patients with connective tissue disease (CTD) tend to be more severe after COVID-19 infection (p = 0.081). CTD patients also had lower lymphocyte counts, hemoglobin, and platelet counts (p values were 0.033, < 0.001, and 0.071, respectively). Hydroxychloroquine therapy and low- to medium-dose glucocorticoids before COVID-19 diagnosis reduced the progression of COVID-19 to severe/critical conditions (p = 0.001 for hydroxychloroquine; p = 0.006 for glucocorticoids). Our data suggests that COVID-19 in CTD patients may be more severe compared to patients with AS or gout.

A complex COVID-19 case with rheumatoid arthritis treated with tocilizumab.

Recurrences of COVID-19 were observed in a patient with long-term usage of hydroxychloroquine, leflunomide, and glucocorticoids due to her 30-year history of rheumatoid arthritis (RA). Tocilizumab was applied and intended to target both COVID-19 and RA. However, disease of this patient aggravated after usage of tocilizumab. After the discussion of a multiple disciplinary team (MDT) including rheumatologists, antimicrobial treatments were applied to target the potential opportunistic infections (Pneumocystis jirovecii and Aspergillus fumigatus), which were authenticated several days later via high throughput sequencing. As an important cytokine in immune responses, IL-6 can be a double-edged sword: interference in the IL-6-IL-6 receptor signaling may save patients from cytokine release storm (CRS), but can also weaken the anti-infectious immunity, particularly in rheumatic patients, who may have received a long-term treatment with immunosuppressive/modulatory agents. Thus, we suggest careful considerations before and close monitoring in the administration of tocilizumab in rheumatic patients with COVID-19. Besides tocilizumab, several disease-modifying antirheumatic drugs (DMARDs) can also be applied in the treatment of COVID-19. Therefore, we also reviewed and discussed the application of these DMARDs in COVID-19 condition.

Biomarkers in IgG4-related disease: A systematic review.

OBJECTIVE: ImmunoglobulinG4-related disease (IgG4-RD) is a recently recognized disease and, as such, there is a pressing need to identify biomarkers for diagnosis, monitoring disease activity, and predicting prognosis and response to therapy. Here, we review the recent development and identification of biomarkers for IgG4-RD. METHODS: Through extensive literature review and analysis, we updated the biomarkers for IgG4-RD and further put forward our own viewpoints. RESULTS: In addition to traditional biomarkers, such as serum IgG4 concentration and typical histological characteristics, several novel indicators, including IgG2, serum soluble IL-2 receptor (sIL2R), and cc-chemokine ligand 18 (CCL18), indicate inflammation and fibrosis and can be used to accurately diagnose and predict treatment response. Studies to identify target autoantigens in IgG4-RD have shed light on the unmet need for biomarkers that can identify this disorder. Additionally, both serological and histopathologic immune cells involved in antigen-induced responses, innate immune cells (macrophages, mast cells, and the I-IFN/ IL-33 pathway), as well as subsequent acquired immune cells (T and B cell subsets), may also serve as new biomarkers for IgG4-RD. Since IgG4-RD often clinically manifests with multiple organs involvement, non-invasive PET-CT can improve diagnosis and antidiastole levels. CONCLUSION: These novel biomarkers provide information to help diagnose IgG4-RD, monitor disease activity, as well as predict prognosis and response to therapy.

Clinical characteristics of IgG4-RD patients infected with COVID-19 in Hubei, China.

Objective: IgG4-related disease (IgG4-RD) is an immune-mediated multi-organ, chronic and progressive disease. Therefore, we conducted a study to investigate the susceptibility of COVID-19 in IgG4-RD patients in Hubei province, and to characterize the clinical manifestation of COVID-19 in IgG4-RD patients. Methods: A follow-up system that includes over 200 IgG4-RD patients across the country during the past ten years. A total of ninety-one patients with IgG4-RD who live in Hubei, China were identified and responded to our survey. Medical history, clinical symptoms, laboratory tests, CT imaging, and treatment were obtained through a standardized data collection form, and then independently reviewed by two investigators. Results: 2 of 91 cases were infected with COVID-19. Both of them were classified as moderate type. The symptoms such as fever and cough and radiologic features were similar to other COVID-19 patients. Neither of them episode recurrent of IgG4-RD nor progressed to severe or critical condition of COVID-19 under the condition of continuous oral low-dose of glucocorticoids. Besides, patient 2 took a long time for SARS-CoV-2 nucleic acid to turn negative. Conclusion: IgG4-RD patients may belongs to the susceptible population of COVID-19 infection, and thus need more careful personal protection. Early identification and properly treatment are very important to prevent IgG4-RD patients with COVID-19 from progression to severe condition.