Submandibular gland tissue RNAseq and spatial transcriptome analyses in IgG4-related disease.

OBJECTIVE: To identify genes that could provide clues leading to the discovery of drugs to treat IgG4-related disease (IgG4-RD). METHODS: Submandibular gland tissue bulk RNAseq analysis of 45 cases with a definite diagnosis of IgG4-RD was integrated with Visium spatial transcriptome analysis of 2 cases to identify pathogenic genes expressed in tertiary lymphoid tissues. RESULTS: Bulk RNAseq and pathway analyses showed upregulation of cell cycle and T cell-related signals in IgG4-RD. Spatial transcriptome analysis identified the cluster corresponding to germinal centers and the top 38 common genes that showed significant variations in expression compared with other clusters. The top 20 genes were extracted by comparing the bulk RNAseq data. Network analysis identified CDK1 as the ge most strongly associated of the top 20 genes. CONCLUSION: The CDK1 gene may be a regulator of the pathogenesis of IgG4-RD and provide clues for drug discovery.

Analysis of the saliva microbiome in patients with immunoglobulin G4-related disease.

OBJECTIVES: This article aims to investigate the saliva microbiome in patients with immunoglobulin G4-related disease (IgG4RD) compared with primary Sjögren's syndrome (SS). METHODS: Saliva samples were collected from 11 IgG4RD and 11 SS patients who visited IMSUT Hospital, The Institute of Medical Science, The University of Tokyo. Deoxyribonucleic acid (DNA) was extracted from the samples, and primers were used to amplify the V3-V4 regions of bacterial and archaeal 16S ribosomal RNA (rRNA) genes, which was then analysed by paired-end sequencing. Amplicon reads were processed using QIIME2 to generate representative sequences. The Greengenes database was used to identify the bacterial flora in each sample and compare them between groups. RESULTS: The IgG4RD and SS groups exhibited differences in bacterial diversity. Cluster analyses of attributed classification groups by species and disease showed that IgG4RD and SS cases formed individual clusters. Significant differences in relative abundance between IgG4RD and SS were observed for the following organisms: Mogibacterium (P = .0051), Solobacterium moorei (P = .0195), Slackia (P = .0356), and Moryella (P = .0455). CONCLUSIONS: Salivary microbiome analysis of IgG4RD and SS patients revealed significantly higher relative proportions of Mogibacterium, S. moorei, Slackia, and Moryella bacteria in IgG4RD compared with SS.

Extraction of characteristic serum microRNAs and prediction of target genes in IgG4-related dacryoadenitis and sialadenitis.

OBJECTIVES: To identify the specific microRNAs (miRNAs) in IgG4-related dacryoadenitis and sialadenitis (IgG4-DS) and predict the targeted genes. METHODS: miRNAs in the serum of nine patients with IgG4-DS, three patients with primary Sjögren's syndrome, and three healthy controls were analysed using the human miRNA chip, and miRNAs that exhibited significant fluctuation in expression in IgG4-DS patients were extracted. The respective target genes were predicted using an existing database, and expression of the target genes was evaluated in actual submandibular gland tissues affected by IgG4-DS. RESULTS: Serum miR-125a-3p and miR-125b-1-3p levels were elevated in IgG4-DS. Six candidate target genes (glypican 4, forkhead box C1, protein tyrosine phosphatase non-receptor type 3, hydroxycarboxylic acid receptor 1, major facilitator superfamily domain containing 11, and tumour-associated calcium signal transducer 2) were downregulated in the affected submandibular gland tissue. CONCLUSION: Overexpression of miR-125a-3p and miR-125b-1-3p is a hallmark of IgG4-DS. These miRNAs appear to be involved in the pathogenesis of IgG4-DS.

Eicosapentaenoic acid changes muscle transcriptome and intervenes in aging-related fiber type transition in male mice.

Age-related sarcopenia is associated with a variety of changes in skeletal muscle. These changes are interrelated with each other and associated with systemic metabolism, the details of which, however, are largely unknown. Eicosapentaenoic acid (EPA) is a promising nutrient against sarcopenia and has multifaceted effects on systemic metabolism. In this study, we hypothesized that the aging process in skeletal muscle can be intervened by the administration of EPA. Seventy-five-week-old male mice were assigned to groups fed an EPA-deprived diet (EPA-) or an EPA-enriched diet with 1 wt% EPA (EPA+) for 12 wk. Twenty-four-week-old male mice fed with normal chow were also analyzed. At baseline, the grip strength of the aging mice was lower than that of the young mice. After 12 wk, EPA+ showed similar muscle mass but increased grip strength compared with EPA-. EPA+ displayed higher insulin sensitivity than EPA-. Immunohistochemistry and gene expression analysis of myosin heavy chains (MyHCs) revealed fast-to-slow fiber type transition in aging muscle, which was partially inhibited by EPA. RNA sequencing (RNA-Seq) analysis suggested that EPA supplementation exerts pathway-specific effects in skeletal muscle including the signatures of slow-to-fast fiber type transition. In conclusion, we revealed that aging skeletal muscle in male mice shows lower grip strength and fiber type changes, both of which can be inhibited by EPA supplementation irrespective of muscle mass alteration.NEW & NOTEWORTHY This study demonstrated that the early phenotype of skeletal muscle in aging male mice is characterized by muscle weakness with fast-to-slow fiber type transition, which could be ameliorated by feeding with EPA-enriched diet. EPA induced metabolic changes such as an increase in systemic insulin sensitivity and altered muscle transcriptome in the aging mice. These changes may be related to the fiber type transition and influence muscle quality.

The Influence of Glucocorticoid Receptor on Sex Differences of Gene Expression Profile in Skeletal Muscle.

Skeletal muscle functions as a locomotory system and maintains whole-body metabolism. Sex differences in such skeletal muscle morphology and function have been documented; however, their underlying mechanisms remain elusive. Glucocorticoids are adrenocortical hormones maintaining homeostasis, including regulating whole-body energy metabolism in addition to stress response. In skeletal muscle, glucocorticoids can reduce the synthesis of muscle proteins and simultaneously accelerate the breakdown of proteins to regulate skeletal muscle mass and energy metabolism via a transcription factor glucocorticoid receptor (GR). We herein evaluated the related contributions of the GR to sex differences of gene expression profiles in skeletal muscle using GR-floxed (GRf/f) and skeletal muscle-specific GR knockout (GRmKO) mice. There were no differences in GR mRNA and protein expression levels in gastrocnemius muscle between males and females. A DNA microarray analysis using gastrocnemius muscle from GRf/f and GRmKO mice revealed that, although most gene expression levels were identical in both sexes, genes related to cholesterol and apolipoprotein synthesis and fatty acid biosynthesis and the immunological system were predominantly expressed in males and females, respectively, in GRf/f but not in GRmKO mice. Moreover, many genes were up-regulated in response to starvation in GRf/f but not in GRmKO mice, many of which were sex-independent and functioned to maintain homeostasis, while genes that showed sex dominance related to a variety of functions. Although the genes expressed in skeletal muscle may be predominantly sex-independent, sex-dominant genes may relate to sex differences in energy metabolism and the immune system and could be controlled by the GR.

Correlation among body composition and metabolic regulation in a male mouse model of Cushing's syndrome.

Glucocorticoids play a critical role in the regulation of homeostasis, including metabolism. In patients with Cushing's syndrome, chronic glucocorticoid excess disrupts physiological internal milieu, resulting in central obesity, muscle atrophy, fatty liver, and insulin resistance. However, the relationship among various metabolic effects of glucocorticoids remains unknown. In the present study, we studied a male mouse model of Cushing's syndrome and indicated that glucocorticoid excess alters metabolic phenotype and body composition involving possible communication among skeletal muscle, liver, and adipose tissue.

The effects of bolus supplementation of branched-chain amino acids on skeletal muscle mass, strength, and function in patients with rheumatic disorders during glucocorticoid treatment.

OBJECTIVES: To test the effects of bolus supplementation of branched-chain amino acids (BCAA) on skeletal muscle mass, strength, and function in patients with rheumatic disorders taking glucocorticoid (GC). METHODS: Patients with rheumatic disorders treated with prednisolone (≥10 mg/day) were randomized to ingest additional daily 12 g of BCAA (n = 9) or not (n = 9) for 12 weeks. At baseline, and 4, 8, and 12 weeks, they underwent bioelectrical impedance analysis, muscle strength and functional tests, and computed tomography analysis for cross-sectional area of mid-thigh muscle. RESULTS: Disease activities of the patients were well controlled and daily GC dose was similarly reduced in both groups. Limb muscle mass was recovered in both groups. Whole-body muscle mass and muscle strength and functional mobility were increased only in BCAA (+) group. The effects of BCAA supplementation on recovering skeletal muscle mass were prominent in particular muscles including biceps femoris muscle. CONCLUSIONS: This trial is the first-in-man clinical trial to demonstrate that BCAA supplementation might be safe and, at least in part, improve skeletal muscle mass, strength, and function in patients with rheumatic disorders treated with GC.

Quantitative analysis of skeletal muscle mass in patients with rheumatic diseases under glucocorticoid therapy--comparison among bioelectrical impedance analysis, computed tomography, and magnetic resonance imaging.

OBJECTIVES: To determine the availability of bioelectrical impedance analysis (BIA), computed tomography (CT), and magnetic resonance imaging (MRI) for measurement of skeletal muscle mass in patients with rheumatic diseases and quantitatively assess skeletal muscle loss after glucocorticoid (GC) treatment. METHODS: The data from 22 patients with rheumatic diseases were retrospectively obtained. The muscle mass of body segments was measured with a BIA device in terms of skeletal muscle mass index (SMI). Cross-sectional area (CSA) was obtained from CT and MRI scans at the mid-thigh level using the image analysis program. We further assessed the data of three different measurements before and after GC treatment in 7 patients with rheumatic diseases. RESULTS: SMI of whole body was significantly correlated with estimated muscle volume and mid-thigh muscle CSA with CT and MRI (p < 0.01). Significant correlations between SMI and mid-thigh muscle CSA of each leg were also found (p < 0.01). All the three measurements were negatively correlated with GC dosage (p < 0.01). Significant decline in mid-thigh muscle CSA with CT and MRI was found after GC treatment in 7 patients (p < 0.02). Those patients showed significant decline in SMI of whole body after GC treatment, but not in SMI of each leg. On the other hand, significant correlations between mid-thigh muscle CSA with CT and MRI were found before and after GC treatment (p < 0.01). CONCLUSIONS: GC-related skeletal muscle loss could be quantitatively assessed with BIA, CT, or MRI in patients with rheumatic diseases, and CT and MRI appeared to be more accurate than BIA.

HLA-DRB1 Is Associated with Therapeutic Responsiveness in IgG4-related Disease.

Objective Glucocorticoids are key drugs used in remission induction therapy for IgG4-related disease (IgG4-RD). However, the therapeutic outcomes vary widely, with some patients requiring long-term maintenance therapy and others relapsing repeatedly, whereas still others can tolerate withdrawal. These variations underscore the need for personalized treatment strategies for IgG4-RD. We examined the relationship between human leukocyte antigen (HLA) genotypes and the response to glucocorticoid treatment in patients with IgG4-RD. Methods Eighteen IgG4-RD patients visiting our hospital were included in the study. Peripheral blood samples were collected, HLA genotypes were determined, and the response to glucocorticoid treatment (maintenance dose at the time of last observation, glucocorticoid dose when the serum IgG4 level was the lowest after remission induction therapy, and occurrence of relapse) was examined retrospectively. Results The DQB1*12:01 genotypes were associated with a prednisolone maintenance dose of <7 mg/day. A prednisolone dose ≥10 mg with a minimum serum IgG4 level was significantly more common in B*40:01 and DRB1-GB-7-Val (DRB1*04:01, *04:03, *04:05, *04:06, and *04:10) patients than other alleles. Relapse also tended to be more common in DRB1-GB-7-Val carriers than other alleles. Conclusion These data suggest that HLA-DRB1 is associated with glucocorticoid treatment responsiveness and is important for follow-up monitoring of serum IgG4 levels during glucocorticoid tapering. We believe that these data will contribute to the future development of personalized medicine for IgG4-RD.

A case of IgG4-related disease associated with ulcerative colitis that was successfully treated with a JAK inhibitor.

Glucocorticoids (GC) are the standard of care for the induction and maintenance of remission in immunoglobulin G4 (IgG4)-related diseases. However, IgG4-related diseases often relapse with GC dose reduction, not only making GC dose reduction difficult but also necessitating GC dose escalation in many cases. Therefore, other immunosuppressive drugs are required to maintain remission. Here, we report a 39-year-old man with ulcerative colitis and IgG4-related disease who experienced a relapse of both diseases despite treatment with tacrolimus and 6-mercaptopurine. Following the initiation of tofacitinib, a Janus-associated kinase inhibitor, it was possible to reduce the GC dose while maintaining remission of both diseases. This case highlights the potential utility of Janus-associated kinase inhibitors in managing complex cases of IgG4-related disease, especially those with concurrent conditions such as ulcerative colitis.

IgG4-related Disease Emerging after COVID-19 mRNA Vaccination.

A 78-year-old Japanese woman with no history of rheumatic disease received 2 doses of the BNT162b2 COVID-19 mRNA vaccine. Two weeks later, she noticed bilateral swelling in the submandibular region. Blood tests showed hyper-immunoglobulin (Ig)G4emia, and 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) revealed the strong accumulation of FDG in the enlarged pancreas. She was diagnosed with IgG4-related disease (IgG4-RD) according to the American College of Rheumatology (ACR)/the European League Against Rheumatism (EULAR) classification criteria. Treatment was started with prednisolone at 30 mg/day, and the organ enlargement improved. We herein report a case of IgG4-RD that may have been associated with an mRNA vaccine.

Positive antiphospholipid antibodies and pulmonary embolism in a patient with adalimumab-induced lupus.

It is known that administration of tumor necrotic factor (TNF) inhibitors induces lupus. The case of a Crohn's disease patient who had been treated with adalimumab (ADA) and showed positive anti-DNA and antiphospholipid antibodies and developed pulmonary embolism is presented. Fortunately, early diagnosis and intervention helped her survive. Although ADA was withdrawn, the Crohn's disease did not recur, and the autoantibodies became negative without any steroid therapy. It is important to recognise that administration of TNF inhibitors may be associated with antiphospholipid syndrome. It is necessary to perform therapeutic interventions such as TNF inhibitor withdrawal and prompt anticoagulant therapy when such pathology is suspected.

The crucial role of muscle glucocorticoid signaling in accelerating obesity and glucose intolerance via hyperinsulinemia.

Metabolic crosstalk from skeletal muscle to multiple organs is important for maintaining homeostasis, and its dysregulation can lead to various diseases. Chronic glucocorticoid administration often induces muscle atrophy and metabolic disorders such as diabetes and central obesity; however, the detailed underlying mechanism remains unclear. We previously reported that the deletion of glucocorticoid receptor (GR) in skeletal muscle increases muscle mass and reduces fat mass through muscle-liver-fat communication under physiological conditions. In this study, we show that muscle GR signaling plays a crucial role in accelerating obesity through the induction of hyperinsulinemia. Fat accumulation in liver and adipose tissue, muscle atrophy, hyperglycemia, and hyperinsulinemia induced by chronic corticosterone (CORT) treatment improved in muscle-specific GR-knockout (GR-mKO) mice. Such CORT-induced fat accumulation was alleviated by suppressing insulin production (streptozotocin injection), indicating that hyperinsulinemia enhanced by muscle GR signaling promotes obesity. Strikingly, glucose intolerance and obesity in ob/ob mice without CORT treatment were also improved in GR-mKO mice, indicating that muscle GR signaling contributes to obesity-related metabolic changes, regardless of systemic glucocorticoid levels. Thus, this study provides insight for the treatment of obesity and diabetes by targeting muscle GR signaling.

The differential diagnosis of IgG4-related disease based on machine learning.

INTRODUCTION: To eliminate the disparity and maldistribution of physicians and medical specialty services, the development of diagnostic support for rare diseases using artificial intelligence is being promoted. Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is a rare disorder often requiring special knowledge and experience to diagnose. In this study, we investigated the possibility of differential diagnosis of IgG4-RD based on basic patient characteristics and blood test findings using machine learning. METHODS: Six hundred and two patients with IgG4-RD and 204 patients with non-IgG4-RD that needed to be differentiated who visited the participating institutions were included in the study. Ten percent of the subjects were randomly excluded as a validation sample. Among the remaining cases, 80% were used as training samples, and the remaining 20% were used as test samples. Finally, validation was performed on the validation sample. The analysis was performed using a decision tree and a random forest model. Furthermore, a comparison was made between conditions with and without the serum IgG4 concentration. Accuracy was evaluated using the area under the receiver-operating characteristic (AUROC) curve. RESULTS: In diagnosing IgG4-RD, the AUROC curve values of the decision tree and the random forest method were 0.906 and 0.974, respectively, when serum IgG4 levels were included in the analysis. Excluding serum IgG4 levels, the AUROC curve value of the analysis by the random forest method was 0.925. CONCLUSION: Based on machine learning in a multicenter collaboration, with or without serum IgG4 data, basic patient characteristics and blood test findings alone were sufficient to differentiate IgG4-RD from non-IgG4-RD.

Amino Acid Profile in 18 Patients with Rheumatic Diseases Treated with Glucocorticoids and BCAAs.

The administration of glucocorticoids to patients with rheumatic diseases often results in glucocorticoid-induced myopathy. We previously found that administration of branched-chain amino acids (BCAA) to such patients improves the loss of skeletal muscle, however, their individual differences were often observed. The present study, therefore, aims to identify specific parameters associated with BCAA-induced increases in skeletal muscle mass. Eighteen patients with rheumatic diseases treated with prednisolone were randomly assigned to receive additional BCAAs for 12 wk. Serum biochemistry, plasma fibroblast growth factor (FGF) 19 and 21, and plasma and urinary amino acid concentrations were assessed. The relationship between these parameters and the cross-sectional area (CSA) of the biceps femoris (slow-twitch muscle) and rectus femoris (fast-twitch muscle) was assessed using computed tomography. BCAA supplementation increased serum levels of creatinine and albumin and decreased ammonia and urinary 3-methylhistidine levels. With or without BCAA supplementation, each plasma amino acid concentration decreased during the study period, but the decrease was lower in patients receiving BCAA. Interestingly, a positive correlation was observed between plasma isoleucine, aspartate, and glutamate concentrations and improvement in the biceps femoris muscle atrophy. Plasma amino acid concentrations in patients with rheumatic diseases treated with glucocorticoids decreased despite tapering the dose of glucocorticoids, with a smaller decrease in the BCAA-treated group. Plasma BCAA, aspartic acid, and glutamate concentrations correlated positively with the rate of improvement in biceps femoris muscle atrophy, suggesting that these amino acids are associated with the BCAA-induced increase in muscle mass.

Drug-induced Bullous Pemphigoid and Lupus Erythematosus Occurring under Anti-TNF-α and IL-6 Therapy in a Patient with Rheumatoid Arthritis.

A 65-year-old Japanese woman, who was diagnosed with rheumatoid arthritis and Sjögren's syndrome with various autoantibodies including anti-DNA antibody, developed bullous pemphigoid (BP) and hematological abnormalities like lupus erythematosus after adalimumab therapy. The discontinuation of adalimumab resolved those disorders but polyarthritis thereafter relapsed. The introduction of abatacept was not effective, but tocilizumab was found to be effective for polyarthritis, however, thereafter both bullous disease and severe pancytopenia developed. Discontinuation of tocilizumab was effective, but polyarthritis again developed, and baricitinib resolved it. There is an increasing number of reports of drug-induced BP and lupus erythematosus, and biologics might trigger an alteration in the pathophysiological/clinical course of rheumatic disorder.

Elevated Serum IgG4 Complicated by Pericardial Involvement with a Patchy (18)F-FDG Uptake in PET/CT: Atypical Presentation of IgG4-related Disease.

IgG4-related pericardial involvement has rarely been reported and its clinical features remain unknown. We herein report a case of a 50-year-old woman with pericarditis who presented with a fever, elevated C-reactive protein levels, elevated serum IgG4 concentrations, and thickened pericardium with a patchy (18)F-fluorodeoxyglucose (FDG) uptake. A biopsy specimen of (18)F-FDG accumulated in the mediastinal lymph nodes revealed an abundant infiltration of IgG4-bearing plasma cells without fibrosis. Moderate-dose glucocorticoids promptly resolved the physical, serological, and imaging abnormalities, thus indicating a relatively acute and reversible nature of IgG4-related pericardial involvement.