Factors related to renal cortical atrophy development after glucocorticoid therapy in IgG4-related kidney disease: a retrospective multicenter study

Effects of Corticosteroid Treatment on Olfactory Dysfunction in LATY136F Knock-In Mice

OBJECTIVE

Immunoglobulin G4-related disease (IgG4-RD) is a systemic inflammatory condition affecting multiple organs, including the pancreas, salivary glands, lungs, kidneys, skin, and lymph nodes. Clinically, it is characterized by elevated serum IgG and IgG4 levels and tissue infiltration by IgG4-positive plasma cells, lymphocytes, fibrosis, and phlebitis obliterans. IgG4-RD is linked to increased Th2-dominant cytokines, contributing to eosinophilia, elevated serum IgG4, and fibrosis. A notable feature is its good response to corticosteroid therapy. To investigate the effects of corticosteroid treatment on olfactory dysfunction in LATY136F knock-in mice, which exhibited increased production of Th2-type IgG1 (the murine homolog of human IgG4) and developed multiorgan tissue lesions similar to those observed in IgG4-RD patients.

METHODS

LATY136F knock-in mice (n=24) were divided into groups that received prednisolone or saline at different ages. Olfactory function was assessed using a behavioral test with cycloheximide. Histological and immunohistochemical analyses were performed to evaluate the olfactory epithelium thickness as well as the presence of mature and immature olfactory neurons.

RESULTS

Corticosteroid-treated mice exhibited significantly improved olfactory function compared to the controls. Histological analysis revealed a significant increase in olfactory epithelium thickness and mature (olfactory marker protein-positive) and immature (growth-associated protein 43-positive) olfactory neurons in the treated groups compared with the control group.

CONCLUSION

Corticosteroid treatment effectively improved olfactory dysfunction and promoted olfactory epithelium regeneration in LATY136F knock-in mice, suggesting the potential therapeutic benefits of corticosteroid treatment for patients with IgG4-RD experiencing olfactory dysfunction. However, further research on topical nasal steroid therapy in untreated patients is warranted. The results support further investigation into topical nasal steroid therapies for treating olfactory dysfunction in untreated patients, potentially influencing clinical practice and patient management strategies for IgG4-RD globally.

Improved Renal Function in Initial Treatment Improves Patient Survival, Renal Outcomes, and Glucocorticoid-Related Complications in IgG4-Related Kidney Disease in Japan

Introduction

We aimed to clarify long-term renal prognosis, complications of malignancy, glucocorticoid (GC) toxicity, and mortality in immunoglobulin G4 (IgG4)-related kidney disease (IgG4-RKD).

Methods

Reviewing the medical records of 95 patients with IgG4-RKD, we investigated clinical and pathologic features at baseline, the course of renal function, complications of malignancy, GC toxicity, and mortality during follow-up (median 71 months). The standardized incidence ratio (SIR) of malignancy and standardized mortality ratio were calculated using national statistics. Factors related to outcomes were assessed by Cox regression analyses.

Results

At diagnosis, the median estimated glomerular infiltration rate (eGFR) was 46 ml/min per 1.73 m2. GC achieved initial improvement. Additional renal function recovery within 3-months of initial treatment occurred in patients with highly elevated serum IgG and IgG4 levels and hypocomplementemia. During follow-up, 68%, 17%, and 3% of the patients had chronic kidney disease (CKD), >30% eGFR decline, and end-stage renal disease (ESRD), respectively. Age-adjusted and sex-adjusted Cox regression analyses indicated that eGFR (hazard ratio [HR], 0.71) and extensive fibrosis (HR, 2.58) at treatment initiation had a significant impact on the time to CKD. Ten patients died, and the standardized mortality ratio was 0.94. The SIR of malignancy was 1.52. The incidence rate (IR) of severe infection was 1.80/100 person-years. Cox regression analyses showed that the best eGFR within 3 months after treatment initiation were associated with lower mortality (HR 0.67) and fewer severe infections (HR 0.63).

Conclusion

This study suggests that more renal function recovery through early treatment initiation may improve patient survival, renal outcomes, and some GC-related complications in IgG4-RKD.

Clues to mortality trends and their related factors in IgG4-related disease: A Japanese single-centre retrospective study

OBJECTIVES

This study aimed to clarify mortality trends and their related factors in immunoglobulin G4-related disease (IgG4-RD) with various organ involvement.

METHODS

We retrospectively reviewed the medical records of patients with IgG4-RD at a single rheumatology centre in Japan. We calculated the standardized mortality ratio using Japanese national mortality statistics. Cox regression analyses were also performed to assess mortality-related factors.

RESULTS

A total of 179 patients with IgG4-RD were included with a median follow-up period of 47 months. The standardized mortality ratio in our cohort was 0.86 (95% confidence interval 0.41-1.59). Univariate Cox regression analyses indicated that the number of affected organs at diagnosis (hazard ratio 1.45, 95% confidence interval 1.02-2.05), estimated glomerular infiltration rate <45 ml/min/1.73 m2 at diagnosis (vs. ≥45, hazard ratio 8.48, 95% confidence interval 2.42-29.79), and the presence of malignancy during the clinical course (hazard ratio 5.85, 95% confidence interval 1.62-21.15) had a significant impact on the time to death.

CONCLUSIONS

Our findings suggest that in the rheumatology department, IgG4-RD does not significantly affect long-term patient survival. However, multi-organ involvement, renal dysfunction, and malignancy may be associated with higher mortality trends in IgG4-RD. Early detection and appropriate management of risk factors may improve the long-term prognosis of patients with IgG4-RD.

Identification of risk factors for elevated serum IgG4 levels in subjects in a large-scale health checkup cohort study

Introduction

To allow the identification of IgG4-related disease (IgG4-RD) from a subclinical phase as it is important to understand the risk of elevated serum IgG4 levels. We planned to evaluate serum IgG4 levels in the participants of the Nagasaki Islands Study (NaIS), a large-scale health checkup cohort study.

Methods

This study included 3,240 individuals who participated in the NaIS between 2016 and 2018 and consented to participate in the study. Serum IgG4, IgG, and IgE levels and human leukocyte antigen (HLA) genotyping results of the NaIS subjects as well as lifestyle habits and peripheral blood test results were analyzed. The magnetic bead panel assay (MBA) and the standard nephelometry immunoassay (NIA) were used to measure serum IgG4 levels. The data were evaluated using multivariate analysis to identify lifestyle and genetic factors associated with elevated serum IgG4 levels.

Results

Serum IgG4 levels measured with the NIA and MBA showed a tight positive correlation between the two groups (correlation coefficient 0.942). The median age of the participants in the NaIS was 69 years [63-77]. The median serum IgG4 level was 30.2 mg/dL [IQR 12.5-59.8]. Overall, 1019 (32.1%) patients had a history of smoking. When the subjects were stratified into three groups based on the smoking intensity (pack-year), the serum IgG4 level was significantly higher among those with a higher smoking intensity. Accordingly, the multivariate analysis identified a significant relationship between smoking status and serum IgG4 elevation.

Conclusion

In this study, smoking was identified as a lifestyle factor correlating positively with elevated serum IgG4 levels.

Recent advances in IgG4-related kidney disease

Recent advances in the management and understanding of immunoglobulin (Ig)G4-related kidney disease (RKD) have emphasized the importance of urgent treatment in IgG4-related tubulointerstitial nephritis. On the other hand, to avoid long-term glucocorticoid toxicity, strategies for early withdrawal of steroids or combination of immunosuppressants, such as rituximab, and the minimum dose of steroids have been pursued. However, disease recurrence after reducing or stopping steroid therapy hampers early withdrawal of glucocorticoid maintenance therapy. In addition, knowledge has accumulated in diagnostic approaches including differential diagnosis of anti-neutrophil cytoplasmic antibodies-associated vasculitis, idiopathic multicentric Castleman's disease, and Rosai-Dorfman disease with kidney lesion, which leads to earlier and precise diagnosis of IgG4-RKD. This review summarizes recent progress in the differential diagnosis of IgG4-RKD and related treatment strategies and recent topics of hypocomplementaemia, membranous glomerulonephritis, and IgG4-related pyelitis and periureteral lesion.

Glucocorticoids in the treatment of IgG4-related disease-Prospects for new international treatment guidelines

Immunoglobulin G4-related disease (IgG4-RD) is a chronic fibro-inflammatory disease that may cause dysfunction in various organs. Worldwide multidisciplinary experts attending the Fourth International Symposium on IgG4-Related Disease in Japan in 2021 discussed treatments for IgG4-RD, especially glucocorticoid (GC) therapy. This review describes the efficacy, safety, and cost of treatments for IgG4-RD based on findings presented at the international symposium. A medium dose of GC was considered appropriate for the initial treatment of IgG4-RD. A randomized controlled trial and an open-label prospective study have shown that long-term maintenance GC therapy (prednisolone ≥ 5 mg/day) could prevent disease relapse. In addition, two open-label randomized controlled trials reported the effects of combinational use of GC and synthetic immunosuppressive agents, mycophenolate mofetil and leflunomide, on relapse prevention. Moreover, an open-label single-arm study showed an excellent rate of clinical response to rituximab. Many observational studies have shown the efficacy of an appropriate GC regimen in patients with IgG4-RD. Synthetic immunosuppressive agents and a molecular-targeted agent can be potent alternatives to GCs, but additional studies are required comparing their efficacy, risk of infection, and costs.

Development of IgG4-related pancreatitis and kidney disease 7 years after the onset of undiagnosed lymphadenopathy: A case report

This report describes a patient diagnosed with immunoglobulin G4 (IgG4)-related pancreatitis and kidney disease 7 years after the onset of undiagnosed lymphadenopathy. A 48-year-old Japanese woman presented with fatigue and leg oedema. Computed tomography showed perigastric lymphadenopathy, for which she underwent a laparoscopic biopsy of the perigastric lymph nodes. Although histopathological examination of the lymph nodes did not lead to a definitive diagnosis, serological tests revealed elevated serum IgG4 levels (558 mg/dl) and IgG4 immunostaining of the lymph nodes showed IgG4-positive plasma cell infiltration, leading to the suspicion of IgG4-related disease. Further workup revealed no organ lesion other than lymphadenopathy. At age 55 years, despite having no subjective symptoms, contrast-enhanced computed tomography showed low-density lesions in the tail of the pancreas and the left kidney. Histopathological examination showed lymphocyte infiltration, consisting of a mixture of plasma cells and eosinophils, in both organs and obliterative phlebitis in the pancreas. IgG4 immunostaining of the kidney specimens showed 160 IgG4-positive cells per high-powered field, with the IgG4+/IgG+ cell ratio being almost 100%, leading to a diagnosis of IgG4-related pancreatitis and kidney disease. Treatment with prednisolone for 2 months resulted in lesion improvement. Although the diagnosis of IgG4-related lymphadenopathy is often challenging in patients with lymphadenopathy alone, findings in the present patient emphasise the importance of long-term follow-up, as it may allow early detection of involvement of other organs by IgG4-related disease.

Persistent enlargement of the pancreatic gland after glucocorticoid therapy increases the risk of relapse in IgG4-related autoimmune pancreatitis

OBJECTIVES

This study aims to clarify the relationship between the changes of pancreatic size after glucocorticoid (GC) therapy and relapse in IgG4-related autoimmune pancreatitis (AIP).

METHODS

We prospectively enrolled 205 newly diagnosed IgG4-related AIP patients. 145 patients were followed up for more than 3 years. These patients were divided into three groups according to the changes of pancreatic size after treatment of 6 months: pancreatic swelling, normal size, and pancreatic atrophy. Baseline clinical and laboratory parameters were compared among three groups. Kaplan-Meier survival analysis was performed in the 134 patients based on GC therapy. Besides, Cox regression analysis and logistic regression analysis were performed to identify risk factors associated with relapse and the potential variables affecting changes of pancreatic size after treatment.

RESULTS

Age at diagnosis, white blood cell count, and serum IgG1 level at baseline were significantly different among the three groups. After treatment of 6 months, the pancreas of most patients (n = 81, 55.9%) could return to normal size, while persistent pancreatic swelling was found in 24.1% patients (n = 35), and atrophy was observed in 20.0% of the patients (n = 29). Kaplan-Meier survival analysis presented patients with pancreatic swelling after 6 months of GC therapy were more likely to relapse in the follow-up of 3 years. Persistent pancreatic swelling after treatment and salivary gland involvement at baseline were independent risk variables associated with relapse in IgG4-related AIP patients, while GC-based therapy was a protective factor of relapse. Logistic regression analysis revealed that older age at diagnosis was associated with pancreatic atrophy and higher baseline serum IgG1 level was associated with pancreatic swelling after treatment of 6 months.

CONCLUSIONS

Patients with persistent pancreatic swelling after GC-based therapy of 6 months were more likely to relapse in the follow-up of 3 years. Older age at diagnosis and higher baseline serum IgG1 level were potential variables associated with pancreatic atrophy or swelling after treatment of 6 months. Key Points • Patients with persistent pancreatic swelling after glucocorticoid-based therapy were more likely to relapse in IgG4-related autoimmune pancreatitis. • Older age at diagnosis was associated with pancreatic atrophy after glucocorticoid-based therapy. • Higher baseline serum IgG1 level was associated pancreatic swelling after glucocorticoid-based therapy.

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

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.

Serum IgG4 levels at diagnosis can predict unfavorable outcomes of untreated patients with IgG4-related disease

The outcomes of patients with immunoglobulin G4 (IgG4)-related disease (IgG4-RD) who are not treated are unclear. This study aimed to clarify these outcomes and identify the factors related to them. We retrospectively evaluated various clinical features including laboratory data and involved organs at diagnosis in 107 patients with IgG4-RD, who were followed up for more than 6 months, at a single center in Japan. We compared the clinical features of the 27 untreated patients with those of the 80 patients treated with glucocorticoid. The patient outcomes were investigated, and logistic regression analysis was performed to identify factors related to them. The patients comprised 73 men and 34 women (median age 67 years). The untreated patients had significantly lower IgG4-RD responder index (9 vs. 12) and fewer affected organs (1 vs. 3) than did those treated with glucocorticoid. Of these 27 patients, 8 experienced deterioration of IgG4-RD after the diagnosis. In the age- and sex-adjusted logistic regression analysis, serum IgG4 elevation (per 100 mg/dL, odds ratio 1.194, 95% confidence interval 1.017–1.402) was the only significant factor related to disease deterioration in untreated patients with IgG4-RD, whereas not serum IgG4 levels (per 100 mg/dL, odds ratio 0.995, 95% confidence interval 0.921–1.075) but history of allergy (OR 3.134, 95% confidence interval 1.094–8.977, P = 0.033) related to deterioration in patients who underwent treatment. Serum IgG4 levels may be a useful predictor of unfavorable outcomes in untreated patients with IgG4-RD, who tend to have fewer affected organs and lower IgG4-RD responder index.

Renal Involvement in IgG4-Related Disease: From Sunlight to Twilight

IgG4-Related Disease (IgG4-RD) is a fibroinflammatory condition characterized by a typical histopathological pattern (dense lymphoplasmacytic infiltrate with prevalent IgG4+ plasma cells and storiform fibrosis), which may involve the kidney both directly (IgG4-related kidney disease, IgG4-RKD) or indirectly, as a consequence of post-renal ureteral obstruction due to retroperitoneal fibrosis (IgG4-RD RF). The most frequent presentation of IgG4-RKD is IgG4-related tubulointerstitial nephritis (TIN), but a glomerular disease can be present, in most of the cases a membranous nephropathy. Albeit steroid-responsive, in some cases renal manifestations may lead to progressive and permanent organ damage. In this review we describe four clinical cases representative of typical and less typical renal manifestations of IgG4-RD, emphasizing a potential, subclinical, early involvement of the kidney in the disease.

Tertiary lymphoid tissue in early-stage IgG4-related tubulointerstitial nephritis incidentally detected with a tumor lesion of the ureteropelvic junction: a case report

Background

IgG4-related kidney disease causes renal impairment of unknown pathogenesis that may progress to kidney failure. Although ectopic germinal centers contribute to the pathogenesis of the head and neck lesions of IgG4-related disease, the presence of tertiary lymphoid tissue (TLT) containing germinal centers in IgG4-RKD has rarely been reported.

Case presentation

We report a 72-year-old Japanese man who had IgG4-related tubulointerstitial nephritis (TIN) with TLT formation incidentally detected in a resected kidney with mass lesion of IgG4-related ureteritis in the ureteropelvic junction. During follow-up for past surgical resection of a bladder tumor, renal dysfunction developed and a ureter mass was found in the right ureteropelvic junction, which was treated by nephroureterectomy after chemotherapy. Pathology revealed no malignancy but abundant IgG4-positive cell infiltration, obliterative phlebitis and storiform fibrosis, confirming the diagnosis of IgG4-related ureteritis. In the resected right kidney, lymphoplasmacytes infiltrated the interstitium with focal distribution in the renal subcapsule and around medium vessels without storiform fibrosis, suggesting the very early stage of IgG4-TIN. Lymphocyte aggregates were also detected at these sites and consisted of B, T, and follicular dendritic cells, indicating TLT formation. IgG4-positive cells infiltrated around TLTs.

Conclusions

Our case suggests that TLT formation is related with the development of IgG4-TIN and our analysis of distribution of TLT have possibility to elucidate IgG4-TIN pathophysiology.

Long-term effects of intensive B cell depletion therapy in severe cases of IgG4-related disease with renal involvement

IgG4-related disease (IgG4-RD) is an immune-mediated disorder often showing elevated serum IgG4 concentrations, dense T and B lymphocyte infiltration, and IgG4-positive plasma cells and storiform fibrosis. We prospectively evaluated for 4 years 5 patients with histologically proven IgG4-RD of whom 3 had tubulointerstitial nephritis (TIN) and 2 had retroperitoneal fibrosis (RPF). They received an intensive B depletion therapy with rituximab. The estimated glomerular filtration rate of TIN patients after 1 year increased from 9 to 24 ml/min per 1.73 m2. IgG/IgG4 dropped from 3236/665 to 706/51 mg/dl, C3/C4 went up from 49/6 to 99/27 mg/dl, and the IgG4-RD responder index fell from 10 to 1. CD20+ B cells decreased from 8.7 to 0.5%. A striking drop in interstitial plasma cell infiltrate as well as normalization of IgG4/IgG-positive plasma cells was observed at repeat biopsy. Both clinical and immunological improvement persisted over a 4-year follow-up. Treating these patients who were affected by aggressive IgG4-RD with renal involvement in an effort to induce a prolonged B cells depletion with IgG4 and cytokine production decrease resulted in a considerable rise in eGFR, with IgG4-RD RI normalization and a noteworthy improvement in clinical and histological features. Furthermore, the TIN subgroup was shown not to need for any maintenance therapy.

Long-term changes in renal function after treatment initiation and the importance of early diagnosis in maintaining renal function among IgG4-related tubulointerstitial nephritis patients in Japan

BACKGROUND

The present study aimed to investigate associations between long-term renal function, whether IgG4-related tubulointerstitial nephritis (TIN) was diagnosed by renal biopsy at initial examination, chronic kidney disease (CKD) stage, and histological stage in patients with IgG4-related TIN.

METHODS

This study used a retrospective cohort design including almost all patients who underwent renal biopsy at Fujita Health University Hospital and Nagoya University or its affiliated hospitals in Aichi between April 2003 and March 2015 (n = 6977 renal biopsies). The primary outcome was longitudinal changes in eGFR. Main exposures were whether IgG4-related TIN was diagnosed by renal biopsy at the initial examination, CKD stage, and its histological stage. Linear mixed models were performed to examine associations.

RESULTS

Of the 6977 samples, there were 24 patients (with 201 records due to repeated measures) with IgG4-related TIN (20 men, mean age, 68.7 ± 9.7 years). They were followed up 6.6 ± 2.8 years after the renal biopsy and underwent glucocorticoid treatment. We found significant increase in eGFR from the baseline to 2 and 6 months after treatment initiation, which was maintained until 60 months. Patients initially diagnosed with IgG4-related TIN had higher eGFR from the baseline (at the start of treatment) to 60 months than those who were not. Compared with patients with CKD stage 3, patients with CKD stages 4 and 5 had lower eGFR at the baseline and other time points. Patients with histological stage B had comparatively lower eGFR at each point than stage A patients. Those mean differences of eGFR were stable from the baseline to 60 months.

CONCLUSIONS

After the treatment initiation, renal function rapidly improved and maintained for a long period, even with advanced CKD stage. We showed importance of early diagnosis of IgG4-related TIN in maintaining eGFR.

Different factors underlie recurrent and de novo organ involvement in immunoglobulin G4-related disease

OBJECTIVES

In IgG4-related disease (IgG4-RD), relapse including recurrent organ involvement (ROI) and de novo organ involvement (DNOI) occurs frequently during the clinical course. This study aimed to clarify the differences between the risk factors underlying ROI and DNOI in IgG4-RD.

METHODS

We retrospectively investigated factors related to ROI and DNOI in 86 IgG4-RD patients. For assessment of factors related to ROI and DNOI, we performed uni- and multivariate Cox regression analyses. On stepwise multivariate analysis, we applied the variables with P < 0.1 in the univariate analysis and the predictors of relapse suggested in past reports.

RESULTS

During the mean follow-up period of 63.1 months, ROI was detected at 1.0-120 months after diagnosis in 20 patients, 4 of whom were not receiving glucocorticoid (GC) at the time of ROI. In contrast, DNOI was detected at 5.0-120 months after diagnosis in 15 patients, 8 of whom were not receiving GC at the time of DNOI. In the multivariate analysis, blood eosinophil counts at diagnosis [per 100/μl; hazard ratio (HR) 1.072 (95% CI 1.018, 1.129)] and continuation of GC [vs discontinuation or observation without GC; HR 0.245 (95% CI 0.076, 0.793)] had a significant impact on the time to DNOI, whereas age [HR 0.942 (95% CI 0.899, 0.986)] and ANA positivity [vs negativity; HR 6.632 (95% CI 1.892, 23.255)] had a significant impact on the time to ROI.

CONCLUSION

The present study suggests that the risk factors of ROI and DNOI are different in IgG4-RD, highlighting the need for different preventative strategies.

IgG4-related disease: a clinical perspective

IgG4-related disease (IgG4-RD) is a recently recognized fibro-inflammatory disorder that can affect almost any organ. Common presentations include major salivary and lacrimal gland enlargement, orbital disease, autoimmune pancreatitis, retroperitoneal fibrosis and tubulointerstitial nephritis. The main histopathological features are a dense, polyclonal, lymphoplasmacytic infiltrate rich in IgG4+ plasma cells, storiform fibrosis and obliterative phlebitis. The precise pathogenic mechanisms of IgG4-RD are still unclear. CD4+ T and B cells, including IgG4-expressing plasmablasts, constitute the major inflammatory cell populations and are believed to cause organ damage and tissue fibrosis. The diagnosis of the disease may be challenging and should be based on specific histopathological findings, typical laboratory and radiological aspects and an appropriate clinical context. The first-line treatment of IgG4-RD is based on glucocorticoids, which are usually efficacious. However, B cell depletion induced by rituximab has also been found to induce remission in steroid-resistant disease or has been used as steroid-sparing agent for relapsing disease. This review provides an update on clinical and therapeutic aspects of IgG4-RD.

Abundant a proliferation-inducing ligand (APRIL)-producing macrophages contribute to plasma cell accumulation in immunoglobulin G4-related disease

Background

This study aimed to investigate the contribution of a proliferation-inducing ligand (APRIL), a member of the tumor necrosis factor (TNF) superfamily implicated in plasma cell survival, to the development of plasma cell–rich lesions in immunoglobulin G4–related disease (IgG4-RD).

Methods

We performed immunohistochemical staining for APRIL with Stalk-1 and Aprily-8 antibodies specifically recognizing APRIL-producing cells and secreted APRIL, respectively, in renal and submandibular lesions of IgG4-RD in comparison with those of Sjögren’s syndrome and sialolithiasis.

Results

Numerous Stalk-1-positive APRIL-producing cells were detectable in lesions of IgG4-RD. These cells, identified as CD163-positive M2 macrophages, secreted APRIL that distributed close to and even on infiltrating plasma cells. In contrast, APRIL-producing cells and the secreted form of APRIL were rarely detectable in lesions of Sjögren’s syndrome or sialolithiasis. Notably, APRIL expression decreased concomitantly with the level of plasma cell infiltration after successful glucocorticoid treatment.

Conclusions

Abundant infiltration into tissue lesions of APRIL-producing M2 macrophages and retention of secreted APRIL in plasma–cell–rich areas support a role for APRIL in the pathogenesis of plasma cell–rich lesions in IgG4-RD.

Glucocorticoids and steroid sparing medications monotherapies or in combination for IgG4-RD: a systematic review and network meta-analysis

Objective

To assess the safety and efficacy of glucocorticoids (GCs), immunosuppressive agents (IM) and rituximab (RTX), alone or in combination, for the treatment of IgG4-RD.

Methods

Relevant articles published were searched in the databases with relevant key words. Network meta-analysis was conducted, with various outcomes including relapse rate, remission rate and adverse events. Data were calculated with odds ratio (ORs) and 95% CI. P-score was used to rank the treatments.

Results

A total of 15 studies involving 1169 patients were included. Network meta-analysis indicated that RTX maintenance therapy had the lowest relapse rate of all treatments (OR = 0.10, 95% CI [0.01, 1.63]), whereas GCs + IM was associated with a lower relapse rate compared with GCs alone (OR = 0.39, 95% CI [0.20, 0.80]). Further, patients treated with GCs + IM had a higher remission rate than those given GCs (OR= 3.36, 95% CI [1.44, 7.83]), IM (OR= 55.31, 95% CI [13.73, 222.73]) monotherapies or RTX induction therapy only (OR= 7.38, 95% CI [1.56, 34.94]). The rate of adverse events was comparable among the different treatment groups.

Conclusion

Treatment of IgG4-RD patients with GCs and IM was associated with higher remission rates and lower relapse rates, as well as comparable safety profiles compared with GC, IM and RTX induction therapy. RTX maintenance therapy had a larger reduction in the relapse rate compared with GC and IM. The current evidence should be carefully scrutinized as the included studies were observational in design. Larger randomized controlled trials are needed to confirm.

Immunoglobulin G4-related Disease: An Overview

Immunoglobulin G4-related disease (IgG4-RD) is a recently established systemic disease that is characteristically associated with elevated serum immunoglobulin G4 (IgG4) levels and believed to be caused by autoimmune mechanisms. The clinical features of IgG4-RD include (i) systemic distribution, (ii) imaging findings of swelling, nodules, and/or wall thickening, (iii) high serum IgG4 levels, (iv) abundant IgG4-bearing plasma cell infiltration and fibrosis in affected organs, (v) a favorable response to corticosteroid therapy, and (vi) coexistence with other IgG4-RD manifestations simultaneously or in a metachronous fashion. The concept of IgG4-RD was established based on the culmination of specific discoveries. Specifically, a close association between autoimmune pancreatitis (AIP) and high serum IgG4 levels, massive IgG4-bearing plasma cell infiltration in pancreatic tissues affected by AIP, and systemic other organ involvements in AIP with similar IgG4-bearing plasma cell features opened the gateway from AIP to IgG4-RD. The systemic distribution of IgG4-RD seems to be capable of affecting every organ, causing well-established members including AIP, lacrimal and salivary gland lesions such as Mikulicz’s disease, respiratory diseases, sclerosing cholangitis, kidney diseases, and retroperitoneal fibrosis. IgG4-RD has been diagnosed worldwide, and international collaboration efforts on the disease have led to consensus publications on its nomenclature, pathology findings, and management approach. The algorithms developed for the comprehensive diagnostic criteria for IgG4-RD have remarkably increased detection sensitivity. Oral glucocorticoids are the first-line agents for remission induction, and certain patients with high disease activity may benefit from maintenance therapy afterwards. Originally, IgG4-RD had been considered reversible and to have a good prognosis; however, long-term afflictions sometimes result in transition to advanced-stage conditions with dysfunction and/or complicating malignancy. The immunological abnormalities in IgG4-RD have been reported in both innate and adaptive immune systems; however, it remains unclear whether IgG4 has a pathogenic role or a protective one in disease onset and progression.

A case of IgG4-related kidney disease with predominantly unilateral renal atrophy

A 73-year-old Japanese woman was diagnosed with type 1 autoimmune pancreatitis (AIP) without kidney lesions. She was treated with prednisolone (PSL) 30 mg/day, and her AIP symptoms promptly improved, after which the PSL dose was gradually tapered to 5 mg/day. Her renal function had remained normal (serum creatinine 0.7 mg/dL) until 1 year before the current admission without any imaging abnormalities in the kidney. However, during this past year her renal function gradually declined (serum creatinine 1.1 mg/dL). Follow-up computed tomography incidentally revealed unilateral renal atrophy, which rapidly progressed during the subsequent 10-month period without left kidney atrophy. A diagnosis of IgG4-RKD probably due to TIN was made, and we increased the dose of prednisolone to 30 mg/day. 1 month after administration, multiple low-density lesions on both kidneys were improved slightly but almost all lesions persisted as atrophic scars. Our case suggested that unilateral renal atrophy can develop in patients with IgG4-related tubulointerstitial nephritis without hydronephrosis caused by retroperitoneal fibrosis, and that monitoring the serum creatinine levels is not always sufficient, thereby highlighting the importance of regular imaging monitoring to detect newly developing kidney lesions.

LatY136F knock-in mouse model for human IgG4-related disease

Background

The adaptor protein Linker for activation of T cell (LAT) is a key signaling hub used by the T cell antigen receptor. Mutant mice expressing loss-of-function mutations affecting LAT and including a mutation in which tyrosine 136 is replaced by a phenylalanine (Lat^Y136F) develop lymphoproliferative disorder involving T helper type 2 effector cells capable of triggering a massive polyclonal B cell activation that leads to hypergammaglobulinemia G1 and E and to non-resolving inflammation and autoimmunity. The purpose of this study was to evaluate whether the phenotypes of Lat^Y136F knock-in mice resemble the immunohistopathological features of immunoglobulin G4-related disease (IgG4-RD).

Methods

Lat^Y136F knock-in mice were sacrificed at 4–20 weeks of age, and pancreas, kidney, salivary gland and lung were obtained. All organs were stained with hematoxylin-eosin and with Azan for estimation of collagen in fibrosis, and the severity scores of inflammation and fibrosis were evaluated. Immunostainings were performed to analyze the types of infiltrating cells. In addition, the effects of corticosteroid treatment on the development of tissue lesions and serum levels of IgG1 were assessed.

Results

Tissue lesions characterized by inflammatory mononuclear cell infiltration and fibrosis were detected in pancreas, kidney, and salivary gland starting from 6 weeks of age. Immunostainings showed pronounced infiltration of plasma cells, CD4-positive T cells, and macrophages. Infiltrating plasma cells predominantly expressed IgG1. The extent of inflammation in pancreas and salivary glands was markedly reduced by corticosteroid treatment.

Conclusions

Lat^Y136F knock-in mice displayed increased production of Th2-type IgG1 (a homologue of human IgG4) and developed multiple organ tissue lesions reminiscent of those seen in patients with IgG4-RD. Moreover, the development of these tissue lesions was highly sensitive to corticosteroid treatment like in IgG4-RD. For these reasons we consider the Lat^Y136F knock-in mouse strain to represent a promising model for human IgG4-RD.