Elevated serum IgG4 levels in diagnosis and treatment response in patients with idiopathic retroperitoneal fibrosis

Clinical characteristics and outcomes of autoimmune pancreatitis based on serum immunoglobulin G4 levels: A single-center, retrospective cohort study

Autoimmune pancreatitis (AIP) is a complex, poorly understood disease gaining increasing attention. "Clinical Characteristics and Outcome of AIP Based on Serum IgG4 levels," investigated AIP with a focus on serum immunoglobulin (Ig) G4 levels. The 213 patients with AIP were classified according to serum IgG4 levels: Abnormal (elevated) and normal. Patients with higher IgG4 levels exhibited a more active immune system and increased relapse rates. Beyond IgG4, the IgA levels and age independently contributed to relapse risk, guiding risk assessment and tailored treatments for better outcomes. However, limitations persist, such as no IgA correlation with IgG4 levels, absent data on autoantibody-positive AIP cases critical for Asian diagnostic criteria, and unexplored relapse rates in high serum IgG AIP by subtype. Genetic factors and family histories were not addressed. As the understanding and referral of seronegative AIPs increase, there's a growing need for commercially available, highly sensitive, and specific autoantibodies to aid in diagnosing individuals with low or absent serum IgG4 levels.

Clinical characteristics and outcome of autoimmune pancreatitis based on serum immunoglobulin G4 level: A single-center, retrospective cohort study

BACKGROUND

Autoimmune pancreatitis (AIP) has been linked with elevated immunoglobulin (Ig) G4 levels. The characteristics and outcomes of AIP based on serum markers have not been fully evaluated.

AIM

To compare clinical features, treatment efficacy, and outcome of AIP based on serum IgG4 levels and analyze predictors of relapse.

METHODS

A total of 213 patients with AIP were consecutively reviewed in our hospital from 2006 to 2021. According to the serum IgG4 level, all patients were divided into two groups, the abnormal group (n = 148) with a high level of IgG4 [> 2 × upper limit of normal (ULN)] and the normal group (n = 65). The t-test or Mann-Whitney U test was used to compare continuous variables. Categorical parameters were compared by the χ2 test or Fisher's exact test. Kaplan-Meier curves and log-rank tests were established to assess the cumulative relapse rates. Univariate and multivariate analyses were used to investigate potential risk factors of AIP relapse.

RESULTS

Compared with the normal group, the abnormal group had a higher average male age (60.3 ± 10.4 vs 56.5 ± 12.9 years, P = 0.047); higher level of serum total protein (72.5 ± 7.9 g/L vs 67.2 ± 7.5 g/L, P < 0.001), IgG4 (1420.5 ± 1110.9 mg/dL vs 252.7 ± 106.6 mg/dL, P < 0.001), and IgE (635.6 ± 958.1 IU/mL vs 231.7 ± 352.5 IU/mL, P = 0.002); and a lower level of serum complement C3 (100.6 ± 36.2 mg/dL vs 119.0 ± 45.7 mg/dL, P = 0.050). In addition, a lower number of cases with abnormal pancreatic duct and pancreatic atrophy (23.6% vs 37.9%, P = 0.045; 1.6% vs 8.6%, P = 0.020, respectively) and a higher rate of relapse (17.6% vs 6.2%, P = 0.030) were seen in the abnormal group. Multivariate analyses revealed that serum IgG4 [(> 2 × ULN), hazard ratio (HR): 3.583; 95% confidence interval (CI): 1.218-10.545; P = 0.020] and IgA (> 1 × ULN; HR: 5.908; 95%CI: 1.199-29.120; P = 0.029) and age > 55 years (HR: 2.383; 95%CI: 1.056-5.378; P = 0.036) were independent risk factors of relapse.

CONCLUSION

AIP patients with high IgG4 levels have clinical features including a more active immune system and higher relapse rate. Several factors, such as IgG4 and IgA, are associated with relapse.

Clinical significance of soluble interleukin-2 receptor measurement in patients with idiopathic retroperitoneal fibrosis

BACKGROUND

Idiopathic retroperitoneal fibrosis (iRPF) is a rare chronic fibro-inflammatory disorder of unknown etiology. Activated T-helper cells, which shed soluble interleukin-2 receptor (sIL-2R) into the circulation, may play a pathogenetic role. Hence, measuring sIL-2R may be of value in monitoring disease activity and treatment response in iRPF patients.

METHODS

We performed a prospective inception cohort study of 82 patients with untreated (re)active iRPF stratified by elevated (> 623 U/mL) or normal sIL-2R level at baseline and compared disease characteristics among these groups. Baseline and changes in sIL-2R levels following treatment with tamoxifen (TMX) or prednisone (PDN) were analyzed and related to treatment response.

RESULTS

Median sIL-2R level was 668 U/mL (IQR 502.8-827.5); 48 patients (59%) had elevated baseline sIL-2R levels. Patients with elevated sIL-2R presented with higher CRP (P = 0.049) and serum creatinine (sCr) levels (P < 0.001) and more often had hydroureteronephrosis (P = 0.01). There was an age and sex adjusted linear association between baseline sIL-2R and both CRP (P = 0.02) and sCr (P < 0.001). Baseline and serial levels of sIL-2R were predictive and concordant, respectively, with clinical response in patients treated with PDN. ROC curve analyses of sIL-2R on a continuous scale and PDN treatment success showed an AUC of 0.84. A serum sIL-2R cut-off value for PDN treatment success of ≤ 703 U/mL was found with a sensitivity of 100% and specificity of 72%.

CONCLUSION

Serial measurement of sIL-2R may be of value in monitoring disease activity and PDN treatment response in iRPF patients.

IgG4-Related Disease With Gastrointestinal Involvement: Case Reports and Literature Review

IgG4-related disease is an immune-mediated chronic, systemic, and autoinflammatory disease that can affect various organs throughout the body. The most commonly affected areas are the pancreas and biliary system. Due to the diverse clinical manifestations of the disease, it affects widely distributed organs. Thus, it is often easy to misdiagnose or miss. The digestive tract is a rarely affected system, and most IgG4-related gastric diseases manifest as tumors detected by endoscopy. This article reports two special cases with IgG4-related disease involving atrophic gastritis and intestinal polyps to provide a more empirical and theoretical basis for clinical diagnosis and treatment.

Into Clinical Practice: Diagnosis and Therapy of Retroperitoneal Fibrosis

PURPOSE OF THE REVIEW

We aim to review the most relevant diagnostic features and treatment options of retroperitoneal fibrosis, in order to provide a useful guide for clinical practice.

RECENT FINDINGS

The recent literature highlights the role of imaging studies such as computed tomography, magnetic resonance imaging and positron emission tomography as useful tools for the diagnosis of retroperitoneal fibrosis, with retroperitoneal biopsy being reserved to atypical cases. The treatment approach is mainly conservative and is based on the use of medical therapies plus urological interventions. Medical therapies essentially comprise glucocorticoids and immunosuppressants-either traditional or biological agents such as rituximab. Surgical ureterolysis is only left for refractory cases. Recent findings in retroperitoneal fibrosis highlight the possibility of a non-invasive diagnostic approach and a conservative treatment strategy.

Treatment Response to Idiopathic Retroperitoneal Fibrosis-associated Hydronephrosis With a Focus on IgG4/IgG3 Serum Concentration Ratio

OBJECTIVE

Hydronephrosis, a common complication of idiopathic retroperitoneal fibrosis (iRPF), may lead to poor renal outcomes unless resolved in a timely manner IgG4-related diseases characterized by elevated serum IgG4 levels are responsible for a few iRPF cases However, the underlying immunologic features of most iRPF cases have not been clearly defined, and these cases exhibit varied responses to medical treatment Thus, we investigated the predictive factors for hydronephrosis-associated outcomes among iRPF patients.

METHODS

We retrospectively included 18 iRPF patients with hydronephrosis in a tertiary referral hospital from 2012 to 2019 Hydronephrosis improvement was assessed on images taken 6 months after diagnosis Categorical variables were compared using chi-square or Fisher's exact test Continuous variables were compared using Mann-Whitney U-test.

RESULTS

On follow-up images, 8 patients (444%) showed an improvement in hydronephrosis Patients with improvement more frequently had reverse serum IgG4/IgG3 ratio (875% vs 30%, p=0025), abdominal aorta involvement (875% vs 30%, p=0025) and glucocorticoid treatment administration (875% vs 30%, p=0025) than those without improvement The proportion of elevated serum IgG4 level did not differ between the two groups Even in the 14 cases with normal serum IgG4 levels, reverse serum IgG4/IgG3 ratio was more frequently observed in patients with improvement than in those without improvement (833% vs 125%, p=0026).

CONCLUSION

The reverse serum IgG4/IgG3 ratio was associated with hydronephrosis improvement in iRPF patients, suggesting it to be a suitable serologic marker for predicting favourable responses to glucocorticoid treatment.

Metallic ureteral stent in restoring kidney function: Nine case reports

BACKGROUND

Retroperitoneal fibrosis is an exceptionally rare disease characterized by proliferation of fibrous tissue and inflammation in the retroperitoneum. It features many symptoms in the kidneys and in other organs and usually leads to ureteral obstruction.

CASE SUMMARY

Here we present 9 consecutive cases of idiopathic retroperitoneal fibrosis (IRPF) in patients who presented to the Department of Nephrology or Department of Rheumatology, Xuanwu Hospital, Capital Medical University, Beijing, China, between January 2012 and June 2017 with ureteral obstruction due to external compression of the ureter that led to hydronephrosis and kidney dysfunction. Computed tomography imaging was used to identify hydronephrosis and ureteral obstruction and to evaluate kidney function. Each patient was diagnosed with IRPF based on clinical observation and computed tomography examination results. To restore kidney function, a retrograde metallic stent was placed in the ureter under X-ray guidance 2 d after each patient’s admission. No perioperative complications occurred in any patient, but postoperative complications occurred in two patients as follows: Patient 2 had stent migration and repeated metallic stent infections that resolved with treatment; and patient 4 had postoperative hematuria because he resumed normal activities too soon after stent placement (contrary to instruction). Placement of the metallic ureteral stents provided relief from ureteral obstruction and restored kidney function in all patients.

CONCLUSION

Our 9-case series underscores the utility and efficacy of applying the Resonance^® metallic ureteral stent to treat ureteral obstruction in patients with IRPF. For all retroperitoneal fibrosis cases in our series, ureteral stents provided effective relief and were shown to reduce the incidence rate of perioperative and postoperative complications.

Clinical and Prognostic Significance of Serum IgG4 in Chronic Periaortitis. An Analysis of 113 Patients

Objective: Chronic periaortitis (CP) is a rare fibro-inflammatory disorder that incorporates idiopathic retroperitoneal fibrosis, inflammatory abdominal aortic aneurysms, and perianeurysmal retroperitoneal fibrosis. CP is included in the spectrum of IgG4-related disease. Since CP patients rarely undergo diagnostic biopsies, serum IgG4 levels are often used to classify CP as IgG4-related. However, the clinical and prognostic significance of serum IgG4 in CP is unknown.

Methods: We measured serum IgG4 in active CP patients and compared the clinical characteristics, response to therapy and outcome of patients with high and normal levels. We also tested the diagnostic significance of IgG4 by comparing its levels in CP patients, healthy and disease controls (malignancies, Erdheim-Chester disease, large-, and small-vessel vasculitis).

Results: We studied 113 consecutive patients with active CP. Twenty-four (21.2%) had high serum IgG4 (>135 mg/dL). The demographic, laboratory, and clinical characteristics of patients with high and normal IgG4 were similar, and so were the rates of ureteral obstruction and the disease characteristics on CT, MRI, and ¹⁸F-FDG-PET. Patients with high IgG4 only had a higher frequency of extra-retroperitoneal fibro-inflammatory lesions (p = 0.005). There were no significant differences in response to therapy and relapses between the two groups. Serum IgG4 levels did not discriminate CP from controls.

Conclusions: Serum IgG4 levels are high in a minority of CP patients and do not identify specific clinical or prognostic subgroups; only a higher frequency of extra-retroperitoneal lesions is found in high-IgG4 patients. Serum IgG4 levels do not help in the differential diagnosis between CP and its mimics.

Relapse patterns and predictors of IgG4-related diseases involved with autoimmune pancreatitis: A single-center retrospective study of 115 patients

OBJECTIVE

Autoimmune pancreatitis is an autoimmune disorder accompanied by clinicopathological manifestations that have been established as immunoglobulin (IgG)4-related diseases (IgG4-RD). Other IgG4-RD are often involved with autoimmune pancreatitis. They sometimes relapse despite a favorable response to steroid therapy. This study aimed to clarify the patterns and risk factors for extrapancreatic relapse.

METHODS

We reviewed the data of 115 patients diagnosed with definite autoimmune pancreatitis type 1 and followed up for > 1 year. We analyzed two items: the timing and pattern of extrapancreatic relapse, and risk factors for relapse with three common manifestations: IgG4-related sclerosing cholangitis (SC), IgG4-related dacryoadenitis and sialadenitis (DS), and IgG4-related retroperitoneal fibrosis (RF).

RESULTS

Remission was achieved in all patients, except one. The extrapancreatic relapse rates were 11.0%, 19.7%, and 40% within 3, 5, and 10 years, respectively. Of 26 patients with extrapancreatic relapse, nine (34.6%) relapsed with a new IgG4-RD. Based on multivariate analysis, the interval between symptom onset and steroid initiation, and the presence of RF at onset were significant risk factors for relapse with SC and RF, respectively.

CONCLUSIONS

Our results indicate that they may be various extrapancreatic relapse patterns especially in autoimmune pancreatitis with other organ involvement. Patients with a delayed initiation of steroids or RF at onset should be carefully followed up as high-risk groups for SC and RF relapse.

IgG4-related disease: a complex under-diagnosed clinical entity

IgG4-related disease (IgG4-RD) encompasses a spectrum of complex fibro-inflammatory disorders which are often under diagnosed due to unfamiliarity by clinicians. A challenging multitude of clinical manifestations makes the diagnosis cumbersome. The primary clinical feature in IgG4-RD entails a tumor-like presentation coupled with tissue-destructive lesions. Histopathological findings include lymphoplasmacytic infiltrate, storiform fibrosis, and obliterative phlebitis. These findings, in combination with elevated serum immunoglobulin G4 levels, are diagnostic in the setting of single- or multi-organ involvement. A closer understanding of the role of T cells and B cells in the increased production of IgG4 has led to a notion that IgG4 can act as a pathogen, anti-inflammatory agent, or rheumatoid factor. Glucocorticoids are the primary treatment modality; however, relapse is common with prolonged therapy. Alternatively, immunomodulatory agents are being increasingly used as therapy. The aim of this article is to raise awareness of IgG4-RD and review the diagnostic algorithm, as IgG4-RD often mimics a wide array of clinical conditions. In addition, we summarize the pathogenesis and current treatment guidelines of IgG4-RD for clinicians. Awareness and accurate diagnosis are crucial in preventing progression to chronic diseases, thereby diminishing disease-related morbidity and mortality.