Potential Added Value of 18F-FDG PET Metabolic Parameters in Predicting Disease Relapse in Type 1 Autoimmune Pancreatitis.

BACKGROUND: The predictive value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) metabolic parameters for predicting AIP relapse is currently unknown. This study firstly explored the value of 18F-FDG PET/CT parameters as predictors of type 1 AIP relapse. METHODS: This multicenter retrospective cohort study analyzed 51 patients who received 18F-FDG PET/CT prior to treatment and did not receive maintenance therapy after remission. The study collected baseline characteristics and clinical data and conducted qualitative and semi-quantitative analysis of pancreatic lesions and extrapancreatic organs. The study used three thresholds to select the boundaries of pancreatic lesions to evaluate metabolic parameters, including the maximum standard uptake value (SUVmax), mean standard uptake value (SUVmean), total lesion glycolysis (TLG), metabolic tumor volume (MTV), and tumor-to-normal liver standard uptake value ratio (SUVR). Univariate and multivariate analyses were performed to identify independent predictors and build a recurrence prediction model. The model was internally validated using the bootstrap method and a nomogram was created for clinical application. RESULTS: In the univariable analysis, the relapsed group showed higher levels of SUVmax (6.0 ± 1.6 vs. 5.2 ± 1.1; P = 0.047), SUVR (2.3 [2.0-3.0] vs. 2.0 [1.6-2.4]; P = 0.026), and TLG2.5 (234.5 ± 149.1 vs. 139.6 ± 102.5; P = 0.020) among the 18F-FDG PET metabolic parameters compared to the non-relapsed group. In the multivariable analysis, serum IgG4 (OR, 1.001; 95% CI, 1.000-1.002; P = 0.014) and TLG2.5 (OR, 1.007; 95% CI, 1.002-1.013; P = 0.012) were independent predictors associated with relapse of type 1 AIP. A receiver-operating characteristic curve of the predictive model with these two predictors demonstrated an area under the curve of 0.806. CONCLUSION: 18F-FDG PET/CT metabolic parameters, particularly TLG2.5, are potential predictors for relapse in patients with type 1 AIP. A multiparameter model that includes IgG4 and TLG2.5 can enhance the ability to predict AIP relapse.

Diabetes mellitus in patients with type 1 autoimmune pancreatitis at diagnosis and after corticosteroid therapy.

BACKGROUND: A high prevalence of diabetes mellitus (DM) coexisting with autoimmune pancreatitis (AIP) is observed. However, evidence on the circumstances under which corticosteroid therapy (CST) for AIP improves or worsens DM is scarce. This study aimed to demonstrate and identify predictors of DM control under the influence of CST. METHODS: Patients diagnosed with type 1 AIP were enrolled from a prospectively maintained cohort and were classified into three groups according to the chronology in which AIP and DM were diagnosed: pre-existing DM (pDM), concurrent DM (cDM), and non-DM (nDM). The responses of DM to CST were assessed when corticosteroid was ceased or tapered to a maintenance dose and classified as 'improvement' and 'non-improvement' (including 'no change' and 'exacerbation'). RESULTS: Among 101 patients with type 1 AIP, 52 (51.5%) patients were complicated with DM at the time of AIP diagnosis, with 36 patients in the cDM group and 16 patients in the pDM group. The incidences of diffuse pancreatic swelling (72.2%) and pancreatic body/tail involvement (91.7%) were significantly higher in the cDM group than in both the pDM and nDM groups. Of the 52 patients with DM, CST was administered in 48 cases. Multivariate logistic analysis identified that elevated serum gamma-glutamyl transferase (GGT) level at AIP diagnosis [odds ratio (OR) = 0.032, 95% confidence interval (CI): 0.003-0.412, P = 0.008] and pancreatic atrophy after CST (OR = 0.027, 95% CI: 0.003-0.295, P = 0.003) were negatively associated with DM control improvement. CONCLUSIONS: Patients with diffuse pancreatic swelling and pancreatic body/tail involvement in pancreatitis tended to be complicated with cDM at AIP diagnosis. CST exerted a beneficial effect on the clinical course of DM in nearly half of the AIP patients complicated with DM at diagnosis, particularly in those without elevated serum GGT levels at diagnosis and who did not experience pancreatic atrophy after CST.

Affinity Purification Coupled to Stable Isotope Dilution LC-MS/MS Analysis to Discover IgG4 Glycosylation Profiles for Autoimmune Pancreatitis.

Type 1 autoimmune pancreatitis (AIP) is categorized as an IgG4-related disease (IgG4-RD), where a high concentration of plasma IgG4 is one of the common biomarkers among patients. IgG Fc-glycosylation has been reported to be potential biosignatures for diseases. However, human IgG3 and IgG4 Fc-glycopeptides from populations in Asia were found to be isobaric ions when using LC-MS/MS as an analytical tool. In this study, an analytical workflow that coupled affinity purification and stable isotope dilution LC-MS/MS was developed to dissect IgG4 glycosylation profiles for autoimmune pancreatitis. Comparing the IgG4 and glycosylation profiles among healthy controls, patients with pancreatic ductal adenocarcinoma (PDAC), and AIP, the IgG4 glycosylations from the AIP group were found to have more digalactosylation (compared to PDAC) and less monogalactosylation (compared to HC). In addition, higher fucosylation and sialylation profiles were also discovered for the AIP group. The workflow is efficient and selective for IgG4 glycopeptides, and can be used for clinical biosignature discovery.

Pancreatic tumor in type 1 autoimmune pancreatitis: a diagnostic challenge.

BACKGROUND: The co-occurrence of type 1 autoimmune pancreatitis (AIP) and pancreatic tumor (PaT) has been previously reported. Pure AIP cases have favorable prognosis and are primarily treated with steroids, while AIP cases with PaT are associated with poor prognosis where the primary management is pancreatic resection. However, it's a challenge to timely identify the concurrent PaT in AIP because of their similar clinical and radiological manifestations. METHODS: We retrospectively reviewed the data in two medical centers from January 2010 to April 2019. The inclusion criteria were as follows: 1) completion of abdominal CT imaging before invasive procedures to the pancreas, 2) a final diagnosis of type 1 AIP using the 2011 international consensus diagnostic criteria, 3) follow-up duration of at least one month unless AIP and PaT were identified simultaneously. The presence of PaT in AIP was made based on histopathological confirmation, and the absence of PaT in AIP was defined as no pathological or radiological evidence of concurrent PaT. Clinical and radiological characteristics including gender, age, surveillance period, serum IgG4 and Ca-199 levels, biopsy, extrapancreatic involvement, CT and MR (if performed) imaging characteristics were compared between AIP with and without PaT. The Fisher's exact test was used for qualitative variables, and nonparametric Mann-Whitney test for quantitative variables. A p value ≤0.05 was considered statistically significant. RESULTS: A total of 74 patients with type 1 AIP were included, of which 5 (6.7%) had the concurrent PaT. The subtypes were pancreatic ductal adenocarcinoma (3/5), solitary extramedullary plasmacytoma in the pancreas (1/5) and cholangiocarcinoma in the pancreatic segment (1/5), respectively. Gender (p = 0.044), the pattern of pancreatic enlargement (p = 0.003), heterogeneity (p = 0.015), low-density (p = 0.004) on CT and rim enhancement on MRI (p = 0.050) differed significantly between AIP with and without PaT. None of the low-density characteristics on CT or other assessed MRI characteristics could significantly differentiate the two groups (p>0.05). CONCLUSIONS: Female, focal pancreatic enlargement, pancreatic heterogeneity, low-density on CT and rim enhancement on MRI are suggestive of the concurrent PaT in type 1 AIP. The characteristics of low-density on CT or other MRI characteristics did not provide further diagnostic values.

Correlation between long-term outcome and steroid therapy in type 1 autoimmune pancreatitis: relapse, malignancy and side effect of steroid.

OBJECTIVES: Autoimmune pancreatitis (AIP) responds well to corticosteroid therapy (CST), and CST is essential to induce remission. However, the correlation between long-term outcome and CST has not been evaluated. We aimed to clarify the correlation between long-term outcome of AIP and CST. MATERIAL AND METHODS: We retrospectively evaluated relapse, risk of malignancy and side effects of CST by focusing on the correlation with CST in 84 patients with type 1 AIP. RESULTS: The incidence of relapse was 23.8%. The frequency of relapse after CST administration was significantly lower in patients taking CST for >6 months than in those who did not (22% versus 67%; p = 0.036). The incidence of malignancy was 10.7%. The standardized incidence ratio of malignancy was 2.14 [95% confidence interval 0.74-3.54]. There were no significant correlations between development of malignancy and CST. The incidences of total and serious side effects due to CST were 75% and 19.1%, respectively. Relapse was the only significant independent predictive risk factor for serious side effects in a multivariate analysis (odds ratio 4.065; 95% confidence interval 1.125-14.706; p = 0.032). The cumulative dose of corticosteroid was significantly higher in patients with serious side effects than in those without (12,645 mg versus 7322 mg; p = 0.041). CONCLUSIONS: CST reduces relapse of AIP. However, CST causes serious side effects, particularly in relapsing patients. Alternative maintenance therapy to prevent relapse is needed.

Incidence and outcome of lung involvement in IgG4-related autoimmune pancreatitis.

We evaluated the incidence and outcome of lung involvement in 35 patients with autoimmune pancreatitis (AIP). Our results indicate that lung involvement is commonly observed in AIP (40%). In addition, corticosteroid treatment improved the lung lesions and appeared to reduce the probability of relapse compared with pancreatic lesions (0% vs 36%). This is the first report to assess the long-term outcome of lung involvement in AIP (52 ± 33 months).

The role of CD19+ CD24high CD38high and CD19+ CD24high CD27+ regulatory B cells in patients with type 1 autoimmune pancreatitis.

BACKGROUND: Patients with type 1 autoimmune pancreatitis (AIP) have several immunologic and histologic abnormalities. It is known that depletion of B cells by rituximab is effective for treatment of IgG4-related disease (IgG4-RD) such as type 1 AIP, suggesting that B cells may be a key player in IgG4-RD. However, the role of regulatory B cells (Bregs) in type 1 AIP is unclear, and the objective of this paper is to clarify the role of Bregs in the pathophysiology of type 1 AIP by analyzing circulating Bregs. METHOD: We recruited 21 patients with type 1 AIP as determined by the International Consensus Diagnostic Criteria for AIP (ICDC). No patients received corticosteroid treatments. For comparison, we recruited 14 patients with chronic pancreatitis (CP), 20 patients with pancreatic cancer, and 25 healthy subjects as controls. We analyzed Bregs as CD19+ CD24high CD38high and CD19+ CD24high CD27+ from peripheral blood by flow cytometry. RESULTS: In peripheral blood, CD19+ CD24high CD38high Bregs were significantly increased in type 1 AIP patients compared with CP, pancreatic cancer, and healthy controls. Although not significant different, CD19+ CD24high CD27+ Bregs of type 1 AIP were decreased compared to those of other groups. IL-10(+) B cells were not significantly different from type 1 AIP patients and healthy controls. In untreated type 1 AIP patients, the number of CD19+ CD24high CD38high Bregs and IgG4 were not correlated. CONCLUSIONS: Our data suggested that CD19+ CD24high CD38high Bregs seemed to increase reactively to suppress the disease activity, and are consistent with the hypothesis that CD19+ CD24high CD27+ Bregs might be involved in the development of type 1 AIP, although it still remains unclear whether the decrease of CD19+ CD24high CD27+ cells is cause or effect of AIP.

Inflammation of colon adenoma in the setting of type 1 autoimmune pancreatitis.

Although immunoglobulin G4-related diseases (IgG4-RD) have been found to affect many organs, little is known about their effects on the colonic mucosae. Pathological examination of colon adenomas has shown inflammatory cell infiltration into the stroma. We therefore assessed the clinicopathological characteristics of colon adenomas in patients with type 1 autoimmune pancreatitis (AIP-1), a representative IgG4-RD. Both colon adenomas from patients with (IgG4 adenomas) and without (Non-IgG4 adenomas) IgG4-RD were characterized by moderate to severe lymphoplasmacytic and eosinophilic inflammation without fibrosis or phlebitis. The ratio of IgG4-positive to IgG-positive plasma cells (IgG4/IgG ratio) and the numbers of IgG4-positive plasma cells were significantly higher in IgG4 adenomas than in Non-IgG4 adenomas. IgG4-positive plasma cells tended to be distributed diffusely in lower areas of the mucosae in IgG4 adenomas. We were unable to confirm whether IgG4 adenomas constituted an IgG4-RD. However, IgG4 adenomas in the setting of IgG4-RD may provide useful pathological information, supplementing a diagnosis of IgG4-RD outside the colon, or may facilitate examination for IgG4-RD, especially AIP-1. IgG4 adenomas warrant further investigation.

Comparison of histopathological features of pancreatic carcinoma and type 1 autoimmune pancreatitis.

Type 1 autoimmune pancreatitis (AIP-1) is an immunoglobulin G (IgG)-4-related disease (IgG4-RD), characterized by elevated serum immunoglobulin G4 (IgG4) and infiltration by IgG4(+) plasma cells. Pancreatic carcinoma (PC) sometimes shows infiltration by IgG4(+) plasma cells, but details have been unclear. We compared pathological findings and expression of IgG4 and IgG in fibroses in 18 PC patients to those from 9 AIP-1 patients. Fibroses were divided into areas of ductal adenocarcinoma (DA) and obstructive pancreatitis (OP). Serum IgG4 levels were lower than the cut-off value in all PC patients with no IgG4-RD. Diffuse lymphoplasmacytic infiltration and eosinophil infiltration were characteristic of fibroses in PC. Though AIP-1 samples often had storiform fibrosis even in biopsies, PC did not show storiform fibrosis. Ratios of IgG4(+) plasma cells/IgG(+) plasma cells (IgG4/IgG ratios) in DA and OP were significantly lower than in AIP-1. However, high-density IgG4(+) plasma cell foci were detected in PC fibroses, particularly around peripheral nerves, vessels, and lymphoid follicles; between lobules and invasion fronts; and within neutrophilic abscesses. In conclusion, the IgG4/IgG ratio is useful in distinguishing PC from AIP-1, and should be evaluated in three or more areas, as PC can show localized high-density IgG4(+) plasma cell areas.

A prospective study on the histological evaluation of type 1 autoimmune pancreatitis using endoscopic ultrasound-guided fine needle biopsy with a 19-gauge Franseen needle.

BACKGROUND/PURPOSE: To assess the diagnostic efficacy and safety of endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) using a 19-gauge Franseen needle for autoimmune pancreatitis (AIP). METHODS: Twenty patients suspected of having type 1 AIP were prospectively enrolled and underwent EUS-FNB with a 19-gauge Franseen needle. Their data were compared with those of historical controls: a total of 29 type 1 AIP patients had EUS-FNB with a 22-gauge Franseen needle. RESULTS: Specimens suitable for histological evaluation were obtained from 19 of the 20 patients (95%), and the median total tissue area was 11.9 mm2. The histological diagnosis rate of AIP was 65% (95% CI: 43.2%-82%). Adverse events were observed in three patients (15%), and a switch to 22-gauge needles occurred during transduodenal puncture in two patients. Compared to those punctured with 22-gauge needles, patients punctured with 19-gauge needles had greater prevalence of each characteristic feature of lymphoplasmacytic sclerosing pancreatitis, but the difference was not statistically significant. CONCLUSIONS: EUS-FNB using a 19-gauge Franseen needle demonstrated favorable performance for the histological diagnosis of AIP and allowed for large tissue samples, potentially facilitating pathological diagnosis. However, during transduodenal puncture, maneuverability is reduced; therefore, the needle may need to be selected according to the puncture site.

Possible involvement of CCL1-CCR8 interaction in lymphocytic recruitment in IgG4-related sclerosing cholangitis.

BACKGROUND & AIMS: IgG4-related sclerosing cholangitis and type 1 autoimmune pancreatitis (IgG4-SC/AIP) are characterized by massive lymphoplasmacytic infiltration including Th2 and regulatory T cells (Tregs). This study was conducted to address which chemotactic factors are involved in this condition. METHODS: Chemokine expression profiles in tissue were examined in IgG4-SC/AIP (n=17), classical primary sclerosing cholangitis (IgG4(low) PSC, n=17), PSC with elevated serum/tissue IgG4 levels (IgG4(high) PSC, n=5), and primary biliary cirrhosis (n=7). We focused on five chemotactic factors/receptors (CCL1-CCR8, CCL17/CCL22-CCR4), given that CCR4 and CCR8 are predominantly expressed in both Th2 and Tregs. RESULTS: In conjunction with higher expression levels of IL-4 and IL-10, expression values of CCL1 and CCR8 transcripts were significantly higher in IgG4-SC/AIP than in IgG4(low) PSC (p=0.002) and IgG4(high) PSC (p=0.023). CCL1 and CCR8 were also overexpressed in IgG4(high) PSC than in IgG4(low) PSC (p=0.023). No difference was seen for CCL17, CCL22, and CCR4. In situ hybridization revealed CCL1 to be predominantly expressed in the pancreatic duct epithelium, peribiliary glands, and vascular endothelial cells including the ones involved in obliterative phlebitis in IgG4-SC/AIP, in contrast to IgG4(high) PSC where this chemotactic factor was positive in several infiltrating lymphocytes. These CCL1-expressing sites were infiltrated by CCR8(+) lymphocytes. On immunohistochemistry, GATA3(+) Th2 lymphocytes and FOXP3(+) Tregs were significantly larger in number in IgG4-SC/AIP, with the GATA3(+)/T-bet(+) cell ratio to be shifted in favour of Th2 in periductal and perivascular areas. CONCLUSIONS: CCL1-CCR8 interaction may play a critical role in lymphocytic recruitment in IgG4-SC/AIP, leading to duct-centred inflammation and obliterative phlebitis.

Type 1 Autoimmune Pancreatitis Unmasked by COVID-19 Vaccine.

Autoimmune pancreatitis is a rare fibro-inflammatory disease with 2 distinct subtypes of which each has their own clinical presentation, risk factors, and histopathological patterns. We present a case of newly diagnosed type 1 autoimmune pancreatitis in a symptomatic 54-year-old man with stable ulcerative colitis 1 month after COVID-19 vaccination. Previous reports have indicated that vaccinations can trigger autoimmune disease in predisposed individuals. This case discusses the occurrence of autoimmune pancreatitis triggered after COVID-19 vaccination.

Autoimmune pancreatitis: What we know so far.

Autoimmune pancreatitis (AIP) is a rare, often-missed disease that involves inflammation of the pancreas and strictures of the pancreatic duct. Its prevalence and incidence in the United States remain scarce. The disease has a varied presentation and often mimics pancreatic malignancy, which can make the diagnosis challenging. Most patients have an excellent response to corticosteroid therapy. Immunomodulators may be used in some cases. Rituximab is an effective, emerging treatment in steroid-refractory cases. This study aims to review the two distinct types of AIP and provide a detailed analysis of the diagnostic approach and treatment modalities.

Combination of autoimmune pancreatitis and peripheral neuropathy on an IgG4-related disease patient with 4 years following-up.

Type1 autoimmune pancreatitis (AIP) is the first recognized and the most common manifestation of IgG4-related disease. However, AIP patient presented with neuropathy in the extremities have not been reported previously. We reported a rare combination of autoimmune pancreatitis and peripheral neuropathy on an IgG4-related disease patient based on histological features to expand the clinical spectrum of IgG4-related disease.

Interleukin-35 promotes the differentiation of regulatory T cells and suppresses Th2 response in IgG4-related type 1 autoimmune pancreatitis.

BACKGROUND: IgG4-related disease (IgG4-RD) is a systemic inflammatory disease, which includes type 1 autoimmune pancreatitis (AIP). Interleukin-35 (IL-35) exhibits immunosuppressive effects in several autoimmune diseases. However, the expression of IL-35 had not been reported so far in type 1 AIP. We evaluated the association between IL-35 and several cytokines, which mediate the function of Tregs in type 1 AIP. METHODS: Plasma was collected from patients with type 1 AIP, alcoholic chronic pancreatitis (ACP), and healthy controls (HC) and assayed for cytokine expression. Total mRNA separated from peripheral blood was isolated from naïve Tregs (nTregs) and effector Tregs (eTregs). EBI3 and IL-12p35 gene expressions were tested in these cells by quantitative PCR. In addition, expression of IL-35 subunits in the pancreatic tissues of patients with type 1 AIP and ACP was analyzed by immunohistochemistry. RESULTS: IL-35 was significantly elevated in type 1 AIP (n = 32) plasma compared with ACP (n = 16) and HC (n = 22), but IL-27 was not. We also detected many cells expressing both EBI3 and IL-12p35 in type 1 AIP tissues. Moreover, in peripheral blood lymphocyte, the percentage of nTregs and eTregs of CD4+ T cells in patients with type 1 AIP (n = 14) compared with HC (n = 15) was significantly decreased and increased, respectively. There were no significant differences of gene expression in patients with type 1 AIP and HC. CONCLUSIONS: This study identified elevated expression of plasma IL-35 and tissue IL-35 subunits in patients with type 1 AIP. This might lead to inflammation suppression via activated eTregs. IL-35 might be associated with this anti-inflammatory role, especially against the Th2 response through several cytokines and the differentiation of Tregs in type 1 AIP.

Immunostaining With Immunoglobulin G Subclass Antibody Cocktail for Diagnosis of Type 1 Autoimmune Pancreatitis.

BACKGROUND.: Immunoglobulin (Ig) G4-related diseases (RDs) are systemic diseases in which serum IgG4 levels are frequently elevated. They can cause diffuse or focal tumor formation, organ swelling, and tissue thickening in organs infiltrated by IgG4+ plasma cells. The diagnostic criteria for IgG4-RDs include an IgG4/IgG ratio >40%, but counting IgG+ cells can be difficult because of the weakness of IgG staining density. We hypothesized that an antibody cocktail of mixed IgG1, IgG2, IgG3, and IgG4 (AC-IgG) might give immunohistochemistry results comparable with those of IgG in IgG4-RD. METHODS.: We compared AC-IgG reactivity with IgG expression in type 1 autoimmune pancreatitis (AIP), a representative IgG4-RD. We compared immunohistochemistry results using AC-IgG and IgG-only in 10 cases of AIP. The coefficient of variation (Cv) was used to analyze differences between AC-IgG and IgG findings in AIP by 13 board-certified pathologists. RESULTS.: Although mean values for IgG+ cells did not significantly differ between AC-IgG (34.3; range = 27.4-37.1) and IgG (30.0; range = 23.0-45.6; P = .6254), Cv was lower for AC-IgG (33.4%) than for IgG (51.4%; regression equation; y[IgG] = 0.988x + 0.982; correlation coefficient = 0.907). The data showed that the results of both methods were largely consistent. CONCLUSION.: AC-IgG could replace IgG to count IgG+ cells because of its lower Cv.

Rare case of Helicobacter pylori-positive multiorgan IgG4-related disease and gastric cancer.

A 61-year-old male from Northeast China presented with a 2-mo history of abdominal distension, pruritus and jaundice. Laboratory testing revealed an elevated serum IgG4 level. A computed tomography scan showed a typical feature of autoimmune pancreatitis (AIP) and cholecystocholangitis. Early gastric cancer was incidentally discovered when endoscopic untrasound-guided fine needle aspiration (EUS-FNA) of the pancreas was carried out. The patient underwent radical subtotal gastrectomy for gastric cancer combined with cholecystectomy. Helicobacter pylori (H. pylori) and IgG4-positive plasmacytes were detected in gastric cancer tissue, pancreatic EUS-FNA sample and resected gallbladder specimen by immunohistochemistry. The patient was diagnosed with H. pylori-positive IgG4-related AIP and sclerosing cholecystocholangitis as well as H. pylori-positive gastric cancer. He responded well to steroid therapy and remains healthy with no signs of recurrence at one year follow-up. We speculate that H. pylori might act as a trigger via direct or indirect action in the initiation of onset of gastric cancer and multiorgan IgG4-related disease.

Potential role of Th17 cells in the pathogenesis of type 2 autoimmune pancreatitis.

Th17 cells have been shown to play an important role in the pathogenesis of a variety of autoimmune diseases. The aim of this study was to investigate the potential role of Th17 cells in autoimmune pancreatitis (AIP). Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to determine gene expression of the signature cytokines of Th17 cells IL-17A and IL-21 and of the Th17 lineage-specific transcription factor retinoic acid receptor-related orphan receptor C (RORC) in human tissue specimens of AIP, classical chronic pancreatitis (CP), and normal pancreas (NP). Infiltrating immune cells were characterized by immunohistochemistry (IHC). Gene expression of IL-17A, IL-21, and RORC were found to be significantly increased in AIP. Accordingly, the number of Th17 cells was significantly increased in AIP compared to NP or CP. Both gene expression analysis and IHC revealed a clear difference between type 1 and 2 AIP. In the periductal compartment of type 2 AIP, which is characterized by granulocytic epithelial lesions (GELs), the number of infiltrating Th17 cells and neutrophilic granulocytes was significantly increased compared to type 1 AIP. Our data suggest that Th17 cells play a role in the pathogenesis of AIP, in particular of type 2 AIP. Cross-talk between Th17 cells and neutrophilic granulocytes mediated via IL-17A may be a potential mechanism by which neutrophils are recruited to the duct and acinar cells with subsequent destruction, a process that is pathognomonic for type 2 AIP.

A non-invasive screening technique for type 1 autoimmune pancreatitis.

INTRODUCTION: Type 1 autoimmune pancreatitis (AIP) is the pancreatic manifestation of a systemic fibroinflammatory IgG4-related disease. Accurate diagnosis of AIP can avoid major hepatobiliary and pancreatic surgery as it respond dramatically to corticosteroid therapy. AIM: This research investigated the feasibility of using peripheral blood cell immunohistochemistry, serum IgG4, T-cell receptor (TCR) and serum isoelectric focusing electrophoresis in the screening of type 1 autoimmune pancreatitis (AIP). MATERIAL AND METHODS: The peripheral blood from 3 type 1 AIP patients, 10 pancreatic cancer patients and 40 normal controls was collected. Sediment smears were jointly incubated with anti-IgG4 and anti-IgG. The percentage of IgG4/IgG positive cells was counted and serum TCR and IgG4 were detected through the whole process. After serum isoelectric focusing electrophoresis, anti-IgG4 and anti-IgG were used to confirm the components of serum. RESULTS: In the serum isoelectric focusing electrophoresis, IgG4 and IgG strips showed mirrored distribution in type 1 AIP patients, while there were no strips in the normal controls and pancreatic cancer. Compared with pancreatic tumor patients and healthy controls, serum TCR was significant increased in AIP. The percentage of IgG4/IgG positive cells of peripheral blood cell immunohistochemistry was related to serum IgG4 and hormone therapy reactions. CONCLUSIONS: Peripheral blood cell immunohistochemistry, serum IgG4, TCR and serum isoelectric focusing electrophoresis is suitable for the screening of type 1 AIP and monitoring its response assessment.

Autoimmune pancreatitis: updated concepts of a challenging diagnosis.

Autoimmune pancreatitis is a benign process characterized by inflammation and fibrosis. It is now known that cases of "autoimmune pancreatitis" actually consist of two distinct pathologic entities. Type 1 autoimmune pancreatitis is a manifestation of a systemic process, immunoglobulin G subclass 4 (IgG4)-related disease. IgG4-related disease can affect virtually every organ system in the body. Type 1 affects older patients and is characterized by an elevated serum IgG4 level and sites of extrapancreatic disease. Type 2 autoimmune pancreatitis is a disease process confined to the pancreas. It affects younger patients and is associated with inflammatory bowel disease. Type 2 is not associated with elevated IgG4 levels or extrapancreatic disease. Both subtypes can mimic malignancy, particularly pancreatic cancer. Awareness of the clinical and imaging features of the subtypes of autoimmune pancreatitis is important to avoid an incorrect diagnosis of malignancy.