What are the useful biological and functional markers of early-stage chronic pancreatitis?

Silymarin attenuates escitalopram (cipralex) induced pancreatic injury in adult male albino rats: a biochemical, histological, and immunohistochemical approach

Depression is a prevalent global problem since ages, predominately treated with SSRI. Cipralex, is an antidepressant of the SSRIs class used as a remedy for mood, depression and anxiety. Silymarin (SIL), a natural free radical scavenging, has an antioxidant and anti-inflammatory properties. This hypothesis evaluates, for the first time, the role of cipralex on the structure of the endocrine and exocrine components of the pancreas and assess the beneficial effects of SIL on these changes. Forty-five rats were divided into control, cipralex, and cipralex plus SIL groups. During sacrifice, all rats and pancreases were weighed and the ratio of pancreatic weight (PW) to rat weight (RW) was calculated, blood samples were collected to estimate fasting glucose, insulin and amylase levels, the specimens were prepared for histological, immunohistochemical (inducible nitric oxide synthase [iNOS], tumour necrosis factor-alpha [TNF-α], caspase 3, proliferating cell nuclear antigen [PCNA], and anti-insulin antibody), and morphometrical studies. Cipralex group exhibited marked destruction of the pancreatic architecture of the exocrine and endocrine parts, with a dense collagen fiber deposition. Also, there is highly significant decrease (P<0.001) of PW/RT ratio, insulin, and amylase levels, the number and diameter of islets of Langerhans, the number of PCNA positive immunoreactive cells, and the number of insulin positive β-cells. Furthermore, a highly significant increase of glucose level, iNOS, TNF-α, and caspase-3 positive immunoreactive cells in the islets of Langerhans and acinar cells were observed. SIL improves the pancreatic histological architecture, weight loss, biochemical, and immunohistochemical analyses. Administering SIL is advantageous in managing cipralex induced pancreatic injury via its anti-inflammatory, antioxidant, and anti-apoptotic qualities.

Endoscopic and Conservative Management of Chronic Pancreatitis and Its Complications

Chronic pancreatitis is a progressive inflammatory disease of the pancreas potentially giving rise to several complications. For this reason, patients need long-term care and treatment by medical, interventional, and sometimes surgical measures. This article reviews current state-of-the-art strategies and guidelines for treating chronic pancreatitis with conventional and endoscopic measures.

Pathogenic mechanisms of pancreatitis

Pancreatitis is inflammation of pancreas and caused by a number of factors including pancreatic duct obstruction, alcoholism, and mutation in the cationic trypsinogen gene. Pancreatitis is represented as acute pancreatitis with acute inflammatory responses and; chronic pancreatitis characterized by marked stroma formation with a high number of infiltrating granulocytes (such as neutrophils, eosinophils), monocytes, macrophages and pancreatic stellate cells (PSCs). These inflammatory cells are known to play a central role in initiating and promoting inflammation including pancreatic fibrosis, i.e., a major risk factor for pancreatic cancer. A number of inflammatory cytokines are known to involve in promoting pancreatic pathogenesis that lead pancreatic fibrosis. Pancreatic fibrosis is a dynamic phenomenon that requires an intricate network of several autocrine and paracrine signaling pathways. In this review, we have provided the details of various cytokines and molecular mechanistic pathways (i.e., Transforming growth factor-β/SMAD, mitogen-activated protein kinases, Rho kinase, Janus kinase/signal transducers and activators, and phosphatidylinositol 3 kinase) that have a critical role in the activation of PSCs to promote chronic pancreatitis and trigger the phenomenon of pancreatic fibrogenesis. In this review of literature, we discuss the involvement of several pro-inflammatory and anti-inflammatory cytokines, such as in interleukin (IL)-1, IL-1β, IL-6, IL-8 IL-10, IL-18, IL-33 and tumor necrosis factor-α, in the pathogenesis of disease. Our review also highlights the significance of several experimental animal models that have an important role in dissecting the mechanistic pathways operating in the development of chronic pancreatitis, including pancreatic fibrosis. Additionally, we provided several intermediary molecules that are involved in major signaling pathways that might provide target molecules for future therapeutic treatment strategies for pancreatic pathogenesis.

Utility of different serum fibrosis markers in diagnosing patients with chronic pancreatitis and pancreatic adenocarcinoma

AIM: To estimate the levels of serum cytokines in chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC) patients in order to evaluate their usefulness as possible biomarkers.

METHODS: The study included 167 Caucasian patients: 74 with PDAC (28 men and 42 women, aged 30-88 years), 78 with CP (50 men and 21 women, aged 20-79 years) and 15 age-matched healthy controls hospitalized in the Department of Digestive Tract Diseases, Medical University of Lodz, Poland between 2006 and 2013. Serum MCP-1, transforming growth factor (TGF)-β1, HA and s-Fr were measured in patients with CP (n = 78), PDAC (n = 74) and healthy controls (n = 15) using ELISA (Corgenix United Kingdom Ltd R and D Systems). The severity of CP was assessed according to the Cambridge classification.

RESULTS: Both patients with CP and PDAC had a significantly higher mean TGF-β1 serum level (1066 ± 582 and 888 ± 356 vs 264 ± 93, P < 0.0001), mean s-Fr (2.42 ± 1.385 and 2.41 ± 1.275 vs 0.6 ± 0.370, P < 0.0001) and mean HA (199 ± 254 and 270 ± 358 vs 40 ± 26, P < 0.0001) compared to controls. There was no difference in mean MCP-1 between all the groups. There were no significant differences in any cytokine levels between the PC and PDAC groups. No significant differences between serum cytokines depending on age, gender or smoking status were found in CP patients. Mean s-Fr concentration was significantly higher in CP, lasting longer than 5 years compared to those with a shorter disease clinical course (2.639 ± 1.125 vs 1.870 ± 0.970, P < 0.03). There was no correlation between tumor size, localization or TNM classification and serum TGF-β1, MCP-1, s-Fr and HA levels in patients with PDAC. No significant differences between cytokines depending on diabetes presence in CP were found. Nevertheless, mean serum TGF-β1 concentration in PDAC patients was higher in those with diabetes compared to the remaining group (986 vs 839, P = 0.043).

CONCLUSION: Serum TGF-β1, s-Fr and HA may be considered additional diagnostic markers of CP and PDAC. TGF-β1 may be useful to predict endocrine insufficiency in PDAC.

Monocyte chemoattractant protein-1, transforming growth factor-beta1, nerve growth factor, resistin and hyaluronic acid as serum markers: comparison between recurrent acute and chronic pancreatitis

BACKGROUND

Diagnostic parameters that can predict the presence of chronic pancreatitis (CP) in patients with recurrent pain due to pancreatitis would help to direct appropriate therapy. This study aimed to compare the serum levels of monocyte chemoattractant protein-1 (MCP-1), transforming growth factor-beta1 (TGF-beta1), nerve growth factor (NGF), resistin and hyaluronic acid (HA) in patients with recurrent acute pancreatitis (RAP) and CP to assess their ability to differentiate the two conditions.

METHODS

Levels of serum markers assessed by enzyme-linked immunosorbent assay (ELISA) were prospectively compared in consecutive patients with RAP, CP and in controls, and stepwise discriminant analysis was performed to identify the markers differentiating RAP from CP.

RESULTS

One hundred and thirteen consecutive patients (RAP=32, CP=81) and 78 healthy controls were prospectively enrolled. The mean (SD) age of the patients was 32.0 (14.0) years; 89 (78.8%) were male. All markers were significantly higher in CP patients than in the controls (P<0.001); MCP-1, NGF and HA were significantly higher in RAP patients than in the controls (P<0.001). Stepwise discriminant analysis showed significant difference (P=0.002) between RAP and CP for resistin with an accuracy of 61.9%, discriminant scores of ≤-0.479 and ≥0.189 indicating RAP and CP, respectively. The other markers had no differential value between RAP and CP.

CONCLUSION

Serum resistin is a promising marker to differentiate between RAP and CP and needs validation in future studies, especially in those with early CP.

Chronic pancreatitis: A diagnostic dilemma

Typical clinical symptoms of chronic pancreatitis are vague and non-specific and therefore diagnostic tests are required, none of which provide absolute diagnostic certainly, especially in the early stages of disease. Recently-published guidelines bring much needed structure to the diagnostic work-up of patients with suspected chronic pancreatitis. In addition, novel diagnostic modalities bring promise for the future. The assessment and diagnosis of pancreatic exocrine insufficiency remains challenging and this review contests the accepted perspective that steatorrhea only occurs with > 90% destruction of the gland.

Quantitative analysis of diagnosing pancreatic fibrosis using EUS-elastography (comparison with surgical specimens)

BACKGROUND

An accurate diagnosis of pancreatic fibrosis is clinically important and may have potential for staging chronic pancreatitis. The aim of this study was to diagnose the grade of pancreatic fibrosis through a quantitative analysis of endoscopic ultrasound elastography (EUS-EG).

METHODS

From September 2004 to October 2010, 58 consecutive patients examined by EUS-EG for both pancreatic tumors and their upstream pancreas before pancreatectomy were enrolled. Preoperative EUS-EG images in the upstream pancreas were statistically quantified, and the results were retrospectively compared with postoperative histological fibrosis in the same area. For the quantification of EUS-EG images, 4 parameters (mean, standard deviation, skewness, and kurtosis) were calculated using novel software. Histological fibrosis was graded into 4 categories (normal, mild fibrosis, marked fibrosis, and severe fibrosis) according to a previously reported scoring system.

RESULTS

The fibrosis grade in the upstream pancreas was normal in 24 patients, mild fibrosis in 19, marked fibrosis in 6, and severe fibrosis in 9. Fibrosis grade was significantly correlated with all 4 quantification parameters (mean r = -0.75, standard deviation r = -0.54, skewness r = 0.69, kurtosis r = 0.67). According to the receiver operating characteristic analysis, the mean was the most useful parameter for diagnosing pancreatic fibrosis. Using the mean, the area under the ROC curves for the diagnosis of mild or higher-grade fibrosis, marked or higher-grade fibrosis and severe fibrosis were 0.90, 0.90, and 0.90, respectively.

CONCLUSIONS

An accurate diagnosis of pancreatic fibrosis may be possible by analyzing EUS-EG images.

Serum proteome profiling of pancreatitis using recombinant antibody microarrays reveals disease-associated biomarker signatures

PURPOSE

Pancreatitis is an inflammatory state of the pancreas, for which high-performing serological biomarkers are lacking. The aim of the present study was to evaluate the use of affinity proteomics for identifying potential markers of disease and stratifying pancreatitis subtypes.

EXPERIMENTAL DESIGN

High-content, recombinant antibody microarrays were applied for serum protein expression profiling of 113 serum samples from patients with chronic, acute, and autoimmune pancreatitis, as well as healthy controls. The sample groups were compared using supervised classification based on support vector machine analysis.

RESULTS

This discovery study showed that pancreatitis subtypes could be discriminated with high accuracy. Using unfiltered data, the individual subtypes, as well as the combined pancreatitis cohort, were distinguished from healthy controls with high AUC values (0.96-1.00). Moreover, characteristic protein patterns and AUC values in the range of 0.69-0.95 were observed for the individual pancreatitis entities when compared to each other, and to all other samples combined.

CONCLUSIONS AND CLINICAL RELEVANCE

This study demonstrated the potential of the antibody microarray approach for stratification of pancreatitis. Distinct candidate multiplex serum biomarker signatures for chronic, acute, and autoimmune pancreatitis were defined, which could enhance our fundamental knowledge of the underlying molecular mechanisms, and potentially lead to improved diagnosis.

Autoimmune pancreatitis: the clinicopathological characteristics of the subtype with granulocytic epithelial lesions

Autoimmune pancreatitis (AIP) has been established as a distinct form of chronic pancreatitis that is distinguishable from other types such as alcoholic, hereditary or obstructive chronic pancreatitis. AIP seems to be a global disease, since it has been reported in many different countries, especially from Japan, USA and Europe (Germany, Italy, United Kingdom). Typical histopathological findings in the pancreas in AIP include a periductal lymphoplasmacytic infiltration with fibrosis, causing narrowing of the involved ducts. The typical clinical features include presentation with obstructive jaundice/pancreatic mass and a dramatic response to steroids. However, while the reports from Japan describe uniform changes called lymphoplasmacytic sclerosing pancreatitis (LPSP) in the pancreas from AIP patients, the reports from Europe and USA distinguish two histopathologic patterns in AIP patients: one with the characteristics of LPSP and another with slightly different histological features, called idiopathic duct centric pancreatitis (IDCP) or AIP with granulocytic epithelial lesions (GELs). This article reviews the evidence that GEL-positive AIP or IDCP is a second type of AIP, distinct from LPSP, in regard to pancreatic pathology, immunology and epidemiology.

Autoimmune pancreatitis

BACKGROUND

Autoimmune pancreatitis (AIP) is a relatively newly recognized type of pancreatitis that is characterized by diffuse or focal swelling of the pancreas due to lymphoplasmacytic infiltration and fibrosis of the pancreatic parenchyma.

MATERIAL AND METHODS

A PubMed literature search was performed using the keywords "autoimmune pancreatitis". Sometimes, bibliographies were cross-referenced and related article searches were performed once an article of interest was identified.

RESULTS

Pathologically, AIP shows narrowing of the pancreatic ducts and the intrapancreatic portion of the common bile duct. Obstructive jaundice is a common symptom at presentation, and pancreatic cancer represents an important clinical differential diagnosis. In late stages of the disease, the normal pancreatic parenchyma is often replaced by large amounts of fibrosis. Histologically, there seem to be two subtypes of the disease-one showing infiltration with IgG4-positive plasma cells but lacking granulocytic epithelial lesions (GELs), the other showing GELs but lacking strong IgG4 positivity. AIP is in at least some instances the pancreatic manifestation of a clinicopathological entity of IgG4-related systemic sclerosing disease. On the basis of pancreatic imaging, together with serological measurement of IgG4 and evaluation of other organ involvement, many AIP patients can be identified. The remaining patients require further diagnostic work-up. In these patients, pancreatic core needle biopsy and, as AIP responds to steroid treatment, also a trial with steroids, can help to differentiate AIP from pancreatic cancer. OUTLOOK AND DISCUSSION: This review presents the pathological, radiologic and laboratory findings of AIP. Moreover, the treatment and pathogenesis are discussed.

Independent contribution of common CFTR variants to chronic pancreatitis

OBJECTIVE

We have assessed whether CFTR gene has a major impact on chronic pancreatitis (CP) pathogenesis than that provided by the CFTR mutations. For this aim, we have evaluated clinical parameters, CFTR mutations, and 3 potential regulatory CFTR variants (coding single-nucleotide polymorphisms): c.1540A>G, c.2694T>G, and c.4521G>A.

METHODS

CFTR gene analysis was performed in a cohort of 136 CP patients and 93 controls from Spanish population using current scanning techniques (single-strand conformation polymorphism/heteroduplex, denaturing gradient gel electrophoresis, and denaturing high-performance liquid chromatography) and direct sequencing.

RESULTS

A higher frequency of CFTR mutations were observed in patients (39%) than in controls (15%; P < or = 0.001), differences being mostly attributable to the prevalence of the cystic fibrosis (CF)-causing mutations (P = 0.009). The analysis of variants has shown statistically significant differences between patients and controls for c.4521G>A (Pcorrected = 0.036). Furthermore, the multi-marker analysis revealed that the 1540A;2694G;4521A (AGA) haplotype was more prevalent in CP than controls (Pcorrected = 0.042). Remarkably, this association was unrelated to CF-causing mutations (P = 0.006).

CONCLUSIONS

Our results corroborate the higher susceptibility of CF carriers to CP and, furthermore, suggest that the AGA haplotype could contribute to an increased risk in the development of CP irrespective of other CF-causing mutations.

Protection against chronic pancreatitis and pancreatic fibrosis in mice overexpressing pancreatic secretory trypsin inhibitor

OBJECTIVES

Mutations in the gene encoding for pancreatic secretory trypsin inhibitor (PSTI) can contribute to chronic pancreatitis. In the current study, we tested whether overexpression of PSTI-I in mice protects against chronic pancreatitis and pancreatic fibrosis.

METHODS

Rat PSTI-I expression was targeted to pancreatic acinar cells in transgenic mice. Chronic pancreatitis was achieved by intraperitoneal injection of cerulein for 10 weeks. Pancreatitis severity was assessed by histological grading of inflammatory infiltrate, atrophy, and fibrosis; quantitation of myeloperoxidase (MPO) activity; quantitative morphometric analysis of collagen content; and measurements of type I collagen, fibronectin, and transforming growth factor beta mRNA expression.

RESULTS

Cerulein administration to nontransgenic mice produced histological evidence of inflammatory infiltrate, glandular atrophy, and parenchymal fibrosis and increased collagen production, MPO activity, and collagen I and fibronectin mRNA levels. In cerulein-treated PSTI transgenic mice, there were significant reductions in inflammatory infiltrate, MPO activity, fibrosis, and collagen I and fibronectin mRNA levels. Transgenic mice treated with cerulein had significantly less collagen than nontransgenic mice.

CONCLUSIONS

The severity of chronic pancreatitis and pancreatic fibrosis is significantly reduced in mice expressing rat PSTI-I. We propose that pancreatic trypsin inhibitors play a protective role in the pancreatic response to repeated injurious events.

Identification of trypsin-inhibitory site and structure determination of human SPINK2 serine proteinase inhibitor

Human serine proteinase inhibitor Kazal-type 2 (SPINK2) functions as a trypsin/acrosin inhibitor and is synthesized mainly in the testis and seminal vesicle where its activity is engaged in fertility. The SPINK2 protein contains a typical Kazal domain composed by six cysteine residues forming three disulfide bridges. The expression of SPINK2 is closely related to cancer such as lymphomas, in that a high transcript level of SPINK2 in patients with primary cutaneous follicle center cell lymphomas have better prognosis with lower mortality. To clarify the role of SPINK2 in cancer, we performed quantitative real-time PCR and showed that the expression level of SPINK2 is significantly elevated in most leukemia cell lines except B-lymphoblast TK-6 cells. The molecular function and structural features of SPINK2 were also investigated by employing the recombinant active and mutant inactive SPINK2 proteins to determine its key P2-P2' (Pro(23)-Arg(24)-His(25)-Phe(26)) active site. The inhibition assay results demonstrated that Arg(24) at the P1 site is crucial for the specificity of SPINK2 on target enzyme. Although His(25) at the P1' and Phe(26) at the P2' residues are also involved in trypsin-SPINK2 interaction, Pro(23) at the P2 site may not be directly participated in interacting with trypsin. In addition, we determined the 3D solution structure of SPINK2 and used this structure to predict the SPINK2-proteinase complex structure and binding properties. These studies not only provide critical information about the structural properties and biophysical features of the SPINK2 proteinase inhibitor, but also suggest its important role in tumor progression and response to treatment.

[Autoimmune pancreatitis]

Autoimmune pancreatitis has been established as a special entity of pancreatitis. It is an enigmatic disease since it is adding an autoimmune etiology to the existing causes of pancreatitis. Morphological hallmarks of the disease are narrowing of the pancreatic duct system and the bile duct by periductal lymphoplasmocytic inflammation. This results in many cases in obstructive jaundice due to a mass-forming lesion in the pancreatic head mimicking pancreatic ductal adenocarcinoma. Therefore, patients will frequently undergo surgery. Histopathologically, the disease can be diagnosed by IgG4-positive plasma cells. Serologically, patients may present with elevated serum IgG and IgG4 levels. Other autoantibodies are also described. Association with other autoimmune manifestations in a wide range of organs is frequent. Autoimmune pancreatitis will respond to steroid treatment, which is of specific importance because pancreatic cancer is one of its clinical differential diagnoses. It is important to positively diagnose autoimmune pancreatitis, especially if the bile ducts are affected, since cholangitis may be or become a prominent problem before or after surgery.

Multidimensional degradomics identifies systemic autoantigens and intracellular matrix proteins as novel gelatinase B/MMP-9 substrates

The action radius of matrix metalloproteinases or MMPs is not restricted to massive extracellular matrix (ECM) degradation, it extends to the proteolysis of numerous secreted and membrane-bound proteins. Although many instances exist in which cells disintegrate, often in conjunction with induction of MMPs, the intracellular MMP substrate repertoire or degradome remains relatively unexplored. We started an unbiased exploration of the proteolytic modification of intracellular proteins by MMPs, using gelatinase B/MMP-9 as a model enzyme. To this end, multidimensional degradomics technology was developed by the integration of broadly available biotechniques. In this way, 100-200 MMP-9 candidate substrates were isolated, of which 69 were identified. Integration of these results with the known biological functions of the substrates revealed many novel MMP-9 substrates from the intracellular matrix (ICM), such as actin, tubulin, gelsolin, moesin, ezrin, Arp2/3 complex subunits, filamin B and stathmin. About 2/3 of the identified candidates were autoantigens described in multiple autoimmune conditions and in cancer (e.g. annexin I, nucleolin, citrate synthase, HMGB1, alpha-enolase, histidyl-tRNA synthetase, HSP27, HSC70, HSP90, snRNP D3). These findings led to the insight that MMPs and other proteases may have novel (immuno)regulatory properties by the clearance of toxic and immunogenic burdens of abundant ICM proteins released after extensive necrosis. In line with the extracellular processing of organ-specific autoantigens, proteolysis might also assist in the generation of immunodominant 'neo-epitopes' from systemic autoantigens. The study of proteolysis of ICM molecules, autoantigens, alarmins and other crucial intracellular molecules may result in the discovery of novel roles for proteolytic modification.

Diagnosis of autoimmune pancreatitis by core needle biopsy: application of six microscopic criteria

Autoimmune pancreatitis (AIP) has been established as a special entity of chronic pancreatitis (CP). However, its clinical distinction from pancreatic cancer and other types of CP is still difficult. The aim of this study was to evaluate the efficacy of pancreatic core needle biopsy for the diagnosis of AIP. In 44 core needle biopsy specimens, we assessed the following microscopic features: granulocytic epithelial lesions (GELs), more than ten IgG4-positive plasma cells/HPF, more than ten eosinophilic granulocytes/HPF, cellular fibrosis with inflammation, lymphoplasmacytic infiltration, and venulitis. All biopsies that showed four or more of the six features (22 of 44) were obtained from 21 of 26 patients whose clinical diagnosis and follow-up were consistent with AIP. All non-AIP CP patients (n = 14) showed three or less than three of the features in their biopsies. GELs were only observed in biopsy specimens from AIP patients. In conclusion, our data indicate that the six criteria we applied were able to recognize AIP in 76% of biopsy specimens using a cut-off level of four. When the specimens that revealed only three features but showed GELs were added, the sensitivity rose to 86%. Pancreatic core needle biopsy can therefore make a significant contribution to the diagnosis of AIP.

Diagnostic efficiency of amylase and type IV collagen in predicting chronic pancreatitis

Chronic pancreatitis, an irreversible inflammatory disease of the pancreas, is associated with the replacement of the destroyed parenchyma by extended development of fibrosis. Despite marked progress in diagnostic tools, no consensus has been reached in diagnosis of chronic pancreatitis. In this study we examined the hematological and biochemical parameters among 40 chronic pancreatitis patients within 18 to 67 yrs. ESR level and ALP activity was elevated in 40% cases. Serum amylase activity increased in 32 patients and it showed significant correlation with ALP (r=0.458, p=0.003), CA-19.9 (r=0.556, p<0.001), and calcium level (r=-0.472, p=0.002). Type IV collagen level in chronic pancreatitis also elevated (164.4 ± 55.5 ng/ml) and showed negative significant correlation with calcium level (r= -0.505, p=0.001). However, no significant correlation was observed between amylase activity and type IV collagen (r=0.289, p= 0.07).

Usefulness of serum IgG4 in the diagnosis and follow up of autoimmune pancreatitis: A systematic literature review and meta-analysis

High circulating serum immunoglobulin G4 (IgG4) levels have been proposed as a marker of autoimmune pancreatitis (AIP). The aim of the present study was to review the data existing in the English literature on the usefulness of the IgG4 serum levels in the diagnosis and follow up of patients with AIP. A total of 159 patients with AIP and 1099 controls were described in seven selected papers reporting the usefulness of serum IgG4 in diagnosing AIP. In total, 304 controls had pancreatic cancer, 96 had autoimmune diseases, and the remaining 699 had other conditions. The summary receiver-operating characteristic curve analysis was carried out by means of Meta-DiSc open-access software. Serum IgG4 showed good accuracy in distinguishing between AIP and the overall controls, pancreatic cancer and other autoimmune diseases (area under the curve [+/- SE]: 0.920 +/- 0.073, 0.914 +/- 0.191, and 0.949 +/- 0.024, respectively). The studies analyzed showed significantly heterogeneous specificity values in each of the three analyses performed. The analysis of the four studies comparing AIP and pancreatic cancers also showed significantly heterogeneous values of sensitivities and odds ratios. Regarding the usefulness of IgG4 as a marker of efficacy of steroid treatment, a decrease in the serum concentrations of IgG4 was found in the four available studies. The serum IgG4 subclass is a good marker of AIP, and its determination should be included in the diagnostic workup of this disease. However, the heterogeneity of the studies published until now means that more studies are necessary in order to better evaluate the true accuracy of IgG4 in discriminating AIP versus other autoimmune diseases.