Two critical genes (HLA-DRB1 and ABCF1)in the HLA region are associated with the susceptibility to autoimmune pancreatitis

IgG4 autoantibodies and autoantigens in the context of IgG4-autoimmune disease and IgG4-related disease

Immunoglobulins are an essential part of the humoral immune response. IgG4 antibodies are the least prevalent subclass and have unique structural and functional properties. In this review, we discuss IgG4 class switch and B cell production. We review the importance of IgG4 antibodies in the context of allergic responses, helminth infections and malignancy. We discuss their anti-inflammatory and tolerogenic effects in allergen-specific immunotherapy, and ability to evade the immune system in parasitic infection and tumour cells. We then focus on the role of IgG4 autoantibodies and autoantigens in IgG4-autoimmune diseases and IgG4-related disease, highlighting important parallels and differences between them. In IgG4-autoimmune diseases, pathogenesis is based on a direct role of IgG4 antibodies binding to self-antigens and disturbing homeostasis. In IgG4-related disease, where affected organs are infiltrated with IgG4-expressing plasma cells, IgG4 antibodies may also directly target a number of self-antigens or be overexpressed as an epiphenomenon of the disease. These antigen-driven processes require critical T and B cell interaction. Lastly, we explore the current gaps in our knowledge and how these may be addressed.

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.

Hashimoto's thyroiditis and coexisting disorders in correlation with HLA status-an overview

Hashimoto's thyroiditis (HT), also known as chronic lymphocytic thyroiditis, is a frequent disorder of the thyroid gland caused by autoimmune-trigged lymphocytic infiltration and destruction of the thyroid gland. With the progressive destruction of the organ, the thyroid gland shrinks in size, thus commonly leading to hypothyroidism. Therapy of HT is mainly focused on managing the thyroid dysfunction by oral substitution of L‑thyroxine. However, patients with HT often complain about a broad spectrum of symptoms, with some of them hardly explained by HT itself. Several other disorders are known to be associated with HT. The etiology of HT seems to be multifactorial, including environmental influences such as iodine supply, infections, and stress as triggers of immune modulation. In addition, also a genetic background based on changes of the human leukocyte antigen (HLA) status seems to be evident. The paper will provide an overview of diseases related to HT, including their correlation to certain HLA patterns. This presentation should give a broader view on HT-related disorders and facilitate detailed examination and management of patients with HT.

HLA-DRB1∗16 and -DQB1∗05 alleles are strongly associated with autoimmune pancreatitis in a cohort of hundred patients

BACKGROUND/OBJECTIVES

Autoimmune diseases are often associated with human leukocyte antigen (HLA) haplotypes, indicating that changes in major histocompatibility complex (MHC)-dependent self-peptide or antigen presentation contribute to autoimmunity. In our study, we aimed to investigate HLA alleles in a large European cohort of autoimmune pancreatitis (AIP) patients.

METHODS

Hundred patients with AIP, diagnosed and classified according to the International Consensus Diagnostic Criteria (ICDC), were prospectively enrolled in the study. Forty-four patients with chronic pancreatitis (CP) and 254 healthy subjects served as control groups. DNA was isolated from blood samples and two-digit HLA typing was performed with sequence-specific primer (SSP-) PCR. HLA allele association strength to AIP was calculated as odds ratio.

RESULTS

We uncovered a strong enrichment of HLA-DQB1 homozygosity in type 1 and type 2 AIP patients. Moreover, a significantly increased incidence of the HLA-DRB1∗16 and HLA-DQB1∗05 alleles and a concomitant lack of the HLA-DRB1∗13 allele was detected in AIP type 1 and type 2 patients. In contrast, the HLA-DQB1∗02 allele was underrepresented in the 'not otherwise specified' (NOS) AIP subtype. We detected no significant difference in the HLA-DRB3, HLA-DRB4 and HLA-DRB5 allele frequency in our cohort.

CONCLUSIONS

Although AIP type 1 and type 2 are characterized by distinct histopathological characteristics, both subtypes are associated with the same HLA alleles, indicating that the disease might rely on similar immunogenic mechanisms. However, AIP NOS represented another subclass of AIP.

IgG4-related diseases of the digestive tract

IgG4-related conditions affecting the digestive tract are part of a multi-organ fibro-inflammatory disorder termed IgG4-related disease (IgG4-RD), with autoimmune pancreatitis and IgG4-related cholangitis being the most prominent manifestations. Gastrointestinal symptoms include jaundice, weight loss, abdominal pain, biliary strictures, and pancreatic and hepatic masses that mimic malignant diseases. IgG4-RD manifestations occur less frequently elsewhere in the digestive tract, namely in the oesophagus, retroperitoneum or intestine. Evidence-based European guidelines frame the current state-of-the-art in the diagnosis and management of IgG4-related digestive tract disease. Diagnosis is based on histology (if available), imaging, serology, other organ involvement and response to therapy (HISORt criteria). Few biomarkers beyond serum IgG4 concentrations are reliable. The first-line therapy (glucocorticoids) is swiftly effective but disease flares are common at low doses or after tapering. Second-line therapy might consist of other immunosuppressive drugs such as thiopurines or rituximab. Further trials, for example, of anti-CD19 drugs, are ongoing. Although an association between IgG4-RD and the development of malignancies has been postulated, the true nature of this relationship remains uncertain at this time.

IGg4-related Disease Presenting as Rapidly Progressive Renal Failure and Inguinal Iymphadenopathy

A 58-year-old man presented with swelling in the left inguinal region and loss of appetite, nausea and azotemia with a serum creatinine of 5.2 mg/dL and urine albumin of 1+ and normal size kidneys with no hematuria. His serum creatinine increased to 9 mg/dL over 1 month, his total proteins were 10.8 and serum albumin was 3.3 g/dL, and lymph node excision biopsy showed fragments of lymphoid tissue with interfollicular areas containing sheets of plasma cells and atretic germinal centers. In view of unexplained renal failure, he underwent renal biopsy, which showed interstitial inflammatory infiltrate composed of lymphocytes and rich in plasma cells with storiform fibrosis and a possibility of IgG4-related renal disease was reported. On further evaluation, serum electrophoresis showed no M band. Serum IgG4 levels were 18.2 g/L (0.03–2 g/L). A diagnosis of IgG4-related renal disease was confirmed.

Clinical Usefulness of Serum Autotaxin for Early Prediction of Relapse in Male Patients with Type 1 Autoimmune Pancreatitis

BACKGROUND

Serum IgG4 level is a useful diagnostic marker for autoimmune pancreatitis (AIP), but it is difficult to use to predict relapse.

AIMS

We investigated whether serum autotaxin (ATX) level is predictive of AIP relapse after steroid therapy.

METHODS

Fifty-six patients with type 1 AIP were investigated. We measured serum ATX at the time of diagnosis. We selected 24 males for whom serum samples during steroid therapy had been obtained and measured serum ATX at steroid therapy for induction of remission and at maintenance therapy. In the relapse group, we also measured ATX at the time of relapse.

RESULTS

ATX was significantly higher in female patients than in male patients. In order to clarify changes in ATX during steroid therapy, we focused on 24 male patients. We found that ATX decreased significantly during steroid therapy for induction of remission and at the time of maintenance therapy. In half of all patients who relapsed during maintenance therapy, ATX was significantly elevated at the time of relapse compared with that of induction therapy (P = 0.039). When we compared ATX at the time of maintenance therapy between patients with relapse and without, we observed significantly higher ATX in the former (P = 0.024). We found that the combination of ATX and elastase-1 could predict relapse with high accuracy (95%).

CONCLUSIONS

Preliminary evidence suggests that serum ATX might serve as a candidate biomarker to predict relapse of AIP as well as to monitor the effect of steroid therapy.

Histopathological findings in the landscape of IgG4-related pathology in patients with pituitary dysfunction: Review of six cases

IgG4-related hypophysitis (IgG4-RH) is increasingly being reported as an isolated entity or, less frequently, as a manifestation of a multiorgan IgG4-related disease (IgG4-RD), in which typical histopathology is a cornerstone for the diagnosis. We aimed to describe the histopathological changes in the surgical specimens from patients with clinical signs of pituitary disease that fulfilled the current diagnostic criteria for IgG4-RH. Histopathological features were correlated with clinical and radiological findings. Of 19 patients with pituitary dysfunction and inflammatory changes in the surgical pituitary specimen operated on during 2011-2019, we identified five patients with typical IgG4-related pathology (lymphoplasmacytic infiltration with more than 10 IgG4-positive plasma cells per one high power microscopic field, representing at least 40% of all plasma cells and at least focal storiform fibrosis). One patient with diabetes insipidus and pachymeningitis with IgG4-related changes in a biopsy from the dura was also included. Additional histopathological changes that typically are not part of the IgG4-RH were observed: Rathke's cleft cyst in four and granulomatous changes in two patients. One patient had an elevated serum IgG4 level and systemic manifestations that could be associated with the systemic IgG4-RD. Our findings indicate that pure IgG4-RH is uncommon. All patients with pituitary dysfunction, beyond typical IgG4-related pathology, had other pathological findings that could trigger the secondary IgG4-response. Both primary pathology and secondary IgG4-related features should be reported in patients with pituitary dysfunction because their co-occurrence may cause atypical clinical and imaging features, and unexpected response to surgical and pharmacological treatment. The current criteria for the diagnosis of IgG4-RH can lead to overdiagnosis of IgG4-RH if additional pathological changes are not taken into consideration. The classification criteria of IgG4-RD proposed by the American College of Rheumatology/European League Against Rheumatism could help classify patients more properly as IgG4-RH if applied to the pituitary gland.

IgG4-related disease: Changing epidemiology and new thoughts on a multisystem disease

IgG4-related disease (IgG4-RD) represents an immune-mediated fibroinflammatory condition with peculiar histopathologic changes that can affect various organs. In 2012 its unified nomenclature was published, which allows to abandon other synonymous names. Up to now, only little is known about its epidemiology around the world. However, although it is generally considered a rare condition, the number of patients with IgG4-RD is increasing enormously. Likewise, the annual number of publications on this subject has increased progressively. The spectrum of clinical manifestations in IgG4-RD is highly variable, depending on the severity of the disease as well as the presence of organ(s) involvement. This review gives an overview on changing epidemiology of IgG4-RD focusing the attention on the large cohorts of patients published in the literature.

ABC-F translation factors: from antibiotic resistance to immune response

Energy-dependent translational throttle A (EttA) from Escherichia coli is a paradigmatic ABC-F protein that controls the first step in polypeptide elongation on the ribosome according to the cellular energy status. Biochemical and structural studies have established that ABC-F proteins generally function as translation factors that modulate the conformation of the peptidyl transferase center upon binding to the ribosomal tRNA exit site. These factors, present in both prokaryotes and eukaryotes but not in archaea, use related molecular mechanisms to modulate protein synthesis for heterogenous purposes, ranging from antibiotic resistance and rescue of stalled ribosomes to modulation of the mammalian immune response. Here, we review the canonical studies characterizing the phylogeny, regulation, ribosome interactions, and mechanisms of action of the bacterial ABC-F proteins, and discuss the implications of these studies for the molecular function of eukaryotic ABC-F proteins, including the three human family members.

Immune mechanisms of fibrosis and inflammation in IgG4-related disease

PURPOSE OF REVIEW

To summarize recent advances in the understanding of the pathogenesis of IgG4-related disease.

RECENT FINDINGS

Limited data exist to explain genetic susceptibility to IgG4-related disease and the underlying triggers for this disease have not yet been identified. Cytotoxic CD4 T cells and activated B cells infiltrate affected organs and express proinflammatory and profibrotic molecules. Antigen presented by activated B cells likely reactivates cytotoxic CD4 T cells in disease tissues and these T cells in turn induce the targeted apoptotic death of host cells in certain organs - which presumably present the same antigenic peptide on human leukocyte antigen class II molecules of relevance that was also presented on B cells during reactivation. A subsequent exaggerated tissue remodeling process is orchestrated by cytokines, chemokines, and enzymes secreted by both activated B cells and CD4CTLs. These molecules induce an overexuberant repair process resulting in fibrosis and loss of target organ function.

SUMMARY

In IgG4-related disease, presumably self-reactive cytotoxic CD4 T cells infiltrate tissues, are reactivated by T cells and induce apoptotic death. Molecules secreted by activated B cells and by CD4CTLs drive an exaggerated wound healing response resulting in fibrosis and compromised tissue function.

Autoimmune pancreatitis - An ongoing challenge

Autoimmune pancreatitis is a rare form of chronic pancreatitis. The first descriptions of the disease date back to the 1990s. Etiology is multifactorial, with the use of genetic, environmental and complex immunological mechanisms. It is classified into two subtypes. Type 1 is part of a group of diseases called IgG4-related disease. Clinically is autoimmune pancreatitis manifested by icterus and abdominal discomfort. It can rarely present as acute pancreatitis. There is also a completely asymptomatic form of the disease. The diagnosis is based on abnormalities in histology, imaging methods, serology, the involvement of other organs in relation to IgG4-related disease, and a significant positive response to corticosteroid therapy. Differential diagnosis between the focal form of autoimmune pancreatitis and pancreatic cancer can be complicated, with endosonography playing an important role. In the treatment, we use corticosteroids and other immunosuppressants including biological therapy. Patients with the asymptomatic disease should also be treated to prevent late complications and exocrine and endocrine insufficiency. In addition to drug treatment, endoscopic and/or surgical treatment may be necessary. Even after recovery, the disease can relapse. The relationship between autoimmune pancreatitis and malignancies has not been clearly confirmed. The goal of this review is to provide a comprehensive look at autoimmune pancreatitis and translate latest scientific knowledge into clinical practice.

Clinicopathological differential diagnosis of IgG4-related disease: A historical overview and a proposal of the criteria for excluding mimickers of IgG4-related disease

IgG4-related disease (RD) is a relatively new entity, which was first proposed in 2001. Since then, clinical and pathological characteristics of the disease have been investigated. As IgG4-RD has been studied extensively, the diagnostic criteria for IgG4-RD of each organ and the comprehensive diagnostic criteria for IgG4-RD have also been developed. However, one of the biggest challenges in the field is distinguishing between IgG4-RD and mimickers, which show overlapping features with IgG4-RD. It is now known that some non-IgG4-RDs may meet the diagnostic criteria of IgG4-RD and can be misdiagnosed as IgG4-RD. However, accurate diagnosis is crucial, as the treatments for IgG4-RD and those for other diseases that may be misdiagnosed as IgG4-RD are different. This prompted us to create and propose comprehensive exclusion criteria for IgG4-RD. In this review, we have described the comprehensive exclusion criteria for IgG4-RD, with a historical overview of the disease. These exclusion criteria were recently created by the Research Program for Intractable Disease of the Ministry of Health, Labor, and Welfare of Japan, All Japan IgG4 team, to support correct and accurate diagnosis of IgG4-RD.

Bilateral orbital involvement of IgG4-related disease detected on 18F-Fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography: A Clinical Case Report

RATIONALE

IgG4-related disease (IgG4-RD) is a systemic immune-mediated fibro-inflammatory condition, which could involve multiple structures, including the pancreas, salivary glands, and lymph nodes. However, cases of IgG4-RD involving the bilateral orbits, salivary glands, submandibular glands, lymph nodes, and prostate are rare.

PATIENT CONCERNS

A 51-year-old man complaining of bilateral exophthalmos, reduced vision, and weight loss of 15 kg over 2 years presented to our department for evaluation.

DIAGNOSES

Based on the elevated serum IgG4 level, postoperative pathology, and the features of F-fluoro-2-deoxy-D-glucose (F-FDG) positron emission tomography/computed tomography (PET/CT), which revealed diffuse increased FDG uptake in many structures, he was diagnosed with IgG4-related disease involving the bilateral orbits, salivary glands, submandibular glands, lymph nodes, and prostate.

INTERVENTIONS

Because of the significant bilateral proptosis and exposure keratoconjunctivitis in the right eye, bilateral soft-tissue masses located in the orbits were resected, and the patient was started on oral methylprednisolone with gradual tapering.

OUTCOMES

The patient's symptoms gradually relieved after the operation and glucocorticoid therapy. Four months later, cranial axial CT revealed remarkable narrowing of soft-tissue masses in the bilateral orbits, and his serum IgG4 level reduced sharply.

LESSONS

IgG4-RD should be considered in cases of diffuse FDG uptake in the bilateral orbits, salivary glands, submandibular glands, lymph nodes, and prostate on PET/CT.

New Thalidomide-Resembling Dicarboximides Target ABC50 Protein and Show Antileukemic and Immunomodulatory Activities

We identified novel dicarboximides that were selectively cytotoxic towards human leukemia cells. Using chemical and biological methods, we characterized the biological activity, identified cellular protein targets and defined the mechanism of action of the test dicarboximides. The reported IC₅₀ values (concentration required to reduce cell survival fraction to 50% of control) of selected dicarboximides were similar or lower than IC₅₀ of registered anticancer drugs, for example cytarabine, sorafenib, irinotecan. Test compounds induced apoptosis in chronic myelogenous (K562) and acute lymphoblastic (MOLT-4) leukemia cells by activation of receptor and mitochondrial apoptotic pathways and increased the expression of proapoptotic genes (BAX, NOXA, HTRA2, TNFRSF10B, ESRRBL1). Selected dicarboximides displayed immunomodulatory activity and downregulated IKZF1 and IKZF3 transcription factors in K562 and MOLT-4 leukemia cells. ATP-binding cassette protein 50 (ABC50) was identified as a target for dicarboximides. Cancer cells with knocked down ABC50 showed increased resistance to dicarboximides. Based on the structure of dicarboximides and thalidomide, novel proteolysis-targeting chimeras (PROTACs) were synthesized and used as tools to downregulate ABC50 in leukemia cells.

IgG4-related disease in the Japanese population: a genome-wide association study

BACKGROUND

IgG4-related disease is a newly recognised immunopathological entity that includes autoimmune pancreatitis, IgG4-related sialadenitis, and IgG4-related kidney disease. To understand the genetic landscape of IgG4-related disease, we did a genome-wide association study.

METHODS

We did a genome-wide association study of Japanese individuals, initially screening 857 patients with IgG4-related disease at 50 Japanese research institutions and DNA samples from 2082 healthy control participants from the Nagahama Prospective Genome Cohort for the Comprehensive Human Bioscience. From Oct 27, 2008, to July 22, 2014, we enrolled 835 patients and used data from 1789 healthy participants. Only patients with confirmed diagnosis of IgG4-related disease according to the international diagnostic criteria were included. Genotyping was done with the Infinium HumanOmni5Exome, HumanOmni2.5Exome, or HumanOmni2.5 Illumina arrays, and genomic distributions were compared between case and control samples for 958 440 single nucleotide polymorphisms. The HLA region was extensively analysed using imputation of HLA alleles and aminoacid residues. Fine mapping of the FCGR2B region was also done. Associations between clinical manifestations of disease and the genetic variations identified in these two genes were examined.

FINDINGS

We identified the HLA-DRB1 (p=1·1×10-11) and FCGR2B (p=2·0×10-8) regions as susceptibility loci for IgG4-related disease. We also identified crucial aminoacid residues in the β domain of the peptide-binding groove of HLA-DRB1, in which the seventh aminoacid residue showed the strongest association signal with IgG4-related disease (p=1·7×10-14), as has been reported with other autoimmune diseases. rs1340976 in FCGR2B showed an association with increased FCGR2B expression (p=2·7×10-10) and was in weak linkage disequilibrium with rs1050501, a missense variant of FCGR2B previously associated with systemic lupus erythematosus. Furthermore, rs1340976 was associated with the number of swollen organs at diagnosis (p=0·011) and IgG4 concentration at diagnosis (p=0·035).

INTERPRETATION

Two susceptibility loci for IgG4-related disease were identified. Both FCGR2B and HLA loci might have important roles in IgG4-related disease development. Common molecular mechanisms might underlie IgG4-related disease and other immune-related disorders FUNDING: The Japanese Ministry of Health, Labour, and Welfare, the Japanese Agency of Medical Research and Development, and Kyoto University Grant for Top Global University Japan Project.

The ATP-Binding Cassette Gene ABCF1 Functions as an E2 Ubiquitin-Conjugating Enzyme Controlling Macrophage Polarization to Dampen Lethal Septic Shock

Sepsis is a bi-phasic inflammatory disease that threatens approximately 30 million lives and claims over 14 million annually, yet little is known regarding the molecular switches and pathways that regulate this disease. Here, we have described ABCF1, an ATP-Binding Cassette (ABC) family member protein, which possesses an E2 ubiquitin enzyme activity, through which it controls the Lipopolysaccharide (LPS)- Toll-like Receptor-4 (TLR4) mediated gram-negative insult by targeting key proteins for K63-polyubiquitination. Ubiquitination by ABCF1 shifts the inflammatory profile from an early phase MyD88-dependent to a late phase TRIF-dependent signaling pathway, thereby regulating TLR4 endocytosis and modulating macrophage polarization from M1 to M2 phase. Physiologically, ABCF1 regulates the shift from the inflammatory phase of sepsis to the endotoxin tolerance phase, and modulates cytokine storm and interferon-β (IFN-β)-dependent production by the immunotherapeutic mediator, SIRT1. Consequently, ABCF1 controls sepsis induced mortality by repressing hypotension-induced renal circulatory dysfunction.

Immunophenotype involved in IgG4-related disease

As stated in the comprehensive diagnostic criteria for IgG4-related disease (IgG4-RD), IgG4-RD is characterized by elevated serum IgG4 level and pathological findings, characterized by infiltration of IgG4-positive plasma cells. In addition to fibrotic changes, dysregulated activation of lymphocytes is considered as one of major pathogenic events in IgG4-RD. Among lymphocytes, the importance of plasmablast, T follicular helper (Tfh) cells, T type 2 helper (Th2) cells, T regulatory (Treg) cells, and CD4 positive T cells with cytotoxic activity has been reported. Conversely, comprehensive immunophenotyping in patients with IgG4-RD revealed that there are two different axes consisting plasmablast-Tfh cells and Treg cells. There is need for research to seek out molecules associated with these immunocompetent cell interactions. It is believed that this will contribute to the future application to disease-specific treatment for IgG4-RD.

Correlation of T follicular helper cells and plasmablasts with the development of organ involvement in patients with IgG4-related disease

Objective

To assess the role of an abnormal immune network in the pathology of IgG4-related disease (IgG4-RD).

Methods

Sixteen patients diagnosed with IgG4-RD at our institution were selected. Peripheral immunocompetent cells were immunophenotyped by multicolour flow cytometry to assess the association between clinical manifestation and pathological findings.

Results

Compared with healthy controls, IgG4-RD patients showed comparable proportions of Th1 and Th17 cells, but higher proportions of Treg and follicular helper T (Tfh) cells. Further, the proportions of class-switched memory B cells and plasmablasts were higher in patients. Among all phenotypes, in particular, the plasmablast proportion increased from 4.2% (controls) to 16.5% (patients). The serum IgG levels were found to be correlated with the proportions of plasmablasts and Tfh cells, but not with those of other T cell subsets. In patients with extraglandular symptoms, only plasmablasts, Tfh cells and memory Treg cells were increased. Histopathological examination revealed a marked Tfh (CD4+ Bcl6+) cell infiltration; the increase of Tfh cells in the peripheral blood thus reflected the degree of Tfh cell infiltration into the tissue. Although steroid therapy reduced plasmablast and Tfh cell proportions, the memory Treg cell proportion remained unchanged.

Conclusion

The association found between Tfh cells and plasmablasts, linked with biological plausibility, suggests that Tfh cells contribute to the pathogenesis of IgG4-RD. Our results also suggested that controlling the Tfh cell-plasmablast axis could be a novel therapeutic strategy for treating IgG4-RD.

Immunoglobulin G4-related kidney diseases: An updated review

This review will encompass definition, pathogenesis, renal clinical manifestations and treatment of immunoglobulin G4-related diseases (IgG4-RDs). IgG4-RD is a recently recognized clinical entity that often involves multiple organs and is characterized by high levels of serum immunoglobulins G4, dense infiltration of IgG4⁺ cells and storiform fibrosis. Cellular immunity, particularly T-cell mediated immunity, has been implicated in the pathogenesis of IgG4-RDs. The most frequent renal manifestations of IgG4-RD are IgG4-related tubulointerstitial nephritis, membranous glomerulopathy and obstructive nephropathy secondary to urinary tract obstruction due to IgG4-related retroperitoneal fibrosis. IgG4-RD diagnosis should be based on specific histopathological findings, confirmed by tissue immunostaining, typical radiological findings and an appropriate clinical context. The first line treatment is the steroids with two warnings: Steroid resistance and relapse after discontinuation. In the case of steroid resistance, B cell depleting agents as rituximab represent the second-line treatment. In the case of relapse after discontinuation, steroid treatment may be associated with steroid sparing agents. Since the disease has been only recently identified, more prospective, long-term studies are needed to an improved understanding and a more correct and safe treatment.

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.

The role of the innate immune response regulatory gene ABCF1 in mammalian embryogenesis and development

ABCF1 is an ABC transporter family protein that has been shown to regulate innate immune response and is a risk gene for autoimmune pancreatitis and arthritis. Unlike other members of ABC transporter family, ABCF1 lacks trans-membrane domains and is thought to function in translation initiation through an interaction with eukaryotic translation initiation factor 2 (eIF2). To study ABCF1 expression and function in development and disease, we used a single gene trap insertion in the Abcf1 gene in murine embryonic stem cells (ES cells) that allowed lineage tracing of the endogenous Abcf1 promoter by following the expression of a β-galactosidase reporter gene. From the ES cells, heterozygous mice (Abcf1+/-) were produced. No live born Abcf1-/- progeny were ever generated, and the lethality was not mouse strain-specific. Thus, we have determined that Abcf1 is an essential gene in development. Abcf1-/- mice were found to be embryonic lethal at 3.5 days post coitum (dpc), while Abcf1+/- mice appeared developmentally normal. Abcf1+/- mice were fertile and showed no significant differences in their anatomy when compared with their wild type littermates. The Abcf1 promoter was found to be active in all organs in adult mice, but varies in levels of expression in specific cell types within tissues. Furthermore, we observed high promoter activity in the blastocysts and embryos. Overall, Abcf1 expression in embryos is required for development and its expression in adults was highly correlated with actively proliferating and differentiating cell types.

The management of autoimmunity in patients with cholestatic liver diseases

Cholestatic liver diseases are rare diseases that often lead to cirrhosis and its consequent complications. In addition to liver-related morbidity, patients with cholestatic liver diseases often suffer from autoimmune diseases that affect several organs and tissues. The robust and efficient data collection and collaboration between hepatologists and rheumatologists have led to significant advancements in understanding the relationship between the cholestatic liver diseases and associated autoimmune diseases. In this paper, we discuss the cholestatic liver diseases (primary biliary cirrhosis, primary sclerosing cholangitis and immunoglobulin G4 associated cholangitis) and associated autoimmune diseases.

A high-throughput sequence analysis of Japanese patients revealed 11 candidate genes associated with type 1 autoimmune pancreatitis susceptibility

The pathogenesis of autoimmune pancreatitis is unknown. In the present study we used high-throughput sequencing with next generation sequencing to identify the candidate genes associated with AIP. A total of 27 type 1 AIP patients and 30 healthy blood donors were recruited, and DNA samples were isolated from their mononuclear cells. A high-throughput sequencer with an original custom panel of 1031 genes was used to detect the genetic variants in each sample. Polymorphisms of CACNA1S (c.4642C>T), rs41554316, rs2231119, rs1042131, rs2838171, P2RX3 (c.195delG), rs75639061, SMAD7 (c.624delC) and TOP1 (c.2007delG), were identified as candidate genetic variants in patients with type 1 AIP. P2RX3 and TOP1 were significantly associated with AIP, even after adjusting bay means of Bonferroni's correction. In addition, we also identified eight candidate genetic variants that were associated with the relapse of type 1 AIP, namely: rs1143146, rs1050716, HLA-C (c.759_763delCCCCCinsTCCCG), rs1050451, rs4154112, rs1049069, CACNA1C (c.5996delC) and CXCR3 (c.630_631delGC). Finally polymorphisms of rs1050716 and rs111493987 were identified as candidate genetic variants associated with extra-pancreatic lesions in patients with type 1 AIP. These candidates might be used as markers of AIP susceptibility and could contribute to the pathogenesis of type 1 AIP.

Immunogenetics of IgG4-Related AIP

Autoimmune pancreatitis (AIP) is a unique form of chronic pancreatitis characterized by high serum IgG4 concentration and a variety of complicating extra-pancreatic lesions. AIP has the features of a complex disease that is caused by multifactorial genes. However, the genetic factors underlying AIP have not been elucidated conclusively. Association studies by the candidate-gene approach and genome-wide association studies (GWAS) have revealed several susceptibility genes for AIP, including HLA DRB1*04:05-DQB1*04:01, FCRL3, CTLA4, and KCNA3, albeit in small-scale analyses. Thus, GWAS of large sample sizes and multinational collaborative meta-analyses are needed to identify the precise genetic variants that are associated with AIP onset. Systems genetics approaches that integrate DNA sequencing, expression quantitative trait locus (eQTL) mapping, proteomics, and metabolomics will also be useful in clarifying the pathogenesis of AIP.

Eosinophilia in Rheumatologic/Vascular Disorders

Peripheral and tissue eosinophilia can be a prominent feature of several unique rheumatologic and vascular diseases. These diseases span a wide range of clinical features, histologic findings, therapeutic approaches, and outcomes. Despite the rare nature of these entities--which makes large-scale studies challenging--knowledge has continued to grow regarding their epidemiology, pathophysiology, and management. This review compares and contrasts 5 rheumatologic and vascular conditions in which eosinophilia can be seen: eosinophilic granulomatosis with polyangiitis (Churg-Strauss), immunoglobulin G4-related disease, diffuse fasciitis with eosinophilia, eosinophilia-myalgia syndrome, and eosinophilic myositis.

Investigation of susceptibility genes triggering lachrymal/salivary gland lesion complications in Japanese patients with type 1 autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a unique form of chronic pancreatitis characterized by high serum IgG4 concentration and a variety of complicating extra-pancreatic lesions. In particular, lachrymal/salivary gland lesions tend to manifest in a highly active AIP disease state, and several genes are speculated to be associated with the onset of this complication. We therefore searched for candidate susceptibility genes related to lachrymal/salivary gland lesions in a genome-wide association study (GWAS) with the GeneChip Human Mapping 500k Array Set (Affymetrix, CA) that was followed by fine mapping of additional single nucleotide polymorphisms (SNPs) in strongly significant genes with TaqMan assays. Venous blood samples were obtained from 50 type 1 AIP patients with lachrymal/salivary gland lesions (A group) and 53 type 1 AIP patients without (B group). The mean values of IgG and IG4 were both significantly different (P<0.05) between the groups. SNPs that showed a significant association with the A group at the genome-wide level (P<0.0001) were identified and subsequently used in fine SNP mapping of candidate genes. In total, five SNPs had a positive association with complicated AIP (most notably rs2284932 [P=0.0000021]) and five SNPs possessed a negative association (particularly rs9371942 [P=0.00000039]). Among them, KLF7, FRMD4B, LOC101928923, and MPPED2 were further examined for complication susceptibility using additional SNPs that were not included in the GWAS. Individual genotyping of KLF7 rs2284932 revealed that the frequency of the minor C allele was significantly increased (P=0.00062, Pc=0.0018, OR=2.98, 95%CI=1.58-5.65) in group A. The minor T allele of rs4473559 in FRMD4 demonstrated a significant association in the A group (P=0.00015, OR=3.38, 95%CI=1.77-7.65). In the LOC101928923 gene, the frequency of the minor C allele of rs4379306 was significantly decreased in group A in both TaqMan and GWAS analyses. Lastly, the minor C allele of MPPED2 rs514644 carried a significantly increased risk of complications. These four genes may be linked with the onset of lachrymal/salivary gland lesions in type 1 AIP patients and require further study.

ABCF1 extrinsically regulates retinal pigment epithelial cell phagocytosis

Intracellular ABCF1 is identified and characterized as a new ligand to extrinsically stimulate retinal pigment epithelial cell phagocytosis. A new approach developed in this study is broadly applicable to many other phagocytes and will enable systematic elucidation of their ligands to broaden understanding of extrinsic regulation and cargo recognition.

Phagocytosis of shed photoreceptor outer segments (POSs) by retinal pigment epithelial (RPE) cells is critical to retinal homeostasis and shares many conserved signaling pathways with other phagocytes, including extrinsic regulations. Phagocytotic ligands are the key to cargo recognition, engulfment initiation, and activity regulation. In this study, we identified intracellular protein ATP-binding cassette subfamily F member 1 (ABCF1) as a novel RPE phagocytotic ligand by a new approach of functional screening. ABCF1 was independently verified to extrinsically promote phagocytosis of shed POSs by D407 RPE cells. This finding was further corroborated with primary RPE cells and RPE explants. Internalized POS vesicles were colocalized with a phagosome marker, suggesting that ABCF1-mediated engulfment is through a phagocytic pathway. ABCF1 was released from apoptotic cells and selectively bound to shed POS vesicles and apoptotic cells, possibly via externalized phosphatidylserine. ABCF1 is predominantly expressed in POSs and colocalized with the POS marker rhodopsin, providing geographical convenience for regulation of RPE phagocytosis. Collectively these results suggest that ABCF1 is released from and binds to shed POSs in an autocrine manner to facilitate RPE phagocytosis through a conserved pathway. Furthermore, the new approach is broadly applicable to many other phagocytes and will enable systematic elucidation of their ligands to understand extrinsic regulation and cargo recognition.

IgG4-related disease

IgG4-related disease is a protean condition that mimics many malignant, infectious, and inflammatory disorders. This multi-organ immune-mediated condition links many disorders previously regarded as isolated, single-organ diseases without any known underlying systemic condition. It was recognised as a unified entity only 10 years ago. Histopathology is the key to diagnosis. The three central pathology features of IgG4-related disease are lymphoplasmacytic infiltration, storiform fibrosis, and obliterative phlebitis. The extent of fibrosis is an important determinant of responsiveness to immunosuppressive therapies. IgG4-related disease generally responds to glucocorticoids in its inflammatory stage, but recurrent or refractory cases are common. Important mechanistic insights have been derived from studies of patients treated by B-cell depletion. Greater awareness of this disease is needed to ensure earlier diagnoses, which can prevent severe organ damage, disabling tissue fibrosis, and even death. Identification of specific antigens and T-cell clones that drive the disease will be the first steps to elucidate the pathogenesis of IgG4-related disease.

Cystic fibrosis transmembrane conductance regulator gene variants are associated with autoimmune pancreatitis and slow response to steroid treatment

BACKGROUND

Autoimmune pancreatitis (AIP) is a distinct type of chronic pancreatitis. To date, the association of CFTR gene variants with AIP has not been studied.

METHODS

The entire coding and intronic regions of the CFTR gene were examined using next-generation sequencing in 89 AIP patients. Clinical features, including imaging, histology, serology, steroid treatment response and extra-pancreatic involvement, were compared between AIP patients with and without CFTR gene variants.

RESULTS

A total of 28.1% (25/89) of the AIP patients carried 26 CFTR variants, including nine with I556V, seven with 5T, four with S42F, two with I125T, and one each with R31C, R553X, S895N, and G1069R. The presence of CFTR variants and age was independent predictors of the response to steroid treatment, as shown by multivariate analysis.

CONCLUSIONS

CFTR variants are associated with AIP. Because AIP patients with CFTR variants show slower and reduced steroid treatment responses, different treatments should be considered in AIP patients with CFTR variants.

Immunoglobulin G4-related tubulointerstitial nephritis associated with interstitial pulmonary disease: Report of a case with review of literature

Immunoglobulin G4-related disease (IgG4-RD) is an emerging clinicopathological entity. Renal involvement is dominated by tubulointerstitial nephritis (TIN) with IgG4-positive plasma cells and fibrosis. IgG4-RD commonly affects middle-aged to elderly men with accompanying extra-renal lesions such as sialadenitis, lymphadenopathy, or type 1 autoimmune pancreatitis, all of which respond favorably to corticosteroid therapy. The disease burden of IgG4-related kidney disease (IgG4-RKD) in India remains largely underestimated. We report a case of IgG4-RKD manifesting as TIN associated with interstitial pulmonary disease, illustrating typical clinico-pathologic, serologic, immuno-histochemical, and ultrastructural features of this condition. In view of potential amelioration of renal dysfunction with appropriate therapy, the need for awareness of this condition and early diagnosis is highlighted.

Possible involvement of Toll-like receptor 7 in the development of type 1 autoimmune pancreatitis

BACKGROUND

High serum immunoglobulin G4 (IgG4) levels and IgG4-positive plasma cell infiltration are characteristic of type 1 autoimmune pancreatitis (AIP). It is unclear whether innate immunity is a cause of type 1 AIP; the possible involvement of microbial infection has been suggested in its pathogenesis. To clarify the pathogenesis of type 1 AIP, we investigated Toll-like receptors (TLRs) in type 1 AIP patients.

METHODS

We studied nine cases of type 1 AIP with ten cases of alcoholic chronic pancreatitis (ACP) and three of the samples from non-tumorous lesion of neuroendocrine tumor (NET) as control subjects. We counted the number of TLR1-11-positive cells immunohistochemically stained with anti-TLR1-11 antibodies. To identify TLR-positive cells in pancreata from type 1 AIP patients, we used a double-immunofluorescence method and counted the numbers of identifiable CD68-, CD163-, CD123-, and CD20-positive cells.

RESULTS

In type 1 AIP, TLR7 (8.815 ± 1.755), TLR8 (3.852 ± 1.489), and TLR10 (3.852 ± 0.921) were highly expressed. Only the ratio of TLR7 per monocyte was significantly higher in type 1 AIP (0.053 ± 0.012) than in ACP (0.007 ± 0.004; p < 0.01) and non-tumorous lesion of NET (0.000 ± 0.000; p < 0.01). In type 1 AIP, the CD163 to TLR7 ratio (0.789 ± 0.031) was significantly higher both than that of CD123 to TLR7 ratio (0.034 ± 0.006; p < 0.001) and CD20 to TLR7 ratio (0.029 ± 0.010; p < 0.001).

CONCLUSIONS

TLR7 might be key pattern-recognition receptors involved in the development of type 1 AIP.

Human cationic trypsinogen but not serine peptidase inhibitor, Kazal type 1 variants increase the risk of type 1 autoimmune pancreatitis

BACKGROUND AND AIM

Autoimmune pancreatitis (AIP) is a distinct disease entity. Whether the genes involved in pancreatic acinar cell injury, cationic trypsinogen gene (protease, serine, 1 [trypsin 1] [PRSS1]) and the pancreatic secretory trypsin inhibitor gene (serine peptidase inhibitor, Kazal type 1 [SPINK1]), are associated with AIP remains to be explored.

METHODS

Genetic analyses of PRSS1 variants (exon 2 and 3) and SPINK1 variants (exon 1, 2, and 3) including the intronic areas in 118 patients with AIP and 200 control subjects were performed by direct DNA sequencing. Clinical features including imaging, histology, serology, response to steroid, and extra-pancreatic organ involvement in AIP patients with and without variants were compared.

RESULTS

A total of 19 PRSS1 variants and one SPINK1 variant were identified in 20 (16.9%) out of 118 AIP patients. They included one K92N, nine R116C, seven T137M, one C139S, and one C139F of PRSS1 and one 2(IVS3 + 2) of SPINK1. No PRSS1 or SPINK1 variant was identified in the control group. Patients with PRSS1 variants had an increased risk of AIP with odds ratio 22.37 (95% confidence interval: 2.96-168.8, P = 0.003) and higher frequency of serum IgG4 above 280 mg/dL. Using immunosuppressive agent and PRSS1 variant were predictors of less disease relapse in univariate analysis. Presence of PRSS1 variants was the only negative predictor for disease relapse in multivariate analysis.

CONCLUSIONS

We found a significantly higher frequency of PRSS1 variants in AIP patients than in geographically and ethnically matched control subjects. PRSS1 variants are associated with less disease relapse in AIP.

Primary Biliary Cirrhosis and Primary Sclerosing Cholangitis: a Review Featuring a Women's Health Perspective

Primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) are two major types of chronic cholestatic liver disease. Each disorder has distinguishing features and variable progression, but both may ultimately result in cirrhosis and hepatic failure. The following offers a review of PBC and PSC, beginning with a general overview of disease etiology, pathogenesis, diagnosis, clinical features, natural course, and treatment. In addition to commonly associated manifestations of fatigue, pruritus, and fat-soluble vitamin deficiency, select disease-related topics pertaining to women's health are discussed including metabolic bone disease, hyperlipidemia and cardiovascular risk, and pregnancy-related issues influencing maternal disease course and birth outcomes. This comprehensive review of PBC and PSC highlights some unique clinical considerations in the care of female patients with cholestatic liver disease.

IgG4-related disease

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is an immune-mediated condition that can affect almost any organ and is now being recognized with increasing frequency. IgG4-RD is characterized by a lymphoplasmacytic infiltrate composed of IgG4(+) plasma cells, storiform fibrosis, obliterative phlebitis, and mild to moderate eosinophilia. The diagnosis of IgG4-RD unifies many eponymous fibroinflammatory conditions that had previously been thought to be confined to single organs. IgG4-RD lesions are infiltrated by T helper cells, which likely cause progressive fibrosis and organ damage. IgG4 antibodies are generally regarded as noninflammatory. Although autoreactive IgG4 antibodies are observed in IgG4-RD, there is no evidence that they are directly pathogenic. Rituximab-induced B cell depletion in IgG4-RD leads to rapid clinical and histological improvement accompanied by swift declines in serum IgG4 concentrations. Although IgG autoantibodies against various exocrine gland antigens have been described in IgG4-RD, whether they are members of the IgG4 subclass is unknown. The contribution of autoantibodies to IgG4-RD remains unclear.

Identification of commensal flora-associated antigen as a pathogenetic factor of autoimmune pancreatitis

OBJECTIVES

Autoimmune pancreatitis (AIP) is a chronic fibro-inflammatory disease of the pancreas constituting, in part, a recently defined nosological entity of IgG4-related systemic sclerosing diseases. The pathogenetic factors of AIP have not been fully elucidated. We previously established a mouse model of AIP using chronic exposure to a commensal bacteria, Escherichia coli.

METHODS

To determine the pathogenetically relevant antigen of E. coli, the outer membrane fractions of E. coli were subjected to two-dimensional gel electrophoresis followed by immunoblotting against sera from the AIP model. Immunoreactive spots were determined using MALDI TOF/MS and Mascot search. The recombinant protein of the identified antigen was examined for their ability to induce AIP-like disorder in C57BL/6 mice. Furthermore, the antibody titer against that antigen was determined in AIP patients.

RESULTS

One representative spot reacting with sera from E. coli-inoculated mice was identified as FliC from E. coli, based on the results of TOF/MS. The repeated inoculation of recombinant FliC in C57BL/6 mice induced AIP-like pancreatitis and higher titers of anti-lactoferrin and anti-carbonic anhydrase II. Sera from patients with AIP had the highest antibody titer, while those from patients with pancreatic diseases other than AIP had a higher antibody titer against E. coli and FliC, compared with pancreatic disease-free controls.

CONCLUSIONS

FliC from E. coli may pathogenetically generate an AIP-like inflammation status. A reconsideration of the importance of commensal bacteria as an environmental factor(s) capable of inducing autoimmunity could provide insight to overcoming AIP.

Mechanisms and assessment of IgG4-related disease: lessons for the rheumatologist

Recognition of IgG4-related disease as an independent chronic inflammatory disorder is a relatively new concept; previously, the condition was thought to represent a subtype of Sjögren's syndrome. IgG4-related disease is characterized by elevated serum levels of IgG4 and inflammation of various organs, with abundant infiltration of IgG4-bearing plasma cells, storiform fibrosis and obliterative phlebitis representing the major histopathological features of the swollen organs. The aetiology and pathogenesis of this disorder remain unclear, but inflammation and subsequent fibrosis occur due to excess production of type 2 T-helper-cell and regulatory T-cell cytokines. The disease can comprise various organ manifestations, such as dacryoadenitis and sialadenitis (also called Mikulicz disease), type 1 autoimmune pancreatitis, kidney dysfunction and lung disease. Early intervention using glucocorticoids can improve IgG4-related organ dysfunction; however, patients often relapse when doses of these agents are tapered. The disease has also been associated with an increased incidence of certain malignancies. Increased awareness of IgG4-related disease might lead to consultation with rheumatologists owing to its clinical, and potentially pathogenetic, similarities with certain rheumatic disorders. With this in mind, we describe the pathogenic mechanisms of IgG4-related disease, and outline considerations for diagnosis and treatment of the condition.

Current status of research on autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis characterized clinically by frequent presentation with obstructive jaundice, histologically by lymphoplasmacytic infiltration with fibrosis, and therapeutically by a dramatic response to steroids. AIP have recently been classified into two subtypes, lymphoplasmacytic sclerosing pancreatitis (LPSP) and idiopathic duct centric pancreatitis (IDCP). The pathogenesis of AIP may involve genetic susceptibility, autoantibodies, molecular mimicry, imbalance of T-cell-mediated immune regulation, and gene mutation. In this article, we will systematically review typical and atypical clinical, imaging and histopathological features of AIP, with an emphasis placed on the advances in the diagnosis and treatment of this disease.

Gene expression profiling in treatment-naive schizophrenia patients identifies abnormalities in biological pathways involving AKT1 that are corrected by antipsychotic medication

Distinct gene expression profiles can be detected in peripheral blood mononuclear cells (PBMCs) in patients with schizophrenia; however, little is known about the effects of antipsychotic medication. This study compared gene expression profiles in PMBCs from treatment-naive patients with schizophrenia before and after antipsychotic drug treatment. PBMCs were obtained from 10 treatment-naive schizophrenia patients before and 6 wk after initiating antipsychotic drug treatment and compared to PMBCs collected from 11 healthy community volunteers. Genome-wide expression profiling was conducted using Illumina HumanHT-12 expression bead arrays and analysed using significance analysis of microarrays. This analysis identified 624 genes with altered expression (208 up-regulated, 416 down-regulated) prior to antipsychotic treatment (p < 0.05) including schizophrenia-associated genes AKT1, DISC1 and DGCR6. After 6-8 wk treatment of patients with risperidone or risperidone in combination with haloperidol, only 106 genes were altered, suggesting that the treatment corrected the expression of a large proportion of genes back to control levels. However, 67 genes continued to show the same directional change in expression after treatment. Ingenuity® pathway analysis and gene set enrichment analysis implicated dysregulation of biological functions and pathways related to inflammation and immunity in patients with schizophrenia. A number of the top canonical pathways dysregulated in treatment-naive patients signal through AKT1 that was up-regulated. After treatment, AKT1 returned to control levels and less dysregulation of these canonical pathways was observed. This study supports immune dysfunction and pathways involving AKT1 in the aetiopathophysiology of schizophrenia and their response to antipsychotic medication.

Cutaneous sarcoidosis in a chronic hepatitis C patient receiving pegylated interferon and ribavirin therapy

A 61-year-old Japanese woman suffered from a small, painful, subcutaneous nodule on the sole of her foot that was 10 mm across in diameter during pegylated interferon (PEG IFN) and ribavirin (RBV) combination therapy for chronic hepatitis C. Skin biopsy revealed multiple non-caseating granulomas composed of epithelioid histiocytes with multinucleate giant cells, which was consistent with sarcoidosis. Ophthalmologic examination revealed uveitis. Thoracic computed tomography (CT) showed multiple bilateral hilar lymphadenopathies and a diffuse micronodular interstitial pattern of the lungs. Genetic analysis indicated a probable homozygous haplotype of A*02:01-C*15:02-B*51:01-DRB1*16:02-DQB1*05:02 in human leukocyte antigen regions. The patient was observed carefully without any additional medication because no significant systemic symptoms were noted. Combination therapy was continued for 2 months afterwards. She was asymptomatic for over 3 years of follow up, and repeated hematological and biological investigations and chest CT showed improvement. In conclusion, clinicians should bear sarcoidosis in mind as a complication during PEG IFN and RBV combination therapy. They should also be aware of the usually good prognosis of PEG IFN-induced cutaneous sarcoidosis in order not to prematurely discontinue a treatment necessary for liver disease; maintenance of PEG IFN treatment may be advised with careful follow up.

Genetic risk factors for pancreatic disorders

A combination of genetic, environmental, and metabolic factors contribute to the development and recurrence of acute and chronic pancreatitis; information on all of these is required to manage patients effectively. For example, variants that affect regulation of the protease, serine (PRSS)1-PRSS2, and claudin (CLDN)2 loci, rather than their coding sequences, interact with other genetic and environmental factors to affect disease development. New strategies are needed to use these data and determine their contribution to pathogenesis, because these variants differ from previously studied, rare variants in exons (coding regions) of genes such as PRSS1, SPINK1, cystic fibrosis transmembrane conductance regulator (CFTR), chymotrypsin (CTR)C, and calcium-sensing receptor (CASR). Learning how various genetic factors affect pancreatic cells and systems could lead to etiology-based therapies rather than treatment of symptoms.

IgG4-related tubulointerstitial nephritis with plasma cell-rich renal arteritis

Immunoglobulin G4 (IgG4)-related tubulointerstitial nephritis is a newly recognized clinicopathologic entity that may occur as an isolated renal lesion or as part of a multisystem disorder. It is characterized by plasma cell-rich interstitial nephritis with abundant IgG4-positive plasma cells and IgG-dominant tubulointerstitial immune deposits. We report the first case of IgG4-related tubulointerstitial nephritis with multifocal plasma cell-rich renal arteritis presenting as acute kidney injury in a 72-year-old man. Seven weeks of prednisone therapy led to nearly complete recovery of kidney function. This case enlarges the morphologic spectrum of this disorder and emphasizes the need to distinguish it from other causes of renal vasculitis.

Commensal Flora, is it an Unwelcomed Companion as a Triggering Factor of Autoimmune Pancreatitis?

The etiopathogenesis of many autoimmune disorders has not been identified. The aim of this paper is to focus on the involvement of bacterial exposure, as an environmental factor, in the pathogenesis of autoimmune pancreatitis (AIP), which is broadly categorized as autoimmune disorders involving pancreatic lesions. Avirulent and/or commensal bacteria, which may have an important role(s) as initiating/progressing factors in the pathogenesis of autoimmune disorder AIP, will be emphasized.

Distinguishing autoimmune pancreatitis from pancreaticobiliary cancers: current strategy

OBJECTIVE

A review of the literature to identify current modalities for the diagnosis of autoimmune pancreatitis (AIP) with the objective of establishing a strategy to distinguish it from pancreaticobiliary cancers.

BACKGROUND

Pancreatic and biliary manifestations of AIP mimic pancreaticobiliary cancers. Misdiagnosis of AIP can result in major surgery for a steroid-responsive disease.

METHODS

A review of the literature was performed to identify recent advances in the diagnosis of AIP and evaluate outcomes with various diagnostic strategies to minimize operative intervention for an autoimmune disease.

RESULTS

Diagnostic criteria for AIP are based on histology, imaging, serology, extrapancreatic organ involvement, and response to steroid therapy. The most commonly involved extrapancreatic sites are bile duct, kidney, and retroperitoneum. The Mayo Clinic diagnostic strategy utilizes core biopsy of the pancreas and the Japanese strategy depends on a characteristic pancreatogram. The rate of operative intervention was similar with both strategies and none of the patients with cancer received steroid therapy. Immunoglobulin G subtype 4 (IgG4)-associated cholangitis mimics cholangiocarcinoma and presence of more than 10 IgG4-positive plasma cells/high power field on endoscopic biopsy of the bile duct was diagnostic for AIP in 88% patients. Biliary complications and early relapse are common after surgical resection and immunomodulatory drugs can maintain long-term remission.

CONCLUSION

Criteria based on histology, imaging, endoscopy, serology, extrapancreatic organ involvement, and response to steroid therapy improve the diagnostic yield for AIP. Application of diagnostic and therapeutic protocols by a multidisciplinary team will optimize outcomes with a decline in the rate of operative intervention for AIP, a steroid-responsive disease with propensity for relapse.