Antibodies to carbonic anhydrase in systemic lupus erythematosus and other rheumatic diseases

Spontaneous regression of tumours. Possible cross reactivity of autoantibodies against carbonic anhydrase I

Spontaneous tumour regression in patients after high dose therapy and autologous stem cell transplantation or patients with standard therapy is accompanied with the presence of high titers autoantibodies against carbonic anhydrase I (CA I). The concomitant presence of aplastic anaemia-like syndrome in these patients points to parallel bone marrow suppression during this period. It seems that CA I, an 'obscure' enzyme, does not have any significant physiological role in humans. One possible explanation points to the fact that autoantibodies against CA I may target another antigen(s) which is(are) important in tumour growth as well as in normal haematopoiesis. One of the candidates for such a target is the DNA polymerase theta.

Association of autoantibody levels with different stages of age-related macular degeneration (AMD): Results from the population-based Gutenberg Health Study (GHS)

PURPOSE

Anti-retinal autoantibodies are assumed to be associated with age-related macular degeneration (AMD). To our knowledge, this is the first evaluation of autoantibodies in human sera of participants with different stages of AMD in a large population-based, observational cohort study in Germany.

METHODS

The Gutenberg Health Study (GHS) is a population-based, observational cohort study in Germany, including 15,010 participants aged between 35 and 74. Amongst others, non-mydriatic fundus photography (Visucam PRO NM™, Carl Zeiss Meditec AG, Jena, Germany) was performed. Fundus images of the first 5000 participants were graded based on the Rotterdam Eye Study classification. Sera of participants with AMD (n=541) and sera of age-matched participants without AMD (n=490) were analyzed by antigen-microarrays. Besides descriptive statistics, autoantibody-levels were compared by Mann-Whitney-U test and the associations of level of autoantibodies with AMD were calculated by logistic regression analysis. Likewise, possible associations of the autoantibodies and both clinical and laboratory parameters on AMD subjects were analyzed.

RESULTS

Autoantibodies against transferrin (p<0.001) were significantly downregulated in participants with early AMD and soft, distinct drusen (≥63 μm) or pigmentary abnormalities only compared to Controls. Mitogen-activated protein kinase 3 (p=0.041), glutathione peroxidase 4 (p=0.048), clusterin (p=0.045), lysozyme (p=0.19), protein kinase C substrate 80K-H (p=0.02), heat shock 70 kDa protein 1A (p=0.04) and insulin (p=0.018) show a trend between Control and participants with early AMD and soft, distinct drusen (≥63 μm) or pigmentary abnormalities only.

CONCLUSIONS

This study contributes to a growing knowledge of autoantibodies in association with different AMD stages compared to controls in the context of a large population-based study in Germany. Especially autoantibodies against inflammatory proteins were downregulated in participants with early AMD and soft, distinct drusen (≥63 μm) or pigmentary abnormalities only.

Anti-carbonic anhydrase II antibody reflects urinary acidification defect especially in proximal renal tubules in patients with primary Sjögren syndrome

Primary Sjögren syndrome (pSS) is a systemic autoimmue disease featured by excessive autoantibody production. It has been demonstrated that anti-carbonic anhydrase II (anti-CA II) antibody is correlated with renal tubular acidosis in pSS; however, no further details about urinary acidification defect have been reported, and the antibody's relationship with other organ impairments remains unknown. This case-control study aimed to examine anti-CA II antibody levels in relation to various systemic complications in pSS, and evaluate its potential role as a organ-specific biomarker in a Chinese cohort. Serum anti-CA II antibody levels were determined using ELISA in 123 patients with pSS and 72 healthy controls. The medical records of the patients were collected, and the correlation between serum anti-CA II antibody and clinical/immunological parameters was investigated. Serum anti-CA II antibody level and its positive rate were significantly increased in pSS patients compared with controls, and ANA-positive patients presented even higher titers of the antibody. In anti-CA II positive group, remarkably higher urine pH and bicarbonate, as well as lower urine titratable acid and serum potassium were observed, which indicated renal tubular acidification dysfunction both involving bicarbonate reabsorption and acid secretion. In addition, platelet count and complement 3, complement 4 levels decreased, whereas serum IgG, IgA and γ-globulin levels increased notably in accord with a higher EULAR SS disease activity index score in these patients. Further analysis showed that anti-CA II antibody was most elevated in patients with defect in bicarbonate reabsorption, reflecting proximal renal tubular injury, rather than in patients with distal renal tubular acidosis as previously reported. In conclusion, anti-CA II antibody reflects renal (especially proximal renal tubular) and hematologic impairment as well as increased disease activity in pSS. It may act as a serum biomarker of systemic damage of pSS.

Correlation of photoreceptor damage with anti-retina antibodies level in aqueous humor in macular edema patients

This study aimed to investigate the correlation between the severity of photoreceptor damage and the level of anti-retina antibodies (ARAs) in aqueous humor, including recoverin, CA II and enolase-α IgG antibody of macular edema patients. Aqueous humor samples were collected from macular edema patients and from cataract patients. Patients were divided into three groups according to the severity of discontinuity of ellipsoid zone (EZ) shown on optical coherence tomography (OCT) imaging: cataract patients with intact EZ, macular edema patients with mild EZ damage, and macular edema patients with severe EZ damage. The level of ARAs was determined with enzyme-linked immunosorbent assay (ELISA). The correlation between the level of ARAs and the degree of photoreceptor damage was analyzed. The level of ARAs of the intact EZ group was significantly lower than that in the severely damaged group (P < 0.05). The level of recoverin IgG of the intact EZ group was significantly lower than mildly damaged group (P = 0.030). In a subgroup analysis, the level of recoverin IgG of DME patients was correlated with their central retinal thickness (CRT) (r = 0.462, P = 0.035). The level of ARAs in aqueous humor of patients with DME and RVO-ME was correlated with the degree of photoreceptor damage.

The Diagnostic Performance of Early Sjögren's Syndrome Autoantibodies in Juvenile Sjögren's Syndrome: The University of Florida Pediatric Cohort Study

Objectives

The aim of this study was to evaluate the clinical validity of early Sjögren's syndrome (SS) autoantibodies (eSjA), which were originally marketed for early diagnosis of SS, for juvenile SS (JSS) in a recently identified pediatric cohort.

Methods

A total of 105 symptomatic subjects with eSjA results available were evaluated at the Center for Orphaned Autoimmune Disorders at the University of Florida and enrolled for this study. JSS diagnosis was based on the 2016 ACR/EULAR SS criteria. Demographic/clinical/laboratory parameters were compared between JSS (n = 27) and non-JSS (n = 78) for % positivity, sensitivity, and specificity of eSjA (SP1, anti-salivary protein; CA6, anti-carbonic anhydrase VI; PSP, anti-parotid secretory protein) and classic SS-autoantibodies (cSjA; ANA, SSA/SSB, RF, and others) either alone or in combination. Associations between eSjA and diagnostic/glandular parameters were also determined by Fisher's exact test.

Results

Compared to non-JSS, JSS patients exhibited sicca symptoms demonstrating reduced unstimulated salivary flow rate (USFR) and abnormal glandular features revealed by salivary gland ultrasound (SGUS). Among cSjA, ANA demonstrated the highest sensitivity of 69.2%, while SSA, SSB, and RF showed around 95% specificities for JSS diagnosis. The % positive-SSA was notably higher in JSS than non-JSS (56% vs. 5%). Of eSjA, anti-CA6 IgG was the most prevalent without differentiating JSS (37%) from non-JSS (32%). Sensitivity and specificity of eSjA were 55.6 and 26.9%, respectively. Autoantibodies with potentially applicable specificity/sensitivity for JSS were seen only in cSjA without a single eSjA included. There were no associations detected between eSjA and focus score (FS), USFR, SSA, SGUS, and parotitis/glandular swelling analyzed in the entire cohort, JSS, and non-JSS. However, a negative association between anti-PSP and parotitis/glandular swelling was found in a small group of positive-SSA (n = 19, p = 0.02) whereas no such association was found between anti-PSP-positive compared to anti-PSP-negative. JSS and non-JSS groups differed in FS, USFR, and EULAR SS Patient Reported Index Dryness/Mean in CA6/PSP/ANA, SP1, and SSA-positive groups, respectively. Additionally, a higher FS was found in RF-positive than RF-negative individuals.

Conclusions

eSjA underperformed cSjS in differentiating JSS from non-JSS. The discovery of clinical impact of eSjA on early diagnosis of JSS necessitates a longitudinal study.

Triosephosphate isomerase, carbonic anhydrase, and creatinine kinase-brain isoform are possible antigen targets in patients with achalasia

BACKGROUND

Idiopathic achalasia is an uncommon esophageal motor disorder. The disease involves interaction between inflammatory and autoimmune responses. However, the antigens related to the disease are still unknown.

AIM

To identify the possible antigen targets in muscle biopsies from lower esophageal sphincter (LES) of achalasia patients.

METHODS

Esophageal biopsies of patients with type I and type II achalasia and esophagogastric junction outflow obstruction (EGJOO) were analyzed. Lower esophageal sphincter muscle biopsy from a Healthy organ Donor (HD) was included as control for two-dimensional gel electrophoresis. Immunoblotting of muscle from LES lysate with sera of type I, type II achalasia, or type III achalasia, sera of EGJOO and sera of healthy subjects (HS) was performed. The target proteins of the serum were identified by mass spectrometry Matrix-assited laser desorption/ionization time-of-flight (MALDI-TOF).

KEY RESULTS

The proteomic map of muscle from LES tissue lysates of type I, and type II achalasia, EGJOO, and HD were analyzed and divided into three important regions. We found a difference in the concentration of certain spots. Further, we observed the serum reactivity of type I achalasia and type II achalasia against 45 and 25 kDa bands of type I achalasia tissue. Serum of type III achalasia and EGJOO mainly recognized 25 kDa band. Bands correspond to triosephosphate isomerase (TPI) (25 kDa), carbonic anhydrase (CA) (25 kDa) and creatinine kinase-brain (CKB) isoform (45 kDa).

CONCLUSIONS AND INFERENCES

We identify three antigen targets, TPI, CA, and CKB isoform, which are recognized by sera from patients with achalasia.

Unique properties of IgG4 antibody and its clinical application in autoimmune pancreatitis

BACKGROUND

Autoimmune pancreatitis (AIP) is defined as a unique form of chronic pancreatitis characterized by clinical presentation with obstructive jaundice, a dense lymphoplasmacytic infiltrate and fibrosis histologically, and a dramatic response to steroids therapeutically. The possible role of IgG4 in driving the pathology of AIP is a controversial subject that has not been addressed satisfactorily.  Objective: The purpose of this review is to discuss the unique biology of IgG4 that are important for its role and the clinical applications for serologic detection.

METHODS

Review of current literature about IgG4 antibody in the clinical application in AIP.

RESULTS

High serum levels of IgG4 are an important biomarker and broadly used for diagnosis, differentiation from diseases especially pancreatic cancer, and as a parameter to indicate disease activity, extra-pancreatic lesions, and treatment monitoring. However, some controversial studies show it has a limited specificity and sensitivity in these conditions.  Conclusion: Although increasing studies have promoted our understanding of the structure and function of IgG4, there is still dilemma between the beneficial and the adverse aspect of IgG4 in the pathogenesis of AIP.

Sera of patients with spontaneous tumour regression and elevated anti-CA I autoantibodies change the gene expression of ECM proteins

Spontaneous tumour regression after high‐dose therapy and autologous stem cell transplantation is associated with the aplastic anaemia‐like syndrome and the presence of polyclonal autoantibodies against carbonic anhydrase I (CA I). When tumour cells were grown in vitro in the presence of patients’ sera positive for anti‐CA I autoantibodies, their morphological pattern was altered. These changes were accompanied by modifications in the gene expression profile. We observed downregulation of genes of the basal lamina assembly (collagen type IV alpha 4, the laminin subunit gamma 2), the extracellular matrix (collagen type I alpha 1), the cytoskeleton (keratin 14 type I), the collagen triple helix repeat containing 1 and the proto‐oncogene WNT7B. On the other hand, the expression of the CA 1 gene was increased in the tumour cells. It was also noticed that the presence of anti‐CA I autoantibodies did not impair tumour cell proliferation and cell viability in vitro. These findings were observed only in the presence of patients’ sera positive for anti‐CA I autoantibodies.

Antibodies reacting to carbonic anhydrase isozymes (I and II) and albumin in sera from dogs

IgGs to carbonic anhydrase isozymes (CA-I and CA-II) and albumin were identified in dog serum. IgG titers were determined in the sera of asymptomatic dogs, and in dogs with atopic dermatitis, diarrhea and/or vomiting, diabetes and/or pancreatitis, kidney disease, hepatic disease, and thyroid gland disease, using ELISA. Low titres of IgG-reactive CA-I, CA-II, BSA, and CSA were found in the sera of healthy beagles. Compared with healthy beagles, there was a significant difference in the titers of antibodies against CA-I in asymptomatic dogs, dogs with diabetes and/or pancreatitis, or thyroid gland disease, or hepatic disease. Compared with healthy beagles, there was a significant difference in the antibody titer of anti-CA-II IgG in asymptomatic dogs and in those with hepatic disease. There was a significant difference in the antibody titer of anti-BSA IgG between healthy beagles and dogs with hepatic disease.

Recent Advances in Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis that is characterized clinically by frequent presentation with obstructive jaundice, histologically by a dense lymphoplasmacytic infiltrate with fibrosis, and therapeutically by a dramatic response to corticosteroid therapy. Two distinct diseases, type 1 and type 2 AIP, share these features. However, these 2 diseases have unique pancreatic histopathologic patterns and differ significantly in their demographic profiles, clinical presentation, and natural history. Recognizing the popular and long-standing association of the term "AIP" with what is now called "type 1 AIP," we suggest using "AIP" solely for type 1 AIP and to acknowledge its own distinct disease status by using "idiopathic duct-centric chronic pancreatitis" (IDCP) for type 2 AIP. AIP is the pancreatic manifestation of immunoglobulin G4-related disease (IgG4-RD). The etiopathogenesis of AIP and IgG4-RD is largely unknown. However, the remarkable effectiveness of B-cell depletion therapy with rituximab in patients with AIP and IgG4-RD highlights the crucial role of B cells in its pathogenesis. IDCP is less commonly recognized, and little is known about its pathogenesis. IDCP has no biomarker but is associated with inflammatory bowel disease in ~25% of patients. Recently, the international consensus diagnostic criteria for AIP identified combinations of features that are diagnostic of both diseases. Both AIP and IDCP are corticosteroid responsive; however, relapses are common in AIP and rare in IDCP. Therefore, maintenance therapy with either an immunomodulator (eg, azathioprine, 6-mercaptopurine, or mycophenolate mofetil) or rituximab is often necessary for patients with AIP. Long-term survival is excellent for both patients with AIP and patients with IDCP.

Autoimmune pancreatitis as an initial manifestation of systemic lupus erythematosus

Abstract We report a case of systemic lupus erythematosus that concomitantly occurred with autoimmune pancreatitis. The clinical manifestations of pancreatitis improved in response to steroid therapy. Although the pathogenesis of autoimmune pancreatitis is still controversial, as is that of systemic lupus erythematosus, the observations in the present case suggest the presence of an autoimmune mechanism underlying autoimmune pancreatitis.

A comprehensive review of autoantibodies in primary Sjögren's syndrome: clinical phenotypes and regulatory mechanisms

Sjögren's syndrome (SS) is a systemic autoimmune disease characterized by periepithelial lymphocytic infiltrates in affected tissues and the production of plethora of autoantibodies. Among them autoimmune responses against Ro/SSA and La/SSB are of major importance since their detection is routinely used for disease diagnosis and clinical characterization. Although the exact mechanisms underlying disease pathogenesis are not fully understood, the important role of salivary gland epithelial cells (SGEC) in the initiation and development of the local immune responses is well-established. SGECs are also capable to mediate the exposure of the Ro/SSA and La/SSB autoantigens to the immune system by elevated apoptosis and autoantigen release in apoptotic bodies and/or by the secretion of autoantigen-containing exosomes. The expression of these autoantigens in epithelial cells appears to be tightly regulated. Up-to-date, signaling of certain innate immunity receptors, such as TLR3, appear to be implicated in the regulation of Ro/SSA and La/SSB expression by SGECs, whereas the deregulated expression of certain miRNAs that are predicted to target them in SS patients suggests a regulatory feedback at the post-transcriptional level. In the periphery, the humoral autoimmune responses are further regulated by the development of an active network of idiotypic-antiidiotypic antibodies. The plethora of mechanisms suggests that autoimmune humoral responses in SS are tightly regulated. In this review, the major humoral autoimmune responses, recent advances on the role of epithelial cells in their development, as well as possible regulatory mechanisms will be discussed.

Overlap of epitopes recognized by anti-carbonic anhydrase I IgG in patients with malignancy-related aplastic anemia-like syndrome and in patients with aplastic anemia

High titers of anti-carbonic anhydrase I (anti-CA I) autoantibodies were detected in the sera of patients with malignancies who developed an aplastic anemia-like (AA-like) syndrome after a high-dose therapy (HDT) and autologous stem cell transplantation (ASCT). It was found, that the presence of these anti-CA I autoantibodies is associated with spontaneous tumor regression. The main immunodominant epitopes of carbonic anhydrase isoform I (CA I) have previously been identified using epitope extraction technique in combination with mass spectrometric detection and bioinformatic verification. Similarly, the sera of patients with bona fide aplastic anemia (AA) who poorly responded to immunosuppressive treatment with anti-thymocyte globulin (ATG) demonstrated high titers of anti-CA I antibodies. In order to reveal differences between these antibodies, we applied the same methodology of epitope mapping procedure. Surprisingly, the anti-CA I antibodies from the both groups of patients compatibly recognized the same four candidate CA I epitopes--DGLAV, NVGHS, SLKPI, SSEQL. This finding may indicate common pathophysiological mechanisms in these two syndromes. However, at this moment it remains unresolved if anti-CA I antibodies are implicated in marrow or tumor suppression or are just an epi-phenomenon.

Antibodies against carbonic anhydrase in patients with aplastic anemia

BACKGROUND/AIMS

Antibodies against carbonic anhydrase (CA) have been detected in patients with an aplastic anemia (AA)-like syndrome after autologous stem cell transplantation.

METHODS

We analyzed sera of 53 bona fide AA patients before and after treatment with anti-thymocyte globulin (ATG) or bone marrow transplantation for the presence of anti-CA antibodies.

RESULTS

Anti-CA antibodies were detected in 20 patients (38%) and were associated with older age at diagnosis of AA. Antibody-positive patients showed poor response to ATG treatment (complete response 14%) and inferior long-term survival (36% at 10 years), when compared to antibody-negative patients (complete response and 10-year survival both 64%). Two thirds of patients with antibodies at diagnosis of AA became antibody negative after treatment with ATG. Clearance of the antibody did not appear to be associated with hematological improvement.

CONCLUSION

Antibodies against CA are detected frequently at diagnosis of AA, and their presence identifies a subset of patients with poor response to immunosuppressive treatment.

Subgroups of Sjögren syndrome patients according to serological profiles

Sjögren Syndrome (SS) is a systemic, autoimmune disorder characterized by lymphocytic infiltration of the exocrine glands. Different clinical associations have been described for each of the diverse autoantibodies found in SS patients. Antibodies directed against the Ro/La ribonucleoprotein complexes have been correlated with younger age, more severe dysfunction of the exocrine glands and a higher prevalence of extraglandular manifestations. Anti-nuclear antibodies and rheumatoid factors have been associated to extraglandular manifestations and an active immunological profile, while cryoglobulins are markers of more severe disease and correlate to lymphoma development and death. Antibodies to cyclic citrullinated peptides are scarce in SS and have been linked in some cases to the development of non-erosive arthritis. Furthermore, the presence of anti-mitochondrial antibodies and anti-smooth muscle antibodies in the sera of primary SS patients is considered indicative of primary biliary cirrhosis and autoimmune hepatitis, respectively. In addition, anti-centromere antibodies have been associated with a clinical phenotype intermediate between primary SS and systemic sclerosis, while antibodies against carbonic anhydrase have been related to renal tubular acidosis. Finally, an association of anti-muscarinic antibodies with cytopenias and a higher disease activity has also been described in primary SS. In conclusion, although not all of the above mentioned antibodies are useful for predicting distinct patient subgroups in SS, knowledge of the clinical associations of the different autoantibody specificities encountered in SS can advance our understanding of the disease and improve patient management.

Autoantibodies in Sjögren's syndrome: clinical presentation and regulatory mechanisms

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease mostly affecting the exocrine glands. A large number of autoantibodies have been detected in the serum of patients with pSS. Among them, anti-Ro/SSA and anti-La/SSB autoantibodies are the most common; they serve as disease markers and are involved in the pathogenesis of neonatal lupus syndrome (NLS). Other autoantibodies are associated with significant clinical phenotypes, such as cryoglobulins with development of non-Hodgkin's lymphoma, anti-centromere antibodies with Raynaud's phenomenon and anti-mitochondrial antibodies with liver pathology. As a result, pSS patients can be schematically categorized in subgroups according to their serological profile. Although the clinical utility of these autoantibodies is appreciated, little is known about the mechanisms related to their production and the regulation of the autoimmune response. In the present review, the clinical subsets of patients with pSS related to different autoantibodies as well as the regulating mechanisms of their production with special emphasis on idiotypic/anti-idiotypic network are discussed.

Autoimmune pancreatitis

Autoimmune pancreatitis is becoming a more widely recognized form of pancreatitis that can mimic pancreatic or biliary malignancy. The combination of serological, histological and radiographic findings makes it unique among pancreatic diseases. The presence of autoantibodies, IgG4 and a lymphoplasmacytic infiltrate reflect its autoimmune etiology. The dramatic response to steroids is also a distinguishing feature and differentiates it from other pancreatic diseases.

Carbonic anhydrase III: A new target for autoantibodies in autoimmune diseases

The objective of this study was to identify new autoantibodies that could be useful for the diagnosis of rheumatoid arthritis (RA) using immunoblotting on synovial membrane proteins which represent the best source of candidate RA autoantigens. A new target protein with a molecular weight of 26 kDa was found to be recognized by autoantibodies in RA sera and was identified using MALDI-TOF mass spectrometry and second-dimension electrophoresis as carbonic anhydrase III (CAIII). Three similar protein spots at 26 kDa were recognized by both human sera and monoclonal antibody (mAb) directed against CAIII on immunoblotting using the human recombinant CAIII. Interestingly, CAIII expression within the synovial membrane was not observed in non-RA patients and was differentially expressed among RA patients. The sensitivity of these new autoantibodies for RA, using an immunoenzymatic technique, was 17%. Specificity was high when comparing non-autoimmune diseases (100%), while it was found to be weak (67%) when comparing some other autoimmune diseases, and particularly systemic lupus erythematosus (SLE). In conclusion, this study demonstrates that these new autoantibodies against CAIII are not restricted to RA. However the expression of CAIII in the synovial membrane of RA warrants further investigation of the pathophysiological relevance of this finding.

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.

Autoimmunity against carbonic anhydrase II affects retinal cell functions in autoimmune retinopathy

Autoantibodies against various retinal proteins, including anti-carbonic anhydrase II (CAII) autoantibodies, have been found in patients with cancer-associated retinopathy and autoimmune retinopathy without diagnosed cancer. We studied sera from retinopathy patients that showed reactivity with a 30-kDa retinal protein, which was identified as carbonic anhydrase II (CAII), and immunolabeled cells in human retina. The goal of the study was to examine whether patients' autoantibodies induce pathogenic effects on the catalytic function of CAII, which may have metabolic consequences on cell survival. Our findings revealed that anti-CAII autoantibodies have the capacity to induce cellular damage by impairing CAII cellular function through inhibiting the catalytic activity of CAII in a dose dependent manner, decreasing intracellular pH, increasing intracellular calcium, which in effect decreases retinal cell viability. The destabilized catalytic function of CAII and alterations in cytosolic pH were found very early, suggesting that autoantibodies are the inducers of apoptosis. In summary, our study showed that anti-CAII autoantibodies provoke pathogenic effects on retinal cells by decreasing cell survival by blocking the CAII cellular functions. The current experiments may facilitate better understanding the role of the immune system in retinal degeneration and help to develop better strategies for therapy of autoimmune retinopathy.

Antibodies to carbonic anhydrase in patients with connective tissue diseases: relationship with lung involvement

The aim of this study is to evaluate the presence of antibodies to carbonic anhydrase I and/or II (ACAI and ACAII) in patients affected by connective tissue diseases (CTD) and to investigate their association with lung involvement evaluated by High resolution CT scan (HRCT). Ninety-six patients affected by CTD were studied, i.e. 33 rheumatoid arthritis (RA), 8 psoriatic arthritis (PA), 8 ankylosing spondilitis (AS), 23 Systemic Lupus Erythematosus (SLE), 10 Sjogren Syndrome (SS), and 14 Systemic Sclerosis (SSc). ACA were detected by ELISA. The lung involvement was evaluated by means of a previously described HRCT score. According to a receiver operator characteristic curve, patients were divided into those with HRCT score > or = 10 and those with HRCT score < 10, where HRCT score > or = 10 was predictive of interstitial lung disease. ACAI and/or ACAII were detected in 30/96 patients (31.2%) (P < 0.0001 in comparison with controls). In particular, the prevalence of ACAI and/or ACAII was significantly higher in patients with RA (P = 0.002), PA (P < 0.0001), SLE (P = 0.0003) and SSc (P < 0.0001). A positive correlation was found between HRCT scores and CRP or ACAI levels (P = < 0.0001 and P = 0.004, respectively). Thirty-nine of 96 patients (40.6%) showed a HRCT score > or = 10 and both their CRP and ACAI levels were significantly higher when compared with patients showing a HRCT score less than 10 (P < 0.0006 and P = 0.0009, respectively). Moreover, C3 and C4 complement fractions inversely correlated with HRCT scores (P = 0.0004 and P < 0.0001, respectively) and lower values of C3 and C4 complement fractions were found in patients with HRCT score > or = 10 than in those with HRCT score less than 10 (P = 0.014 and P = 0.007, respectively). Due to the lower levels of complement fractions detected in patients with HRCT score > or = 10, a possible immune-complex-mediated pathogenic mechanism of lung involvement could be suggested.

Potential for differential diagnosis of autoimmune pancreatitis and pancreatic cancer using carbonic anhydrase II antibody

OBJECTIVES

Pancreatic ductal epithelia contain an abundance of carbonic anhydrase (CA), and the presence of antibodies to this enzyme has been described in autoimmune disorders. We previously found a small amount of an immunoglobulin G-like material in purchased CAII reagents, which led to pseudopositive reactions.

METHODS

We determined the optimum measurement conditions for detecting anti-CAII antibody using an enzyme-linked immunosorbent assay and sera from 140 patients with pancreatic diseases.

RESULTS

Compared with the prevalence of anti-CAII antibody in healthy subjects, a significantly higher seroprevalence of the antibody was detected in patients with autoimmune pancreatitis (AIP) (88.9%, P < 0.02), Sjögren syndrome (67.6%, P < 0.01), and alcoholic chronic pancreatitis (45.8%, P < 0.01). No positive results were obtained among patients with pancreatic cancer. Moreover, the antibody value obtained in the pancreatic cancer patients was actually lower than that obtained in healthy subjects.

CONCLUSIONS

The anti-CAII antibody is probably not a specific marker of AIP because it was present at a higher frequency in the sera of patients with other pancreatic diseases. Nevertheless, the anti-CAII antibody may be a useful tool for the differential diagnosis of AIP and pancreatic cancer.

A new target for autoantibodies in patients with rheumatoid arthritis

Early treatment of rheumatoid arthritis (RA) with disease-modifying antirheumatic drugs can achieve a better disease outcome and reduce the severity of joint damage. The presence of autoantibodies in patient sera can precede onset of the disease and thus be predictive of the development of RA. To date, known autoantibodies in RA are positive in only 50-60% of RA patients at onset of disease and even less before the onset of any RA symptom. The aim of this study was to identify new antibodies that could be useful for the diagnosis of RA using synovial membrane proteins, which represent the best source of candidate RA autoantigens. The humoral reactivity of sera from RA patients was explored using immunoblotting on extracted proteins obtained from synovial membranes from RA after synovectomy or arthroplasty. A new target protein with a molecular weight of 26 kDa was found to be recognized by autoantibodies in RA sera. This protein was identified using MALDI-TOF mass spectrometry and two-dimensional electrophoresis as carbonic anhydrase III with a high level of confidence. In conclusion, this study demonstrates new autoantibodies in RA patients that are directed against carbonic anhydrase III. The sensitivity and specificity of these new autoantibodies for RA have to be further evaluated.

A case of IgG4-related autoimmune disease with multiple organ involvement

A 52-year-old male was admitted with autoimmune pancreatitis (AIP), showing mononuclear cell infiltration in both the pancreas and salivary glands with both normal sialography and anti-SS-A/SS-B antibodies. Although the AIP improved with glucocorticoid treatment, subsequent abdominal computed tomography (CT) revealed a nodular shadow in the bilateral kidneys, which was confirmed as interstitial nephritis by renal biopsy. The patient's serum immunoglobulin G4 (IgG4) level was 10 times higher than the upper limit of the normal range. IgG4-positive mononuclear cell infiltration was detected in the salivary gland, pancreas, and kidney. A new entity proposed as 'IgG4-related autoimmune disease' was considered.

Prevalence of autoantibodies to carbonic anhydrase II and lactoferrin in patients with type 1 diabetes

Recently, the high prevalence of autoantibodies against antigens expressed in exocrine pancreatic cells such as carbonic anhydrase II (ACA) and lactoferrin (ALF) was found in sera from adult Japanese patients with type 1 diabetes. Hence, we determined by ELISA the presence of ACA and ALF both in children (n = 27) and adult (n = 15) Caucasian patients with type 1 diabetes at diagnosis. Among children, ACA were found in one patient (3.7%) and ALF in three (11.1%). Among adults, CAA and ALF were detected in three patients (20%) and in one patient (6.7%), respectively. The prevalence of ACA and ALF observed in our Caucasian patients with type 1 diabetes at diagnosis did not reach the high value previously reported in adult Japanese patients.

Autoantibody explosion in systemic lupus erythematosus: more than 100 different antibodies found in SLE patients

OBJECTIVE

Description of the various autoantibodies that can be detected in patients with systemic lupus erythematosus (SLE).

METHODS

A literature review, using the terms "autoantibody" and "systemic lupus erythematosus", was conducted to search for articles on autoantibodies in SLE, their target antigens, association with disease activity, or other clinical associations.

RESULTS

One hundred sixteen autoantibodies were described in SLE patients. These include autoantibodies that target nuclear antigens, cytoplasmic antigens, cell membrane antigens, phospholipid-associated antigens, blood cells, endothelial cells, and nervous system antigens, plasma proteins, matrix proteins, and miscellaneous antigens. The target of autoantibody, the autoantigen properties, autoantibody frequencies in SLE, as well as clinical associations, and correlation with disease activity are described for all 116 autoantibodies.

CONCLUSIONS

SLE is the autoimmune disease with the largest number of detectable autoantibodies. Their production could be antigen-driven, the result of polyclonal B cell activation, impaired apoptotic pathways, or the outcome of idiotypic network dysregulation.

Detection of autoantibody against carbonic anhydrase II in various liver diseases by enzyme-linked immunosorbent assay using appropriate conditions

BACKGROUND

Immunoglobulin G autoantibody against carbonic anhydrase (CA) II has been detected in the sera of patients with a variety of autoimmune diseases. Antibody against CAII has also been described as a serological marker for distinguishing between cases of autoimmune cholangitis (AIC) and those of primary biliary cirrhosis (PBC). However, the optimal antibody measurement conditions (enzyme-linked immunosorbent assay: ELISA) have not yet been established. Moreover, we also found that a small amount of an IgG-like material exists in purchased CAII reagents, which causes pseudopositive reactions.

METHODS

The sera of 96 patients with liver disease were examined for the presence of anti-CAII antibody using antigen (CAII) not containing the IgG-like material as the most suitable measurement conditions. Compared with the anti-CAII antibody prevalence of 3.8% found in normal subjects, a significantly higher seroprevalence of the antibody was detected in patients with PBC (31.0%, P<0.02), autoimmune hepatitis (AIH) (50.0%, P<0.01) and chronic viral hepatitis (27.5%, P<0.01). But, in cases of PBC, no significant correlation was noted between the level of anti-CAII antibody and the presence of anti-mitochondrial antibodies (AMA).

CONCLUSIONS

While CAII may be a target antigen in autoimmune diseases, the anti-CAII antibody is not likely to be a specific marker of AIC. The optimum measurement conditions for the ELISA for anti-CAII antibody would provide us with valuable information to elucidate the underlying immunological abnormalities in liver diseases.

Autoantibody studies of female patients with reproductive failure

The aim of this study was to investigate the prevalence and character of autoimmune derangements in women with reproductive failure. A total of 108 females (age range 17-43, mean 27.5 years), including 16 with primary menstrual cycle disturbances and polycystic ovaries (PCO), 20 with polycystic ovary syndrome (PCOS), 38 with endometriosis (E), and 34 with chronic anovulation, luteal phase insufficiency, subfertility or unexplained infertility (INF) were investigated. A control group of 392 women was formed from an unselected population sample (age range 17-43, mean 31.0 years). All sera were tested by indirect immunofluorescence method to assess common autoantibodies: nuclear (ANA), smooth muscle (SMA), parietal cell (PCA), thyroid microsomal (TMA), reticulin (ARA), mitochondrial (AMA) and liver/kidney microsomal autoantibodies (LKMA). Enzyme-linked immunosorbent assay was used to detect antibodies against beta2-glycoprotein I (anti-beta 2GPI) and carbonic anhydrase (anti-CA). Our results showed that 40.7% of patients' sera and 14.8% of control sera contained one or more common autoantibodies, ANA and SMA were most frequently detected (difference between two groups P<0.005). Anti-beta 2GPI were found in eight cases (7.4%), including two patients with INF but without other autoantibodies. Anti-CA were revealed in nine cases (8.3%) including patients' PCOS, E and INF. A comparison of patients' clinical data with antibody assay results did not reveal any significant associations. Our results indicate a high prevalence of autoimmune reactions in women with reproductive failure due to the most common causes PCO, PCOS and E as well as in unexplained infertility. This might reflect the propensity to develop autoimmune reactions in such patients, including pathogenic autoimmune reactions to specific target antigens.

Carbonic anhydrase isozymes in the human pancreas

Recently, an increasing number of carbonic anhydrase (CA) isozymes have been discovered in the human pancreas. These isozymes are classified as the CA family with various molecular structures and different subcellular localizations: cytoplasmic CA II, mitochondrial CA VB, secretory CA VI, membrane-bound CA IV, and transmembrane CA IX and XII. However, there is little evidence concerning their pathophysiological roles. Here, we reviewed the expression of CA isozymes in the human pancreas and proposed hypotheses related to their physiological and pathological roles.

Elevated serum levels of antibodies to carbonic anhydrase I and II in patients with chronic pancreatitis

An immune-mediated reaction to pancreatic structures has been postulated for the pathogenesis of chronic pancreatitis (CP). Several reports demonstrate the presence of antibodies to the pancreatic ductal epithelium in some patients suffering from CP. Serum antibodies to carbonic anhydrase I (anti-CA I) and II (anti-CA II) are present in patients affected by idiopathic CP. The aim of this study was to evaluate the presence of anti-CA I and anti-CA II in a series of patients with CP. We studied 78 consecutive CP patients (62 male, 16 female; mean age 48.6 +/- 10.2 years) referred to the Verona University Center for the Study of the Pancreas. As a control group, we studied 26 healthy subjects recruited from among the medical and nursing staff of the center. Serum anti-CA I and anti-CA II levels were quantified by enzyme-linked immunosorbent assay using a standard method with minor modifications. The mean absorbance of antibodies was higher in CP patients than in control subjects (anti-CA I: 0.064 +/- 0.042 vs. 0.047 +/- 0.015, p = 0.051; and anti-CA II: 0.038 +/- 0.02 vs. 0.029 +/- 0.014, p = 0.033). Positive results were arbitrarily defined as absorbance values >0.067 for anti-CA I and 0.047 for anti-CA II. We found anti-CA I and anti-CA II positivity in 21 of 78 (27%) and 20 of 78 (26%) of CP patients, respectively, and in only two of 26 control subjects (7.7%) (p = 0.032 and 0.039). Twenty-two of 26 subjects in the control group (84.6%) and 48 of 78 patients (61.5%) in the CP group tested negative for both antibodies (p = 0.03). None of the control subjects and 12 of 78 (16.6%) of the CP patients tested positive for both anti-CA I and anti-CA II. We observed a significant correlation between anti-CA I and anti-CA II serum levels in control subjects (R = 0.423; p = 0.016) and in CP patients (R = 0.584; p < 0.0001). No correlation was found between serum antibody levels and any of the following variables: length of disease, alcohol consumption, smoking habits, pancreatic surgery, pancreatic calcifications, diabetes, and steatorrhea. Serum levels of anti-CA I and anti-CA II are elevated in some patients suffering from CP.

A study of anti-carbonic anhydrase II antibodies in rheumatic autoimmune diseases

Autoantibodies to human carbonic anhydrase II (CAII) were screened by ELISA in 109 sera from Asian Japanese patients with systemic lupus erythematosus (SLE), primary Sjögren's syndrome (Sjs), progressive systemic sclerosis (PSS) and dermatomyositis (DM). Anti-CAII antibodies were positive in 24.1% of SLE, 20.0% of primary Sjs, 16.7% of PSS and 25.0% of DM. On the other hand, sera from atopic dermatitis, bullous pemphigoid and psoriasis patients showed no activity for anti-CAII antibodies. CAII could be a common exonuclear autoantigen in subsets of rheumatic autoimmune diseases.

Carbonic anhydrase in human pancreas: hypotheses for the pathophysiological roles of CA isozymes

Among more than ten isozymes of the carbonic anhydrase (CA) family, only cytoplasmic CA II and membrane-bound CA IX have been reported to be expressed in human pancreas. To study the mRNA expression of CA isozymes in human pancreas, reverse transcriptase-polymerase chain reaction (RT-PCR)-Southern blot analysis and cDNA sequencing following RT-PCR were employed. CA II, IV, VI, IX, and XII were clearly identified in polyA+ RNA from normal human pancreas by RT-PCR-Southern blotting. Results with cultured pancreatic tumor cell, lines suggest that CA II, IV, IX, and XII are expressed in the ductal cells, and CA VI is expressed in the acinar cells. We propose a hypothesis for the pathophysiological function of CA isozymes in human pancreas; (1) the intraluminal CA isozymes (CA IV, VI, and possibly XII) form a mutually complementary system with cytoplasmic CA II to regulate the luminal pH of the pancreatic duct system and work as a self-defense mechanism against pancreatitis; (2) CA II and other CA isozymes play a pathological role in the autoimmune process of idiopathic chronic pancreatitis.

Association of antiretinal antibodies and cystoid macular edema in patients with retinitis pigmentosa

PURPOSE

To report the association of antiretinal antibodies in patients with bilateral cystoid macular edema and retinitis pigmentosa.

METHODS

In a prospective study, 30 consecutive patients with bilateral cystoid macular edema and retinitis pigmentosa were tested for antiretinal antibodies. As control subjects, 30 consecutive patients with retinitis pigmentosa who did not have cystoid macular edema and 50 normal subjects without retinitis pigmentosa or cystoid macular edema were tested for antiretinal antibodies. Laboratory personnel performing the antiretinal antibody testing were masked regarding the diagnosis of each patient.

RESULTS

Twenty-seven (90%) of 30 patients with retinitis pigmentosa with cystoid macular edema had antiretinal protein antibody activity, compared with three (6%) of 50 normal controls (P < .001) and only four (13%) of 30 control patients with retinitis pigmentosa (P < .001).

CONCLUSIONS

We found a significant association between cystoid macular edema and the presence of circulating antiretinal antibodies in patients who presented with retinitis pigmentosa and cystoid macular edema. This study suggests that patients with retinitis pigmentosa with cystoid macular edema may have an autoimmune process that is contributing to the formation of cystoid macular edema in retinitis pigmentosa, but to date, there is no direct evidence that the cystoid macular edema is caused by the antiretinal antibodies.

Antibody to carbonic anhydrase II is present in primary biliary cirrhosis (PBC) irrespective of antimitochondrial antibody status

Antibody to carbonic anhydrase II, an enzyme abundantly present in biliary epithelium, has been proposed as a diagnostic marker for antimitochondrial antibody-negative PBC. In this study we determine its prevalence and clinical significance in a large series of patients with antimitochondrial antibody-positive and -negative PBC. Reactivity to carbonic anhydrase II was sought by Western immunoblotting in sera from 215 consecutive patients with PBC (26 antimitochondrial antibody-negative), 13 with autoimmune hepatitis, 25 with primary Sjögren's syndrome (pSS), 12 with systemic sclerosis, 19 with systemic lupus erythematosus and 73 healthy subjects. The prevalence of antibody to carbonic anhydrase II (titre 1:100) in PBC was 8%. No specific reactivity to carbonic anhydrase II was found in antimitochondrial antibody-negative PBC (7% versus 8% in antimitochondrial antibody-positive PBC). Ascites (P = 0.006) and Sjögren's syndrome (SS) (P = 0.022) in PBC were significantly associated with presence of the antibody. In patients with SS associated with PBC, the prevalence (19%) was similar to that observed in pSS (16%). At a serum dilution of 1:40, the prevalence of positive sera in PBC rose to 27% but disease specificity was reduced. Our findings in a large population of PBC patients rule out a relation between presence of antibody to carbonic anhydrase II and lack of antimitochondrial antibody. The higher prevalence of ascites found in positive patients warrants further evaluation.

Human carbonic anhydrase XII: cDNA cloning, expression, and chromosomal localization of a carbonic anhydrase gene that is overexpressed in some renal cell cancers

We report the cloning and characterization of a tumor-associated carbonic anhydrase (CA) that was identified in a human renal cell carcinoma (RCC) by serological expression screening with autologous antibodies. The cDNA sequence predicts a 354-amino acid polypeptide with a molecular mass of 39,448 Da that has features of a type I membrane protein. The predicted sequence includes a 29-amino acid signal sequence, a 261-amino acid CA domain, an additional short extracellular segment, a 26-amino acid hydrophobic transmembrane domain, and a hydrophilic C-terminal cytoplasmic tail of 29 amino acids that contains two potential phosphorylation sites. The extracellular CA domain shows 30-42% homology with known human CAs, contains all three Zn-binding histidine residues found in active CAs, and contains two potential sites for asparagine glycosylation. When expressed in COS cells, the cDNA produced a 43- to 44-kDa protein in membranes that had around one-sixth the CA activity of membranes from COS cells transfected with the same vector expressing bovine CA IV. We have designated this human protein CA XII. Northern blot analysis of normal tissues demonstrated a 4.5-kb transcript only in kidney and intestine. However, in 10% of patients with RCC, the CA XII transcript was expressed at much higher levels in the RCC than in surrounding normal kidney tissue. The CA XII gene was mapped by using fluorescence in situ hybridization to 15q22. CA XII is the second catalytically active membrane CA reported to be overexpressed in certain cancers. Its relationship to oncogenesis and its potential as a clinically useful tumor marker clearly merit further investigation.

Antibodies to carbonic anhydrase in endometriosis: prevalence, specificity, and relationship to clinical and laboratory parameters

OBJECTIVE

To investigate the presence and clinical association of serum autoantibodies to carbonic anhydrase (CA) in women with and without endometriosis.

DESIGN

Sera were tested in an ELISA against human and bovine CAI and/or CAII isoenzymes and by Western immunoblotting of trypsin-digested fragments of human CAII as antigens. The ELISA positivity was defined as mean + 2 SD of 100 control sera. Positive sera also were tested for the presence of antiendometrial antibodies and antinuclear antibodies (ANA) by indirect immunofluorescence assays (IFA) on endometrial (ECC) and HEp-2 cells, antibodies to single-stranded (ss) and double-stranded (ds) DNA by the Farr-type RIA and Crithidia IFA, and extractable nuclear antigens (Sm, nRNP, Ro, and La) by an ELISA.

PATIENTS

Sera from 319 patients with laparoscopic diagnosed pelvic endometriosis (100 stage I, 95 stage II, 67 stage III, and 57 stage IV), 100 with other gynecologic disorders, and 100 control women were used.

RESULTS

In the ELISA, 113 of 319 (35.4%) endometriosis sera had elevated immunoglobulin G antibodies against nondenatured CA isoenzymes. The reactivity of sera from the endometriosis group was significantly higher (35%) in all four subgroups of patients than each of the nonendometriosis sera (< 12% and < 6%, respectively). No stage-dependent variation of an autoantibody pattern was evident. However, anti-CA autoantibodies were present in 66.3% of women with endometriosis-associated infertility. The frequency of anti-CA autoantibodies was significantly higher (by 51.7%) in women with antiendometrial antibodies detectable by IFA. In addition, in sera positive for anti-CA antibodies, the frequency of ANA also was increased (20/113 [17.6%]) with titers of 1:40 to 1:1,080. The ANA-positive sera were negative for anti-ssDNA, anti-dsDNA, anti-Sm, anti-nRNP, and anti-La. However, three sera were positive for anti-Ro antibodies. Immunoblotting study of autoantibody reactivity with trypsin-digested subfragments of human CAII revealed consistent immunoreactivity with 14 to 6.2-kd range CAII peptides.

CONCLUSIONS

[1] A subgroup of patients with endometriosis have autoantibodies directed to native and linear epitopes of the CA protein. [2] Prevalence of anti-CA antibodies was associated with antiendometrial antibodies and ANA. [3] Anti-CA antibodies were associated with a higher predictive value of the disease when all patient subgroups were considered together.

Development and characterization of a rodent model of immune-mediated cholangitis

The cholangiopathies are a group of hepatobiliary diseases in which intrahepatic bile duct epithelial cells, or cholangiocytes, are the target for a variety of destructive processes, including immune-mediated damage. We tested the hypothesis that cholangitis could be induced in rodents by immunization with highly purified cholangiocytes. Inbred Wistar rats were immunized with purified hyperplastic cholangiocytes isolated after bile duct ligation from either syngeneic Wistar or allogeneic Fischer 344 rats; control rats were immunized with bovine serum albumin (BSA) or hepatocytes. After immunization with cholangiocytes, recipient animals developed histologic evidence of nonsuppurative cholangitis without inflammation in other organs; groups immunized with BSA or hepatocytes showed no cholangitis. Immunohistochemical studies revealed that portal tract infiltrates around bile ducts consisted of CD3-positive lymphocytes, some of which expressed major histocompatibility complex class II antigen; B cells and exogenous monocytes/macrophages were essentially absent. Transfer of unfractionated ConA-stimulated spleen cells from cholangiocyte-immunized (but not BSA-immunized) rats into recipients also caused nonsuppurative cholangitis. Moreover, these splenocytes from cholangiocyte-immunized (but not BSA-immunized) rats were cytotoxic in vitro for cultured rodent cholangiocytes; no cytotoxicity was observed against a rat hepatocyte cell line. Also, a specific antibody response in sera of cholangiocyte-immunized rats was demonstrated by immunoblots against cholangiocyte proteins. Finally, cholangiograms in cholangiocyte-immunized rats showed distortion and tortuosity of the entire intrahepatic biliary ductal system. This unique rodent model of experimental cholangitis demonstrates the importance of immune mechanisms in the pathogenesis of cholangitis and will prove useful in exploring the mechanisms by which the immune system targets and damages cholangiocytes.

Comparative epitope mapping of antibodies to collagen in women with silicone breast implants, systemic lupus erythematosus and rheumatoid arthritis

Previous work has shown that women with silicone gel breast implants have an increased frequency of autoantibodies to collagen types I and II. 70 women without a specific autoimmune disease, using criteria of the American College of Rheumatology, but who had silicone breast implants were studied for the presence of serum antibodies to native and denatured human types I and II collagen by ELISA. 82 women with systemic lupus erythematosus (SLE), 94 women with rheumatoid arthritis (RA), and 133 healthy controls were also studied. There was a high frequency of autoantibodies to collagen in each of the groups when compared to the healthy controls. The specificities of these antibodies were found to differ markedly when examined by immunoblotting using peptides derived by cyanogen bromide digestion of the collagens. Sera from women with silicone implants reacted with multiple peptides of type I collagen in an individual-specific manner, but sera from women with SLE or RA reacted weakly with a restricted range of peptides. Against type II collagen, sera from women with RA reacted strongly with multiple peptides, while sera from women with silicone implants or SLE reacted only weakly or not at all. The patterns of reactivity against collagens by sera from women with silicone implants suggest that silicone can act as an adjuvant to enhance the immunogenicity of type I collagen.

Antibodies to carbonic anhydrase in patients with immune cholangiopathies

BACKGROUND/AIMS

Bile duct epithelia contain an abundance of carbonic anhydrase. Antibodies to this enzyme have been described in autoimmune disorders. Serum from patients with immune-mediated liver diseases was studied to determine whether antibodies to carbonic anhydrase II and/or pyruvate dehydrogenase could distinguish autoimmune cholangitis as immunologically distinct from primary biliary cirrhosis.

METHODS

Antibody assays to carbonic anhydrase II (Western blot) and pyruvate dehydrogenase (flow cytometry) were performed on the sera of patients with autoimmune cholangitis (6), primary biliary cirrhosis (12), primary sclerosing cholangitis (12), autoimmune hepatitis (12), and control (Gilbert syndrome; 8).

RESULTS

Reactivity to carbonic anhydrase II was detected in 5 of 6 patients with autoimmune cholangitis, 1 of 12 patients with primary biliary cirrhosis, 1 of 12 patients with autoimmune hepatitis, and no other patients. Individuals with autoimmune cholangitis were more likely than the other patients to be reactive to carbonic anhydrase II (P < 0.001). Patients with primary biliary cirrhosis were more reactive to pyruvate dehydrogenase compared with all other groups (P < 0.001).

CONCLUSIONS

An antibody to human carbonic anhydrase II is frequently detected in the sera of patients with autoimmune cholangitis and is uncommon or not present in other cholangiopathies. These data provide evidence that autoimmune cholangitis and primary biliary cirrhosis represent distinct entities with unique patterns of immunoreactivity.