Autoantibodies to mitochondria in systemic sclerosis. Frequency and characterization using recombinant cloned autoantigen

Long-term outcomes in patients with primary biliary cholangitis complicated with CREST syndrome

Primary biliary cholangitis (PBC) is frequently associated with autoimmune disease. Although PBC complicated with CREST syndrome (PBC-CREST) has been reported, the long-term outcomes of the affected patients have not been fully investigated. Herein, the long-term outcomes of PBC-CREST were evaluated. Next, the GLOBE and UK-PBC scores were validated and compared between the PBC alone and PBC-CREST groups. A total of 302 patients who were diagnosed with PBC between December 1990 and August 2021 at Fukushima Medical University Hospital were included. The liver transplantation (LT)-free survival rates were compared between patients with PBC alone (n = 245) and those with PBC-CREST (n = 57). Moreover, 173 patients, excluding those with liver-related death/LT within 1 year after ursodeoxycholic acid administration, were divided into two subgroups (PBC alone (n = 147) and PBC-CREST (n = 26)), and the GLOBE and UK-PBC scores were compared between the subgroups. The survival rates without LT (3/5/10 years) were 92/87/80% for the PBC-alone group and 98/96/96% for the PBC-CREST group, with a significantly better prognosis in the PBC-CREST group (log-rank P = 0.0172). Multivariate analysis revealed that the presence of CREST syndrome is an independent protective factor for the presence of cirrhosis. The predicted 5/10/15-year risks of liver-related death or LT based on the UK-PBC score were significantly lower in the PBC-CREST group (2.4/7.6/13.2%) than in the PBC-alone group (4.8/11.8/18.8%) (P < 0.05). The predicted 3/5-year LT-free survival rates based on the GLOBE score were significantly higher in the PBC-CREST group (93/88%) than in the PBC-alone group (88/81%) (P < 0.05). Patients with PBC-CREST may have better long-term outcomes than those with PBC alone.

Gastrointestinal Manifestations of Systemic Sclerosis

Systemic sclerosis (SSc) is a rare autoimmune disease characterized by fibroproliferative alterations of the microvasculature leading to fibrosis and loss of function of the skin and internal organs. Gastrointestinal manifestations of SSc are the most commonly encountered complications of the disease affecting nearly 90% of the SSc population. Among these complications, the esophagus and the anorectum are the most commonly affected. However, this devastating disorder does not spare any part of the gastrointestinal tract (GIT), and includes the oral cavity, esophagus, stomach, small and large bowels as well as the liver and pancreas. In this review, we present the current understanding of the pathophysiologic mechanisms of SSc including vasculopathy, endothelial to mesenchymal transformation as well as the autoimmune pathogenetic pathways. We also discuss the clinical presentation and diagnosis of each part of the GIT affected by SSc. Finally, we highlight the latest developments in the management of this disease, addressing the severe malnutrition that affects this vulnerable patient population and ways to assess and improve the nutritional status of the patients.

Pathophysiology and recent findings of primary biliary cirrhosis complicated by systemic sclerosis

Primary biliary cirrhosis (PBC) can be complicated by systemic sclerosis (SSc) and, more specifically, limited cutaneous SSc (lcSSc), which was previously called CREST syndrome. Moreover, combined PBC and SSc has been described in many case reports. Although neither the etiology of PBC nor that of SSc has been elucidated, some genetic and immunological factors are known to be shared. Both disorders are autoimmune fibrotic diseases characterized by increased levels of profibrotic cytokines transforming growth factor β (TGFβ) and interleukin-6, which have recently been suggested to influence T-helper 17 cells and regulatory T cells involved in acquired immunity. lcSSc is accompanied by CREST symptoms, although complete CREST cases are rare, with relatively high prevalence of Raynaud's phenomenon, sclerodactyly and telangiectasia, and lower prevalence of calcinosis and esophageal dysmotility. Because patients with anticentromere antibody positive PBC-SSc are at a high risk of developing portal hypertension, particular attention should be paid to the management of gastroesophageal varices. In addition, the management of SSc-related non-hepatic disorders, such as pulmonary fibrosis, pulmonary hypertension, heart disorder, infection and malignancy, is also important for improved outcomes. Because PBC is often complicated by rheumatic disease, hepatologists should keep the possibility of systemic disorder in mind when examining PBC patients.

Liver immunology

The liver is the largest organ in the body and is generally regarded by nonimmunologists as having little or no lymphoid function. However, such is far from accurate. This review highlights the importance of the liver as a lymphoid organ. Firstly, we discuss experimental data surrounding the role of liver as a lymphoid organ. The liver facilitates tolerance rather than immunoreactivity, which protects the host from antigenic overload of dietary components and drugs derived from the gut and it is instrumental to fetal immune tolerance. Loss of liver tolerance leads to autoaggressive phenomena, which if not controlled by regulatory lymphoid populations, may lead to the induction of autoimmune liver diseases. Liver-related lymphoid subpopulations also act as critical antigen-presenting cells. The study of the immunological properties of liver and delineation of the microenvironment of the intrahepatic milieu in normal and diseased livers provides a platform to understand the hierarchy of a series of detrimental events that lead to immune-mediated destruction of the liver and the rejection of liver allografts. The majority of emphasis within this review will be on the normal mononuclear cell composition of the liver. However, within this context, we will discuss selected, but not all, immune-mediated liver disease and attempt to place these data in the context of human autoimmunity.

Polyautoimmunity and familial autoimmunity in systemic sclerosis

Characterization of the extent to which particular combinations of autoimmune diseases occur in excess of that expected by chance may offer new insights into possible common pathophysiological mechanisms. The goal of this study was to investigate the spectrum of polyautoimmunity (i.e. autoimmune diseases co-occurring within patients) and familial autoimmunity (i.e. diverse autoimmune diseases co-occurring within families) in patients with systemic sclerosis (SSc). A cross-sectional study of two convenience samples of patients with SSc, one in Canada and the other in Colombia, was performed. History of other autoimmune diseases in the SSc patients as well as a family history of autoimmunity was obtained. Of 719 patients, 273 (38%) had at least one other autoimmune disease. A total of 366 autoimmune diseases were reported, of which the most frequent were autoimmune thyroid disease (AITD, 38%), rheumatoid arthritis (RA, 21%), Sjögren's syndrome (18%), and primary biliary cirrhosis (4%). There were 260 (36%) patients with first-degree relatives with at least one autoimmune disease, of which the most frequent were RA (18%) and AITD (9%). Having at least one first-degree relative with autoimmune disease was a significant predictor of polyautoimmunity in SSc patients. No significant differences in polyautoimmunity or familial autoimmunity were noted between diffuse and limited subsets of disease. Our results indicate that polyautoimmunity is frequent in patients with SSc and autoimmune diseases cluster within families of these patients. Clinically different autoimmune phenotypes might share common susceptibility variants, which acting in epistatic pleiotropy may represent risk factors for autoimmunity.

Labordiagnostik bei systemischer Sklerose

For systemic sclerosis, laboratory tests can play a supplementary role to clinical investigations, imaging techniques and functional tests. Typical autoantibodies support early diagnosis and help in assigning patients to subgroups of the disease; negative results for antinuclear antibodies suggest exclusion of the diagnosis. To detect organ involvement and comorbidity, the laboratory contributes by clinical chemistry, in certain cases by histopathological findings and by the cytological assessment of broncho-alveolar lavage fluid. Inflammatory parameters are of minor importance. Multiple autoantibody determinations in the course of the disease are not yet helpful. Numerous additional laboratory parameters are of value for investigating pathogenesis, but have not yet been generally introduced into the routine diagnostics of systemic sclerosis.

Sklerodermie-assoziierte Autoantikörper – klinische und diagnostische Relevanz

In systemic sclerosis (SSc) and its variants, autoantibodies are the best known immunological aberration. In more than 95% of the patients, antinuclear antibodies or other autoantibodies can be detected. In about 90% of SSc patients with antinuclear antibodies, scleroderma associated autoantibodies highly specific for systemic sclerosis are found. These autoantibodies usually exclude each other in individual patients, and they are detectable early, persisting during the course of the disease. SSc patients characterized by scleroderma associated autoantibodies belong to disease subsets which are relatively homogeneous in clinical, genetic and prognostic terms. Besides these diagnostically relevant autoantibodies, numerous additional ones have also been described. These are neither SSc specific nor mutually exclusive, and their antigens have only been partially characterized. Some, however, are thought to be relevant to the as yet unanswered question of whether autoantibodies are directly involved in SSc pathogenesis.

Antibodies in scleroderma: direct pathogenicity and phenotypic associations

Scleroderma is an autoimmune disease involving endothelial cell damage and fibroblast overproduction of extracellular matrix. Several autoantibodies present in the sera of patients with scleroderma, including anti-endothelial cell, antifibroblast, anti-matrix metalloproteinase, and antifibrillin-1 antibodies, may directly contribute to disease pathogenesis. Scleroderma also is characterized by the presence of antinuclear and antinucleolar antibodies, which correlate with particular phenotypes. These include antitopoisomerase-I, anticentromere, antihistone, anti-polymyositis/scleroderma, anti-Th/To, anti-U3-small nucleolar ribonucleoprotein particle, anti-U1-small nuclear ribonucleoprotein particle, anti-RNA polymerase, and anti-B23 antibodies. Other antibodies classically associated with other autoimmune diseases, such as antiphospholipid, antineutrophil cytoplasmic, and antimitochondrial antibodies, also have been described in patients with scleroderma. This review will summarize the various autoantibodies associated with scleroderma, their putative pathogenic roles, and their phenotypic correlations.

Intérêt des anticorps antinucléaires pour le diagnostic, la classification et le pronostic de la sclérodermie systémique

PURPOSE

Systemic sclerosis (SSc) like other connective tissue diseases is characterized by the occurrence of antinuclear auto-antibodies (ANA). We reviewed the diagnostic value and prognostic value of ANA in SSc.

CURRENT KNOWLEDGE AND KEY POINTS

LeRoy proposed new criteria of limited forms of SSc which take into account the immunological profile of the patients. Anticentromere, antitopoisomerase I, antifibrillarin, anti-PM-Scl, antifibrillin or anti-RNA-polymerase I or III are considered as specific anti-autobodies. Whereas anticentromere antibodies are more associated with limited SSc and antitopoisomerase I with diffuse SSc, other auto-antibodies were associated with other organ involvement : anti-RNA-polymerase I or III and renal crisis, anti-U1-RNP and pulmonary hypertension and pulmonary fibrosis, etc. Patient with persistent antitopoisomerase I antibodies have a poor survival, those with antitopoisomerase antibodies that disappear with time have a better prognosis.

FUTURE PROSPECTS AND PROJECTS

A better identification of the patients with SSc, an individual biological profile and organ involvement may help better management of the disease and better access to clinical trials. The development of new immunological tests and their clinical application should help us in that way.

Antinuclear antibodies in dermatology

Antinuclear antibodies are used in the diagnosis and evaluation of patients with connective tissue diseases. The study of antinuclear antibodies has also fundamentally expanded our understanding of nuclear anatomy and function. This article reviews the clinically relevant antinuclear antibodies and their disease associations. Developing an understanding of the utilities and limitations of antinuclear antibodies is essential to providing the expert diagnoses prognoses, and care expected of a dermatologist.

Primary biliary cirrhosis. Is (and how much of) the pathology preventible?

Primary biliary cirrhosis (PBC) is a chronic, progressive cholestatic liver disease, which is invariably fatal. Circumstantial and indirect evidence suggests that autoimmune mechanisms have a role in the pathogenesis of PBC. Antimitochondrial antibodies (AMA) are highly sensitive and specific markers that can predict the development of the disease in a healthy individual. Long-term administration of ursodeoxycholic acid (UDCA), a naturally occurring bile acid, safely slows the progression of PBC, delays the need for liver transplantation, and postpones death. An effort should be made to identify the patients with PBC in the asymptomatic stage by the presence of AMA and to conduct a clinical trial in order to assess the benefit of long-term administration of UDCA on the prevention of the overt disease in these individuals.

Prevalence, kinetics, and therapeutic modulation of autoantibodies against Sp100 and promyelocytic leukemia protein in a large cohort of patients with primary biliary cirrhosis

Antinuclear antibodies (ANA) staining nuclear dot structures predominantly occur in primary biliary cirrhosis (PBC) patients and recognize the Sp100 and promyelocytic leukemia protein (PML). From retrospective analysis of sera from a clinically well-defined Canadian series of 170 PBC patients included into a 24-month therapeutic trial of ursodeoxycholic acid (UDCA), we report the prevalence of these ANA and their dynamics in the course of the disease. Using an enzyme-linked immunosorbent assay (ELISA), anti-Sp100 autoantibodies were shown in 35 (21%) patients. Thirty-three patients (19%) had autoantibodies against PML as determined by indirect immunostaining of cells overexpressing PML. Altogether, anti-nuclear dot autoantibodies were present in 25% of the 170 PBC patients. Their occurrence correlated with an unfavorable disease course, because these patients progressed significantly more frequently from early stages (I/II) to late stages (III/IV) within the 24-month observation period (P < .05). During the course of the disease, the autoantibody levels against the Sp100 full-length protein remained nearly constant in all 35 positive patients. However, 9 patients showed remarkable changes in Sp100 epitope recognition as revealed by ELISA and immunoblotting. When the occurrence of these changes and the treatment of the patients were compared retrospectively, it became evident that 8 of the 9 patients had received UDCA (42% of all Sp100-positive patients treated with UDCA). These findings indicate subtle changes of the Sp100 epitope recognition pattern during the natural course of the disease and its induction or acceleration by UDCA treatment. This implies that UDCA can modulate immunoglobulin (Ig) expression not only quantitatively, but also qualitatively.

Molecular biology of autoantigens in rheumatic diseases

The advent of molecular biologic techniques has provided new approaches that are of great utility to the study of autoimmune-mediated responses. In the past few years, there has been a remarkable accumulation of knowledge concerning the molecular identity and function of autoantigens, and further consolidation for the use of autoantibodies as diagnostic markers in clinical rheumatology. The understanding of basis methodologies in molecular biology applied to the study of autoantigens, in particular, techniques for cloning and analyzing genes that are important in rheumatic diseases, is valuable for both basic scientists and clinicians interested in diagnostic and prognostic markers of various connective tissue diseases.

Anti-M4 antibodies measured by a sulphite oxidase ELISA in patients with both anti-centromere and anti-M2 antibodies

In this study the clinical features of patients with a serological overlap between scleroderma and primary biliary cirrhosis (PBC) were analysed. The entity was defined by the presence of both anti-centromere antibody (ACA) and anti-mitochondrial antibodies to the M2 antigen, pyruvate dehydrogenase. In addition the sera were assayed for anti-mitochondrial antibodies to the M4 antigen measured by an ELISA to sulphite oxidase (SO). First, anti-M2 was detected, not only in 58 out of 60 patients with PBC but also in eight out of 61 patients with ACA. These sera, together with sera from 53 normals and 99 from patients with various connective tissue diseases were then evaluated for anti-SO, which has been proposed by Klein and Berg to be a marker of progressive liver disease. Again, a high proportion (62%) of sera from patients with PBC were positive for anti-SO, and three of the eight patients who had ACA and anti-M2 also reacted with SO. We subsequently identified and included for study a further 10 patients positive for ACA and anti-M2, making a total of 18 patients with this profile. Features of limited cutaneous scleroderma were present in 94% and evidence of liver disease in 56%. Eight out of the 18 patients had anti-SO, and of these four had PBC, two had abnormal biochemical liver function tests but two had no evidence of liver disease. These data confirm that detection of anti-SO is limited to an anti-M2 subpopulation, and may be a marker for liver involvement with prognostic significance in scleroderma patients with ACA.

Autoantibodies to pyruvate dehydrogenase complex in patients with systemic sclerosis. Possible role of anti-E1 alpha antibody as a serologic indicator for development of primary biliary cirrhosis

OBJECTIVE

To determine the prevalence and clinical significance of anti-pyruvate dehydrogenase complex (anti-PDC) antibodies in systemic sclerosis (SSc).

METHODS

Serum samples from patients with limited cutaneous SSc (n = 81) or diffuse cutaneous SSc (n = 63) were examined for anti-PDC antibodies by enzyme-linked immunosorbent assay (ELISA) and immunoblotting.

RESULTS

IgG- and/or IgM-isotype anti-PDC antibodies were demonstrated by ELISA in 26 of 144 patients with SSc (18%). By immunoblotting, 19 patients had IgG anti-PDC antibodies. Among these patients with IgG anti-PDC antibodies, antibody to the E1 alpha subunit was significantly associated with the presence of laboratory abnormalities typical of primary biliary cirrhosis (PBC).

CONCLUSION

Antibody to the E1 alpha subunit of PDC may be a serologic indicator for the development of PBC in patients with SSc.

Mitochondrial antigens, molecular mimicry and autoimmune disease

The immune system is normally tolerant to mitochondrial self-antigens, but responsive against bacteria. Low-titre anti-mitochondrial antibodies (AMA) might be involved in this discrimination. Tolerance is broken in diseases characterised by high titre AMA. Some of these AMA, against cardiolipin, cross-react with DNA. The best studied AMA are those characterising primary biliary cirrhosis (PBC). These are directed against E2 subunits of the oxo-acid dehydrogenase complexes, and also against subunits E1 alpha, E1 beta and X of the pyruvate dehydrogenase complex. AMA of PBC patients also react with bacterial E2s. Reactivities are primarily peptide-specific but with cross-reactivity between mitochondrial and microbial antigens and between E2s of respective complexes. Immunodominant epitopes, for anti E2 AMA, include the conserved sequence flanking the site of lipoyl attachment. It is proposed that the initial stimulus for antibody production is chronic urinary tract infection. AMA themselves are not pathogenic, but CD4+ T-cells would be primed, recognising the lipoyl domain epitope in association with class II HLA. Inappropriate expression of class II antigens on bile duct epithelia, (as found in PBC), might lead to presentation of a particular fragment of HLA-DR alpha, known to be a major MHC presented self-peptide in the mouse. That sequence strongly mimics the lipoyl domain and might be recognised by primed T-cells, initiating the autoimmune cascade. In the mouse, a peptide of ND1 of Complex I is presented in association with class I MHC. Cells exhibiting somatic mutation of such a peptide might thus be subject to attack by CD8+ T-cells. If such peptides were presented by class II HLA, autoimmune diseases might arise, related to mimicry between such peptides and microbial sequences and/or self-antigens. These considerations might apply in Leber's disease and in age-related pathology.

Autoantibodies in the diagnosis of systemic rheumatic diseases

Distinct profiles of autoantibodies directed to intracellular antigens can be detected in the systemic connective tissue diseases. They aid in establishing the correct diagnosis and are included in many sets of diagnostic criteria, such as the ones developed for systemic lupus erythematosus (anti-Smith antigen and anti-double-strand DNA antibodies), mixed connective tissue disease (anti-U1-nuclear ribonucleoprotein antibodies), and Sjögren's syndrome (SS) (anti-SS-A/Ro and anti-SS-B/La antibodies). They are useful prognostic markers in some situations and facilitate clinical and treatment follow-up. Autoantibodies have also been used as probes to gain insights into cell biology, helping to isolate and purify intracellular proteins involved in key cellular functions. We give detailed information on two of the most useful techniques for the detection of autoantibodies in the clinical and research laboratory settings, indirect immunofluorescence and immunoblotting. We also discuss several of the antigen-autoantibody systems found in systemic lupus erythematosus (Smith antigen, U1-nuclear ribonucleoprotein, SS-A/Ro, SS-B/La, proliferating cell nuclear antigen ribosomal ribonucleoprotein, double-strand DNA, histones, antiphospholipids, Ku, Ki/SL), systemic sclerosis (centromere, topo I, RNA polymerases, fibrillarin, polymyositis-Scl, Th/To), polymyositis/dermatomyositis (transferRNA synthetases, signal recognition particle, and others), and SS (SS-A/Ro, SS-B/La, nucleolar organizing region-90, p80-coilin), addressing their clinical significance, common detection methods, immunogenetic associations, and the molecular and cellular biology of the cognate antigens.

Myopathy with mitochondrial alterations in patients with primary biliary cirrhosis and antimitochondrial antibodies

OBJECTIVE

To describe a syndrome of severe progressive myopathy, cardiomyopathy, and gastrointestinal dysmotility in 2 patients with asymptomatic primary biliary cirrhosis (PBC) and circulating antimitochondrial autoantibodies, and to review pertinent literature concerning this syndrome.

METHODS

Clinical, electrophysiologic, serologic, and pathologic studies of the 2 affected patients were conducted.

RESULTS

Skeletal muscle involvement was manifested by progressive weakness of the proximal muscles, marked diaphragmatic dysfunction with consequent hypoventilation and respiratory failure, and moderately elevated levels of muscle-associated enzymes. Serum from both patients contained antimitochondrial antibodies that reacted with components of the mitochondrial keto acid dehydrogenase enzyme complex. Results of electromyography were consistent with a myopathic process. The microscopic and ultrastructural changes in the skeletal muscles were distinct from those of typical myositis, and were notable for striking subsarcolemmal aggregation of abnormal mitochondria in the absence of significant inflammation.

CONCLUSION

Severe skeletal muscle, cardiac, and gastrointestinal pathology with abnormalities of the muscle mitochondria develops in a subset of patients with mild PBC and antimitochondrial antibodies. The pathogenesis of this syndrome is unclear, but may be related to the presence of the antimitochondrial autoantibodies.

Antimitochondrial (pyruvate dehydrogenase) autoantibodies in autoimmune rheumatic diseases

Anti-pyruvate dehydrogenase (PDH) antibodies were determined in 1451 sera of patients with primary biliary cirrhosis (PBC) and several autoimmune rheumatic conditions by ELISA and immunoblotting. They were detected in sera of 93% of the patients with PBC (179 of 192 patients) in 60 of 277 (22%) patients with Sjogren's syndrome (SjS), 34 of 437 (8%) patients with scleroderma, 33 of 191 patients with SLE (17%), and 5 of 55 (10%) patients with rheumatoid arthritis (RA) but in none of the patients with polymyositis or the antiphospholipid syndrome. The ELISA studies were confirmed by immunoblots showing binding of autoimmune rheumatic sera to the same epitope (74 kd) of mitochondria that the PBC sera reacted with. The identical binding characteristics were also confirmed by protein competition assays with purified PDH. In 4 of 53 patients with SjS who were positive for anti-PDH, high titers as in PBC were detected. The anti-PDH antibodies in Sjogren's patients were associated with deranged liver function tests and extraglandular features but did not correlate with any other non-organ-specific antibody. Follow-up studies confirmed the association of the emergence of anti-PDH antibodies with defects in liver function tests. The antibodies were more prevalent in SLE and RA when they were associated with Sjogren's syndrome (30 and 18.8%, respectively). Among patients with different forms of scleroderma, anti-PDH antibodies were noted in subjects with systemic sclerosis, morphea, and Raynaud's phenomenon.(ABSTRACT TRUNCATED AT 250 WORDS)

Stiff-man syndrome: a GABAergic autoimmune disorder with autoantigenic heterogeneity

Autoantibodies that reacted with cell bodies and axon terminals of gamma-aminobutyric acid (GABA)ergic neurons were present in the serum and cerebrospinal fluid in a patient with stiff-man syndrome with type I diabetes. Immunoblot experiments using this patient's serum and cerebrospinal fluid did not corroborate an earlier observation that these autoantibodies are directed against the GABAergic cytosolic enzyme, L-glutamic acid decarboxylase. While L-glutamic acid decarboxylase autoantibodies may be associated with this syndrome, they do not appear to be easily demonstrated.

Autoantibodies to mitochondrial and centromere antigens in primary biliary cirrhosis and systemic sclerosis

High levels of IgG antibodies to the multi-enzyme complex bovine pyruvate dehydrogenase (PDHC) were detected by a sensitive ELISA in all patients with histologically proven primary biliary cirrhosis (PBC), in a minority of patients with systemic sclerosis without overt PBC or with chronic liver diseases of another cause and in no rheumatoid arthritis or normal controls. Most (15/21) but not all of these positive patients recognized a 70-kD (E2) component of PDHC on immunoblotting. Additional recognition of a centromere-associated 140-kD polypeptide was associated with the presence of scleroderma-like features (Raynaud's phenomenon and sclerodactyly) in PBC, further emphasizing the serological and clinical overlap between these two conditions.