Immune pathogenesis of Mixed Connective Tissue Disease: a short analytical review

Childhood mixed connective tissue disease at disease onset: Evidence from a systematic review

OBJECTIVE

Childhood Mixed Connective Tissue Disease (cMCTD) is the rarest pediatric connective tissue disease that includes features of systemic lupus erythematosus, polymyositis/dermatomyositis, juvenile idiopathic arthritis, and systemic sclerosis, identified by Sharp in 1972 and whose diagnosis remains challenging. This systematic review aims to identify clinical features at the onset of cMCTD and manifestations not currently included into the available diagnostic criteria.

METHODS

A systematic literature review was performed in accordance with PRISMA guidelines 2020 using bibliographic databases: MEDLINE via PubMed and EMBASE.

ELIGIBILITY CRITERIA

patients diagnosed with MCTD with onset before 18 years.

STUDIES INCLUDED

registries, retrospective and prospective cohort studies, case series and reports with analysis of data on signs and symptoms of presentation.

RESULTS

39 articles were included (215 subjects, 82.5% female), mean age of 141 months (± 41 months DS, range 2.5-204). The most used criteria for the diagnosis of MCTD were the Kasukawa criteria (54.5%). The clinical manifestations described at onset were Raynaud's phenomenon (69.7%), arthritis (60.9%), muscular involvement (53.5%), dermatological signs (39.5%), swollen fingers or hands (29.3%), arthralgias (25.6%), fever (22.3%), lung involvement (14.4%), sclerodactily (13.5%), lymphadenopathy (10.7%) serositis (10.2%), esophageal involvement (6.9%), nervous system involvement (6.9%), xeroftalmia (3.7%), xerostomia (3.7%), hepatosplenomegaly (2.8%), cardiac involvement (2.8%), hepatitis (2.3%), parotiditis (2.3%), Hashimoto's thyroiditis (0.9%), ocular involvement (0.9%).

CONCLUSIONS

The data from this systematic review suggest great heterogeneity of the clinical presentation of cMCTD for which there are no validated diagnostic criteria that may suggest a new diagnostic approach to allow earlier or more accurate diagnosis in the future.

Identification of Anti-SNRPA as a Novel Serological Biomarker for Systemic Sclerosis Diagnosis

Systemic sclerosis (SSc) is a systemic autoimmune disorder that leads to vasculopathy and tissue fibrosis. A lack of reliable biomarkers has been a challenge for clinical diagnosis of the disease. We employed a protein array-based approach to identify and validate SSc-specific autoantibodies. Phase I involved profiled autoimmunity using human proteome microarray (HuProt arrays) with 90 serum samples: 40 patients with SSc, 30 patients diagnosed with autoimmune diseases, and 20 healthy subjects. In Phase II, we constructed a focused array with candidates identified antigens and used this to profile a much larger cohort comprised of serum samples. Finally, we used a western blot analysis to validate the serum of validated proteins with high signal values. Bioinformatics analysis allowed us to identify 113 candidate autoantigens that were significantly associated with SSc. This two-phase strategy allowed us to identify and validate anti-small nuclear ribonucleoprotein polypeptide A (SNRPA) as a novel SSc-specific serological biomarker. The observed positive rate of anti-SNRPA antibody in patients with SSc was 11.25%, which was significantly higher than that of any disease control group (3.33%) or healthy controls (1%). In conclusion, anti-SNRPA autoantibody serves as a novel biomarker for SSc diagnosis and may be promising for clinical applications.

Posterior Reversible Leucoencephalopathy Syndrome: Case Series, Comments, and Diagnostic Dilemma

PURPOSE OF REVIEW

To report a series of patients with clinical and radiological features suggestive of posterior reversible encephalopathy syndrome (PRES) related to diverse etiologies emphasizing its pathophysiological basis.

RECENT FINDINGS

Posterior reversible encephalopathy syndrome (PRES) may present with a broad range of clinical symptoms from headache and visual disturbances to seizure and altered mentation. Typical imaging findings include posterior-circulation predominant vasogenic edema. Although there are many well-documented diseases associated with PRES, the exact pathophysiologic mechanism has yet to be fully elucidated. Generally accepted theories revolve around disruption of the blood-brain barrier secondary to elevated intracranial pressures or endothelial injury induced by ischemia from a vasoconstrictive response to rising blood pressure or toxins/cytokines. While clinical and radiographic reversibility is common, long-standing morbidity and mortality can occur in severe forms. In patients with malignant forms of PRES, aggressive care has markedly reduced mortality and improved functional outcomes. Various factors that have been associated with poor outcome include altered sensorium, hypertensive etiology, hyperglycemia, longer time to control the causative factor, elevated C reactive protein, coagulopathy, extensive cerebral edema, and hemorrhage on imaging. Reversible cerebral vasoconstriction syndromes (RCVS) and primary angiitis of the central nervous system (PACNS) are invariably considered in the differential diagnosis of new cerebral arteriopathies. Recurrent thunderclap headache (TCH), and single TCH combined with either normal neuroimaging, border zone infarcts, or vasogenic edema, have 100% positive predictive value for diagnosing RCVS or RCVS-spectrum disorders. Diagnosis of PRES in some circumstances can be challenging and structural imaging may not be sufficient to distinguish it from other differential diagnostic considerations like ADEM. Advanced imaging techniques, such as MR spectroscopy or positron emission tomography (PET) can provide additional information to determine the diagnosis. Such techniques are more useful to understand the underlying vasculopathic changes in PRES and may answer some of the unresolved controversies in pathophysiology of this complex disease. Eight patients with PRES resulting from different etiologies varying from pre-eclampsia/eclampsia, post-partum headache with seizures, neuropsychiatric systemic lupus erythematosus, snake bite, Dengue fever with encephalopathy, alcoholic liver cirrhosis with hepatic encephalopathy, and lastly reversible cerebral vasoconstriction syndrome (RCVS). Additionally, a diagnostic dilemma between PRES and acute disseminated encephalomyelitis (ADEM) was notable in one patient. Some of these patients did not have or only very transiently had arterial hypertension. PRES may underlie the clinical conundrum of headache, confusion, altered sensorium, seizures, and visual impairment. PRES need not necessarily be always associated with high blood pressure. Imaging findings may also be variable. Both clinicians and radiologists need to familiarize themselves with such variabilities.

The enigma of mixed connective tissue disease-challenges in routine care

Objectives

As a rare and heterogeneous disease, mixed connective tissue disease (MCTD) represents a challenge. Herein, we aimed to unravel potential pitfalls including correct referral diagnosis, distinction from other connective tissue diseases (CTD) and treatment modalities.

Methods

We characterised the MCTD cohort at our tertiary referral centre. All patients were evaluated for fulfilment of classification criteria of various CTDs. SLEDAI-2 K and EUSTAR-AI were used in accordance with previous research to evaluate disease activity and treatment response.

Results

Out of 85 patients initially referred as MCTD, only one-third (33/85, 39%) fulfilled the diagnostic MCTD criteria and the other patients had undifferentiated CTD (16/85, 19%), non-MCTD overlap syndromes (11/85, 13%) and other rheumatic diseases. In our final cohort of 33 MCTD patients, 16 (48%) also met the diagnostic criteria of systemic sclerosis, 13 (39%) these of systemic lupus erythematosus, 6 (18%) these of rheumatoid arthritis and 3 (9%) these of primary myositis. Management of MCTD required immunomodulating combination therapy in most cases (15/28, 54%), whereas monotherapy was less frequent (10/28, 36%), and only a few (3/28, 11%) remained without immune modulators until the end of the follow-up period. Treatment led to a significant decline in disease activity.

Conclusions

Our study showed a high risk for misdiagnosis for patients with MCTD. As a multi-organ disease, MCTD required prolonged immunomodulating therapy to achieve remission. The establishment of an international registry with longitudinal data from observational multi-centre cohorts might represent a first step to address the many unmet needs of MCTD.

Biomarkers for Inner Ear Disorders: Scoping Review on the Role of Biomarkers in Hearing and Balance Disorders

The diagnostics of inner ear diseases are primarily functional, but there is a growing interest in inner ear biomarkers. The present scoping review aimed to elucidate gaps in the literature regarding the definition, classification system, and an overview of the potential uses of inner ear biomarkers. Relevant biomarkers were categorized, and their possible benefits were evaluated. The databases OVID Medline, EMBASE, EBSCO COINAHL, CA PLUS, WOS BIOSIS, WOS Core Collection, Proquest Dissertations, Theses Global, PROSPERO, Cochrane Library, and BASE were searched using the keywords “biomarker” and “inner ear”. Of the initially identified 1502 studies, 34 met the inclusion criteria. The identified biomarkers were classified into diagnostic, prognostic, therapeutic, and pathognomonic; many were detected only in the inner ear or temporal bone. The inner-ear-specific biomarkers detected in peripheral blood included otolin-1, prestin, and matrilin-1. Various serum antibodies correlated with inner ear diseases (e.g., anti-type II collagen, antinuclear antibodies, antibodies against cytomegalovirus). Further studies are advised to elucidate the clinical significance and diagnostic or prognostic usage of peripheral biomarkers for inner ear disorders, filling in the literature gaps with biomarkers pertinent to the otology clinical practice and integrating functional and molecular biomarkers. These may be the building blocks toward a well-structured guideline for diagnosing and managing some audio-vestibular disorders.

The Serum Cell-Free microRNA Expression Profile in MCTD, SLE, SSc, and RA Patients

Mixed connective tissue disease (MCTD) is a rare disorder characterized by symptoms that overlap two or more Autoimmune Connective Tissue Diseases (ACTDs). The aim of this study was to determine whether miRNAs participating in the TLRs signaling pathway could serve as biomarkers differentiating MCTD or other ACTD entities from a healthy control group and between groups of patients. Although the selected miRNA expression level was not significantly different between MCTD and control, we observed that miR-126 distinguishes MCTD patients from all other ACTD groups. The expression level of miRNAs was significantly higher in the serum of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) patients compared to controls. The miR-145 and -181a levels distinguished RA from other ACDT patients. miR-155 was specific for SLE patients. MiR-132, miR-143, and miR-29a distinguished RA and SLE patients from the systemic sclerosis (SSc) group. Additionally, some clinical parameters were significantly related to the miRNA expression profile in the SLE group. SLE and RA are characterized by a specific serum expression profile of the microRNAs associated with the Toll-like receptors (TLRs) signaling pathway. The analysis showed that their level distinguishes these groups from the control and from other ACTD patients. The present study did not reveal a good biomarker for MCTD patients.

Interferons (IFN-A/-B/-G) Genetic Variants in Patients with Mixed Connective Tissue Disease (MCTD)

Mixed connective tissue disease (MCTD) is a rare complex autoimmune disease in which autoantigens are recognized by endosomal TLRs. Their activation induces a higher secretion of the type I interferons, IFN-γ and the up-regulation of the INF-inducible genes. The present study aimed to investigate whether SNPs that are located in the IFN-A, IFN-B, and IFN-G genes are associated with MCTD. 145 MCTD patients and 281 healthy subjects were examined for IFN-A, IFN-B, and IFN-G genetic variants by TaqMan SNP genotyping assay. ELISA determined IFN-α/-β/-γ serum levels. Among the seven tested SNPs, four polymorphisms: IFN-A rs10757212, IFN-A rs3758236, IFN-G rs2069705, IFN-G rs2069718, as well as INF-G rs1861493A/rs2069705A/rs2069718G haplotype were significantly associated with a predisposition for MCTD. Raynaud's phenomenon, erosive arthritis, swollen hands and fingers, and sclerodactyly were significantly more frequently observed in MCTD patients with IFN-G rs2069718 G allele than in patients with IFN-G rs2069718 A allele. We also found that anti-U1-A autoantibodies most frequently occurred in MCTD patients with rs2069718 GA genotype, while the IFN-G rs2069705 AG and rs2069718 GA genotypes might be a marker of anti-Ro60 presence in MCTD patients. Our results indicate that IFN-G genetic variants may be potential genetic biomarkers for MCTD susceptibility and severity.

Association of anti-RNP with HLADR4 and its prevalence in rheumatoid arthritis patients

BACKGROUND

Autoantibodies are useful diagnostic tools for a variety of rheumatic autoimmune disorders.

OBJECTIVE

The aim of the present study was to investigate autoantibodies against the 70-kD polypeptide of U1 ribonucleoprotein antibodies (RNP) in patients with rheumatoid arthritis (RA) and to investigate the relationship between anti-RNP and HLARD4 in RA patients.

PATIENTS AND METHODS

In this prospective study, we studied 80 RA patients. The patients were classified according to 2010 ACR/EULAR Rheumatoid Arthritis Classification Criteria. The patients were 66 females and 14 males. Patients were classified according to activity, duration of disease, and rheumatoid factor. Thirty healthy individuals were included in the study as a control group. Anti-RNP were determined by enzyme-linked immunosorbent assay and HLADR4 was investigated by gel electrophoresis polymerase chain reaction.

RESULTS

Anti-RNP were positive in 32 patients from 80 patients and negative in all control patients. HLADR4 was positive in 53 RA patients from 80 patients and was positive in 6 controls from 30 controls. There was a positive correlation between HLADR4 and anti-RNP (r = 0.368) (P < 0.01). Anti-RNP levels in rheumatoid patients were higher than anti-RNP levels in control patients. Also, there was a positive correlation between anti-RNP and HLADR4 in rheumatoid patients.

Mixed connective tissue disease-enigma variations?

In 1972, Sharp et al. described a new autoimmune rheumatic disease that they called MCTD, characterized by overlapping features of SSc, SLE, PM/DM, high levels of anti-U1snRNP and low steroid requirements with good prognosis. MCTD was proposed as a distinct disease. However, soon after the original description, questions about the existence of such a syndrome as well as disputes over the features initially described began to surface. The conundrum of whether MCTD is a distinct disease entity remains controversial. We undertook a literature review, focusing on the articles reporting new data about MCTD published in the last decade, to determine whether any new observations help to answer the conundrum of MCTD. After reviewing recent data, we question whether the term MCTD is appropriately retained, preferring to use the term undifferentiated autoimmune rheumatic disease.

Pediatric Mixed Connective Tissue Disease

Pediatric-onset mixed connective tissue disease is among the rare disease entities in pediatric rheumatology and includes features of arthritis, polymyositis/dermatomyositis, systemic lupus erythematosus, and systemic sclerosis. Accurate recognition and diagnosis of the disease is paramount to prevent long-term morbidity. Advances in the genetic and immunologic understanding of the factors involved in the etiopathogenesis provide an opportunity for improvements in prognostication and targeted therapy. The development of a multinational cohort of patients with mixed connective tissue disease would be invaluable to provide more updated data regarding the clinical presentation, to develop a standardized treatment approach, disease activity and outcome tools, and to provide data on long-term outcomes and comorbidities.

U1-RNP and Toll-like receptors in the pathogenesis of mixed connective tissue diseasePart II. Endosomal TLRs and their biological significance in the pathogenesis of mixed connective tissue disease

Mixed connective tissue disease (MCTD) is a chronic autoimmune immunopathological disease of unknown etiology, which is characterized by the presence of various clinical symptoms and the presence of autoantibodies against U1-RNP particles. The U1-RNP component engages immune cells and their receptors in a complex network of interactions that ultimately lead to autoimmunity, inflammation, and tissue injury. The anti-U1-RNP autoantibodies form an immune complex with self-RNA, present in MCTD serum, which can act as endosomal Toll-like receptor (TLR) ligands. Inhibition of TLRs by nucleic acids is a promising area of research for the development of novel therapeutic strategies against pathogenic infection, tumorigenesis and autoimmunity. In this review we summarize current knowledge of endogenous TLRs and discuss their biological significance in the pathogenesis of MCTD. In part I we described the structure, biological function and significance of the U1-RNP complex in MCTD.

Increased levels of anti-heat-shock protein 60 (anti-Hsp60) indicate endothelial dysfunction, atherosclerosis and cardiovascular diseases in patients with mixed connective tissue disease

Heat-shock protein 60 (Hsp60) has been shown to provoke inflammation, and anti-Hsp60 may facilitate the development of atherosclerosis. In this study, we have investigated 30 patients with mixed connective tissue disease (MCTD) and assessed anti-Hsp60 and their relationship to cardiovascular diseases (CVD). Out of 30 patients with MCTD, 15 had CVDs. Anti-Hsp60 antibody was determined by enzyme-linked immunosorbent assay. Since endothelial dysfunction and accelerated atherosclerosis are characteristic to MCTD, a wide array of MCTD-, endothelial dysfunction- and CVD-associated parameters was investigated: serum lipid levels, paraoxonase activity (PON1), rich nuclear ribonucleoprotein U1 (anti-U1RNP), anti-endothelial cell antibodies, anti-cardiolipin and anti-β2-glycoprotein I antibody isotypes (anti-CL and anti-β2GPI), endothelin-1 (ET-1) levels, also intima-media thickness (IMT), a quantitative indicator of atherosclerosis. In MCTD, anti-Hsp60 antibody levels were significantly higher than in healthy individuals (p < 0.02). MCTD patients with CVD had significantly higher levels of anti-Hsp60 compared to MCTD without CVD (p = 0.001). Patients with MCTD had significantly lower high-density lipoprotein cholesterol (p = 0.02) and PON activity (p < 0.001), and significantly increased systolic (p < 0.0002) and diastolic (p < 0.001) blood pressure compared to healthy individuals. Anti-U1RNP levels (p < 0.002) and IMT were higher in patients compared to controls (p = 0.002). The CVD-positive MCTD patients had increased anti-Hsp60 (p < 0.0013), anti-CL IgG (p = 0.0005), ET-1 serum concentration (p < 0.05) and IMT levels (p < 0.001) compared to MCTD patients without CVD. Anti-Hsp60 showed a strong correlation with anti-oxLDL (r = 0.36, p = 0.01) and serum ET-1 (r = 0.62, p < 0.001) and negative correlation with PON activity (r = -0.47, p = 0.01). Anti-Hsp60 indicates endothelial injury, CVD, and can function as a novel atherosclerotic risk factor, also a valuable diagnostic marker in patients with MCTD.

U1-RNP and TLR receptors in the pathogenesis of mixed connective tissue diseasePart I. The U1-RNP complex and its biological significance in the pathogenesis of mixed connective tissue disease

Mixed connective tissue disease (MCTD) is a rare autoimmune syndrome, signified by complex interactions between disease-related phenomena, including inflammation, proliferative vascular arteriopathy, thrombotic events and humoral autoimmune processes. It is still controversial whether MCTD is a distinct clinical entity among systemic connective tissue diseases, although several authors consider that it is distinct and underline characteristic, distinct clinical, serological and immunogenetic features. The putative target of autoimmunity in MCTD is U1-RNP, which is a complex of U1-RNA and small nuclear RNP. Both the U1-RNA component and the specific proteins, particularly U1-70K, engage immune cells and their receptors in a complex network of interactions that ultimately lead to autoimmunity, inflammation, and tissue injury. U1-RNA is capable of inducing manifestations consistent with TLR activation. Stimulation of innate immunity by native RNA molecules with a double-stranded secondary structure may help explain the high prevalence of autoimmunity to RNA binding proteins.

Identification of reference genes in human myelomonocytic cells for gene expression studies in altered gravity

Gene expression studies are indispensable for investigation and elucidation of molecular mechanisms. For the process of normalization, reference genes (“housekeeping genes”) are essential to verify gene expression analysis. Thus, it is assumed that these reference genes demonstrate similar expression levels over all experimental conditions. However, common recommendations about reference genes were established during 1 g conditions and therefore their applicability in studies with altered gravity has not been demonstrated yet. The microarray technology is frequently used to generate expression profiles under defined conditions and to determine the relative difference in expression levels between two or more different states. In our study, we searched for potential reference genes with stable expression during different gravitational conditions (microgravity, normogravity, and hypergravity) which are additionally not altered in different hardware systems. We were able to identify eight genes (ALB, B4GALT6, GAPDH, HMBS, YWHAZ, ABCA5, ABCA9, and ABCC1) which demonstrated no altered gene expression levels in all tested conditions and therefore represent good candidates for the standardization of gene expression studies in altered gravity.

Mixed connective tissue disease presenting with progressive scleroderma symptoms in a 10-year-old girl

Mixed connective tissue disease (MCTD) is a systemic inflammatory disease affecting connective tissue with the underlying autoimmunological mechanism. The core of MCTD is an appearance of symptoms of several other inflammatory diseases of connective tissue – systemic lupus erythematosus, systemic scleroderma, poly- or dermatomyositis, rheumatoid arthritis at the same time, accompanied by a high level of anti-ribonucleoprotein antibodies (anti-U1RNP). The disease was described more than 40 years ago by Sharp et al. During recent years, many efforts to better understand clinical and serological features of MCTD have been made. Diagnosis of MCTD can be difficult. Obligatory international diagnostic criteria are required to be fulfilled. Several versions of such criteria have been proposed, but the most widely used one was described by Kasukawa. There is no consensus about treatment – a choice of drugs depends on symptoms. We present a case of a 10-year-old girl with sclerodactyly and trophic damages of fingers accompanied by symptoms of Raynaud's phenomenon. After an almost 2-year course of the disease, a diagnosis of MCTD has been established.

Loss of lingual sensitivity and slightly increased size signaling schwannoma in a patient with mixed conjunctive tissue disease

The purpose of this study was to describe an unusual case of a lingual schwannoma associated with a mixed connective tissue disease (MCTD). A case report. A lingual schwannoma with loss of lingual sensitivity and slightly increased size in an 18-year-old patient with MCTD was correctly diagnosed through a biopsy and no reoccurrence was observed one year after the surgical removal of the tumor and sensitivity returned 3 months after surgery. This case was considered uncommon, making the clinical diagnosis challenging in view of the diversity of possibilities for its differential diagnosis, thus showing the importance of a biopsy to confirm the diagnosis and long term follow up in such cases.

Clinical course, prognosis, and causes of death in mixed connective tissue disease

OBJECTIVE

To study the survival rate and prognostic indicators of mixed connective tissue disease (MCTD) in a Hungarian population.

METHODS

Two hundred eighty patients with MCTD diagnosed between 1979 and 2011 were followed prospectively. Clinical features, autoantibodies, and mortality data were assessed. Prognostic factors for survival were investigated and survival was calculated from the time of the diagnosis by Kaplan-Meier method.

RESULTS

A total of 22 of 280 patients died: the causes of death were pulmonary arterial hypertension (PAH) in 9 patients, thrombotic thrombocytopenic purpura in 3, infections in 3, and cardiovascular events in 7. The 5, 10, and 15-year survival rates after the diagnosis was established were 98%, 96%, and 88%, respectively. The deceased patients were younger at the diagnosis of MCTD compared to patients who survived (35.5 ± 10.4 vs 41.8 ± 10.7 yrs; p < 0.03), while there was no difference in the duration of the disease (p = 0.835). Our cohort study showed that the presence of cardiovascular events (p < 0.0001), esophageal hypomotility (p = 0.04), serositis (p < 0.001), secondary antiphospholipid syndrome (p = 0.039), and malignancy (p < 0.001) was significantly higher in the deceased patients with MCTD. The presence of anticardiolipin (p = 0.019), anti-β2-glycoprotein I (p = 0.002), and antiendothelial cell antibodies (p = 0.002) increased the risk of mortality.

CONCLUSION

Overall, PAH remained the leading cause of death in patients with MCTD. The prevalence of cardiovascular morbidity and mortality, malignancy, and thrombotic events increased during the disease course of MCTD. The presence of antiphospholipid antibodies raised the risk of mortality.

Anti B-cell therapy against refractory thrombocytopenia in SLE and MCTD patients: long-term follow-up and review of the literature

OBJECTIVE

The objective of this study was to retrospectively evaluate the clinical and immunological effects of anti-B cell treatment in patients with systemic lupus erythematosus (SLE) and mixed connective-tissue disease (MCTD) with autoimmune thrombocytopenia (AITP) refractory to conventional immunosuppressive treatment.

METHODS

Rituximab (RTX) was added to the ongoing treatment of 16 patients (median age 36 years, range 17-84, all female) with treatment-resistant AITP. Thirteen patients had SLE and three had MCTD. RTX was given intravenously on four occasions during four consecutive weeks at a dose of 375 mg/m(2). Clinical and laboratory disease activity variables recorded at every follow-up visit were analyzed.

RESULTS

The median disease duration before RTX treatment was nine years (range 0.2-27) and the median post-treatment follow-up time was 28 months (range 3 to 92). Ten patients (63%) were treated repeatedly with RTX during the follow-up period. Complete depletion of B cells was achieved in 94% of cases one month after RTX treatment. A significant increase (p = 0.0001) of platelet counts was seen already after one month (median 58 × 10(9)/ml vs 110 × 10(9)/ml) whereas within three months platelet counts normalized in 10 patients (median 223 × 10(9)/ml). Three patients did not respond to RTX treatment (median platelet count 69 × 10(9)/ml). High titers of anti-platelet antibodies were detected in seven patients before RTX treatment, and the autoantibody titers decreased significantly (p < 0.03) after RTX treatment in six of these patients who also achieved complete remission. A review of the literature revealed 24 articles including 18 case reports, one retrospective cohort study and five prospective studies documenting the outcomes of 65 RTX-treated patients with SLE- or MCTD-related thrombocytopenia with an overall treatment response rate of 80%. In conclusion, these findings indicate that RTX is an additional potent therapeutic treatment option for SLE patients with AITP refractory to conventional immunosuppressive treatment whereas best response may be expected in patients with high titers of anti-platelet antibodies at baseline.

Derailed B cell homeostasis in patients with mixed connective tissue disease

Mixed connective tissue disease (MCTD) is a systemic autoimmune disorder, characterized by the presence of antibodies to U1-RNP protein. We aimed to determine phenotypic abnormalities of peripheral B cell subsets in MCTD. Blood samples were obtained from 46 MCTD patients, and 20 controls. Using anti-CD19, anti-CD27, anti-IgD and anti-CD38 monoclonal antibodies, the following B cell subsets were identified by flow cytometry: (1) transitional B cells (CD19+CD27-IgD+CD38(high)); (2) naive B cells (CD19+CD27-IgD+CD38(low)); (3) non-switched memory B cells (CD19+CD27+IgD+); (4) switched memory B cells (CD19+CD27+IgD-); (5) double negative (DN) memory B cells (CD19+CD27-IgD-) and (6) plasma cells (CD19+CD27(high)IgD-). The proportion of transitional B cells, naive B cells and DN B lymphocytes was higher in MCTD than in controls. The DN B cells were positive for CD95 surface marker. This memory B cells population showed a close correlation with disease activity. The number of plasma cells was also increased, and there was an association between the number of plasma cells and the anti-U1RNP levels. Cyclophosphamide, methotrexate, and corticosteroid treatment decreased the number of DN and CD27(high) B cells. In conclusion, several abnormalities were found in the peripheral B-cell subsets in MCTD, which reinforces the role of derailed humoral autoimmune processes in the pathogenesis.

Natural HLA-B*2705 protein ligands with glutamine as anchor motif: implications for HLA-B27 association with spondyloarthropathy

The presentation of short viral peptide antigens by human leukocyte antigen (HLA) class I molecules on cell surfaces is a key step in the activation of cytotoxic T lymphocytes, which mediate the killing of pathogen-infected cells or initiate autoimmune tissue damage. HLA-B27 is a well known class I molecule that is used to study both facets of the cellular immune response. Using mass spectrometry analysis of complex HLA-bound peptide pools isolated from large amounts of HLA-B*2705(+) cells, we identified 200 naturally processed HLA-B*2705 ligands. Our analyses revealed that a change in the position (P) 2 anchor motif was detected in the 3% of HLA-B*2705 ligands identified. B*2705 class I molecules were able to bind these six GlnP2 peptides, which showed significant homology to pathogenic bacterial sequences, with a broad range of affinities. One of these ligands was able to bind with distinct conformations to HLA-B27 subtypes differentially associated with ankylosing spondylitis. These conformational differences could be sufficient to initiate autoimmune damage in patients with ankylosing spondylitis-associated subtypes. Therefore, these kinds of peptides (short, with GlnP2, and similar low affinity to all HLA-B27 subtypes tested but with unlike conformations in differentially ankylosing spondylitis-associated subtypes) must not be excluded from future researches involving potential arthritogenic peptides.

Brain-blood barrier breakdown and pro-inflammatory mediators in neonate rats submitted meningitis by Streptococcus pneumoniae

Neonatal meningitis is an illness characterized by inflammation of the meninges and occurring within the birth and the first 28 days of life. Invasive infection by Streptococcus pneumoniae, meningitis and sepsis, in neonate is associated with prolonged rupture of membranes; maternal colonization/illness, prematurity, high mortality and 50% of cases have some form of disability. For this purpose, we measured brain levels of TNF-α, IL-1β, IL-6, IL-10, CINC-1, oxidative damage, enzymatic defense activity and the blood-brain barrier (BBB) integrity in neonatal Wistar rats submitted to pneumococcal meningitis. The cytokines increased prior to the BBB breakdown and this breakdown occurred in the hippocampus at 18 h and in the cortex at 12h after pneumococcal meningitis induction. The time-dependent association between the complex interactions among cytokines, chemokine may be responsible for the BBB breakdown and neonatal pneumococcal severity.

The molecular basis for the presence of two autoimmune diseases occurring simultaneously--preliminary observations based on computer analysis

Specific Human Leukocyte Antigen Class II (HLA II) molecules associated with pemphigus vulgaris (PV), mucous membraine pemphigoid (MMP), and mixed connective tissue disease (MCTD) may react with multiple T cell epitopes within desmoglein 3 (Dsg 3), bullous pemphigoid antigen 2 (BPAG 2), and 70 kDa polypeptide small nuclear ribonucleoproteins (snRNP70) in autoantibody production. We report a group of patients with simultaneous occurrences of PV with MCTD, and MMP with MCTD. In one patient group, we performed serological studies to show presence of antibodies to Dsg 3, Dsg 1, and snRNP70 simultaneously. In the second group, we performed serological studies to show presence of antibodies to BPAG 1, BPAG 2, β4 integrin, and snRNP70 simultaneously. In both groups, HLA II genes were analyzed and the observations were consistent with previously described associations with PV, MMP, and MCTD. It is possible that HLA-DQβ1*0301 allele, present in 10 of 17 patients and DRβ1*04 in some of the others, may have the ability to bind to several relevant T cell epitopes in the snRNP70 molecule. We have utilized a computer model to demonstrate that HLA II-restricted T cell epitopes present within the known autoantigens may be capable of eliciting an immune response. While other explanations and mechanisms exist, the authors suggest that epitope spreading may be one possible mechanism, amongst others, that may result in the simultaneous presence of two separate pathogenic autoantibodies.

Potential role of molecular mimicry between human U1-70 kDa and fungal proteins in the development of T-cell mediated anti-U1-70 kDa autoimmunity

CONTEXT

Molecular mimicry between human and microbial antigens is a possible trigger of autoimmunity. The possible role of this mechanism in the onset of autoimmunity against the human autoantigen U1-70 kDa, typical of mixed connective tissue disease, is not fully elucidated.

OBJECTIVE

We aimed to identify microbial proteins highly similar to U1-70 kDa and potentially triggering anti-U1-70 kDa autoimmunity.

MATERIALS AND METHODS

We compared in silico the amino acid sequence of human U1-70 kDa and those of all the sequenced fungal, viral and bacterial proteins.

RESULTS

Human U1-70 kDa shares highly significant (E<10(-20)) amino acid sequence homology, spanning a segment containing T-cell epitopes, with 13 fungal (but no viral or bacterial) proteins, belonging to human pathogens. Nine of these proteins include the amino acid sequence VLVDVERGRTV, identical to the most frequent U1-70 kDa T-cell epitope in anti-U1-70 kDa positive patients, and sequences highly similar to the epitope DAFKTLFVARVN (identical residues or conservative residue substitutions in positions crucial for epitope binding).

DISCUSSION AND CONCLUSION

Cross-reactivity between human U1-70 kDa and microbial proteins was demonstrated for B-cell epitopes, but never investigated before for T-cell epitopes. Our data identify some fungal proteins as possible triggers of anti-U1-70 kDa autoimmunity via molecular mimicry. Research in this field could improve the understanding of the mechanisms leading to anti-U1-70 kDa autoimmunity, with potential consequences on prevention.

Vitamin D insufficiency in a large MCTD population

OBJECTIVES

The aim of the present study was to evaluate the vitamin D status in patients with mixed connective tissue disease (MCTD) and to determine which clinical symptoms, laboratory parameters and endothelial cell markers are associated with low vitamin D levels.

METHODS

125 female MCTD patients and 48 age- and sex-matched healthy controls were enrolled in the study. The clinical symptoms, autoantibodies (anti-U1-RNP, anti-cardiolipin - anti-CL and anti-endothelial cell antibody - AECA), serum cytokines (IFN-γ, IL-6, IL-12, IL-23, IL-17 and IL-10), soluble endothelial cell markers (endothelin, thrombomodulin - TM, and von Willebrand factor antigen - vWFAg) and serum lipids (total cholesterol, triglyceride, LDL-C, HDL-C, apolipoprotein A1, and apolipoprotein B) were investigated for an association with vitamin D levels by univariate and multivariate statistical analyses.

RESULTS

The mean vitamin D levels were significantly lower in MCTD patients, as compared with the control group (26.16±13.50ng/ml vs. 34.92±9.64ng/ml; p<0.001). In laboratory parameters, vitamin D levels were inversely associated with serum IL-6 (p<0.001), IL-23 (p=0.011), IL-10 (p=0.033) cytokine levels, TM (p=0.001) and endothelin (p=0.033) levels. Low vitamin D levels were also significantly associated with carotid artery intima media thickness (p<0.001), fibrinogen (p=0.010), total cholesterol (p=0.042) and ApoA1 (p=0.004) levels. Among the clinical symptoms, the cardiovascular involvement showed an inverse correlation with vitamin D status in MCTD (p<0.001).

CONCLUSIONS

The prevalence of vitamin D insufficiency is high in patients with MCTD. We assume that vitamin D insufficiency along with inflammatory parameters and lipid abnormalities may provoke cardiovascular events.

Endothelial cell markers reflecting endothelial cell dysfunction in patients with mixed connective tissue disease

INTRODUCTION

The aim of the present study was to investigate the association between cardiovascular risk factors and endothelial dysfunction in patients with mixed connective tissue disease (MCTD) and to determine which biomarkers are associated with atherosclerotic complications, such as cardiovascular disease.

METHODS

Fifty MCTD patients and 38 healthy age-matched and sex-matched controls were enrolled in this study. In order to describe endothelial dysfunction, we assessed flow-mediated dilation (FMD), nitrate-mediated dilation (NMD) and carotid artery intima-media thickness (IMT). We investigated FMD of the brachial artery after reactive hyperemia and NMD after sublingual nitroglycerin administration, while the IMT of the common carotid artery was determined by ultrasound. Anti-U1 ribonucleoprotein (anti-U1RNP) antibodies, anti-cardiolipin (anti-CL) antibodies, anti-endothelial cell antibody (AECA) and endothelial cell markers, such as soluble thrombomodulin (TM) and von Willebrand factor antigen (vWFAg), were assessed.

RESULTS

The endothelium-dependent vasodilation (FMD) was significantly impaired in patients with MCTD, as compared with controls (%FMD: 4.7+/-4.2% vs. 8.7+/-5.0%; P<0.001), while the percentage NMD did not differ (%NMD: 14.3+/-6.6% vs. 17.1+/-6.7%; P=0.073). Mean carotid IMT values were higher in patients than in controls (IMT: MCTD, 0.64+/-0.13 mm vs. controls, 0.53+/-0.14 mm; P<0.001). FMD negatively correlated with disease duration, the levels of apolipoprotein A1, the paraoxonase-1 activity, and systolic blood pressure in MCTD patients. The percentage FMD was significantly lower in MCTD patients with cardiovascular diseases (CVD), than in those without CVD (%FMD: 3.5+/-2.9 vs. 5.8+/-4.8, P<0.0002), while percentage NMD did not differ between patients with and without CVDs. Serum levels of autoantibodies (anti-U1RNP, AECA and anti-CL) were significantly higher in MCTD patients and differed between MCTD patients with and without CVD. Endothelial cell markers such as soluble TM (12.2+/-8.1 ng/ml vs. 3.2+/-1.3 ng/ml; P<0.001) and vWFAg (224.1+/-115% vs. 89.4+/-27.1%, P<0.001) were the highest in MCTD patients with CVD.

CONCLUSIONS

FMD is a reliable sensitive marker of endothelial cell dysfunction in MCTD. Beside the traditional risk factors, anti-U1RNP, AECA and anti-CL antibodies may be important not only in the pathogenesis of MCTD but in the induction of endothelial cell activation, and may play crucial roles in the development of early atherosclerosis in MCTD.

The U1-snRNP complex: structural properties relating to autoimmune pathogenesis in rheumatic diseases

The U1 small nuclear ribonucleoprotein particle (snRNP) is a target of autoreactive B cells and T cells in several rheumatic diseases including systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD). We propose that inherent structural properties of this autoantigen complex, including common RNA-binding motifs, B and T-cell epitopes, and a unique stimulatory RNA molecule, underlie its susceptibility as a target of the autoimmune response. Immune mechanisms that may contribute to overall U1-snRNP immunogenicity include epitope spreading through B and T-cell interactions, apoptosis-induced modifications, and toll-like receptor (TLR) activation through stimulation by U1-snRNA. We conclude that understanding the interactions between U1-snRNP and the immune system will provide insights into why certain patients develop anti-U1-snRNP autoimmunity, and more importantly how to effectively target therapies against this autoimmune response.

Sensorineural Hearing Loss in Patients with Mixed Connective Tissue Disease: Immunological Markers and Cytokine Levels

Objective.

To investigate the frequency of sensorineural hearing loss (SNHL) in patients with mixed connective tissue disease (MCTD).

Methods.

The study population consisted of 71 patients with MCTD (69 female; 2 male), with a mean age of 57.1 ± 7.9 years and a mean disease duration of 14.5 ± 8.0 years. All patients underwent audiological evaluation that included pure tone and speech audiometry. In addition, the systemic manifestations of the disease and drug therapy were recorded. All patients were tested for presence of autoantibodies. Fifty-one age-matched healthy subjects served as controls.

Results.

SNHL was found in 33 (46.4%) of the 71 patients with MCTD. There was no correlation between SNHL and age and disease duration. An association was found between Raynaud’s phenomenon (p < 0.03), secondary antiphospholipid syndrome (APS) (p < 0.05), and SNHL. MCTD patients with SNHL had higher serum levels of anti-U1RNP (p < 0.05), antiendothelial cell antibodies (p < 0.001), and IgG type anticardiolipin antibodies (p < 0.0001) than patients without SNHL. Serum levels of interferon-γ and tumor necrosis factor-α were increased in MCTD patients with SNHL compared to patients without SNHL. The absolute number of natural (CD4+CD25highFoxP+) regulatory T cells (Treg) was lower compared to patients without SNHL.

Conclusion.

In MCTD, SNHL is a specific organ manifestation and appears frequently. We have found that pathogenic autoantibodies, decreased levels of regulatory T cells, and overexpression of proinflammatory cytokines may play a role in the pathogenesis of immune mediated inner ear disorders in MCTD.

Clinical interpretation of antinuclear antibody tests in systemic rheumatic diseases

Autoantibody tests have been used extensively in diagnosis and follow-up of patients in rheumatology clinics. Immunofluorescent antinuclear antibody test using HEp-2 cells is still considered the gold standard for screening of autoantibodies, and most of specific autoantibodies are currently tested by ELISA as a next step. Among the many autoantibody specificities described, some have been established as clinically useful diagnostic markers and are included in the classification criteria of diseases. Despite a long history of routine tests and attempts to standardize such assays, there are still limitations and problems that clinicians need to be aware of. Clinicians should be able to use autoantibody tests more efficiently and effectively with a basic knowledge on the significance of and potential problems in autoantibody tests.