Synovial nitric oxide concentrations are increased and correlated with serum levels in patients with active Behçet's disease: a pilot study

Finding the Needle in the Haystack: Serological and Urinary Biomarkers in Behçet's Disease: A Systematic Review

Urinary and serological markers play an essential role in the diagnostic process of autoimmune diseases. However, to date, specific and reliable biomarkers for diagnosing Behçet's disease (BD) are still lacking, negatively affecting the management of these patients. To analyze the currently available literature on serological and urinary BD biomarkers investigated in the last 25 years, we performed a systematic literature review using the Population, Intervention, Comparison, and Outcomes (PICO) strategy. One hundred eleven studies met the eligibility criteria (6301 BD patients, 5163 controls). Most of them were retrospective, while five (5%) were prospective. One hundred ten studies (99%) investigated serological biomarkers and only two (2%) focused on urinary biomarkers. One hundred three studies (93%) explored the diagnostic potential of the biomolecules, whereas sixty-two (56%) tested their effect on disease activity monitoring. Most articles reported an increase in inflammatory markers and pro-oxidant molecules, with a decrease in antioxidants. Promising results have been shown by the omics sciences, offering a more holistic approach. Despite the vast number of investigated markers, existing evidence indicates a persistent gap in BD diagnostic/prognostic indices. While new steps have been taken in the direction of pathogenesis and disease monitoring, international efforts for the search of a diagnostic marker for BD are still needed.

Behcet disease: an undifferentiating and complex vasculitis

Behçet Disease is a relapsing and remitting variable vessel vasculitis characterized by recurrent mucocutaneous ulcers that can involve almost every organ system in the body. Indeed, the presence of recurrent oral or genital ulcers with other auto-inflammatory symptoms should raise suspicion for this elusive disease. It is unique among the vasculitides in that it can affect vessels of small, medium, and large size and tends to involve venous rather than arterial circulation, and its effects on the pulmonary venous circulation are particularly notable for their role in disease mortality. Classically seen in Mediterranean, Middle-Eastern, and eastern Asian countries, and relatively rare in the United States, prevalence has been increasing, prompting an increased need for internists to be aware of Behcet's clinical presentation and treatment. As early recognition and diagnosis of the disease is key to successful treatment and better prognosis, this review provides a brief summary of the current etiological theories, important clinical manifestations, and treatments including newer biologic alternatives.

Behçet syndrome: from pathogenesis to novel therapies

Behçet syndrome is a chronic disease hallmarked by inflammation of the blood vessels that is related to an autoimmune reaction caused by inherited susceptibility due to specific genes and environmental factors, probably components of infectious microorganisms, which turn on or get going the disease in genetically susceptible subjects. The more common clinical expression of the disease is represented by a triple-symptom complex of recurrent oral aphthous ulcers, genital ulcers, and uveitis, sometimes associated with inflammatory arthritis, phlebitis, iritis, as well as inflammation of the digestive tract, brain, and spinal cord. The treatment strategies used to manage the manifestations of Behçet syndrome have gradually progressed, and a number of new therapeutic resources have been implemented in recent years, allowing better control of pathogenic mechanisms, reducing symptoms and suffering, and ameliorating patient's outcome.

Serum angiostatin levels in patients with Behçet's disease: does angiogenesis play a role in the pathogenesis of Behçet's disease?

Angiogenesis plays an important role in the pathogenesis of inflammatory diseases, but the possible role of angiogenesis in Behçet's disease (BD) has not yet been studied. The aim of this study was to determine angiostatin levels in patients with BD and the role of angiogenesis in the pathogenesis of the disease. Thirty-seven patients with BD (mean age: 28·6±5·4 years, mean disease duration: 9·3±3·7 years) and 18 healthy controls were enrolled to the study. Twenty-four patients were in active and 13 patients were in inactive stage of the disease. The mean serum angiostatin level of patients with BD was 113·9±53·2 and 60·7±20·1 ng/ml in healthy controls. The mean serum angiostatin level was 142·7±43·1 ng/ml in active and 86·9±15·5 ng/ml in inactive patients with BD. Serum angiostatin levels were significantly high in patients with BD compared with healthy controls (P<0·001) and it was significantly high in active patients compared with inactive patients with BD (P<0·001). In inactive patients with BD, serum angiostatin concentrations were found to be higher compared with healthy controls (P<0·01). In active BD patients, the mean serum angiostatin level was correlated with the deep vein thrombosis (r = 0·482, P = 0·05), uveitis (r = 0·582, P = 0·01), and arthritis (r = 0·492, P = 0·05). According to these results; elevated serum angiostatin levels in patients with BD suggest the possible role of angiogenesis in the pathogenesis of the disease and its high levels in inactive Behçet's patients is related with the continuous activation of the disease even in the subclinical period.

Outcome measures used in clinical trials for Behçet syndrome: a systematic review

Behçet syndrome (BS) is a multisystem vasculitis that is most active during young adulthood, causing serious disability and significant impairment in quality of life. Differences in the disease course, severity, and organ involvement between patients, depending on the age at presentation and sex, makes it impossible to determine a single management strategy. The diversity and variability in the outcome measures used in clinical trials in BS makes it difficult to compare the results or inform physicians about the best management strategy for individual patients. There is a large unmet need to determine or develop validated outcome measures for use in clinical trials in BS that are acceptable to researchers and regulatory agencies. We conducted a systematic review to describe the outcomes and outcome measures that have been used in clinical trials in BS. This review revealed the diversity and variability in the outcomes and outcome measures and the lack of standard definitions for most outcomes and rarity of validated outcome tools for disease assessment in BS. This systematic literature review will identify domains and candidate instruments for use in a Delphi exercise, the next step in the development of a core set of outcome measures that are properly validated and widely accepted by the collaboration of researchers from many different regions of the world and from different specialties, including rheumatology, ophthalmology, dermatology, gastroenterology, and neurology.

Mitochondrial carrier homolog 1 (Mtch1) antibodies in neuro-Behçet's disease

Efforts for the identification of diagnostic autoantibodies for neuro-Behcet's disease (NBD) have failed. Screening of NBD patients' sera with protein macroarray identified mitochondrial carrier homolog 1 (Mtch1), an apoptosis-related protein, as a potential autoantigen. ELISA studies showed serum Mtch1 antibodies in 68 of 144 BD patients with or without neurological involvement and in 4 of 168 controls corresponding to a sensitivity of 47.2% and specificity of 97.6%. Mtch1 antibody positive NBD patients had more attacks, increased disability and lower serum nucleosome levels. Mtch1 antibody might be involved in pathogenic mechanisms of NBD rather than being a coincidental byproduct of autoinflammation.

Ocular Behçet disease: current therapeutic approaches

PURPOSE OF REVIEW

To alert physician to timely recognition and current treatment of recurrent hypopyon iridocyclitis or panuveitis in ocular Behçet disease (OBD).

RECENT FINDINGS

Interferon-α, rituximab, intravitreal triamcinolone, and biological response modifiers by tumor necrosis factor inhibitors such as infliximab and adalimumab are being used increasingly for the treatment of severe sight-threatening ocular inflammation including retinal vasculitis and cystoid macular edema (CME).

SUMMARY

Biological agents offer tremendous potential in the treatment of OBD. Given that OBD predominantly afflicts the younger adults in their most productive years, dermatologist, rheumatologist, internist, or general practitioners supervising patients with oculo-articulo-oromucocutaneous syndromes should be aware of systemic Behçet disease. Early recognition of ocular involvement is important and such patients should strongly be instructed to visit immediately an ophthalmologist, as uveitis management differs from extraocular involvements with high ocular morbidity from sight-threatening complications due to relapsing inflammatory attacks in the posterior segment of the eye. A single infliximab infusion should be considered for the control of acute panuveitis, whereas repeated long-term infliximab infusions were proved to be more effective in reducing the number of episodes in refractory uveoretinitis with faster regression and complete remission of CME.

Ocular Behçet disease: current therapeutic approaches

PURPOSE OF REVIEW

To alert physician to timely recognition and current treatment of recurrent hypopyon iridocyclitis or panuveitis in ocular Behçet disease (OBD).

RECENT FINDINGS

Interferon-α, rituximab, intravitreal triamcinolone, and biological response modifiers by tumor necrosis factor inhibitors such as infliximab and adalimumab are being used increasingly for the treatment of severe sight-threatening ocular inflammation including retinal vasculitis and cystoid macular edema (CME).

SUMMARY

Biological agents offer tremendous potential in the treatment of OBD. Given that OBD predominantly afflicts the younger adults in their most productive years, dermatologist, rheumatologist, internist, or general practitioners supervising patients with oculo-articulo-oromucocutaneous syndromes should be aware of systemic Behçet disease. Early recognition of ocular involvement is important and such patients should strongly be instructed to visit immediately an ophthalmologist, as uveitis management differs from extraocular involvements with high ocular morbidity from sight-threatening complications due to relapsing inflammatory attacks in the posterior segment of the eye. A single infliximab infusion should be considered for the control of acute panuveitis, whereas repeated long-term infliximab infusions were proved to be more effective in reducing the number of episodes in refractory uveoretinitis with faster regression and complete remission of CME.

Ex vivo effects of flavonoïds extracted from Artemisia herba alba on cytokines and nitric oxide production in Algerian patients with Adamantiades-Behçet's disease

Background

Adamantiades-Behçet's disease (ABD) is a chronic multisystemic inflammation with unknown pathophysiology. This disorder is associated with a dysregulation of the cytokine network that hyperactivates neutrophils and macrophages. In this study, we investigate the modulatory effects of flavonoïd compounds extracted from Algerian medicinal plant Artemisia herba alba on Th1 and Th2 cytokines and nitric oxide production.

Methods

The modulatory effects of flavonoïds extracted from Artemisia herba alba on cytokines and nitric oxide production by peripheral blood mononuclear cells isolated from Algerian ABD patients and healthy controls were respectively measured by means of ELISA assays and Griess modified method.

Results

Our results show that flavonoïds significantly reduce the production of interleukin-12, the key effector of T helper 1 (Th1) cells and nitric oxide in a dose-dependent manner in Adamantiades-Behçet's disease. In contrast, the production of IL-4, the key marker of Th2 cells was increased.

Conclusion

This study suggests that in vitro supplementation with flavonoïds extracted from Artemisia herba alba could have potential immuno-modulatory effects characterised by a down-regulation and up-regulation of Th1 and Th2 cytokines, respectively. Moreover, flavonoïds may prevent nitric oxide induced damages.

Preventive effects of ethyl pyruvate on endotoxin-induced uveitis in rats

PURPOSE

Recent studies indicate that ethyl pyruvate (EP) exerts anti-inflammatory properties; however, the effect of EP on ocular inflammation is not known. The efficacy of EP in endotoxin-induced uveitis (EIU) in rats was investigated.

METHODS

EIU in Lewis rats was developed by the subcutaneous injection of lipopolysaccharide (LPS; 150 μg). EP (30 mg/kg body weight) or its carrier was injected intraperitoneally 1 hour before or 2 hours after lipopolysaccharide injection. Animals were killed after 3 and 24 hours followed by enucleation of eyes and collection of the aqueous humor (AqH). The number of infiltrating cells and levels of proteins in the AqH were determined. The rat cytokine/chemokine multiplex method was used to determine level of cytokines and chemokines in the AqH. TNF-α and phospho-nuclear factor kappa B (NF-κB) expression in ocular tissues were determined immunohistochemically. Human primary nonpigmented ciliary epithelial cells (HNPECs) were used to determine the in vitro efficacy of EP on lipopolysaccharide-induced inflammatory response.

RESULTS

Compared to controls, AqH from the EIU rat eyes had a significantly higher number of infiltrating cells, total protein, and inflammatory cytokines/chemokines, and the treatment of EP prevented EIU-induced increases. In addition, EP also prevented the expression of TNF-α and activation of NF-κB in the ciliary bodies and retina of the eye. Moreover, in HNPECs, EP inhibited lipopolysaccharide-induced activation of NF-κB and expression of Cox-2, inducible nitric oxide synthase, and TNF-α.

CONCLUSIONS

Our results indicate that EP prevents ocular inflammation in EIU, suggesting that the supplementation of EP could be a novel approach for the treatment of ocular inflammation, specifically uveitis.

Oxidases and oxygenases in regulation of neutrophil redox pathways in Behçet's disease patients

This study aimed to determine plasma and neutrophil oxidase activities that may contribute to vascular inflammation in Behçet's disease (BD) patients. Cyclooxygenase (COX), NADPH oxidase and myeloperoxidase (MPO) activity was determined in neutrophils isolated from BD patients and healthy controls. Functional assay of NADPH oxidase was significantly increased in BD patients, both at basal conditions and in response to fMLP stimulation. There was a significant increase in plasma MPO activity in the disease group as compared to controls. Total COX activity was significantly increased in BD neutrophils. The increase in total COX activity was accompanied with enhanced activity of COX-2, differentiated by using the COX-1 isoform-specific inhibitor SC-560. Neutrophil nitrate/nitrite levels showed no significant difference in BD; however, plasma nitrate/nitrite contents in BD patients were significantly greater compared to controls. In conclusion, increased plasma MPO, neutrophil NADPH and COX activities may contribute to intravascular inflammation documented in BD patients.

Association between recurrent aphthous stomatitis and inheritance of a single-nucleotide polymorphism of the NOS2 gene encoding inducible nitric oxide synthase

BACKGROUND

 Recurrent aphthous stomatitis is a common ulcerative disease of the oral mucosa. Recurrent oral aphthous ulceration is also a feature of the more serious and systemic Behçet's disease. Nitric oxide is a free radical synthesized by one of a family of nitric oxide synthase (NOS) enzymes and is an important regulator of inflammation and immunity. Association of NOS3 gene polymorphisms encoding endothelial nitric oxide synthase has been reported in Behçet's disease but not recurrent aphthous stomatitis. The aim of this study was to investigate any association between NOS2 gene polymorphisms that encode inducible nitric oxide synthase and recurrent aphthous stomatitis.

METHODS

 This is a case control association study. Eighty-three Jordanian recurrent aphthous stomatitis patients and 83 age, gender and ethnically matched controls were genotyped for three NOS2 single-nucleotide polymorphisms, rs10459953, rs1060822 and rs2297518. Chi-squared analysis was used to compare the allele frequencies and genotypes.

RESULTS

 There was a significant association between recurrent aphthous stomatitis and inheritance of single-nucleotide polymorphism rs2297518 (P = 0.006). Although no direct association was demonstrated between rs10459953 or rs1060822 and recurrent aphthous stomatitis, a strong linkage disequilibrium was identified between rs1060822 and rs2297518.

CONCLUSION

 Inheritence of a NOS2 single-nucleotide polymorphism rs2297518 is associated with increased risk of recurrent aphthous stomatitis in a Jordanian population. Confirmatory studies in other populations and investigation of other NOS2 gene polymorphisms will enhance our understanding of the functional basis of this association and help elucidate the role of inducible nitric oxide synthase in recurrent aphthous stomatitis.

Evaluation of current therapeutic strategies in Behçet's disease

Behçet's disease (BD) is a chronic relapsing vasculitis with multifunctional pathogenesis. The mucocutaneous and ocular lesions are the commonest manifestations, but BD also affects the musculoskeletal, intestinal, cardiac, and central nervous system. BD therapy is based on the suppression of the inflammatory process, using immunomodulating and immunosuppressive agents. In selected cases, invasive procedures may be required.

Assessment of serum homocysteine, endothelin-1, and nitric oxide levels in behçet's disease

BACKGROUND

Some prominent features of Behçet's disease (BD) are arterial and venous thromboses as a result of endothelial dysfunction. Hyperhomocysteinemia is responsible for vascular endothelial injury due to an increased frequency of thrombogenesis. Endothelin-1 (ET-1) is a vasoconstrictor whereas nitric oxide (NO) is an endothelial vasorelaxing peptide that is responsible for the inhibition of platelet adhesion.

AIM

To evaluate serum levels of homocysteine (Hcy) and determine whether hyperhomocysteinemia is considered as a contributing risk factor for venous and arterial thromboses of BD, and to correlate serum levels of ET-1 and NO with disease activity.

MATERIALS AND METHODS

We measured serum levels of Hcy, ET-1, and nitrite (NO(2) (-)) in 25 patients who fulfilled the criteria of the International Study Group for BD, and compared them to those of 15 healthy control subjects. Levels of Hcy and ET-1 were measured by using enzyme-linked immunosorbent assay (ELISA), whereas serum nitrite (NO(2) (-)) levels were measured by using Griess reaction as an indicator for NO production. All the patients were screened for a history of venous thrombosis and subdivided into thrombotic and nonthrombotic subgroups according to their thrombotic history. Patients with BD were divided into two subgroups, active and inactive, according to their clinical and laboratory findings.

RESULTS

There were significant increases in serum levels of Hcy, ET-1, and nitrite in BD patients compared to those in controls. There was a significant increase in serum Hcy levels in thrombotic compared to nonthrombotic subgroups. Positive correlations were detected between the serum ET-1 and nitrite levels with disease activity in BD patients.

CONCLUSION

Hyperhomocysteinemia may play some role in the development of venous and arterial thromboses in BD. Increased NO production might ave critical biological activities that are relevant to pathological events in the active period of the disease.

Prevention of endotoxin-induced uveitis in rats by plant sterol guggulsterone

PURPOSE

To investigate the anti-inflammatory effects of guggulsterone, an antioxidant and antitumor agent, in endotoxin-induced uveitis (EIU) in rats and to elucidate the underlying molecular mechanism or mechanisms related to ocular inflammation.

METHODS

EIU was induced by subcutaneous injection of lipopolysaccharide (LPS; 150 μg) into Lewis rats treated with guggulsterone (30 mg/kg body weight, intraperitoneally) or its carrier. After 24 hours the rats were killed, eyes were enucleated, and aqueous humor (AqH) was collected. Numbers of infiltrating cells and levels of matrix metalloproteinase-2 (MMP-2), nitric oxide (NO), and prostaglandin E(2) (PGE(2)) were determined in AqH by specific ELISAs. An antibody array was used to measure the expression of various inflammatory cytokines in AqH. The expression of MMP-2, iNOS, Cox-2, phospho-IκB, and phospho-NF-κB was determined immunohistochemically. Human primary nonpigment ciliary epithelial cells (HNPECs) were used to determine the in vitro efficacy of guggulsterone on the LPS-induced inflammatory response.

RESULTS

Compared with control, the EIU rat eye AqH had a significantly higher number of infiltrating cells, total protein, and inflammatory markers, such as MMP-2, NO, and PGE(2), and the treatment of guggulsterone prevented EIU-induced increases. Guggulsterone also prevented the expression of MMP-2, iNOS, and Cox-2 proteins and of IκB and NF-κB in various eye tissues. Moreover, in cultured HNPECs, guggulsterone inhibited LPS-induced expression of inflammatory proteins.

CONCLUSIONS

These results for the first time demonstrate that the plant sterol guggulsterone suppresses ocular inflammation in EIU, suggesting that the supplementation of guggulsterone could be a novel approach for the treatment of ocular inflammation.

Aldose reductase inhibition prevents endotoxin-induced uveitis in rats

PURPOSE

The purpose of the present study was to elucidate the role of the polyol pathway enzyme aldose reductase (AR) in the mediation of ocular inflammation in a rat model of endotoxin-induced uveitis (EIU).

METHODS

EIU was induced by a subcutaneous injection of 200 microg lipopolysaccharide (LPS) in male Lewis rats treated with the AR inhibitor, zopolrestat (25 mg/kg body weight, intraperitoneally) or its carrier. The rats were killed 24 hours after LPS injection, the eyes were enucleated immediately, and aqueous humor (AqH) was collected. The number of infiltrating cells, protein concentration, and levels of nitric oxide (NO), tumor necrosis factor (TNF)-alpha, and prostaglandin E(2) (PGE(2)) in the AqH were determined. Immunohistochemical analysis was performed in paraformaldehyde-fixed eye sections by staining with antibodies against iNOS, COX-2, TNF-alpha, NF-kappaB, and AR. The levels of reactive oxygen species (ROS) in rat eye sections were determined by dihydroethidium (hydroethidine) fluorescence staining.

RESULTS

In the EIU rat eye AqH, both the number of infiltrating cells and protein concentrations of the inflammatory markers, TNF-alpha, NO, and PGE(2) were significantly higher than in the control rats, and inhibition of AR by zopolrestat suppressed the LPS-induced increases. The LPS-induced increased expression of AR, TNF-alpha, iNOS, and COX-2 proteins in the ciliary body, corneal epithelium, and retinal wall was also significantly inhibited by zopolrestat. Furthermore, AR inhibition prevented the LPS-induced increased levels of ROS and activation of NF-kappaB in the ciliary body, corneal epithelium, and retinal wall of the rat eye. AR inhibition also prevented the LPS-induced activation of NF-kappaB and expression of COX-2 and iNOS in the human monocyte cell line U-937.

CONCLUSIONS

The results indicate that AR inhibition suppresses the inflammation in EIU by blocking the expression and release of inflammatory markers in ocular tissues, along with the attenuation of NF-kappaB activation. This finding suggests that AR inhibition could be a novel therapeutic target for the treatment of uveitis and associated ocular inflammation.

Physiopathologie de la maladie de Behçet

SUBJECT

Pathophysiology of Behçet's disease (BD) is complex. Recent experimental data shed new light on the mechanisms leading to organ lesions.

MAIN ISSUES

Neutrophils and cytotoxic lymphocytes are now recognized as key effector cells in BD. Genetic susceptibility, environmental factors (virus and/or bacterial infections), inflammatory response abnormalities (heat shock proteins, dysregulated NO production) and abnormal immune response play also a major role in BD pathogeny.

PERSPECTIVES

Better understanding of the BD pathophysiology will allow the development of new therapies more specific of BD.