Activation of neutrophils, eosinophils, and lymphocytes in the lower respiratory tract in Wegener's granulomatosis

The Contribution of Innate Immunity in Large-Vessel Vasculitis: Detangling New Pathomechanisms beyond the Onset of Vascular Inflammation

Large-vessel vasculitis (LVV) are autoimmune and autoinflammatory diseases focused on vascular inflammation. The central core of the intricate immunological and molecular network resides in the disruption of the "privileged immune state" of the arterial wall. The outbreak, initially primed by dendritic cells (DC), is then continuously powered in a feed-forward loop by the intimate cooperation between innate and adaptive immunity. If the role of adaptive immunity has been largely elucidated, knowledge of the critical function of innate immunity in LVV is still fragile. A growing body of evidence has strengthened the active role of innate immunity players and their key signaling pathways in orchestrating the complex pathomechanisms underlying LVV. Besides DC, macrophages are crucial culprits in LVV development and participate across all phases of vascular inflammation, culminating in vessel wall remodeling. In recent years, the variety of potential pathogenic actors has expanded to include neutrophils, mast cells, and soluble mediators, including the complement system. Interestingly, new insights have recently linked the inflammasome to vascular inflammation, paving the way for its potential pathogenic role in LVV. Overall, these observations encourage a new conceptual approach that includes a more in-depth study of innate immunity pathways in LVV to guide future targeted therapies.

[Vasculitides and eosinophilic pulmonary diseases]

Eosinophilic granulocytes form peripheral effector cells controlled by Th2 lymphocytes, which cause local cell, tissue, and functional disorders of infiltrated organs via the release of cytotoxic basic proteins and oxygen radicals. Diseases associated with eosinophilia include systemic and organ-related forms. The lungs are involved in eosinophilic granulomatosis with polyangiitis (EGPA, formerly known as Churg-Strauss syndrome), acute and chronic eosinophilic pneumonia, as well as in an organ manifestation in hypereosinophilic syndrome and certain parasitic diseases. In particular, the lungs are frequently affected in vasculitis of small vessels, including EGPA, granulomatosis with polyangiitis (GPA), and microscopic polyangiitis (MPA). Among these, EGPA is the most frequent pulmonary eosinophil vasculitis representative. In addition, there are various overlap syndromes in which characteristic features of EGPA can be detected in the context of other anti-neutrophil cytoplasmic antibody (ANCA-)associated vasculitides. Occasionally, non-ANCA-associated pulmonary vasculitides occur with eosinophilia (e.g., Schönlein-Henoch purpura, Kawasaki disease, drug-induced hypersensitivity, and paraneoplastic syndrome). Herein, the pulmonary vasculitides accompanying eosinophilia are presented with respect to both the lung manifestations and pulmonary eosinophilia.

[Vasculitides and eosinophilic pulmonary diseases]

Eosinophilic granulocytes form peripheral effector cells controlled by Th2 lymphocytes, which cause local cell, tissue, and functional disorders of infiltrated organs via the release of cytotoxic basic proteins and oxygen radicals. Diseases associated with eosinophilia include systemic and organ-related forms. The lungs are involved in eosinophilic granulomatosis with polyangiitis (EGPA, formerly known as Churg-Strauss syndrome), acute and chronic eosinophilic pneumonia, as well as in an organ manifestation in hypereosinophilic syndrome and certain parasitic diseases. In particular, the lungs are frequently affected in vasculitis of small vessels, including EGPA, granulomatosis with polyangiitis (GPA), and microscopic polyangiitis (MPA). Among these, EGPA is the most frequent pulmonary eosinophil vasculitis representative. In addition, there are various overlap syndromes in which characteristic features of EGPA can be detected in the context of other anti-neutrophil cytoplasmic antibody (ANCA-)associated vasculitides. Occasionally, non-ANCA-associated pulmonary vasculitides occur with eosinophilia (e.g., Schönlein-Henoch purpura, Kawasaki disease, drug-induced hypersensitivity, and paraneoplastic syndrome). Herein, the pulmonary vasculitides accompanying eosinophilia are presented with respect to both the lung manifestations and pulmonary eosinophilia.

Eosinophils in vasculitis: characteristics and roles in pathogenesis

Eosinophils are multifunctional granular leukocytes that are implicated in the pathogenesis of a wide variety of disorders, including asthma, helminth infection, and rare hypereosinophilic syndromes. Although peripheral and tissue eosinophilia can be a feature of many types of small-vessel and medium-vessel vasculitis, the role of eosinophils has been best studied in eosinophilic granulomatosis with polyangiitis (EGPA), where eosinophils are a characteristic finding in all three clinical stages of the disorder. Whereas numerous studies have demonstrated an association between the presence of eosinophils and markers of eosinophil activation in the blood and tissues of patients with EGPA, the precise role of eosinophils in disease pathogenesis has been difficult to ascertain owing to the complexity of the disease process. In this regard, results of clinical trials using novel agents that specifically target eosinophils are providing the first direct evidence of a central role of eosinophils in EGPA. This Review focuses on the aspects of eosinophil biology most relevant to the pathogenesis of vasculitis and provides an update of current knowledge regarding the role of eosinophils in EGPA and other vasculitides.

Dysregulation of histone deacetylase and histone acetyltransferase in development of Wegener's granulomatosis

OBJECTIVES

We investigated the function of the decreases in histone deacetylase (HDAC) and histone acetyltransferase (HAT) in Wegener's granulomatosis (WG) patients compared with healthy subjects.

METHODS

Seven patients with WG, diagnosed according to the American College of Rheumatology criteria, were examined. Fresh peripheral blood mononuclear cells were isolated from the WG patients and healthy subjects, and then whole-cell proteins were prepared. We measured the total HDAC and HAT activity in peripheral blood mononuclear cells from WG patients. The HDAC2 expression was analyzed by Western blot.

RESULTS

We found that total HDAC activity was significantly decreased in WG patients compared to that in healthy subjects (p < 0.05). Furthermore, we found a negative correlation between total HDAC activity and C-reactive protein titer. Total HAT activity was significantly increased in WG patients.

CONCLUSIONS

These results demonstrated reduced HDAC activity and an increase in HAT activity in WG. These were associated with concomitant induction of WG-related inflammation. Thus, dysregulation of HDAC and HAT may contribute to the disease pathogenesis of WG.

Transcription of proteinase 3 and related myelopoiesis genes in peripheral blood mononuclear cells of patients with active Wegener's granulomatosis

OBJECTIVE

Wegener's granulomatosis (WG) is a systemic inflammatory disease that is associated with substantial morbidity. The aim of this study was to understand the biology underlying WG and to discover markers of disease activity that would be useful for prognosis and treatment guidance.

METHODS

Gene expression profiling was performed using total RNA from peripheral blood mononuclear cells (PBMCs) and granulocyte fractions from 41 patients with WG and 23 healthy control subjects. Gene set enrichment analysis (GSEA) was performed to search for candidate WG-associated molecular pathways and disease activity biomarkers. Principal components analysis was used to visualize relationships between subgroups of WG patients and controls. Longitudinal changes in proteinase 3 (PR3) gene expression were evaluated using reverse transcription-polymerase chain reaction, and clinical outcomes, including remission status and disease activity, were determined using the Birmingham Vasculitis Activity Score for WG (BVAS-WG).

RESULTS

Eighty-six genes in WG PBMCs and 40 in WG polymorphonuclear neutrophils (PMNs) were significantly up-regulated relative to controls. Genes up-regulated in WG PBMCs were involved in myeloid differentiation, and these included the WG autoantigen PR3. The coordinated regulation of myeloid differentiation genes was confirmed by GSEA. The median expression values of the 86 up-regulated genes in WG PBMCs were associated with disease activity (P = 1.3 x 10(-4)), and WG patients with low-level expression of the WG signature genes showed expression profiles that were only modestly different from that in healthy controls (P = 0.07). PR3 transcription was significantly up-regulated in WG PBMCs (P = 1.3 x 10(-5), false discovery rate [FDR] 0.002), but not in WG PMNs (P = 0.03, FDR 0.28), and a preliminary longitudinal analysis showed that the fold change in PR3 RNA levels in WG PBMCs corresponded to changes in the BVAS-WG score over time.

CONCLUSION

Transcription of PR3 and related myeloid differentiation genes in PBMCs may represent novel markers of disease activity in WG.

Increased plasma myeloperoxidase levels in systemic lupus erythematosus

The objective of the study was to quantify plasma myeloperoxidase (MPO) levels in systemic lupus erythematosus (SLE) patients and to evaluate a correlation between MPO levels and disease activity. 71 female SLE patients and 70 controls were studied. Patients were divided into two groups: Group I (n = 48) with SLEDAI-2K score 0-5 and Group II (n = 23) with SLEDAI-2K score > or = 6. Mann-Whitney test and Spearman rank correlation were used. Two-sided P values < 0.05 were considered significant and P values > or = 0.05 and < 0.08 were considered as a tendency. The median age of patients and controls were comparable and the mean disease duration was 99.2 +/- 61.7 months. MPO levels were higher in patients than controls [5.99 (4.38-8.64) vs. 5.00 (3.33-7.08) ng/ml, P = 0.02]. We did not find correlation between MPO levels and SLEDAI-2k (r = 0.07, P = 0.58). MPO levels were not affected by treatment with prednisone, cyclophosphamide or azathioprine, however, a tendency of lower levels was observed among patients under antimalarial drugs. There was no significant difference in MPO plasma levels between Group I and Group II (5.83 vs. 6.02 ng/ml, P = 0.99). MPO levels were higher in patients with arthritis than in those without arthritis (8.15 vs. 5.56 ng/ml, P = 0.010). No difference was observed among patients with and without other organs/systems involvement. SLE patients presented increased MPO plasma levels than healthy controls. Despite the lack of correlation between MPO plasma levels and disease activity, the higher MPO levels in patients with articular involvement suggests MPO may play a different role in the inflammatory process of some SLE manifestations.

[Bronchoalveolar lavage]

Bronchoalveolar lavage (BAL) has become an established method for the diagnosis of infectious and interstitial lung diseases. Using a bronchoscope material from the peripheral airways and alveolar spaces can be obtained. When standard protocols are followed the procedure is generally well tolerated and in combination with clinical tests allows a reliable diagnosis in many cases. Certain clinical entities, e.g. alveolar proteinosis and Langerhans cell histiocytosis can be diagnosed by BAL alone without resorting to invasive diagnostic tests. In other diseases, BAL allows to narrow the range of the differential diagnosis. However, biopsies can often still not be avoided completely. A combination of both methods together with the clinical findings represents a powerful tool for diagnosis and research into the pathologic alterations in inflammatory and fibroising lung diseases.

Respiratory system involvement in antineutrophil cytoplasmic-associated systemic vasculitides: clinical, pathological, radiological and therapeutic considerations

Wegener's granulomatosis (WG), microscopic polyangiitis (MPA) and Churg- Strauss syndrome (CSS) are small-vessel vasculitides that, because of their frequent association with antineutrophil cytoplasmic antibodies (ANCA), are usually referred to as ANCA-associated systemic vasculitides (AASV). The diagnosis of AASV is made on the basis of clinical findings, biopsy of an involved organ and the presence of ANCA in the serum. Lung disease is a very common and important clinical feature of AASV. In WG, almost all patients have either upper airway or lower respiratory tract disease. Solitary or multiple nodules, frequently cavitated, and masses are the most common findings on chest radiography. Asthma is a cardinal symptom of CSS, often preceded by allergic rhinitis. Pulmonary transient and patchy alveolar infiltrates are the most common radiographic findings. In MPA, diffuse alveolar haemorrhage as a result of alveolar capillaritis is the most frequent manifestation of respiratory involvement, and is clinically expressed as haemoptysis, respiratory distress and anaemia. However, diffuse alveolar haemorrhage may also be subclinical and should be suspected when a chest radiograph demonstrates new unexplained bilateral alveolar infiltrates in the context of falling haemoglobin levels. Normal and high-resolution CT have a higher sensitivity than chest radiography for demonstrating airway, parenchymal and pleural lesions. However, many of these radiological findings are nonspecific and, therefore, their interpretation must take into account all clinical, laboratory and pathological data. Therapy of AASV is commonly divided into two phases: an initial 'remission induction' phase, in which more intensive immunosuppressant therapy is used to control disease activity, and a 'maintenance' phase, which uses less intensive therapy, for maintaining disease remission while lowering the risk of adverse effects of immunosuppressant drugs. In patients with AASV refractory to standard therapy with corticosteroids and oral cyclophosphamide, new therapeutic options are now available. Recurrence of pulmonary symptoms suggesting a flare indicates the need for a careful search for an opportunistic lung infection or iatrogenic pulmonary complications. In conclusion, involvement of the respiratory system is a very common and important organ manifestation of AASV. Respiratory system involvement comprises a wide spectrum of clinical features and radiological findings, and because of its frequency and prognostic significance, a complete assessment of the respiratory system should be included in the work-up of all patients with AASV.

Eosinophil activation in Wegener's granulomatosis: a harbinger of disease progression?

PURPOSE

To investigate the relation between eosinophil activation in tissue from patients with an active, limited form of Wegener's granulomatosis (WG) affecting the eye and subsequent systemic disease activity.

METHODS

Analysis of ocular specimens obtained from 10 patients was performed. Sections were probed with antibodies to assess the presence of major basic protein (MBP) and eosinophil cationic protein (ECP).

RESULTS

Four of the 10 specimens demonstrated the presence of MBP and ECP. WG progressed to the complete form in two of these patients, who received no or inadequate treatment. The other two, treated with cyclophosphamide for one year, did not progress to the complete form of WG during observation after therapy.

CONCLUSIONS

Activated eosinophils in sclera or conjunctiva of patients with ocular limited WG may predict progression to complete WG.

Difficult to diagnose manifestations of vasculitis: Does an interdisciplinary approach help?

In the early stages of disease, primary systemic vasculitides often present with non-specific symptoms that make early diagnosis a challenge. The variety of clinical manifestations found in systemic vasculitis is huge, and some manifestations are frequently not clinically overt at first presentation. A logical implication of the often non-specific and sometimes subclinical presentation of vasculitis is that a systematic diagnostic work-up is necessary. This requires a multidisciplinary approach involving the expert opinion of specialists from many disciplines, such as neurology, radiology, respiratory medicine, pathology and microbiology. There are no generally accepted diagnostic criteria for primary systemic vasculitides, and the application of classification criteria as diagnostic criteria is not feasible and may even be misleading. The demonstration of vasculitis on biopsy is still the gold standard for the diagnosis of vasculitis. In cases where biopsies cannot be obtained, surrogate parameters of vasculitis (e.g. glomerular hematuria or mononeuritis multiplex), along with serology and imaging, can support a clinical diagnosis of vasculitis. This review discusses the approach to the diagnosis of central nervous system and pulmonary manifestations of primary systemic vasculitis. These two examples of difficult to diagnose manifestations of vasculitis illustrate the necessity of an interdisciplinary approach to the diagnostic work-up.

Expression of matrix metalloproteinases in patients with Wegener's granulomatosis

BACKGROUND

Enhanced activity of matrix metalloproteinases (MMPs) has been reported to have a pathogenic role in several diseases such as cancer and cardiovascular disorders, and seems also to play a part in certain autoimmune diseases.

OBJECTIVE

To examine whether enhanced MMP activity may also have a role in the pathogenesis of Wegener's granulomatosis (WG).

METHODS

In a study group of 15 patients with WG and 15 controls, plasma levels and gene expression were measured in freshly isolated peripheral blood mononuclear cells (PBMCs) of several MMPs and their endogenous inhibitors (that is, tissue inhibitors of metalloproteinases (TIMPs)) by enzyme immunoassays and RNase protection assay, respectively.

RESULTS

Whereas patients with WG in remission had enhanced gene expression of several MMPs and TIMPs in PBMCs, those with active disease had a selective up regulation of MMP-2 and MMP-8 compared with healthy controls, and a down regulation of TIMP-1 and TIMP-3 compared with other patients with WG. Moreover, plasma levels of TIMP-1 and MMP-8 correlated significantly with C reactive protein levels, further supporting an association between activation of the MMP/TIMP system and disease activity in WG. Finally, these changes in MMP/TIMP expression in WG were accompanied by increased total MMP activity in PBMC supernatants, particularly in those with active disease, suggesting a matrix degrading net effect.

CONCLUSION

These findings suggest that disturbed MMP and TIMP activity has a role in the pathogenesis of WG.

Dendritic cells overexpressing Fas-ligand induce pulmonary vasculitis in mice

Dendritic cells (DC) genetically engineered to express Fas (CD95) ligand (FasL-DC) have been proposed as immunotherapeutic tools to induce tolerance to allografts. However, we and others recently showed that FasL-DC elicit a vigorous inflammatory response involving granulocytes and can promote Th1-type CD4+ and cytotoxic CD8+ T lymphocytes. This prompted us to evaluate the pathology induced by intravenous injection of FasL-DC in mice. We observed that FasL-DC obtained after retroviral gene transfer of bone marrow precursors derived from Fas-deficient C57Bl/6 mice induce massive pulmonary inflammation and pleuritis one day after a single intravenous injection in C57Bl/6 mice. Two months later, all mice presented granulomatous vasculitis of small to medium sized vessels, alveolar haemorrhage and pleuritis. In these lesions, apoptotic bodies were found in large number. Anti-neutrophilic cytoplasmic and anti-myeloperoxidase autoantibodies were not detected. This study documents that intravenous injection of FasL-DC causes severe lung granulomatous vasculitis. This new animal model for vasculitis is inducible, highly reproducible and shares many features with human Wegener granulomatosis. This model may be an appropriate tool to further investigate the pathogenesis of vasculitis and test new therapeutic strategies. Moreover, our findings highlight the potential severe complications of FasL-DC-based immunotherapy.

Relationship between myeloperoxidase promotor polymorphism and disease severity in sarcoidosis

BACKGROUND

Previously, we demonstrated that the number of polymorphonuclear neutrophils (PMNs) in bronchoalveolar lavage fluid (BALF) is useful in distinguishing sarcoidosis patients with a favorable outcome from those having a more severe course of disease. Neutrophils contain the oxidant-generating enzyme myeloperoxidase (MPO). Cellular levels of MPO can be influenced by functional promotor polymorphisms, ?463G/A and ?129G/A, which may modify disease severity.

METHODS

In the present study, we investigated two MPO promotor polymorphisms in 110 sarcoidosis patients and in 191 ethnically matched controls. Pulmonary disease severity was evaluated by means of radiographic staging, HRCT scoring, lung function, and exercise capacity testing.

RESULTS

No significant differences were found between sarcoidosis patients and healthy controls with regard to either polymorphism. Nor was any association observed between ?463 G/A and ?129 G/A polymorphism and the severity of sarcoidosis.

CONCLUSIONS

The functional MPO promotor polymorphisms ?463G/A and ?129G/A did not explain disease severity in the sarcoidosis population studied. Future studies are needed to identify predictive features useful in guiding therapeutic strategies and to determine difficult-to-treat cases.

[Wegener's granulomatosis - a case report]

The Wegener granulomatosis (WG) is a rare vasculite which involves preferentially the upper airways, lungs and kidneys, although it can presents in a multissistemic form. The authors present a clinical case of WG, its diagnostic methodology and respective follow-up from de last two years and half. There are discussed the most often presentation forms of the disease, the importance of histologic results and the contribution of ANCA's determination for disease diagnosis and follow-up. Although important, the histological results, are not essential for WG diagnosis, since clinic presentation and immunological data (ANCA's) are suggestive of the disease. Airways infections and ANCA's presence seems to be important in the etiopathogenesis of WG.

Elevated expression of interleukin-18 in the granulomatous lesions of muscular sarcoidosis

In an attempt to understand the role of interleukin-18 (IL-18) in the pathogenesis of sarcoidosis, we examined the expression of IL-18 in normal muscle and in muscle biopsies from six patients with muscular sarcoidosis. Western blot analysis demonstrated that IL-18 was identified only in homogenates of granulomatous muscle tissues, but not in normal muscle tissue homogenates. By immunohistochemistry, strongly IL-18-positive cells were distributed predominantly at the boundary zone of the granulomas. They were recognized as activated macrophages by double staining with anti-CD68. Epithelioid cells showed only faint reactivity. Serum IL-18 levels of patients with sarcoidosis were significantly increased compared to those of healthy volunteers. Unlike protein expression, IL-18 mRNA expression was detected even in normal muscles. Our results coupled with those of previous investigations demonstrating activity of IL-18 in inducing interferon-gamma production suggest a significant role of IL-18 in the pathogenesis of sarcoidosis.