Increased expression of vascular endothelial growth factor (VEGF) in Castleman's disease: proposed pathomechanism of vascular proliferation in the affected lymph node

Successful treatment with bortezomib in combination with dexamethasone in a middle-aged male with idiopathic multicentric Castleman's disease: A case report

Multicentric Castleman disease (MCD) is a heterogeneous, life-threatening disease. A subgroup of HIV-negative and HHV-8-negative MCD is defined as idiopathic MCD (iMCD) with a poor prognosis. Here we report an unusual case of a 47-year-old male patient with iMCD who experienced multiple treatment regimens such as chemotherapy, immunomodulatory therapy, and targeted therapy, all of which were considered ineffective. Subsequently, he was started on bortezomib in combination with dexamethasone for six cycles and he was in complete remission. The patient has survived nearly 13 years to date - the longest survival of any iMCD patient treated with bortezomib in combination with dexamethasone. Bortezomib combined with dexamethasone may be an effective salvage strategy for severe and refractory iMCD.

A Case of Kaposi's Sarcoma Associated with Disseminated AIDS: The Management Challenges

Background

As a malignant tumor derived from vascular endothelial cells, Kaposi's sarcoma (KS) is quite common in AIDS patients. Nonspecific clinical symptoms often lead to timely diagnosis or wrong treatment, leading to recurrent disease and poor prognosis. Anti-retroviral therapy (ART) could significantly reduce its morbidity and aggressiveness. As one of the ARTs, liposome anthracyclines are the preferred chemotherapy regimen for disseminated KS with multiple organs or tissue invasion. The curative effect is highly related to the degree of immunosuppression. This is the first case of AIDS with Kaposi's sarcoma, who was cured after ART and two consecutive chemotherapy with doxorubicin liposome without recurrence. This case may provide new ideas and methods for the clinical management of AIDS with Kaposi's sarcoma.

Case Description

The patient, a male aged 60 years, was hospitalized on 21/11/2018 following having a cough, expectoration, and difficulty breathing. He was infected with HIV eight years ago and presented symptoms of blood-stained sputum. The patient complained that he had not received ART before. After admission, he was diagnosed as KS with disseminated AIDS after multiple biopsies and histopathological examinations. The patient was treated with ten months of ART (lamivudine+tenofovir+dolutegravir) and 14 times of chemotherapy with doxorubicin liposome (20 mg/m2, three times per week, seven times per course of treatment). The patient's disease was finally alleviated, and there was no recurrence during the follow-up.

Conclusion

The reconstitution of immune function and consecutive chemotherapy with doxorubicin liposome play a vital role in treating KS. In addition, for the early general symptoms of AIDS patients, such as thrombocytopenia and hemorrhagic purple papules, it is necessary to increase vigilance and obtain the results of histopathological verification as soon as possible to diagnose KS patients at an earlier stage and realize clinical intervention in time.

The lymph node transcriptome of unicentric and idiopathic multicentric Castleman disease

Castleman disease is a polyclonal lymphoproliferative disorder characterized by unicentric or multicentric lymphadenopathy with characteristic histomorphological features, in addition to variable inflammatory symptomatology. The molecular mechanisms and etiologies of unicentric Castleman disease (UCD) and idiopathic multicentric Castleman disease (iMCD) are poorly understood, and identification of targetable disease mediators remains an unmet clinical need. We performed whole exome sequencing on lymph node biopsies from patients with UCD and iMCD and compared the transcriptomic profiles to that of benign control lymph nodes. We identified significantly upregulated genes in UCD (n=443), iMCD (n=316) or both disease subtypes (n=51) and downregulated genes in UCD (n=321), iMCD (n=105) or both (n=10). The transcriptomes of UCD and iMCD showed enrichment and upregulation of elements of the complement cascade. By immunohistochemistry, C4d deposits indicative of complement activation were found to be present in UCD and iMCD, mostly within abnormally regressed germinal centers, but also in association with plasma cell clusters, endothelial cells and stroma cell proliferations. Other enriched gene sets included collagen organization, S1P3 pathway and VEGFR pathway in UCD; and humoral response, oxidative phosphorylation and proteosome in iMCD. Analysis of cytokine transcripts showed upregulation of CXCL13 but not IL6 in UCD and iMCD. Among angiogenic mediators, the VEGFR1 ligand placental growth factor (PGF) was upregulated in both disease subtypes. We hereby report for the first time the whole lymph node transcriptomes of UCD and iMCD, underscoring findings that could aid in the discovery of targetable disease mediators.

Transcriptome and unique cytokine microenvironment of Castleman disease

Castleman disease (CD) represents a group of rare, heterogeneous and poorly understood disorders that share characteristic histopathological features. Unicentric CD (UCD) typically involves a single enlarged lymph node whereas multicentric CD (MCD) involves multiple lymph node stations. To understand the cellular basis of CD, we undertook a multi-platform analysis using targeted RNA sequencing, RNA in-situ hybridization (ISH), and adaptive immune receptor rearrangements (AIRR) profiling of archived tissue from 26 UCD, 14 MCD, and 31 non-CD reactive controls. UCD showed differential expression and upregulation of follicular dendritic cell markers (CXCL13, clusterin), angiogenesis factors (LPL, DLL4), extracellular matrix remodeling factors (TGFβ, SKIL, LOXL1, IL-1β, ADAM33, CLEC4A), complement components (C3, CR2) and germinal center activation markers (ZDHHC2 and BLK) compared to controls. MCD showed upregulation of IL-6 (IL-6ST, OSMR and LIFR), IL-2, plasma cell differentiation (XBP1), FDC marker (CXCL13, clusterin), fibroblastic reticular cell cytokine (CCL21), angiogenesis factor (VEGF), and mTORC1 pathway genes compared to UCD and controls. ISH studies demonstrated that VEGF was increased in the follicular dendritic cell-predominant atretic follicles and the interfollicular macrophages of MCD compared to UCD and controls. IL-6 expression was higher along interfollicular vasculature-associated cells of MCD. Immune repertoire analysis revealed oligoclonal expansions of T-cell populations in MCD cases (2/6) and UCD cases (1/9) that are consistent with antigen-driven T cell activation. The findings highlight the unique genes, pathways and cell types involved in UCD and MCD. We identify potential novel targets in CD that may be harnessed for therapeutics.

Successful treatment with tocilizumab for refractory anemia and slowly progressive renal glomerulosclerosis in multicentric Castleman disease: A case report

RATIONALE

Multicentric Castleman disease (MCD) is a rare lymphoproliferative disorder accompanied by systemic symptoms characterized by polyclonal hypergammaglobulinemia and chronic inflammation due to overexpression of interleukin-6. Histological heterogeneity of renal involvement in MCD has been described, although the number of reports is limited. Tocilizumab, a humanized anti-interleukin-6 receptor antibody, has been reported to be effective for MCD.

PATENT CONCERNS

A 64-year-old man experienced refractory anemia and slowly progressive renal dysfunction with proteinuria, accompanied by persistent inflammation for 11 years.

DIAGNOSIS

Two renal biopsies were obtained. The first biopsy performed 7 years before admission revealed non-specific interstitial inflammation, whereas the second biopsy demonstrated global sclerosis in most glomeruli and interstitial fibrosis. The patient had multiple lymphadenopathies. Cervical lymph node biopsy histological findings were compatible with plasma cell type Castleman disease. The patient had no evidence of human hepatitis virus-8 infection.

INTERVENTION

The patient was treated with 60 mg/d prednisolone followed by 8 mg/kg intravenous tocilizumab every 2 weeks.

OUTCOME

His anemia significantly improved, as well as a marked reduction in proteinuria and stabilization of renal function. He did not experience renal function during the 2-years follow-up period.

LESSONS

The heterogeneity of the renal manifestations of MCD sometimes makes early diagnosis difficult. We need to interpret the histological findings of the renal biopsy carefully. For advanced-stage renal diseases, tocilizumab might be an effective treatment strategy for MCD.

Castleman disease

Castleman disease (CD), a heterogeneous group of disorders that share morphological features, is divided into unicentric CD and multicentric CD (MCD) according to the clinical presentation and disease course. Unicentric CD involves a solitary enlarged lymph node and mild symptoms and excision surgery is often curative. MCD includes a form associated with Kaposi sarcoma herpesvirus (KSHV) (also known as human herpesvirus 8) and a KSHV-negative idiopathic form (iMCD). iMCD can present in association with severe syndromes such as TAFRO (thrombocytopenia, ascites, fever, reticulin fibrosis and organomegaly) or POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder and skin changes). KSHV-MCD often occurs in the setting of HIV infection or another cause of immune deficiency. The interplay between KSHV and HIV elevates the risk for the development of KSHV-induced disorders, including KSHV-MCD, KSHV-lymphoproliferation, KSHV inflammatory cytokine syndrome, primary effusion lymphoma and Kaposi sarcoma. A CD diagnosis requires a multidimensional approach, including clinical presentation and imaging, pathological features, and molecular virology. B cell-directed monoclonal antibody therapy is the standard of care in KSHV-MCD, and anti-IL-6 therapy is the recommended first-line therapy and only treatment of iMCD approved by the US FDA and EMA.

Unicentric Castleman's disease of hepatic hilum and retroperitoneum: a case report for endoscopic ultrasonography differential diagnosis and a literature review

Castleman's disease (CD) is a highly heterogeneous clinico-pathological entity belonging to the lymphoproliferative disorders. CD can occur in any part of the human body where lymph nodes are present. In addition, very few cases have been reported in hepatic hilum. Here, we present a case of a middle-aged female patient who was presented with abdominal pain and diagnosed as localized Castleman's disease of hepatic hilar and retroperitoneal origin. Diagnosing CD is complex due to its resemblance to many other diseases. EUS and FNA may play a more important role in differential diagnosis of CD and other disease in digestive system.

Tufted-angioma-like lesion associated with vascular endothelial growth factor and interleukin-6 in TAFRO syndrome: Is it a common histological feature of multicentric Castleman disease/POEMS syndrome?

The histology of skin lesions of TAFRO (thrombocytopenia, anasarca, reticulin fibrosis/renal failure, and organomegaly) syndrome has rarely been reported. We report herein two cases of TAFRO syndrome with characteristic vascular skin lesions. The lesions resembled a tufted angioma, although those of case 1 partially resembled a glomeruloid hemangioma, which was known as a specific lesion in POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M-protein and skin changes), a variant of multicentric Castleman disease (MCD). The high titer of serum vascular endothelial growth factor and interleukin-6 could explain common characteristic vascular lesions in both TAFRO syndrome and POEMS syndrome/MCD.

Castleman disease mimicking systemic lupus erythematosus: A case report

RATIONALE

Castleman disease (CD) is a nonclonal lymphoproliferative disorder sometimes manifested systemic inflammatory symptoms. Systemic lupus erythematosus (SLE) is an autoimmune disease characterized with multi-system involvement as well as broad spectrum of serum autoantibodies. When these two conditions happened to have similar clinical spectrum features, the confusion with each other occurred.

PATIENT CONCERNS

A 46-year-old man suffered from chronic fever, nephrotic syndrome, acute kidney injury, anemia, thrombocytopenia and serositis, as well as hypocomplementemia and negative anti-nuclear antibody.

DIAGNOSES

Meeting the classification criteria for SLE, the patient was diagnosed as SLE at first. The renal biopsy showed that he had endocapillary proliferative glomerulonephritis with negative immunofluorescence. Finally, he was diagnosed with CD after lymph nodes biopsy.

INTERVENTIONS

The patient was treated with oral prednisone (50 mg daily) but got poor response. After being proved to have CD, he was treated with CHOP chemotherapy.

OUTCOMES

His condition was controlled by CHOP chemotherapy. After six course of chemotherapy, the proteinuria disappeared.

LESSONS

If patients, even qualified by classification criteria of SLE, had negative autoantibody or unsatisfied response to the standard treatment, the original diagnosis should be suspected. The biopsy may be help to identify the final criminals, such as CD.

Castleman Disease Presenting with Pseudotumour Cerebri and Myasthenia Gravis: A Case Report and Literature Review

Castleman disease (CD) is a rare lymphoproliferative disorder that may present with various autoimmune, inflammatory, or neurologic syndromes. This is a case of a 21-year-old woman who presented with signs and symptoms of pseudotumour cerebri (PTC) who subsequently developed myasthenia gravis (MG), and was incidentally found to have a large mass in the posterior mediastinum. Upon resection, the mass was classified as unicentric CD involved with follicular dendritic cell sarcoma. Following treatment with IVIG in the setting of progressive weakness and dyspnea, she has had complete symptom resolution while maintained on a low dose of pyridostigmine for the last two years. There are 13 cases of MG and five cases of optic disc edema described as PTC associated with CD in the literature, but to our knowledge, this is the sole case reported of the intersection of all three conditions in one patient. Increased serum levels of interleukin-6 and vascular endothelial growth factor may provide clues as to the association of CD with these neurologic syndromes.

Atypical Lymphoproliferative Disorders: Castleman's Disease Case Report and Review of the Literature

Castleman's disease (CD) is a rare atypical lymphoproliferative disorder characterized by enlarged hyperplastic lymph nodes with striking vascular proliferations. CD is categorized as being either localized or disseminated and further subdivided into hyaline-vascular, plasma cell, or mixed histopathological patterns. Here we report a case of CD in a 15-year-old girl who presented with a solitary asymptomatic hyaline-vascular mass in the right supraclavicular space. In addition, we discuss the pathogenesis, clinical features and reported comorbidities of unicentric and multicentric CD and evaluate effective treatment strategies based on the results of lymph node biopsy and careful staging. Surgical excision is curative for the localized variants of CD, either hyaline-vascular or plasma cell type. If complete resection is not possible, partial resection or radiotherapy may be useful to control possible systemic manifestations. Multicentric CD, regardless of the histological subtype, is a more aggressive clinical entity, commonly with a chronic or rapidly fatal course. Patients with multicentric CD do not benefit from surgical treatment and should be candidates for systemic therapy (steroids, combination chemotherapy, novel therapies), although this is still in a fairly experimental phase.

Pediatric Intraparotid Castleman's Disease

Castleman's disease (CD) is a rare, benign lymphoepithelial disease of unknown cause that presents most commonly in the mediastinum. There are 2 histologic types of CD: the hyaline vascular type and the plasma cell type. In the head and neck, 98% of these lesions are of the hyaline vascular type. The differential diagnosis of CD includes reactive lymphadenopathy, lymphoproliferative disorders, lymph node metastasis, and other conditions. Approximately 80 cases of CD have been reported in children; head and neck involvement in children is extremely rare. A case of a child with intraparotid CD is presented; the clinical course, histopathologic presentation, radiographic findings, and management of CD are reviewed.

Cervical: Lymphadenopathy

The neck region contains around 300 lymph nodes (LNs) out of 800 LNs in the whole body. The detailed study of LNs by Rouviere in 1932 [1] and the later illustration of metastatic predilection of head and neck malignancies to certain LN regions by Lindberg et al. [2] paved the road to a clinically sound classification. The American Academy of Otolaryngology and Head and Neck Surgery (AAO-HNS) and the American Joint Committee on Cancer (AJCC) developed the currently widely accepted levels classification of the cervical LNs (Table 8.1, Figs. 8.1 and 8.2).

Clinical features and outcomes in patients with human immunodeficiency virus-negative, multicentric Castleman's disease: a single medical center experience

Background

Multicentric Castleman's disease (CD) is commonly associated with poor prognosis, and well-known prognostic factors are scarce. We performed a retrospective analysis to define the clinical features and prognostic factors for patients with multicentric CD.

Methods

Between 1990 and 2013, 32 patients with multicentric CD were identified from the database of the Asan Medical Center, Seoul, Korea. Clinicopathologic data were collected by reviewing the medical records. With the exclusion of 4 patients because of unknown human immunodeficiency virus infection status, 28 human immunodeficiency virus-negative patients with multicentric CD were included in this analysis.

Results

Most of the patients were male (76%) and had a median age of 54 years. Hyaline vascular variant was the most common subtype (N=11, 39%). Hepatosplenomegaly (61%), fever (39%), edema (29%), and ascites (18%) were the most frequently reported symptoms and signs at diagnosis. With a median follow-up of 67 months, the 5-year overall survival (OS) was 77%. Patients with extravascular fluid accumulation (i.e., peripheral edema, ascites, and/or pleural effusions) were significantly associated with a poor survival rate (5-year OS, 94% vs. 56%; P=0.04). The extent of disease involvement was also a significant prognostic factor (5-year OS, 91% for involvement on a single side vs. 73% on both sides of the diaphragm; P=0.03). Other clinicopathologic factors were not significantly associated with patient survival.

Conclusion

Our findings suggest that the hyaline vascular variant is not a rare subtype of multicentric CD. Extravascular fluid accumulation and disseminated disease involvement seem to be significant prognostic factors.

Multicentric Castleman disease mimicking IgG4-related disease: A case report

A 50-year-old woman was referred to our hospital for shoulder joint stiffness. She had a history of polyclonal hypergammaglobulinemia and an elevated C-reactive protein level. Her laboratory data revealed an elevated serum immunoglobulin G4 (IgG4) level, hypergammaglobulinemia, and rheumatoid factor positivity in the absence of anticyclic citrullinated peptide antibody. [18^F]-Fluorodeoxyglucose positron emission tomography showed significant [18^F]-fluorodeoxyglucose uptake in multiple lymph nodes (axillary, hilar, para-aortic, and inguinal). Biopsy of the inguinal lymph node showed expansion of the interfollicular areas by heavily infiltrating plasma cells, consistent with multicentric Castleman disease (MCD). Immunohistochemical analysis revealed a 37.3% IgG4-positive:IgG-positive plasma cell ratio, indicating overlapping IgG4-related disease. However, serological cytokine analysis revealed elevated levels of interleukin-6 (9.3 pg/ml) and vascular endothelial growth factor (VEGF) (1210 pg/ml), which are compatible with MCD. Corticosteroid treatment resolved the serological and imaging abnormalities. IgG4-related disease can mimic MCD, and it is crucial to distinguish between these two diseases. Serum interleukin-6 and VEGF levels may help to discriminate MCD from IgG4-related disease.

Kaposi's sarcoma-associated herpesvirus induces Nrf2 during de novo infection of endothelial cells to create a microenvironment conducive to infection

Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent of Kaposi's sarcoma (KS) and primary effusion B-cell lymphoma. KSHV induces reactive oxygen species (ROS) early during infection of human dermal microvascular endothelial (HMVEC-d) cells that are critical for virus entry. One of the downstream targets of ROS is nuclear factor E2-related factor 2 (Nrf2), a transcription factor with important anti-oxidative functions. Here, we show that KS skin lesions have high Nrf2 activity compared to healthy skin tissue. Within 30 minutes of de novo KSHV infection of HMVEC-d cells, we observed Nrf2 activation through ROS-mediated dissociation from its inhibitor Keap1, Ser-40 phosphorylation, and subsequent nuclear translocation. KSHV binding and consequent signaling through Src, PI3-K and PKC-ζ were also important for Nrf2 stability, phosphorylation and transcriptional activity. Although Nrf2 was dispensable for ROS homeostasis, it was essential for the induction of COX-2, VEGF-A, VEGF-D, Bcl-2, NQO1, GCS, HO1, TKT, TALDO and G6PD gene expression in KSHV-infected HMVEC-d cells. The COX-2 product PGE2 induced Nrf2 activity through paracrine and autocrine signaling, creating a feed-forward loop between COX-2 and Nrf2. vFLIP, a product of KSHV latent gene ORF71, induced Nrf2 and its target genes NQO1 and HO1. Activated Nrf2 colocalized with the KSHV genome as well as with the latency protein LANA-1. Nrf2 knockdown enhanced ORF73 expression while reducing ORF50 and other lytic gene expression without affecting KSHV entry or genome nuclear delivery. Collectively, these studies for the first time demonstrate that during de novo infection, KSHV induces Nrf2 through intricate mechanisms involving multiple signal molecules, which is important for its ability to manipulate host and viral genes, creating a microenvironment conducive to KSHV infection. Thus, Nrf2 is a potential attractive target to intervene in KSHV infection and the associated maladies.

KSHV infection of endothelial cells in vivo causes Kaposi's sarcoma and understanding the steps involved in de novo KSHV infection of these cells and the consequences is important to develop therapies to counter KSHV pathogenesis. Infection of endothelial cells in vitro is preceded by the induction of a network of host signaling agents that are necessary for virus entry, gene expression and establishment of latency. Our previous studies have implicated reactive oxygen species (ROS) as part of this network. In the current study, we show that ROS activate Nrf2, a master transcriptional regulator of genes involved in ROS homeostasis, apoptosis, glucose metabolism and angiogenesis. Besides ROS, KSHV utilizes additional aspects of host signaling to induce Nrf2 activity. We also observed that infection of endothelial cells deficient in Nrf2 resulted in downregulation of multiple genes important in KSHV pathogenesis, such as COX-2 and VEGF, and affected proper expression of two hallmark KSHV genes, lytic ORF50 and latent ORF73. Taken together, this study is the first to demonstrate the importance of Nrf2 during de novo KSHV infection of endothelial cells, and establishes Nrf2 as an attractive therapeutic target to control KSHV infection, establishment of latency and the associated cancers.

Thoracic Castleman disease: computed tomography and clinical findings

AIM

The objective of this study was to evaluate the clinicoradiological findings of thoracic Castleman disease.

METHODS

The study included 34 patients (22 male and 12 female patients; mean age, 32 [SD, 18.1] years) with thoracic Castleman disease. Clinicoradiological findings of the 34 patients were analyzed. Regarding computed tomography findings, lesion number, location, degree of enhancement (moderate, >20 Hounsfield units than back muscle enhancement; high, >40 Hounsfield units), and associated findings were recorded.

RESULTS

Of 34 patients, hyaline-vascular type (HVT) was found in 27 patients (79%), plasma cell type (PCT) in 5 patients (15%), and mixed type (6%) in 2 patients. In HVTs (n = 27), lesions were found, in decreasing order, in the lower neck (n = 9, 33%), pulmonary hilum (n = 6, 22%), and the upper paratracheal area (n = 4, 15%). Ten (37%) of 27 HVT patients had symptoms, whereas all (100%) with PCT had generalized symptoms. In 26 (96%) of 27 HVT patients, disease was unicentric, whereas it was multicentric in all PCT patients. Moderate to high degree of lesion enhancement was seen in 22 (92%) of 24 HVT patients and 4 (80%) of 5 PCT patients. Feeding vessels or draining veins were identified in 12 (44%) of 27 HVT patients and 2 (40%) of 5 PCT patients. The diseases were cured with surgical removal in HVT, whereas they showed variable prognosis in PCT.

CONCLUSIONS

Irrespective of subtypes, Castleman disease is characterized radiologically by unicentric or multicentric enhancing lymph node enlargement; in HVT, they show good prognosis after surgical treatment, but in PCT, they show variable prognosis.

Recent advances in Kaposi sarcoma herpesvirus-associated multicentric Castleman disease

PURPOSE OF REVIEW

The discovery of Kaposi sarcoma herpesvirus (KSHV) led to recognition of KSHV-associated multicentric Castleman disease (MCD) as a distinct lymphoproliferative disorder. The pathogenesis of KSHV-MCD is attributed to proliferation of KSHV-infected B cells, production of KSHV-encoded viral interleukin 6 by these cells, and dysregulation of human interleukin 6 and interleukin 10. This article reviews advances in the field of disease pathogenesis and targeted therapies.

RECENT FINDINGS

Our understanding of the pathogenesis of KSHV-MCD has increased in recent years and improved therapies have been developed. Recent studies demonstrate that the anti-CD20 monoclonal antibody, rituximab, as well as virus-activated cytotoxic therapy using high-dose zidovudine and valganciclovir, can control symptoms and decrease adenopathy. With treatment, 1-year survival now exceeds 85%. Interestingly, even in the absence of pathologic findings of MCD, KSHV-infected patients may have inflammatory symptoms, excess cytokine production, and elevated KSHV viral load similar to KSHV-associated MCD. The term KSHV-associated inflammatory cytokine syndrome has been proposed to describe such patients.

SUMMARY

Recent advances in targeted therapy have improved outcomes in KSHV-MCD, and decreased need for cytotoxic chemotherapy. Improved understanding of the pathogenesis of KSHV-MCD and KSHV-associated inflammatory cytokine syndrome is needed, and will likely lead to additional advances in therapy for these disorders.

Castleman's disease in a patient with melanoma: the role of VEGF

Castleman's disease is a rare lymphoproliferative disorder characterised by lymph node follicular hyperplasia with abnormal interfollicular vascular growth. The authors report a female patient presenting with erythematous and pruritic skin lesion. A shave biopsy of the lesion revealed a Clark level III melanoma and sentinel lymph node biopsy revealed a microscopic focus. Staging positron emission tomography scan revealed an abnormal soft tissue mass with increased 18F-fluorodeoxyglucose accumulation in the anterior mediastinum, raising suspicions of malignancy. The patient underwent an elective resection of the mass and histological sections revealed features of Castleman's disease of the hyaline vascular type. Vascular endothelial growth factor (VEGF) has been associated with the increased vessel density in this condition. VEGF secretion by tumour cells in solid tumours such as melanomas could be a predisposing factor for Castleman's disease. Future research is needed to find an association between VEGF-secreting solid tumours and the development of lymphoproliferative tumours such as Castleman's disease.

[Cervical Castleman disease in childhood: a report of two cases and a review of the literature]

Castleman disease (CD) is a benign lymphoproliferative disorder, rare in children. Head and neck localizations are found only in 14 % of the cases. Two forms have been described: a hyaline vascular type and a plasma cell type. It can also be monocentric or multicentric. Both young patients were affected with an isolated neck localization of Castleman disease. Preoperative diagnosis can be difficult with a thymoma or a lymphoma. CT and MRI can help in the diagnosis, which is confirmed by histopathological assessment. The pathological features and the therapeutic management of CD are discussed. While surgery is the treatment for localized lesions, steroids and chemotherapy are indicated in the multicentric type. Because of the risk of relapse and malignant transformation, long-term follow-up is mandatory.

Complete remission in a patient with human herpes virus-8 negative multicentric Castleman disease using CHOP chemotherapy

Multicentric Castleman disease (MCD) is a rare lymphoproliferative disorder. Although MCD pathogenesis is unclear, studies have suggested that human herpesvirus 8 (HHV-8) may be associated with the disorder. Recent reports have identified MCD cases without viral infection. A 43-year-old woman presented to our hospital for fever and myalgia of 6 months' duration. The complete blood count revealed an elevated leukocyte count (15.1x10(3)/microL) and a decreased hemoglobin level of 10.0 g/dL. The C-reactive protein level was elevated at 276.5 mg/L. Thoracic computed tomography (CT) scans revealed bilateral axillary lymphadenopathy. There was no evidence of HHV-8, human immunodeficiency virus (HIV), or Mycobacterium infection. Histologic evaluation of a lymph node biopsy from the left axilla yielded a diagnosis of MCD. Cyclophosphamide, adriamycin, vincristine, and prednisone (CHOP) were administered for a total of 4 cycles. The patient's fever and lymphadenopathy resolved after the course of chemotherapy. She has been in complete remission for 24 months at this writing. As previously reported, this case report suggests that MCD can develop without viral infection. CHOP chemotherapy may be an effective treatment option for newly diagnosed MCD patients.

[Thoracic manifestations of Castleman's disease]

INTRODUCTION

Castleman's disease is a rare orphan disease. The prevalence is estimated at less than 1/100 000. Respirologists may encounter this disease when its thoracic manifestations occur.

CASE REPORT

The authors report two cases of Castleman's disease with two different thoracic involvements. The first patient was a 20-year-old man without a previous medical history. A chance chest X-ray revealed right basal opacity. A lung biopsy demonstrated giant lymph node polyclonal hyperplasia leading to the diagnosis of a thoracic form of Castleman's disease. Since the patient was completely symptom free, no treatment was proposed. The patient was stable after 10months of medical supervision. The second patient, a 34-year-old woman, had a medical history of myasthenia gravis, autoimmune thrombopenic purpura and haemolytic anaemia. Her general condition deteriorated and upper mediastinal enlargement was noted. A diagnosis of multicentric Castleman's disease was established by means of the biopsy of an axillary lymph node. As the symptoms persisted, she was treated by rituximab. The clinical response was dramatic.

CONCLUSION

The authors call to mind the difficult diagnostic features and therapeutic strategies of Castleman's disease, a rare disease which may involve the thorax.

The KSHV and other human herpesviral G protein-coupled receptors

Kaposi sarcoma-associated herpesvirus (KSHV) is a gamma2-herpesvirus discovered in 1994 and is the agent responsible for Kaposi sarcoma (KS), an endothelial cell malignancy responsible for significant morbidity and mortality worldwide. Over time, KSHV has pirated many human genes whose products regulate angiogenesis, inflammation, and the cell cycle. One of these encodes for a mutated G protein-coupled receptor (GPCR) that is a homologue of the human IL-8 receptor. GPCRs are the largest family of signaling molecules and respond to a wide array of ligands. Unlike its normal counterpart, the mutations present in KSHV vGPCR result in constitutive, ligand-independent signaling activity. Signaling by the KSHV vGPCR results in the elaboration of many mitogenic and angiogenic cytokines that are vital to the biology of KS and other KSHV-driven malignancies. Several other herpesviruses also encode GPCRs, the functions of which are under ongoing investigation. In addition, several human diseases are associated with mutated mammalian GPCRs in germline or somatic cells.

Paraneoplastic syndrome and intrathoracic Castleman disease

We report two cases of intrathoracic Castleman disease presenting with paraneoplastic syndrome. Patient 1 was a 10-year-old girl with short stature. She was found to have delayed bone age, slow growth velocity, and iron-deficiency anemia, which was refractory to treatment. Thrombocytosis and hypergammaglobulinemia were later detected. Chest X-ray revealed a hilar mass. Patient 2 was a 14-year-old boy who had severe cough, progressive mucocutaneous erosion, and dermatitis. Chest X-ray showed a mediastinal mass. Sections of skin biopsy showed findings consistent with pemphigus disease. In each case, the histological diagnosis of Castleman disease was made.

Abrogation of viral interleukin-6 (vIL-6)-induced signaling by intracellular retention and neutralization of vIL-6 with an anti-vIL-6 single-chain antibody selected by phage display

Human herpesvirus 8 (HHV-8) encodes several putative oncogenes, which are homologues to cellular host genes known to function in cell cycle regulation, control of apoptosis, and cytokine signaling. Viral interleukin (vIL-6) is believed to play an important role in the pathogenesis of Kaposi's sarcoma as well as primary effusion lymphoma and multicentric Castleman's disease. Therefore, vIL-6 is a promising target for novel therapies directed against HHV-8-associated diseases. By phage display screening of human synthetic antibody libraries, we have selected a specific recombinant antibody, called monoclonal anti-vIL-6 (MAV), binding to vIL-6. The epitope recognized by MAV was localized on the top of the D helix of the vIL-6 protein, which is a part of receptor binding site III. Consequently, MAV specifically inhibits vIL-6-mediated growth of the primary effusion lymphoma-derived cell line BCBL-1 and blocks STAT3 phosphorylation in the human hepatoma cell line HepG2. Since it was previously found that vIL-6 can also induce signals from within the cell, presumably within the endoplasmic reticulum, we fused the recombinant antibody MAV with the endoplasmic retention sequence KDEL (MAV-KDEL). As a result, COS-7 cells expressing MAV-KDEL and synthesizing vIL-6 ceased to secrete the cytokine. Moreover, we observed that vIL-6 that was bound to MAV-KDEL and retained in the endoplasmic reticulum did not induce STAT3 phosphorylation in HepG2 cells. We conclude that the activity of the intracellularly retained vIL-6 protein is neutralized by MAV-KDEL. Our results might represent a novel therapeutic strategy to neutralize virally encoded growth factors or oncogenes.

Abdominal Castleman disease with mixed histopathology in a patient with iron deficiency anemia, growth retardation and peliosis hepatis

In Castleman disease, also known as giant lymph node hyperplasia, lesions are usually located in the chest. Peliosis hepatis is the presence of multiple blood-filled cysts in the liver. The combination of these two disorders in one patient is rare, with only three cases reported to date. We report the case of a 21-year-old man who presented with growth retardation and iron deficiency anemia. Work-up revealed hepatomegaly and multiple conglomerated giant lymph nodes near the splenic hilum. Once the mass was surgically removed, the patient's anemia rapidly resolved and he showed catch-up growth. The lymphoid tissue exhibited mixed histologic type, so the patient was diagnosed with both hyaline vascular type and plasma cell type Castleman disease. A liver biopsy obtained at surgery showed sinusoidal dilatation and blood-filled cysts, indicating peliosis hepatis. This is the fourth documented case of peliosis hepatis associated with Castleman disease. In addition to describing the case features, we discuss the possible pathogenesis of peliosis hepatis in the setting of Castleman disease.

Marked differences in human melanoma antigen-specific T cell responsiveness after vaccination using a functional microarray

BACKGROUND

In contrast to many animal model studies, immunotherapeutic trials in humans suffering from cancer invariably result in a broad range of outcomes, from long-lasting remissions to no discernable effect.

METHODS AND FINDINGS

In order to study the T cell responses in patients undergoing a melanoma-associated peptide vaccine trial, we have developed a high-throughput method using arrays of peptide-major histocompatibility complexes (pMHC) together with antibodies against secreted factors. T cells were specifically immobilized and activated by binding to particular pMHCs. The antibodies, spotted together with the pMHC, specifically capture cytokines secreted by the T cells. This technique allows rapid, simultaneous isolation and multiparametric functional characterization of antigen-specific T cells present in clinical samples. Analysis of CD8+ lymphocytes from ten melanoma patients after peptide vaccination revealed a diverse set of patient- and antigen-specific profiles of cytokine secretion, indicating surprising differences in their responsiveness. Four out of four patients who showed moderate or greater secretion of both interferon-gamma (IFNgamma) and tumor necrosis factor-alpha (TNFalpha) in response to a gp100 antigen remained free of melanoma recurrence, whereas only two of six patients who showed discordant secretion of IFNgamma and TNFalpha did so.

CONCLUSION

Such multiparametric analysis of T cell antigen specificity and function provides a valuable tool with which to dissect the molecular underpinnings of immune responsiveness and how this information correlates with clinical outcome.

Interleukin-6 and new strategies for the treatment of cancer, hyperproliferative diseases and paraneoplastic syndromes

Interleukin-6 (IL-6) is a pleiomorphic cytokine whose growth factor properties play an important role in the development and progression of many types of cancer. IL-6 is produced in response to a variety of stimuli, and is required for the development of T and B lymphocytes to effector cells. In certain neoplasias, such as multiple myeloma, IL-6 is both produced and required for survival by the cancer cell itself. In other neoplasias, IL-6 may come from tissue surrounding the tumour. Thus, therapeutic strategies aimed at inhibiting the production, expression or action of IL-6 would be quite beneficial in the treatment of cancer. Moreover, IL-6 is a pathophysiological factor in several hyperproliferative diseases and the paraneoplastic syndromes that often accompany cancer, such as cachexia and osteoporosis; thus, anti-IL-6 therapy would be useful in treating these entities as well. This expert opinion acquaints the reader with IL-6, its physiological responses, the cancer types with which it is associated, and discusses the current state of therapy aimed at inhibiting it.

Activation of Src kinase Lyn by the Kaposi sarcoma-associated herpesvirus K1 protein: implications for lymphomagenesis

The K1 gene of Kaposi sarcoma-associated herpesvirus (KSHV) encodes a transmembrane glycoprotein bearing a functional immunoreceptor tyrosine-based activation motif (ITAM). Previously, we reported that the K1 protein induced plasmablastic lymphomas in K1 transgenic mice, and that these lymphomas showed enhanced Lyn kinase activity. Here, we report that systemic administration of the nuclear factor kappa B (NF-kappaB) inhibitor Bay 11-7085 or an anti-vascular endothelial growth factor (VEGF) antibody significantly reduced K1 lymphoma growth in nude mice. Furthermore, in KVL-1 cells, a cell line derived from a K1 lymphoma, inhibition of Lyn kinase activity by the Src kinase inhibitor PP2 decreased VEGF induction, NF-kappaB activity, and the cell proliferation index by 50% to 75%. In contrast, human B-cell lymphoma BJAB cells expressing K1, but not the ITAM sequence-deleted mutant K1, showed a marked increase in Lyn kinase activity with concomitant VEGF induction and NF-kappaB activation, indicating that ITAM sequences were required for the Lyn kinase-mediated activation of these factors. Our results suggested that K1-mediated constitutive Lyn kinase activation in K1 lymphoma cells is crucial for the production of VEGF and NF-kappaB activation, both strongly implicated in the development of KSHV-induced lymphoproliferative disorders.

Kaposi's Sarcoma-associated Herpesvirus-encoded Viral Interleukin-6 Is Secreted and Modified Differently Than Human Interleukin-6

Viral interleukin-6 (vIL-6) is a homolog of cellular IL-6 that is encoded by the Kaposi's sarcoma-associated herpesvirus (KSHV) genome. vIL-6 binds to the IL-6 signal transducer gp130 without the cooperation of the IL-6 high affinity receptor to induce STAT3 DNA binding and cell proliferation. Although vIL-6 is believed to be important in the pathogenesis of KSHV-induced diseases, its secretion and post-translational modifications have not previously been characterized. Pulse-chase analysis revealed that the half-time of vIL-6 secretion is approximately 8-fold longer than that of human IL-6. Yet, the vIL-6 signal sequence targets human IL-6 secretion to nearly wild-type levels. Surprisingly, vIL-6 was not secreted from a cell line that does not express gp130 but expression of human gp130 in these cells enabled the secretion of vIL-6. Consistent with this observation, complete maturation of gp130 N-glycans is inhibited by vIL-6 coexpression, suggesting that the binding of the receptor to vIL-6 occurs intracellularly in early or pre-Golgi compartments. Furthermore, a vIL-6 mutant containing an endoplasmic reticulum retention signal is not secreted but does still induce receptor activation and signaling. Secreted vIL-6 is completely glycosylated at both possible N-glycosylaton sites and contains a large proportion of immature high-mannose glycans that is not typical of cytokines. These findings suggest that vIL-6 may induce gp130 signaling by an exclusively autocrine mechanism that relies on intracellular binding to its receptor. During KSHV infection, vIL-6 may only induce signaling in KSHV-infected cells to benefit the viral life cycle and promote oncogenic transformation.

Scintigraphic evaluation of cardiac metabolism in multicentric Castleman's disease

A 72-year-old woman had insidious onset of heart failure, and was diagnosed as multicentric Castleman's disease. She underwent myocardial imaging with technetium-99m tetrofosmin, 1-123 beta-methyl-iodophenyl pentadecanoic acid (BMIPP). Technetium-99m tetrofosmin studies showed almost normal uptake of the left ventricular myocardium indicating normal myocardial perfusion. 1-123 BMIPP showed reduced uptake in the apical segment of the myocardium, indicating regional fatty acid metabolic abnormalities.

Multicentric Castleman's disease associated with glomerular microangiopathy and MPGN-like lesion: does vascular endothelial cell-derived growth factor play causative or protective roles in renal injury?

A 52-year-old Japanese man presented with fever spikes, generalized fatigue, anorexia, and anasarca. The patient was referred for the evaluation of fever of unknown origin in association with swelling of cervical, axillary, and inguinal lymph nodes. He also manifested nephrotic syndrome, acute renal failure, hepatosplenomegaly, massive pleural effusion, ascites, disseminated intravascular coagulation, and hypergammaglobulinemia. C-reactive protein was positive and plasma vascular endothelial cell-derived growth factor (VEGF) and serum interleukin-6 levels were markedly elevated. Lymph node biopsy results showed that findings were compatible with Castleman's disease of hyaline vascular type associated with interfollicular plasmacytosis. In conjunction with the clinical findings, a diagnosis of multicentric Castleman's disease was made. The patient underwent renal biopsy because of nephrotic syndrome, and the results showed proliferation of mesangial cells, lobulation of glomeruli, and tram track pattern of the capillary wall without immune complex deposition. Electron microscopy showed widening of the subendothelial space. No electron-dense deposits were present in both mesangial and subendothelial regions. Pathologic features were compatible with glomerular microangiopathy and membranoproliferative glomerulonephritis-like lesions. With corticosteroid therapy, systemic symptoms disappeared; both VEGF and interleukin-6 levels were normalized, and he went into complete remission of nephrotic syndrome. In this article, the role VEGF plays in the pathogenesis of nephrotic syndrome and glomerular microangiopathy is discussed.

The Kaposi's sarcoma-associated herpesvirus G protein-coupled receptor has broad signaling effects in primary effusion lymphoma cells

Kaposi's sarcoma-associated herpesvirus (KSHV/human herpesvirus 8 [HHV-8]) is a gamma-2-herpesvirus responsible for Kaposi's sarcoma as well as primary effusion lymphoma (PEL). KSHV is a lymphotropic virus that has pirated many mammalian genes involved in inflammation, cell cycle control, and angiogenesis. Among these is the early lytic viral G protein-coupled receptor (vGPCR), a homologue of the human interleukin-8 (IL-8) receptor. When expressed, vGPCR is constitutively active and can signal via mitogen- and stress-activated kinases. In certain models it activates the transcriptional potential of NF-kappaB and activator protein 1 (AP-1) and induces vascular endothelial growth factor (VEGF) production. Despite its importance to the pathogenesis of all KSHV-mediated disease, little is known about vGPCR activity in hematopoietic cells. To study the signaling potential and downstream effects of vGPCR in such cells, we have developed PEL cell lines that express vGPCR under the control of an inducible promoter. The sequences required for tetracycline-mediated induction were cloned into a plasmid containing adeno-associated virus type 2 elements to enhance integration efficiency. This novel plasmid permitted studies of vGPCR activity in naturally infected KSHV-positive lymphocytes. We show that vGPCR activates ERK-2 and p38 in PEL cells. In addition, it increases the transcription of reporter genes under the control of AP-1, NF-kappaB, CREB, and NFAT, a Ca(2+)-dependent transcription factor important to KSHV lytic gene expression. vGPCR also increases the transcription of KSHV open reading frames 50 and 57, thereby displaying broad potential to affect viral transcription patterns. Finally, vGPCR signaling results in increased PEL cell elaboration of KSHV vIL-6 and VEGF, two growth factors involved in KSHV-mediated disease pathogenesis.

Gamma herpesviruses: pathogenesis of infection and cell signaling

Altered cell signaling is the molecular basis for cell proliferation occurring in association with several gamma herpesvirus infections. Three gamma herpesviruses, namely EBV/HHV-4, KSHV/HHV-8 and the MHV-68 (and/or MHV-72) and their unusual cell-pirated gene products are discussed in this respect. The EBV, KSHV as well as the MHV DNA may persist lifelong in an episomal form in the host carrier cells (mainly in lymphocytes but also in macrophages, in non-hornifying squamous epithelium and/or in blood vessel endothelial cells). Under conditions of extremely limited transcription, the EBV-infected cells express EBNA1 (EB nuclear antigen 1), the KSHV infected cells express LANA1 (latent nuclear antigen 1), while the MHV DNA carrier cells express the latency-associated protein M2. With the full set of latency-associated proteins expressed, EBV carrier cells synthesize additional EBNAs and at least one LMP (latent membrane protein 1). The latent KSHV carrier cells, in addition to LANA1, may express a viral cyclin, a viral Fas-DD-like ICE inhibitor protein (vFLIP) and a virus-specific transformation protein called kaposin (K12). In MHV latency with a wide expression of latency-associated proteins, the carrier cells express a LANA analogue (ORF73), the M3 protein, the K3/IE (immediate early) proteins and M11/bcl-2 homologue proteins. During the period of limited gene expression, the latency-associated proteins serve mainly for the maintenance of the latent episomal DNA (a typical example is EBNA1). In contrast, during latency with a broader spectrum gene expression, the virus-encoded products activate transcription of otherwise silenced cellular genes, which leads to the synthesis of enzymes capable of promoting not only viral but also cellular DNA replication. Thus, the latency-associated proteins block apoptosis and drive host cells towards division and immortalization. Proliferation of hemopoetic cells, which had become gamma herpesvirus DNA carriers, can be initiated and strongly enhanced in the presence of inflammatory cytokines and by virus-encoded analogues of interleukins, chemokines and IFN regulator proteins. At early stages of tumor formation, many proliferating hemopoetic and/or endothelium cells, which had became transcriptionally active under the influence of chemokines and cytokines, may not yet be infected. In contrast, at later stages of oncogenesis, the virus-encoded proteins, inducing false signaling and activating the proliferation pathways, bring the previously infected cells into full transformation burst.

Human interleukin-6 induces human herpesvirus-8 replication in a body cavity-based lymphoma cell line

Human herpesvirus-8 (HHV-8) is etiologically associated with Kaposi's sarcoma (KS), body cavity-based lymphoma (BCBL), and multicentric Castleman's disease (MCD). These HHV-8-associated diseases arise predominantly in acquired immunodeficiency syndrome (AIDS) patients. Human interleukin-6 (huIL-6) elevated in the serum of AIDS patients is suggested to stimulate the growth of KS and BCBL and to augment the symptoms of MCD. To determine whether huIL-6 stimulates HHV-8 replication directly, expression of the HHV-8 ORF-50 immediate-early gene (transcription activator) and ORF-26 late lytic gene (a capsid protein) was assessed in a BCBL-1 cell line stimulated by huIL-6 by means of real-time reverse transcription-polymerase chain reaction. huIL-6 induced both ORF-50 and ORF-26 expression, and the maximal ORF-50 expression appeared earlier than that of ORF-26. The data indicate that huIL-6 reactivates HHV-8 in BCBL-1 cells through inducing ORF-50. We also confirmed the previously reported activities of HHV-8-encoded huIL-6 homologue (viral interleukin-6 [vIL-6]) on human immunodeficiency virus (HIV) replication in U1 cell line and huIL-6 production by MT-4 T cells, and utilizing monoclonal antibodies to the huIL-6 receptor components, we elucidated that gp130 is the signaling molecule necessary for these vIL-6 activities. These data suggest the possible existence of interaction between HIV and HHV-8 via IL-6, and that the blockade of IL-6 signal by anti-IL-6R antibody or anti-gp130 antibody can constitute a strategy to treat HIV/HHV-8 dually infected patients.

Cockroach extract antigen increases bronchial airway epithelial permeability

BACKGROUND

The bronchial epithelial cells of airways are subject to recurrent environmental injury throughout the life of an individual. Recently, a high incidence of asthma has been reported in inner-city children. The increased incidence of asthma in inner-city children is thought to be caused, in part, by frequent exposure to allergens of the common household pest the cockroach.

OBJECTIVE

We sought to investigate whether cockroach extract antigen (CrAg) induces vascular permeability factor, also known as vascular endothelial growth factor (VEGF), and whether it increases permeability in bronchial airway epithelial cells (BAECs).

METHODS

We estimated CrAg-induced VEGF release in BAECs by using an ELISA and VEGF mRNA expression by using an RT-PCR reaction. The influence of CrAg on BAEC barrier function was estimated by measuring electrical resistance with an electric cell substrate impedance-sensing system.

RESULTS

Our results demonstrate that CrAg induces VEGF release in BAECs in a time-dependent manner. The VEGF induction was also confirmed by means of VEGF mRNA expression in CrAg-stimulated BAECs. CrAg decreased electrical resistance across BAEC monolayers. The maximum decrease in electrical resistance was noticed 6 hours after activation and reached a plateau thereafter. Neutralizing antibodies to VEGF significantly inhibited the decrease in BAEC electrical resistance caused by CrAg.

CONCLUSIONS

These data suggest that CrAg induces VEGF release in BAECs and alters bronchial airway permeability.

Expression of vascular endothelial growth factor receptors 1, 2, and 3 in quiescent endothelia

The vascular endothelial growth factor (VEGF) family is involved in angiogenesis, and therefore VEGFs are considered as targets for anti-angiogenic therapeutic strategies against cancer. However, the physiological functions of VEGFs in quiescent tissues are unclear and may interfere with such systemic therapies. In pathological conditions, increased levels of expression of the VEGF receptors VEGFR-1, VEGFR-2, and VEGFR-3 accompany VEGF activity. In this study we investigated normal human and monkey tissues for expression patterns of these receptors. Immunohistochemical staining methods at the light and electron microscopic level were applied to normal human and monkey tissue samples, using monoclonal antibodies (MAbs) against the three VEGFRs and anti-endothelial MAbs PAL-E and anti-CD31 to identify blood and lymph vessels. In human and monkey, similar distribution patterns of the three VEGFRs were found. Co-expression of VEGFR-1, -2, and -3 was observed in microvessels adjacent to epithelia in the eye, gastrointestinal mucosa, liver, kidney, and hair follicles, which is in line with the reported preferential expression of VEGF-A in some of these epithelia. VEGFR-1, -2, and -3 expression was also observed in blood vessels and sinusoids of lymphoid tissues. Furthermore, VEGFR-1, but not VEGFR-2 and -3, was present in microvessels in brain and retina. Electron microscopy showed that VEGFR-1 expression was restricted to pericytes and VEGFR-2 to endothelial cells in normal vasculature of tonsils. These findings indicate that VEGFRs have specific distribution patterns in normal tissues, suggesting physiological functions of VEGFs that may be disturbed by systemic anti-VEGF therapy. One of these functions may be involvement of VEGF in paracrine relations between epithelia and adjacent capillaries.

Highly enhanced expression of the disintegrin metalloproteinase MDC15 (metargidin) in rheumatoid synovial tissue

OBJECTIVE

The aim of the study was to analyze the expression of the disintegrin metalloproteinase MDC15 (metargidin, or ADAM15) at the messenger RNA (mRNA) and protein levels in synovial tissue from osteoarthritis (OA) and rheumatoid arthritis (RA) patients compared with normal specimens.

METHODS

Conventional immunohistochemistry and confocal laser scanning microscopy of immunofluorescently stained sections, as well as in situ hybridization experiments and reverse transcription-polymerase chain reaction were performed for analyses of MDC15 expression on normal, OA, and RA synovial tissue specimens.

RESULTS

In normal synovium, MDC15 expression was detectable at a very low level. MDC15 expression was considerably increased in OA-derived tissue samples, whereas a maximum of signal intensity for MDC15 mRNA and protein was seen in the RA lining layer. The CD68+ macrophage-like synoviocytes (type A) and the CD68- fibroblast-like synoviocytes (type B) were positive for MDC15. Moreover, a very strong expression of MDC15 was also found in CD138+ plasma cells in all RA tissues as well as in OA specimens that contained areas of mononuclear cell infiltrates. CD20+ B cells and CD4+ and CD8+ T cells, however, did not exhibit expression of MDC15, either in the synovial tissue in situ or in preparations of circulating lymphocytes made from the peripheral blood of RA patients or healthy controls.

CONCLUSION

Our results demonstrate high levels of MDC15 expression in macrophage-like and fibroblast-like synoviocytes as well as in plasma cells as a histologic feature most prominent in RA synovial tissue compared with normal or OA synovial tissue. This suggests a potential role of MDC15 in the pathogenesis of cartilage destruction in inflammatory joint disease.