Castleman's disease-associated neuropathy: no evidence of human herpesvirus type 8 infection

Systemic expression of Kaposi sarcoma herpesvirus (KSHV) Vflip in endothelial cells leads to a profound proinflammatory phenotype and myeloid lineage remodeling in vivo

KSHV is the causative agent of Kaposi sarcoma (KS), a spindle-shaped endothelial cell neoplasm accompanied by an inflammatory infiltrate. To evaluate the role of KSHV vFLIP in the pathogenesis of KS, we constructed mice with inducible expression of vFLIP in endothelial cells. Abnormal cells with endothelial marker expression and fusiform appearance were observed in several tissues reminiscent of the spindle cells found in KS. Serum cytokines displayed a profound perturbation similar to that described in KSHV inflammatory cytokine syndrome (KICS), a recently described clinical condition characterized by elevated IL6 and IL10. An increased myeloid component with suppressive immune phenotype was found, which may contribute to functional changes in the microenvironment and cellular heterogeneity as observed in KS. These mice represent the first in vivo demonstration that vFLIP is capable of inducing vascular abnormalities and changes in host microenvironment with important implications for understanding the pathogenesis and treating KSHV-associated diseases.

Kaposi’s sarcoma (KS) is the most common cancer in men infected with HIV, and also among the most frequent malignancies in Sub-Equatorial Africa. KS is a tumor of endothelial cell origin that is caused by infection with a gamma-herpesvirus, called KS herpesvirus (KSHV) or human herpesvirus 8 (HHV-8). KSHV vFLIP is a viral oncoprotein expressed during latent infection. We report here the generation and characterization of mice expressing KSHV vFLIP in an inducible manner in endothelial cells. Transgenic mice showed: 1) systemic endothelial abnormalities, with the presence of fusiform cells reminiscent of the spindle cells found in KS, 2) development of a profound perturbation in serum cytokines, reminiscent of the cytokine storm characteristic of KSHV-associated cytokine syndrome (KICS), and 3) remodeling of myeloid differentiation with expansion of myeloid cells displaying a suppressive immunophenotype that potentially favors host immune evasion, angiogenesis and tumor progression. This is the first example of significant changes in myeloid differentiation, vascular abnormalities and cytokine perturbation entirely initiated by ectopic expression of a single viral gene, making this mouse model a useful system to dissect the mechanisms viruses use to manipulate the host microenvironment culminating in sabotage of immunity and development of vascular lesions.

Optic neuropathy associated with Castleman disease

A 44-year-old woman with Castleman disease presented with acute visual loss in the left eye. A full ophthalmologic examination and imaging were performed. Visual acuity was 20/20 in the right eye and 20/100 in the left eye. Total dyschromatopsia, a relative afferent pupillary defect, and a cecocentral scotoma were observed in the left eye. Mild disc edema, without leaking during fluorescein angiography, was also observed. Magnetic resonance imaging revealed a small cystic epidermoid-like lesion in the right prepontine and suprasellar cistern. Her visual acuity did not improve and deteriorated to 20/200 in the left eye at 22 months after the initial visual loss. Optic neuropathy may rarely be associated with Castleman disease and suggests a poor prognosis.

Paraneoplastic syndromes affecting the nervous system

The paraneoplastic neurologic disorders (PND) are a diverse group of diseases characterized by the presence of neurologic dysfunction in the setting of a remote cancer. PND can affect almost any part of the nervous system, and are most commonly associated with lung cancer (small cell) and gynecologic tumors. Laboratory studies have demonstrated that an autoimmune response links the neurologic disorder and the cancer, and established a model whereby the cancer is believed to initiate the syndrome by expressing a protein antigen normally expressed in the nervous system, leading to anti-tumor immune response followed by autoimmune neurologic symptoms. We review the currently known PND and their pathogenesis.

[Transitional type of Castleman's disease manifested as the POEMS syndrome]

BACKGROUND

Castleman's disease is an atypical lymphoproliferative disorder characterized by angiofollicular hyperplasia of lymph nodes. Histologically, it can be classified into a hyaline-vascular type, plasma-cell type, and transitional (mixed-cell) type, while clinically localized type has been classified as unicentric, or generalized (multicentric) form of the disease.

CASE REPORT

This paper presents a 21 year old male patient with multicentric Castleman's disease, a transitional (mixed-cell) type. The disease was manifested by fever, generalized enlargement of peripheral lymph nodes, breast glands enlargement, hyperemia of the face, and weakness of the lower extremities. We found mediastinal lymphadenopathy, pleural and pericardial effusions, sensorimotor peripheral neuropathy and polyclonal hypergammaglobulinemia. The simultaneous presence of these manifestations of the disease (sensomotor peripheral neuropathy, lymphadenopathy, effusions, endocrinopathy, polyclonal gammaglobulinemia and skin changes) is indentified as POEMS syndrome. The diagnosis of Castleman's disease was based on the results of histopathologic analysis of mediastinal lymph node biopsies after thoracotomy. The patient was treated with corticosteroids (prednisone 80 mg daily for 2 weeks followed by 60 mg daily). A partial response was achieved after 4 months of treatment.

CONCLUSION

A transitional type of multicentric Castleman's disease may be present itself as POEMS syndrome. The effect of corticosteroid therapy in this form of the disease is unpredictable.