Project description:Childhood multicentric Castleman disease (MCD) is a rare and unexplained lymphoproliferative disorder. We report a human herpesvirus-8 (HHV-8)-infected child, born to consanguineous Comorian parents, who displayed isolated MCD in the absence of any known immunodeficiency. We also systematically review the clinical features of the 32 children previously reported with isolated and unexplained MCD. The characteristics of this patient and the geographic areas of origin of most previous cases suggest that pediatric MCD is associated with HHV-8 infection. Moreover, as previously suggested for Kaposi sarcoma, MCD in childhood may result from inborn errors of immunity to HHV-8 infection.
Project description:Idiopathic multicentric Castleman disease (iMCD) is a rare and poorly understood hematologic disorder characterized by lymphadenopathy, systemic inflammation, cytopenias, and life-threatening multiorgan dysfunction. Interleukin-6 (IL-6) inhibition effectively treats approximately one-third of patients. Limited options exist for nonresponders, because the etiology, dysregulated cell types, and signaling pathways are unknown. We previously reported 3 anti-IL-6 nonresponders with increased mTOR activation who responded to mTOR inhibition with sirolimus. We investigated mTOR signaling in tissue and serum proteomes from iMCD patients and controls. mTOR activation was increased in the interfollicular space of iMCD lymph nodes (N = 26) compared with control lymph nodes by immunohistochemistry (IHC) for pS6, p4EBP1, and p70S6K, known effectors and readouts of mTORC1 activation. IHC for pS6 also revealed increased mTOR activation in iMCD compared with Hodgkin lymphoma, systemic lupus erythematosus, and reactive lymph nodes, suggesting that the mTOR activation in iMCD is not just a product of lymphoproliferation/inflammatory lymphadenopathy. Further, the degree of mTOR activation in iMCD was comparable to autoimmune lymphoproliferative syndrome, a disease driven by mTOR hyperactivation that responds to sirolimus treatment. Gene set enrichment analysis of serum proteomic data from iMCD patients (n = 88) and controls (n = 42) showed significantly enriched mTORC1 signaling. Finally, functional studies revealed increased baseline mTOR pathway activation in peripheral monocytes and T cells from iMCD remission samples compared with healthy controls. IL-6 stimulation augmented mTOR activation in iMCD patients, which was abrogated with JAK1/2 inhibition. These findings support mTOR activation as a novel therapeutic target for iMCD, which is being investigated through a trial of sirolimus (NCT03933904).
Project description:Kaposi sarcoma herpesvirus (KSHV)-associated multicentric Castleman disease (MCD) is a rare, polyclonal lymphoproliferative disorder characterized by flares of inflammatory symptoms, edema, cytopenias, lymphadenopathy, and splenomegaly. Diagnosis requires a lymph node biopsy. Pathogenesis is related to dysregulated inflammatory cytokines, including human and viral interleukin-6. Rituximab alone or in combination with chemotherapy, such as liposomal doxorubicin, has led to an overall survival of over 90% at 5 years. Experimental approaches to treatment include virus activated cytotoxic therapy with high-dose zidovudine and valganciclovir and targeting human interleukin-6 activity. Despite successful treatment of KSHV-MCD, patients remain at high risk for developing non-Hodgkin lymphomas.
Project description:Idiopathic multicentric Castleman disease (iMCD) is a rare and poorly-understood cytokine storm-driven inflammatory disorder. Interleukin-6 (IL-6) is a known disease driver in some patients, but anti-IL-6 therapy with siltuximab is not effective in all patients, and biomarkers indicating success at an early time point following treatment initiation are lacking. Here we show, by comparison of levels of 1,178 proteins in sera of healthy participants (N=42), patients with iMCD (N=88), and with related diseases (N=60), a comprehensive landscape of candidate disease mediators and predictors of siltuximab response. C-X-C Motif Chemokine Ligand-13 (CXCL13) is identified and validated as the protein most prominently up-regulated in iMCD. Early and significant decrease in CXCL13 levels clearly distinguishes siltuximab responders from non-responders; a 17% reduction by day 8 following siltuximab therapy initiation is predictive of response at later time points. Our study thus suggests that CXCL13 is a predictive biomarker of response to siltuximab in iMCD.
Project description:Purpose of reviewThe 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 findingsOur 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.SummaryRecent 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.
Project description:Idiopathic multicentric Castleman disease (iMCD) is a rare and poorly-understood cytokine storm-driven inflammatory disorder. Interleukin-6 (IL-6) is a known disease driver in some patients, but anti-IL-6 therapy with siltuximab is not effective in all patients, and biomarkers indicating success at an early time point following treatment initiation are lacking. Here we show, by comparison of levels of 1,178 proteins in sera of healthy participants (N = 42), patients with iMCD (N = 88), and with related diseases (N = 60), a comprehensive landscape of candidate disease mediators and predictors of siltuximab response. C-X-C Motif Chemokine Ligand-13 (CXCL13) is identified and validated as the protein most prominently up-regulated in iMCD. Early and significant decrease in CXCL13 levels clearly distinguishes siltuximab responders from non-responders; a 17% reduction by day 8 following siltuximab therapy initiation is predictive of response at later time points. Our study thus suggests that CXCL13 is a predictive biomarker of response to siltuximab in iMCD.
Project description:Castleman disease is polyclonal lymphoproliferative disorder characterized by unicentric or multicentric lymphadenopathy with characteristic histomorphologic 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 profile to that of benign control lymph nodes. We identified significantly upregulated genes in UCD (443), iMCD (316) or both disease subtypes (51); in addition to downregulated genes in UCD (321), iMCD (105) or both (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 present in UCD and iMCD mostly within abnormally regressed germinal centers, but also in association with plasma cell clusters, endothelial cells and stroma cells 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 IL-6 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 transcriptome of UCD and iMCD, underscoring findings that could aid in the discovery of targetable disease mediators.
Project description:Castleman disease (CD) is a rare lymphoproliferative disorder known to represent at least four distinct clinicopathologic subtypes. Large advancements in our clinical and histopathologic description of these diverse diseases have been made, resulting in subtyping based on number of enlarged lymph nodes (unicentric versus multicentric), according to viral infection by human herpes virus 8 (HHV-8) and human immunodeficiency virus (HIV), and with relation to clonal plasma cells (POEMS). In recent years, significant molecular and genetic abnormalities associated with CD have been described. However, we continue to lack a foundational understanding of the biological mechanisms driving this disease process. Here, we review all cases of CD with molecular abnormalities described in the literature to date, and correlate cytogenetic, molecular, and genetic abnormalities with disease subtypes and phenotypes. Our review notes complex karyotypes in subsets of cases, specific mutations in PDGFRB N666S in 10% of unicentric CD (UCD) and NCOA4 L261F in 23% of idiopathic multicentric CD (iMCD) cases. Genes affecting chromatin organization and abnormalities in methylation are seen more commonly in iMCD while abnormalities within the mitogen-activated protein kinase (MAPK) and interleukin signaling pathways are more frequent in UCD. Interestingly, there is a paucity of genetic studies evaluating HHV-8 positive multicentric CD (HHV-8+ MCD) and POEMS-associated CD. Our comprehensive review of genetic and molecular abnormalities in CD identifies subtype-specific and novel pathways which may allow for more targeted treatment options and unique biologic therapies.