Showing papers by "David C. Fajgenbaum published in 2023"

A novel cryopreservation and biobanking strategy to study lymphoid tissue stromal cells in human disease

Abstract: Non-hematopoietic lymph node stromal cells (LNSCs) regulate lymphocyte trafficking, survival, and function for key roles in host defense, autoimmunity, alloimmunity, and lymphoproliferative disorders. However, study of LNSCs in human diseases is complicated by a dependence on viable lymphoid tissues, which are most often excised prior to establishment of a specific diagnosis. Here, we demonstrate that cryopreservation can be used to bank lymphoid tissue for the study of LNSCs in human disease. Using human tonsils, lymphoid tissue fragments were cryopreserved for subsequent enzymatic digestion and recovery of viable non-hematopoietic cells. Flow cytometry and single-cell transcriptomics identified comparable proportions of LNSC cell types in fresh and cryopreserved tissue. Moreover, cryopreservation had little effect on transcriptional profiles, which showed significant overlap between tonsils and lymph nodes. The presence and spatial distribution of transcriptionally defined cell types was confirmed by in situ analyses. Our broadly applicable approach promises to greatly enable research into the roles of LNSC in human disease.

Serum IL-6 levels following siltuximab administration in castleman disease.

Abstract: e19545 Background: Idiopathic multicentric Castleman disease (iMCD) is a rare and life-threatening disorder. Though etiology is unknown, interleukin-6 (IL-6) is a driver in a portion of cases. Siltuximab is a monoclonal antibody that targets IL-6 and has been approved by the Food and Drug Administration to treat iMCD. Treatment guidelines for iMCD note that IL-6 directed therapy can result in spurious elevation of serum IL-6, based on anecdotal reports. This could lead physicians to erroneously infer treatment failure. Herein we investigate an international natural history registry of CD to evaluate whether IL-6 levels are increased following siltuximab. Methods: Data on peak IL-6 levels measured in patients before and after receiving siltuximab was available for 40 patients. C-reactive protein (CRP) levels measured near peak IL-6 values before and after siltuximab were also collected where available (n=32). Peak IL-6 values were standardized by the upper end of the reference range. Median values and interquartile ranges were calculated for pre- and post-siltuximab CRP and peak IL-6 values. Wilcoxon signed-rank tests were used for statistical comparison. Results: Our cohort consisted of 40 patients who had lymph node histopathology consistent with Castleman disease. An expert panel confirmed 16 iMCD, 5 POEMS-MCD, 1 regional CD, 3 unicentric CD, 11 other diagnoses, and 4 remain to be determined. Breakdown by gender was 50% male (n=20) and 50% female (n=20) with a mean age of 40.76 years. We analyzed peak standardized IL-6 levels before and after treatment with siltuximab. Prior to treatment with siltuximab, the median IL-6 level was 3.18, whereas after treatment with siltuximab, the median IL-6 level was elevated to 557 (p = 1.8 x 10-12). Given that CRP is a well-established biomarker of IL-6 activity, we investigated whether the increased IL-6 was a reflection of increased disease activity in these patients. Here, we found that median CRP before treatment was 59.7 mg/L, whereas after treatment, median CRP decreased to 4.95 mg/L (p = 0.0005) suggesting that IL-6 levels were rising despite reduced disease activity. IL-6 levels rose almost 200-fold while CRP reduced over 10-fold. Conclusions: Our results indicate that IL-6 levels significantly increase after patients receive siltuximab. Given that CRP is a biomarker of IL-6 activity, we infer that IL-6 is artificially elevated but not having a functional impact in the patient. Therefore, IL-6 levels should not be measured after siltuximab is given and they should not be used to guide treatment decisions. [Table: see text]

A model for crowdsourcing high-impact research questions for Castleman disease and other rare diseases

Abstract: There are approximately 10,000 rare diseases that affect around 30,000,000 individuals in the U.S.A., most of which do not have an FDA-approved treatment. This fact highlights the failure of traditional research approaches to overcome the unique challenges of developing rare disease treatments. The Castleman Disease Collaborative Network was founded in 2012 to advance research and treatments for Castleman disease, a rare and deadly disease that involves the immune system attacking the body's vital organs for an unknown cause. It has spearheaded a novel strategy for advancing biomedical research, the Collaborative Network Approach. This approach consists of eight steps, one of which is to identify and prioritize high-impact research questions through crowdsourcing ideas from the entire community of stakeholders: patients, loved ones, physicians, and researchers. Rather than hoping that the right researcher will apply for the right research project at the right time, crowdsourcing high-priority research projects into a research strategy ensures that the most high-impact, patient-centered studies are prioritized. The Castleman Disease Collaborative Network launched an initiative in 2021 to systematically generate this list of community-directed studies to focus Castleman disease research efforts.The Castleman Disease Collaborative Network was able to successfully create a patient-centered research agenda through engaging the entire community of stakeholders. The community contributed important questions about Castleman disease, which were prioritized and reviewed by our Scientific Advisory Board, and the result was a finalized list of studies that address these prioritized questions. We were also able to generate a best practices list which can serve as a model that can be utilized for other rare diseases.Creating a patient-centered research agenda through crowdsourcing research ideas from the community is one of the most important ways that the Castleman Disease Collaborative Network operationalizes its commitment to keeping patients at the center of research and we hope that by sharing these insights we can assist other rare disease organizations to pursue a patient-centric approach.

A novel cryopreservation and biobanking strategy to study lymphoid tissue stromal cells in human disease.

Abstract: Nonhematopoietic lymph node stromal cells (LNSCs) regulate lymphocyte trafficking, survival, and function for key roles in host defense, autoimmunity, alloimmunity, and lymphoproliferative disorders. However, the study of LNSCs in human diseases is complicated by a dependence on viable lymphoid tissues, which are most often excised prior to establishment of a specific diagnosis. Here, we demonstrate that cryopreservation can be used to bank lymphoid tissue for the study of LNSCs in human disease. Using human tonsils and lymph nodes (LN), lymphoid tissue fragments were cryopreserved for subsequent enzymatic digestion and recovery of viable nonhematopoietic cells. Flow cytometry and single-cell transcriptomics identified comparable proportions of LN stromal cell types in fresh and cryopreserved tissue. Moreover, cryopreservation had little effect on transcriptional profiles, which showed significant overlap between tonsils and LN. The presence and spatial distribution of transcriptionally defined cell types were confirmed by in situ analyses. Our broadly applicable approach promises to greatly enable research into the roles of LNSCs in human disease.