JAK2V617F Hematopoietic Stem and Progenitors Are More Resistant to Chronic Blockage of IL-10 Signaling in a Murine Model of Myeloproliferative Neoplasms

• Published in: Blood 2019-11, Vol.134 (Supplement_1), p.4206-4206
• Main Authors: Lai, Hew Yeng, Trieu, Tiffany, Han, Tiffany, Brooks, Stefan, Craver, Brianna, Ramanathan, Gajalakshmi, Fleischman, Angela G.
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2019-131166

Rationale: Chronic inflammation is a key feature of Myeloproliferative Neoplasm (MPN), inflammation drives symptom burden and disease progression. We have found that monocytes from MPN patients persistently produce Tumor Necrosis Factor-alpha (TNF) following Toll-like receptor stimulation due to dampened Interleukin 10 (IL-10) receptor signaling which usually serves to negatively regulate TNF production (Lai et al, 2019). Chronic inflammation leads to hematopoietic stem cell (HSC) exhaustion, and IL-10 plays an important role in HSC self-renewal (Kang et al, 2007). JAK2V617Fknock-in HSC do not have a selective advantage over wild-type cells in competitive repopulation assays, this suggests that JAK2V617FHSC gain a selective advantage only under specific circumstances. Here, we investigate whether blockade of IL-10 signaling allows JAK2V617F HSC to gain a selective advantage over wild-type cells. We hypothesize that blocking IL-10 signaling impairs wild-type but not JAK2V617Fmutant HSC and thereby allowing JAK2 V617Fmutant cells to expand. Results: We used competitive transplantation to assess the impact of blocking IL-10 signaling on the selective advantage of JAK2V617Fversus wild-type HSC. We transplanted equal numbers of whole bone marrow cells from wild-type (CD45.1) and JAK2 V617F(CD45.2) mice into lethally irritated recipients (CD45.1/2). At day 60 post transplantation we injected mice intraperitoneally with 0.1mg IL-10R blocking antibody (n=5) or PBS (n=4) weekly. The relative contribution of JAK2V617Fcells to donor derived peripheral blood leukocytes (n=4) decreased over time (Figure 1A) in the PBS group. In contrast, the relative contribution of JAK2V617Fcells increased after 120 days in the IL-10R blocking antibody group (Figure 1A). Mice were sacrificed at 186 days post-transplant to assess spleen size and quantify hematopoietic stem and progenitor cells. Mice treated with IL-10R blocking antibody had larger spleens than the PBS group (Figure 1B). The LKS (linnegc-kit+Sca-1+), which contains hematopoietic stem and progenitor cells, was expanded in the mice treated with IL-10R blocking antibody (Figure 1C). The relative contribution of JAK2V617Fcells in the LKS compartment (Figure 1D) as well as whole bone marrow (Figure 1E) was higher in the IL-10R blocking antibody group as compared to the untreated group. Bone marrow from these mice were used for secondary transplants to functionally assess HSC fitness, results are forthcoming. Conclusions: In