Contributions
Abstract: EP1059
Type: E-Poster Presentation
Session title: Myeloproliferative neoplasms - Biology & Translational Research
Background
The classic Philadelphia-chromosome negative chronic myeloproliferative neoplasms (CMN) are characterized by clonal proliferation of myeloid cells, increased thrombotic risk, inflammation and splenomegaly. Besides driver mutations (e.g. JAK2-V617F mutation), inflammation plays a key role in pathophysiology in CMN. Amongst other cytokines, IL-6 levels are elevated in CMN-patients. The pleiotropic cytokine IL-6 was described as a master cytokine due to its involvement in a wide range of physiological and pathological mechanisms. It was shown that IL-6 reduction by ruxolitinib correlates with improvement of symptom burden in CMN. Additionally, IL-6 and the downstream molecule STAT3 were described to link inflammation with malignant proliferation. Recently, pro-inflammatory cytokines are discussed as interesting anti-inflammatory targets in CMN treatment to inhibit inflammation driven transformation into myelofibrosis and/or acute leukemia.
Aims
This study aimed to investigate the impact of an anti-IL-6 treatment on disease specific parameters (e.g. cytokine levels in serum, hematocrit, and splenomegaly) in a polycythemia vera - like JAK2-V617F knock-in mouse model.
Methods
JAK2-V617F knock-in mice (11-13 weeks old) were treated (3x/week for three weeks) with anti-IL-6 antibody (clone MP5-20F3) and isotype IgG control, respectively. A wide panel of pro-inflammatory cytokines was measured in serum of treated mice by Eve Technologies Corporation (Mouse Cytokine Array/Chemokine Array 31-Plex; Calgary, AB, Canada). Blood parameters were analyzed by ADVIA®2120i Hematology System (Siemens Healthcare Diagnostics, Erlangen, Germany). For histopathologic analysis, hematoxylin-eosin staining was performed on isolated spleens sections.
Results
Reduced inflammatory cytokine levels (factor 0.3 – 0.8) were measured in serum of anti-IL-6 treated JAK2-V617F mice for CXCL1, CCL11, CXCL2, G-CSF, CXCL10, CXCL5, IL-13, CCL4 and CCL5. Interestingly, high dose isotype IgG control antibody also reduced levels of a number of these cytokines in JAK2-V617F mice.
The reduced inflammatory environment upon anti-IL-6 treatment did not result in improvement of hematological parameters. For example, hematocrit (82.0 % vs 76.0 %) and erythrocyte blood cell (20.8 Tpt/L vs 21.5 Tpt/L) were still significant elevated at the end of anti-IL-6 treatment. Another characteristic parameter of JAK2-V617F mice is a splenomegaly. The reduced cytokine levels showed no impact on the elevated spleen weight and size. In addition, there was no apparent amelioration of spleen histopathology.
Conclusion
Anti-IL-6 treatment was shown to reduce a number of pro-inflammatory cytokine levels in serum of JAK2-V617F mice. However, this change had no apparent impact on hematologic disease parameters. Furthermore, anti-IL6 treatment had no impact on extramedullary hematopoiesis presenting as splenomegaly and on histopathology of the spleen. This suggests that inhibition of IL-6 in CMN may be compensated by IL6-independent inflammatory pathways in vivo and may not be useful as a therapeutic approach in patients.
Keyword(s): IL-6, Inflammation, Myeloproliferative disorder
Abstract: EP1059
Type: E-Poster Presentation
Session title: Myeloproliferative neoplasms - Biology & Translational Research
Background
The classic Philadelphia-chromosome negative chronic myeloproliferative neoplasms (CMN) are characterized by clonal proliferation of myeloid cells, increased thrombotic risk, inflammation and splenomegaly. Besides driver mutations (e.g. JAK2-V617F mutation), inflammation plays a key role in pathophysiology in CMN. Amongst other cytokines, IL-6 levels are elevated in CMN-patients. The pleiotropic cytokine IL-6 was described as a master cytokine due to its involvement in a wide range of physiological and pathological mechanisms. It was shown that IL-6 reduction by ruxolitinib correlates with improvement of symptom burden in CMN. Additionally, IL-6 and the downstream molecule STAT3 were described to link inflammation with malignant proliferation. Recently, pro-inflammatory cytokines are discussed as interesting anti-inflammatory targets in CMN treatment to inhibit inflammation driven transformation into myelofibrosis and/or acute leukemia.
Aims
This study aimed to investigate the impact of an anti-IL-6 treatment on disease specific parameters (e.g. cytokine levels in serum, hematocrit, and splenomegaly) in a polycythemia vera - like JAK2-V617F knock-in mouse model.
Methods
JAK2-V617F knock-in mice (11-13 weeks old) were treated (3x/week for three weeks) with anti-IL-6 antibody (clone MP5-20F3) and isotype IgG control, respectively. A wide panel of pro-inflammatory cytokines was measured in serum of treated mice by Eve Technologies Corporation (Mouse Cytokine Array/Chemokine Array 31-Plex; Calgary, AB, Canada). Blood parameters were analyzed by ADVIA®2120i Hematology System (Siemens Healthcare Diagnostics, Erlangen, Germany). For histopathologic analysis, hematoxylin-eosin staining was performed on isolated spleens sections.
Results
Reduced inflammatory cytokine levels (factor 0.3 – 0.8) were measured in serum of anti-IL-6 treated JAK2-V617F mice for CXCL1, CCL11, CXCL2, G-CSF, CXCL10, CXCL5, IL-13, CCL4 and CCL5. Interestingly, high dose isotype IgG control antibody also reduced levels of a number of these cytokines in JAK2-V617F mice.
The reduced inflammatory environment upon anti-IL-6 treatment did not result in improvement of hematological parameters. For example, hematocrit (82.0 % vs 76.0 %) and erythrocyte blood cell (20.8 Tpt/L vs 21.5 Tpt/L) were still significant elevated at the end of anti-IL-6 treatment. Another characteristic parameter of JAK2-V617F mice is a splenomegaly. The reduced cytokine levels showed no impact on the elevated spleen weight and size. In addition, there was no apparent amelioration of spleen histopathology.
Conclusion
Anti-IL-6 treatment was shown to reduce a number of pro-inflammatory cytokine levels in serum of JAK2-V617F mice. However, this change had no apparent impact on hematologic disease parameters. Furthermore, anti-IL6 treatment had no impact on extramedullary hematopoiesis presenting as splenomegaly and on histopathology of the spleen. This suggests that inhibition of IL-6 in CMN may be compensated by IL6-independent inflammatory pathways in vivo and may not be useful as a therapeutic approach in patients.
Keyword(s): IL-6, Inflammation, Myeloproliferative disorder