Logical modelling of myelofibrotic microenvironment predicts dysregulated progenitor stem cell crosstalk

Idiopathic primary myelofibrosis is an age-related clonal neoplastic disorder of
haematopoiesis characterised by a myeloproliferation and myelofibrosis. Recent
evidence suggests that disease onset results from an altered bone marrow
microenvironment, leading to disrupted crosstalk between progenitor haematopoietic
and mesenchymal stem cells populations. 90% of myelofibrosis cases exhibit ectopic
mutations of JAK2, CALR and, or MPL genes which all converge on the activation of
JAK and STAT signaling pathways. Treatments aiming to target STAT overactivity
have been developed; however, disease management is conducted at advanced
stages of the disease and treatments are not effective. A computational description
of how altered microenvironments can lead to dysregulated crosstalk between
haematopoietic and mesenchymal stem cells populations following STAT activation
would increase our knowledge of disease pathology and influence future treatment
protocols. To meet this aim, we have constructed a logical model that accounts for
the myelofibrotic microenvironment following TPO and lTLR signalling, integrated
with JAK-STAT signalling. The model primarily aims to provide a mechanistic
understanding of the dysregulated crosstalk between progenitor HSC’s, MSC’s and
the microenvironment to predict the onset of PMF with, and without the JAK
activation. Wildtype simulations result in 4 cyclic attractors being obtained, all
depending on combination of inputs being modelled. The model predicted that
presence of TPO and lTLR signalling are both required to facilitate disease onset for
wildtype simulations. For simulations involving JAK knock-in mutated scenarios, the
model resulted in 4 fixed point attractors, with the presence of lTLR alone being
sufficient to drive disease progression.