These observations suggest that ex vivo CRISPR/Cas9 RNP based ELANE knockout of patients' primary hematopoietic stem and progenitor cells followed by autologous transplantation may be an alternative therapy for congenital neutropenia.
Hypotheses underlying our model are: an ELANE mutation causes SCN; CSF3R mutations occur spontaneously at a low rate; in fetal life, hematopoietic stem and progenitor cells expands quickly, resulting in a high probability of several tens to several hundreds of cells with CSF3R truncation mutations; therapeutic granulocyte colony-stimulating factor (G-CSF) administration early in life exerts a strong selective pressure, providing mutants with a growth advantage.
Cyclical neutropenia is usually caused by heterozygous <i>ELANE</i> mutations while congenital neutropenia is genetically heterogeneous with mutations in genes like <i>ELANE, HAX-1, G6PC3</i> and <i>GFI1.</i> The presence of <i>ELANE</i> mutation aids in the establishment of diagnosis and rules out other secondary causes of neutropenia such as autoimmune cytopenia and evolving aplasia.
We propose that acquisition of <i>CSF3R</i> mutations may represent a mechanism by which myeloid precursor cells carrying the <i>ELANE</i> mutations evade the proapoptotic activity of the NE mutants in SCN patients.
We hypothesized that inhibitors of NE, acting either by directly inhibiting enzymatic activity or as chaperones for the mutant protein, might be effective as therapy for CyN and SCN.
Acquisition of CSF3R mutations is a CN-specific phenomenon and is associated with inherited mutations causing CN or cyclic neutropenia, such as ELANE mutations.
Together, these data suggest that SCN disease pathogenesis includes NE mislocalization, which in turn triggers dysfunctional survival signaling and UPR/ER stress.
We identified diminished levels of the natural inhibitor of neutrophil elastase (NE), secretory leukocyte protease inhibitor (SLPI), in myeloid cells and plasma of patients with severe congenital neutropenia (CN).
These results indicate that SCN-iPS cells provide a useful disease model for SCN, and the activation of the Wnt3a/β-catenin pathway may offer a novel therapy for SCN with ELANE mutation.
To differentiate severe congenital neutropenia (SCN) from autoimmune neutropenia (AIN) in patients with persistent neutropenia ≤1000/mm(3) over three months, we evaluated anti-neutrophil auto-antibodies, candidate genes of ELANA, HAX1 and GCSFR, and neutrophil elastase (NE) activity in 38 patients (21 females; average onset age 14.12 ± 2.49 months) in a primary immunodeficiency disease center between 2004 and 2011.