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Background: Homozygous or compound heterozygous mutations in JAGN1 cause severe congenital neutropenia. JAGN1-mutant patients present with severe early-onset bacterial infections and most have been described as low-responders to recombinant granulocyte colony-stimulating factor (G-CSF) therapy. In a murine, hematopoietic JAGN1 knockout model, which displays susceptibility to Candida albicans infection in the absence of neutropenia, treatment with granulocyte-macrophage-CSF (GM-CSF) was able to restore the functional defect of neutrophils. Patients: We present two unrelated patients with biallelic JAGN1 mutations, who were both treated with subcutaneous GM-CSF (sargramostim) after treatment failure to G-CSF. The first patient was an 18-year-old pregnant woman who received GM-CSF at 12 weeks of gestation up to a dose of 10 µg/kg/d for 7 days. The second patient was a 5-month-old girl who received GM-CSF for a total of 9 days at a dose of up to 20 µg/kg/d. GM-CSF did not increase neutrophil counts in our patients. Treatment was stopped when neutrophil numbers declined further, no beneficial effect was noticed, and patients presented with infections. No adverse effects were observed in either patient and the fetus. Both patients ultimately underwent successful hematopoietic stem cell transplantation. Discussion: Both patients showed a high recurrence rate of severe infections on G-CSF treatment. GM-CSF therapy did not ameliorate the clinical phenotype, in contrast to the improvement of neutrophil function observed in the JAGN1 mouse model. No major additional extra-hematopoietic manifestations were evident in our patients. Conclusion: In two unrelated patients, GM-CSF did not have any beneficial effect on neutrophil counts. Patients with JAGN1-mutant SCN with reduced G-CSF responsiveness and elevated infection rate should be evaluated early for stem cell transplantation. [ABSTRACT FROM AUTHOR]

Protein therapeutics frequently face major challenges, including complicated production, instability, poor solubility, and aggregation. De novo protein design can readily address these challenges. Here, we demonstrate the utility of a topological refactoring strategy to design novel granulopoietic proteins starting from the granulocyte-colony stimulating factor (G-CSF) structure. We change a protein fold by rearranging the sequence and optimising it towards the new fold. Testing four designs, we obtain two that possess nanomolar activity, the most active of which is highly thermostable and protease-resistant, and matches its designed structure to atomic accuracy. While the designs possess starkly different sequence and structure from the native G-CSF, they show specific activity in differentiating primary human haematopoietic stem cells into mature neutrophils. The designs also show significant and specific activity in vivo. Our topological refactoring approach is largely independent of sequence or structural context, and is therefore applicable to a wide range of protein targets. Skokowa et al. reconstruct the fold of a granulopoietic cytokine, resulting in de novo, hyperstable, highly active proteins with therapeutic potential for treating several neutropenia disorders. [ABSTRACT FROM AUTHOR]

Dear Editor, Severe congenital neutropenia (SCN) is a heterogeneous group of rare inherited bone marrow failure syndromes characterized by absolute neutrophil count (ANC) lower than 0.5 × 10 SP 9 sp /L, increased susceptibility to bacterial infections, and high propensity to leukemic transformation [[1]]. Manifestations from the digestive system have been rarely reported in I G6PC3- i SCN patients and include inflammatory bowel disease (IBD), most closely resembling Crohn's disease, and IBD-like chronic inflammation of the large bowel [[7]]. [Extracted from the article]

Nicotinamide (vitamin B3) treatment improves response to G-CSF in severe congenital neutropenia patients Keywords: severe congenital neutropenia; cyclic neutropenia; granulocyte colony-stimulating factor; nicotinamide; vitamin B3 EN severe congenital neutropenia cyclic neutropenia granulocyte colony-stimulating factor nicotinamide vitamin B3 788 792 5 02/17/21 20210215 NES 210215 Severe congenital neutropenia (CN) is an inherited bone marrow failure syndrome with markedly reduced granulocyte number and function that often manifests with life-threatening bacterial infections.1 Granulocyte colony-stimulating factor (G-CSF) treatment is the primary therapeutic approach and is aimed at keeping granulocyte levels at or above 1 000/µl to prevent infectious complications.2 Some CN patients require high doses of G-CSF to reach this goal, and a small group of patients is not responsive to G-CSF therapy at all. GLO:1XW/15feb21:bjh17313-fig-0001.jpg PHOTO (COLOR): 1 Effect of nicotinamide (NA) treatment on blood cell counts in congenital neutropenia (CN) and cyclic neutropenia (CyN) patients. [Extracted from the article]

Computational protein design is rapidly becoming more powerful, and improving the accuracy of computational methods would greatly streamline protein engineering by eliminating the need for empirical optimization in the laboratory. In this work, we set out to design novel granulopoietic agents using a rescaffolding strategy with the goal of achieving simpler and more stable proteins. All of the 4 experimentally tested designs were folded, monomeric, and stable, while the 2 determined structures agreed with the design models within less than 2.5 Å. Despite the lack of significant topological or sequence similarity to their natural granulopoietic counterpart, 2 designs bound to the granulocyte colony-stimulating factor (G-CSF) receptor and exhibited potent, but delayed, in vitro proliferative activity in a G-CSF-dependent cell line. Interestingly, the designs also induced proliferation and differentiation of primary human hematopoietic stem cells into mature granulocytes, highlighting the utility of our approach to develop highly active therapeutic leads purely based on computational design. De novo designed cytokines that activate the G-CSF receptor show that the receptor-binding information can be encoded onto stable, miniaturised protein scaffolds that possess potent granulopoietic activity; such novel proteins provide for ideal candidates for protein-based therapeutics. [ABSTRACT FROM AUTHOR]

The article informs about congenital neutropenia have a maturation arrest of granulopoiesis, with few or no mature neutrophils in the peripheral blood, and are subject to the development of severe, life-threatening bacterial infections after birth. Topics include subcutaneous administration of recombinant human granulocyte colony-stimulating factor; and bone marrow transplantation is the curative therapy for the disorder, and risks of severe adverse events.

Severe congenital neutropenia (CN) is a bone marrow failure syndrome characterized by an absolute neutrophil count (ANC) below 500 cells/μL and recurrent, life-threatening bacterial infections. Treatment with granulocyte colony-stimulating factor (G-CSF) increases the ANC in the majority of CN patients. In contrary, granulocyte-monocyte colony-stimulating factor (GM-CSF) fails to increase neutrophil numbers in CN patients in vitro and in vivo, suggesting specific defects in signaling pathways downstream of GM-CSF receptor. Recently, we detected that G-CSF induces granulopoiesis in CN patients by hyperactivation of nicotinamide phosphoribosyl transferase (NAMPT)/Sirtuin 1 signaling in myeloid cells. Here, we demonstrated that, in contrast to G-CSF, GM-CSF failed to induce NAMPT-dependent granulopoiesis in CN patients. We further identified NAMPT signaling as an essential downstream effector of the GM-CSF pathway in myelopoiesis. [ABSTRACT FROM AUTHOR]

We found that hematopoietic cell-specific Lyn substrate 1 (HCLS1 or HS1) is highly expressed in human myeloid cells and that stimulation with granulocyte colony-stimulating factor (G-CSF) leads to HCLS1 phosphorylation. HCLS1 binds the transcription factor lymphoid-enhancer binding factor 1 (LEF-1), transporting LEF-1 into the nucleus upon G-CSF stimulation and inducing LEF-1 autoregulation. In patients with severe congenital neutropenia, inherited mutations in the gene encoding HCLS1-associated protein X-1 (HAX1) lead to profound defects in G-CSF-triggered phosphorylation of HCLS1 and subsequently to reduced autoregulation and expression of LEF-1. Consistent with these results, HCLS1-deficient mice are neutropenic. In bone marrow biopsies of the majority of tested patients with acute myeloid leukemia, HCLS1 protein expression is substantially elevated, associated with high levels of G-CSF synthesis and, in some individuals, a four-residue insertion in a proline-rich region of HCLS1 protein known to accelerate intracellular signaling. These data demonstrate the importance of HCLS1 in myelopoiesis in vitro and in vivo. [ABSTRACT FROM AUTHOR]