Hematologic and cytogenetic remission of 5q-refractory anemia after syngeneic bone marrow transplantation

African-centric TP53 variant increases iron accumulation and bacterial pathogenesis but improves response to malaria toxin

A variant at amino acid 47 in human TP53 exists predominantly in individuals of African descent. P47S human and mouse cells show increased cancer risk due to defective ferroptosis. Here, we show that this ferroptotic defect causes iron accumulation in P47S macrophages. This high iron content alters macrophage cytokine profiles, leads to higher arginase level and activity, and decreased nitric oxide synthase activity. This leads to more productive intracellular bacterial infections but is protective against malarial toxin hemozoin. Proteomics of macrophages reveal decreased liver X receptor (LXR) activation, inflammation and antibacterial defense in P47S macrophages. Both iron chelators and LXR agonists improve the response of P47S mice to bacterial infection. African Americans with elevated saturated transferrin and serum ferritin show higher prevalence of the P47S variant (OR = 1.68 (95%CI 1.07–2.65) p = 0.023), suggestive of its role in iron accumulation in humans. This altered macrophage phenotype may confer an advantage in malaria-endemic sub-Saharan Africa.

A polymorphism in human TP53 (P47S) that predominantly exists in individuals of African descent affects ferroptosis. Here, the authors show that this results in iron accumulation in macrophages leading to more productive infection by intracellular bacteria but improved anti-inflammatory response to the malarial toxin hemozoin.

The 5q- syndrome: a scientific and clinical update

The 5q- syndrome is a subset of the myelodysplastic syndromes characterized by hypolobulated micromegakaryocytic hyperplasia and an interstitial deletion of the long arm of chromosome 5. In this concise review, we discuss the current understanding in regard to the genetic basis of the disorder and provide an updated clinical report on 43 patients with the disease who were seen at our institution.

Danazol treatment of myelodysplastic syndromes

Peripheral cytopenias are common in patients with myelodysplastic syndromes. We previously successfully treated three such patients with improvement of some cytopenias with the impeded androgen danazol. To confirm this finding and elucidate the mechanism of response, we treated an additional 22 patients with myelodysplasia with oral danazol (600-800 mg daily) for 3-12 months. Eleven of 22 evaluable patients taking danazol met our criteria for improvement of peripheral counts, mainly thrombocytopenia. Chromosome analysis, marrow culture studies and serial bone marrow biopsies revealed no alteration of the abnormal clone or normal haematopoiesis in patients on danazol therapy. This suggested that improvement in blood counts was not related to modulation of ineffective haematopoiesis. Investigation of the thrombocytopenia in these patients revealed that most patients presented with markedly elevated platelet associated IgG (PAIgG), elevated plasma platelet-bindable IgG (PBIgG), and an elevated number of monocyte Fc gamma receptors. Treatment with danazol was associated with a decline in monocyte Fc gamma receptor number without significantly altering the elevated PAIgG or PBIgG levels. These results are similar to our observations in patients treated with danazol for chronic idiopathic thrombocytopenia purpura (ITP). Our data suggest that a component of the thrombocytopenia occurring in patients with myelodysplasia may be due to enhanced peripheral blood cell destruction by abnormal macrophages. Danazol may modulate cytopenia by decreasing the number of monocyte Fc gamma receptors. Danazol treatment was associated with minimal toxicity, but clinically meaningful responses were rare.