Abnormal modulation of cell protective systems in response to ischemic/reperfusion injury is important in the development of mouse sickle cell hepatopathy

Abstract

The online version of this article has a Supplementary Appendix. BackgroundSickle cell disease, a genetic red cell disorder inherited in an autosomal recessive manner, occurs throughout the world. Hepatic dysfunction and liver damage may be present in sickle cell disease, but the pathogenesis of these conditions is only partially understood. Design and MethodsTransgenic mice with sickle cell disease (SAD mice) and wild-type mice were exposed to an ischemic/reperfusion stress. The following parameters were evaluated: hematologic profile, transaminase and bilirubin levels, liver histopathology, and mRNA levels of nuclear factor-κB p65, endothelial nitric oxide synthase, inducible nitric oxide synthase, heme oxygenase-1 and phosphodiesterase-1, -2, -3, and -4 genes in hepatocytes obtained by laser-capture microdissection. Immunoblotting was used to analyze the expression of the following proteins: nuclear factor-κB p65 and phospho-nuclear factor-κB p65, heme oxygenase-1, biliverdin reductase, heat shock protein-70, heat shock protein-27 and peroxiredoxin-6. A subgroup of SAD mice was treated with the phosphodiesterase-4 inhibitor rolipram (30 mg/Kg/day by gavage) during the ischemic/reperfusion protocol. ResultsIn SAD mice the ischemic/reperfusion stress induced liver damage compatible with sickle cell disease hepatopathy, which was associated with: (i) lack of hypoxia-induced nuclear factor-κB p65 activation; (ii) imbalance in the endothelial/inducible nitric oxide synthase response to ischemic/reperfusion stress; (iii) lack of hypoxia-induced increased expression of heme oxygenase-1/biliverdin reductase paralleled by a compensatory increased expression of heat shock proteins 70 and 27 and peroxiredoxin-6; and (iv) up-regulation of the phosphodiesterase-1, -2, -3, and -4 genes. In SAD mice the phosphodiesterase-4 inhibitor rolipram attenuated the ischemic/reperfusion-related microcirculatory dysfunction, reduced the inflammatory cell infiltration and induced the heme oxygenase-1/ biliverdin reductase cytoprotective systems. ConclusionsIn SAD mice, sickle cell hepatopathy is associated with perturbed nuclear factor-κB p65 signaling with an imbalance of endothelial/inducible nitric oxide synthase levels, lack of heme oxygenase-1/biliverdin reductase expression and up-regulation of two novel cytoprotective systems: heat shock protein-27 and peroxiredoxin-6.Key words: NF-κB p65, endothelial nitric oxide synthase, inducible nitric oxide synthase, heat shock protein-70, heat shock protein-27, peroxiredoxin-6.

Vascular risk assessment in patients with sickle cell disease

“…10 While studying the transgenic mouse model for SCD exposed to ischemia/reperfusion stress, Siciliano et al elucidated additional mechanisms that disrupt NO homeostasis. 4 Their results, published in this month's issue of Haematologica, show that the sickle cell hepatopathy in SAD mice is associated with an imbalance of endothelial/inducible NO synthase and lack of heme oxygenase-1/biliverdin reductase cytoprotection. In addition, up-regulation of phosphodiesterase-4 genes is noted in hepatocytes in response to ischemia/reperfusion stress.…”

“…These and other manifestations result from chronic hemolysis and intermittent episodes of vascular occlusion that cause both acute and chronic tissue injury and organ dysfunction. 2,3 Two articles in this issue of Haematologica explore unique mechanisms leading to organ damage and clinical sequelae in both the transgenic mouse model for SCD (SAD mice) 4 and in children with SCD, 5 exemplifying the advancements in our knowledge achieved over the last 100 years.…”

“…Inhibition of phosphodiesterase-4 by rolipram attenuated ischemia/reperfusionrelated vasculopathy and inflammation, while inducing the heme oxygenase-1/biliverdin reductase cytoprotective systems, leading to improved hepatocellular survival. 4 The…”

“…1,2 In the last decade, however, such deaths have been significantly reduced. [2][3][4][5] This improvement has been attributed in part to greater iron chelation options and the ability to recognize pre-clinical cardiac iron deposition by Magnetic Resonance Imaging studies (MRI). Patients with low cardiac T2*, as measured by MRI, have a significant risk of developing overt heart failure over a 12-month period if changes to their chelation regime are not made (Figure 1).…”

Dietary -3 fatty acids protect against vasculopathy in a transgenic mouse model of sickle cell disease

“…The lung and liver pathology were analyzed and the liver pathological score, inflammatory cell infiltrate and presence of thrombi were determined by blinded pathologists as previously described. 19,23 Details on the histological analysis are provided in the Online Supplementary Materials and Methods.…”