Peroxiredoxin-2: A Novel Regulator of Iron Homeostasis in Ineffective Erythropoiesis.

AIMS: Iron overload (IO) is a life-threatening complication of chronic hemolytic disorders such as ß-thalassemia. IO results in severe cellular oxidative damage, leading to organ failure. Peroxiredoxin-2 (Prx2), a typical 2-cysteine-(Cys)-peroxiredoxin, is an important component of the cytoprotective system, but its response to IO is still to be fully defined. RESULTS: We studied the effects of IO on Prx2-knockout mice (Prx2-/-). The absence of Prx2 enhanced toxicity due to IO on erythropoiesis. We found that IO failed to induce the typical hepcidin (Hamp) upregulation in Prx2-/- mice due to its failure to activate the signal transducer and activator of transcription-3 (STAT3) with intact Jak2 signaling. In Prx2-/- mice, the loss of Hamp response was also observed after administration of a single dose of oral iron. When lipopolysaccharide (LPS) was used to explore IL6-STAT3 activation in Prx2-/- mice, STAT3 activation and Hamp upregulation were once again defective. Treatment with PEP-fusion-recombinant-Prx2 (PEP Prx2) significantly increased STAT3 activation with upregulation of Hamp expression in both IO- and LPS-exposed Prx2-/- mice. We also confirmed the beneficial effects of PEP Prx2 on Hamp expression through STAT3 activation in ß-thalassemic mice. INNOVATION: We propose that Prx2 plays a key role in responding to cytotoxicity of IO, directly targeting STAT3-transcriptional factor in a Jak2-independent fashion and regulating Hamp in response to canonical stimuli. CONCLUSION: Collectively, our data highlight a novel role of Prx2 in iron homeostasis. Prx2 is a key cytoprotector against IO that is induced either by iron supplementation or due to chronic hemolysis as in ß-thalassemia. Prx2 is required to support STAT3 transcriptional activity and regulation of Hamp expression. Antioxid. Redox Signal. 28, 1-14.

Safety evaluation of a vaccine: Effect in maternal reproductive outcome and fetal anomaly frequency in rats using a leishmanial vaccine as a model.

While the immunogenic potential of the vaccination against infectious diseases was extensively shown, data on the safety assessment of recombinant proteins in vaccine formulations administered during pregnancy are still scarce. In the current study, the antigenicity of a vaccine against leishmaniasis (based on Leishmania braziliensis recombinant protein peroxidoxin) during pregnancy and possible maternal reproductive outcomes and fetal anomalies after immunization with a leishmanial vaccine or adjuvant alone (Bordetella pertussis derived MPLA adjuvant) were assessed. Rats were mated and allocated in three groups: Control-rats received saline; Adjuvant-rats received the adjuvant MPLA, and Vaccine-rats received the combination of MPLA and peroxidoxin. The administration was subcutaneously at the dorsal region, three times (days 0, 7, 14 of pregnancy). On day 21 of pregnancy, all rats were bled for biochemical and immunological measurements. The gravid uterus was weighed with its contents, and the fetuses were analyzed. The immunization with peroxidoxin induced a significant production of circulating IgG levels compared to other groups but caused a significant in post-implantation loss (14.7%) when compared to Control (5.0%) and Adjuvant (4.4%) groups. Furthermore, a significantly high rate of fetal visceral anomalies, such as hydronephrosis and convoluted ureter, was also observed in animals that received vaccine when compared to Control or Adjuvant groups. These data indicate the importance of safety evaluation of vaccines during pregnancy and the limited use of peroxidoxin administration during pregnancy. More importantly, the safety monitoring of immunization with MPLA derived from Bordetella pertussis demonstrated no reproductive outcomes associated with adjuvant administration, suggesting its safe use during pregnancy.

Effect of peroxiredoxin II on the quality and mitochondrial activity of pre-implantation bovine embryos.

Endogenous peroxiredoxin II (PRDX II) protein plays a vital role in early embryonic development. This study assessed the beneficial effects of exogenous PRDX II on bovine embryo development at the cellular and molecular levels. To this end, in vitro maturation (IVM) medium was supplemented with various concentrations of PRDX II (0, 6.25, 12.5, 25, 50, and 100µg/mL). Of these, 12.5µg/mL PRDX II was the most effective and significantly promoted embryonic development. Therefore, this concentration of PRDX II was used in subsequent experiments. The percentage of embryos that developed into Day 8 blastocysts and the total number of cells per blastocyst (38.2% and 150.6±5.1) was higher in the PRDX II-treated group than in the control (26.4% and 128.9±3.9, respectively). Moreover, the percent of TUNEL positive cells was higher (P<0.05) in the control than in the PRDX II-treated. Furthermore, PRDX II added to the IVM media increased mitochondria content in blastocysts and decreased the intracellular ROS levels in oocytes and blastocysts compared with the control (P<0.05). The expression of genes associated with blastocyst quality (CDX2 and IFNτ), antioxidant activity (SOD2), and mitochondrial activity (TFAM) was higher, whereas the expression of a gene involved in the apoptotic pathway (c-FOS) was lower, in the PRDX II-treated than in the control group. In conclusion, supplementation of IVM medium with PRDX II promotes development to the blastocyst stage and improves blastocyst quality through reducing ROS, enhancing embryonic mitochondrial activity, and modulating development- related target genes expression.