Survival analysis and parasite growth in PbA infected C57Bl/6j mice treated with HS-donating drugs.

<p>Survival data (a, c, e) and parasitemia (b, d, f) for infected mice treated with once-daily NaHS at 0.1, 0.5, 2.5 mg/kg (a,b), twice-daily NaHS at 1.25, 2.5 mg/kg, (c,d) and twice-daily NaHS 2.5, and GYY4137 50 mg/kg (e,f). All studies included a vehicle-treated (saline 0.9%) group. Survival is represented by a Kaplan-Meier plot with lethality defined as body temperature below 32°C. Parasitemia is represented as a line graph of means+S.E.M. in percentage of iRBCs in RBC population. Survival data: (a) N = 13 for all groups; (c) N = 14, 14, 15; (e) N = 15 for all groups. Parasitemia data (animals that did not develop cerebral malaria were excluded): (b) N = 11, 12, 13, 12; (d) N = 13, 14, 14; (f) N = 13, 15, 14. No significant differences were detected in the data set with Log-Rank test and repeated measures one-way ANOVA.</p

Effects of hydrogen sulfide gas on in vitro growth and metabolism of <i>P. falciparum</i>.

<p><i>P. falciparum</i> was grown from a starting parasitemia of 0.5% in the presence of added saline (0.9%) and increasing doses of NaHS and GYY4137. After 48 hours, (a) parasitemia was enumerated and (b–d) concentration of H⁺ (pH), glucose (mM) and lactate (mM) in the culture media was quantified. Presented as dot plot of N = 5 cultures in each condition with mean (line)+S.E.M. Significant differences are denoted with asterisks (*) according to p-values of <0.05(*), <0.01 (**) and <0.001(***) as determined by one-way ANOVA with Tukey’s post hoc.</p

Investigation of Hydrogen Sulfide Gas as a Treatment against <i>P. falciparum</i>, Murine Cerebral Malaria, and the Importance of Thiolation State in the Development of Cerebral Malaria

<div><p>Introduction</p><p>Cerebral malaria (CM) is a potentially fatal cerebrovascular disease of complex pathogenesis caused by <i>Plasmodium falciparum</i>. Hydrogen sulfide (HS) is a physiological gas, similar to nitric oxide and carbon monoxide, involved in cellular metabolism, vascular tension, inflammation, and cell death. HS treatment has shown promising results as a therapy for cardio- and neuro- pathology. This study investigates the effects of fast (NaHS) and slow (GYY4137) HS-releasing drugs on the growth and metabolism of <i>P. falciparum</i> and the development of <i>P. berghei</i> ANKA CM. Moreover, we investigate the role of free plasma thiols and cell surface thiols in the pathogenesis of CM.</p> <p>Methods</p><p><i>P. falciparum</i> was cultured <i>in vitro</i> with varying doses of HS releasing drugs compared with artesunate. Growth and metabolism were quantified. C57Bl/6 mice were infected with <i>P. berghei</i> ANKA and were treated with varying doses and regimes of HS-releasing drugs. Free plasma thiols and cell surface thiols were quantified in CM mice and age-matched healthy controls.</p> <p>Results</p><p>HS-releasing drugs significantly and dose-dependently inhibited <i>P. falciparum</i> growth and metabolism. Treatment of CM did not affect <i>P. berghei</i> growth, or development of CM. Interestingly, CM was associated with lower free plasma thiols, reduced leukocyte+erythrocyte cell surface thiols (infection day 3), and markedly (5-fold) increased platelet cell surface thiols (infection day 7).</p> <p>Conclusions</p><p>HS inhibits <i>P. falciparum</i> growth and metabolism <i>in vitro</i>. Reduction in free plasma thiols, cell surface thiols and a marked increase in platelet cell surface thiols are associated with development of CM. HS drugs were not effective <i>in vivo</i> against murine CM.</p> </div

Free plasma thiol (FPT) levels in healthy and terminally ill, PbA-infected C57Bl/6j mice, and the effects of HS donors on FPTs.

<p>Plasma was collected from uninfected and terminally ill infected mice treated with saline and FPT levels were quantified in two separate experiments (a, b). Effects of HS donor drugs, NaHS and GYY4137, on FPT levels in plasma from terminally ill mice were compared to vehicle-treated terminal mice (c,d). Data is represented as dot plots with mean (line). (a) Experiment 1: N = 6, 7; Experiment 3: N = 6, 11; (b) Experiment 1∶7, 11, 10, 11; Experiment 3∶11, 12, 6. Significant differences are denoted with asterisks (*) according to p<0.05 (*) as determined by Student’s t-test and one-way ANOVA with Tukey’s post hoc.</p

Cell surface thiol (CST) levels in healthy and PbA-infected C57Bl/6j mice, and the effects of HS donors on CSTs.

<p>CSTs of platelets (a, c) and leukocyte/erythrocyte/infected erythrocyte fraction (b, d) were analyzed with flow cytometry in healthy mice, and PbA infected mice treated with saline, NaHS (2.5 mg/kg) and GYY4137 (50 mg/kg) before infection and over the course of infection at day 3 (a, c: pre-intervention), day 5, 7 (b,d: post-intervention until terminal). All data is presented as normalized to baseline CSTs as defined by each animal’s uninfected measurements. Day 3 is presented as a dot plot (N = 7, 42) and day 3, 5, 7 are represented as line graphs of geometric mean+S.E. Geometric M (N = 7, 13, 15, 14). Significant differences are denoted with asterisks (*) according to p-values of <0.05 (*), <0.01 (**) and <0.001 (***) as determined by Student’s t-test and ANOVA with Tukey’s Multiple Comparison.</p