Severe malaria and host response: time for a paradigm shift in therapeutic strategies to improve clinical outcome

Coupling calcium dynamics and mitochondrial bioenergetic: an in silico study to simulate cardiomyocyte dysfunction

The coupling of intracellular Ca(2+) dynamics with mitochondrial bioenergetic is crucial for the functioning of cardiomyocytes both in healthy and disease conditions. The pathophysiological signature of the Cardiomyocyte Dysfunction (CD) is commonly related to decreased ATP production due to mitochondrial functional impairment and to an increased mitochondrial calcium content ([Ca(2+)]m). These features advanced the therapeutic approaches which aim to reduce [Ca(2+)]m. But whether [Ca(2+)]m overload is the pathological trigger for CD or a physiological consequence, remained controversial. We addressed this issue in silico and showed that [Ca(2+)]m might not directly cause CD. Through model parameter recalibration, we demonstrated how mitochondria cope up with functionally impaired processes and consequently accumulate calcium. A strong coupling of the [Ca(2+)]m oscillations with the ATP synthesis rate ensures robust calcium cycling and avoids CD. We suggested a cardioprotective role of the mitochondrial calcium uniporter and predicted that a mitochondrial sodium calcium exchanger could be a potential therapeutic target to restore the normal functioning of the cardiomyocyte.

Divergent roles of IRAK4-mediated innate immune responses in two experimental models of severe malaria

Severe malaria represents a clinical spectrum of disease. We propose that innate immune inflammatory responses to malaria play key roles in the pathogenesis and clinical outcomes of distinct severe malaria syndromes. To investigate this hypothesis, mice deficient in IRAK4, central to Toll-like receptor (TLR)-mediated signaling, were studied in two experimental models of malaria: Plasmodium berghei (PbA) and Plasmodium chabaudi (PccAS). Irak4(-/-)mice had decreased pro-inflammatory cytokine production during infection in both models. However, animals were relatively protected from PbA-associated symptoms compared with wild-type mice, whereas Irak4(-/-) animals were more susceptible to PccAS-associated disease. These results show that IRAK4-mediated innate immune inflammatory responses play critical roles in divergent clinical outcomes in murine malaria models. As such, integrated approaches, using more than one model, are required to fully understand the parasite/host interactions that characterize severe malaria, and more importantly, to fully assess the effect of adjunctive therapies targeting innate immune responses to malaria.