Cerebral malaria pathogenesis: Dissecting the role of CD4+ and CD8+ T-cells as major effectors in disease pathology.

Cerebral malaria (CM) is a severe complication of Plasmodium falciparum (P. falciparum) infection, with complex pathogenesis involving multiple factors, including the host's immunological response. T lymphocytes, specifically CD4+ T helper cells and CD8+ cytotoxic T cells, are crucial in controlling parasite growth and activating cells for parasite clearance via cytokine secretion. Contrary to this, reports also suggest the pathogenic nature of T lymphocytes as they are often involved in disease progression and severity. CD8+ cytotoxic T cells migrate to the host's brain vasculature, disrupting the blood-brain barrier and causing neurological manifestations. CD4+ T helper cells on the other hand play a variety of functions as they differentiate into different subtypes which may function as pro-inflammatory or anti-inflammatory. The excessive pro-inflammatory response in CM can lead to multi-organ failure, necessitating a check mechanism to maintain immune homeostasis. This is achieved by regulatory T cells and their characteristic cytokines, which counterbalance the pro-inflammatory immune response. Maintaining a critical balance between pro and anti-inflammatory responses is crucial for determining disease outcomes in CM. A slight change in this balance may contribute to a disease severity owing to an extreme inflammatory response or unrestricted parasite growth, a potential target for designing immunotherapeutic treatment approaches. The review briefly discusses the pathogenesis of CM and various mechanisms responsible for the disruption of the blood-brain barrier. It also highlights the role of different T cell subsets during infection and emphasizes the importance of balance between pro and anti-inflammatory T cells that ultimately decides the outcome of the disease.

CM is potentially fatal complication of P. falciparum infection that presents with high mortality and morbidity. Vaccines are extensively being developed against the Plasmodium parasite but very few of them are effective. Artemisinin Combination Therapy (ACT) is a major treatment for malaria, but its effectiveness is declining due to Plasmodium sp. developing resistance to it, necessitating the need for development of new drugs and treatments. During infection, the parasite is responsible for causing infected red blood cell (RBC) sequestration and cytoadherence in brain vasculature and extreme pro-inflammatory response that ultimately causes endothelial dysfunction and bloodbrain barrier (BBB) disruption. The host initiates a pro-inflammatory response against the parasite which includes activation of cells of both innate and adaptive immune response. These cells control the parasite growth and aid in parasite clearance from host's body. The inflammatory response generally targets foreign pathogens and provides protection against possible infection but can also cause harm to the self when left unchecked. It has been reported that activated immune cells, mainly T-lymphocytes often migrate to brain vasculature and ultimately results in neuronal damage characteristic CM. To counteract the overwhelming pro-inflammatory response, the host immune system deploys an anti-inflammatory response, which often involves regulatory cells and cytokines that help the body maintain immunological homeostasis. The review briefly highlights the necessity of balancing the pro- and anti-inflammatory responses for successful parasite clearance without the deleterious effects to the host that might increase disease severity in CM.

Pathophysiology of Cerebral Malaria: Implications of MSCs as A Regenerative Medicinal Tool.

The severe form of malaria, i.e., cerebral malaria caused by Plasmodium falciparum, is a complex neurological syndrome. Surviving persons have a risk of behavioral difficulties, cognitive disorders, and epilepsy. Cerebral malaria is associated with multiple organ dysfunctions. The adhesion and accumulation of infected RBCs, platelets, and leucocytes (macrophages, CD4+ and CD8+ T cells, and monocytes) in the brain microvessels play an essential role in disease progression. Micro-vascular hindrance by coagulation and endothelial dysfunction contributes to neurological damage and the severity of the disease. Recent studies in human cerebral malaria and the murine model of cerebral malaria indicate that different pathogens as well as host-derived factors are involved in brain microvessel adhesion and coagulation that induces changes in vascular permeability and impairment of the blood-brain barrier. Efforts to alleviate blood-brain barrier dysfunction and de-sequestering of RBCs could serve as adjunct therapies. In this review, we briefly summarize the current understanding of the pathogenesis of cerebral malaria, the role of some factors (NK cells, platelet, ANG-2/ANG-1 ratio, and PfEMP1) in disease progression and various functions of Mesenchymal stem cells. This review also highlighted the implications of MSCs as a regenerative medicine.

MiRNA: Biological Regulator in Host-Parasite Interaction during Malaria Infection.

Malaria is a severe life-threatening disease caused by the bites of parasite-infected female Anopheles mosquitoes. It remains a significant problem for the most vulnerable children and women. Recent research has helped establish the relationship between microRNAs (miRNAs) and many other diseases. MiRNAs are the class of small non-coding RNAs consisting of 18-23 nucleotides in length that are evolutionarily conserved and regulate gene expression at a post-transcriptional level and play a significant role in various molecular mechanisms such as cell survival, cell proliferation, and differentiation. MiRNAs can help detect malaria infection as the malaria parasite could alter the miRNA expression of the host. These alterations can be diagnosed by the molecular diagnostic tool that can indicate disease. We summarize the current understanding of miRNA during malaria infection. miRNAs can also be used as biomarkers, and initial research has unearthed their potential in diagnosing and managing various diseases such as malaria.