Innate immune response in patients with acute Chikungunya disease

Chikungunya disease (CHIKD) is an arbovirose that presents with high morbidity, mainly due to arthralgia. Inflammatory mediators including IL-6, IL-1 beta, GM-CSF and others have been implicated in the pathogenesis of CHIKD, whilst type I interferons can be associated with better outcomes. The role of pattern recognition receptors has been studied incompletely. Here, we evaluated the expression of RNA-specific PRRs, their adaptor molecules and downstream cytokines in acute CHIKD patients. Twenty-eight patients were recruited during the 3rd-5th day after the symptoms onset for clinical examination, peripheral blood collection and qRT-PCR analysis of PBMC to compare to the healthy control group (n = 20). We observed common symptoms of acute CHIKD, with fever, arthralgia, headache and myalgia being the most frequent. Compared with uninfected controls, acute CHIKV infection upregulates the expression of the receptors TLR3, RIG-I and MDA5, and also the adaptor molecule TRIF. Regarding cytokine expression, we found an upregulation of IL-6, IL-12, IFN-alpha, IFN-beta and IFN-gamma, which are related directly to the inflammatory or antiviral response. The TLR3-TRIF axis correlated with high expression of IL-6 and IFN-alpha. Interestingly, greater expression of MDA5, IL-12 and IFN-alpha was related to lower viral loads in CHIKD acute patients. Together, these findings help to complete the picture of innate immune activation during acute CHIKD, while confirming the induction of strong antiviral responses. Drawing the next steps in the understanding of the immunopathology and virus clearance mechanisms of CHIKD should be of utter importance in the aid of the development of effective treatment to reduce the severity of this debilitating disease.

Automated summary

Chikungunya disease (CHIKD) is a viral disease characterized by arthralgia and high morbidity. Inflammatory mediators and type I interferons play important roles in its pathogenesis. This study found that the expression of RNA-specific pattern recognition receptors (PRRs) and their adaptor molecules is upregulated in acute CHIKD patients. Additionally, cytokine expression related to inflammatory and antiviral responses, such as IL-6, IL-12, IFN-alpha, IFN-beta, and IFN-gamma, was significantly increased. Understanding the immune response and virus clearance mechanisms in CHIKD is crucial for developing effective treatments to reduce disease severity.