# TLR4 rs4986790 and TLR9 rs5743836 Polymorphisms and Their Association With Clinical Outcomes of Leishmania infantum Infection in Tunisia

## TL;DR

This study examines how genetic variations in TLR4 and TLR9 genes relate to the severity of Leishmania infantum infection in Tunisia, finding no significant associations.

## Contribution

The study investigates the role of TLR4 rs4986790 and TLR9 rs5743836 polymorphisms in determining clinical outcomes of Leishmania infantum infection in a Tunisian population.

## Key findings

- No significant association was found between TLR4 rs4986790 polymorphism and Leishmania infantum infection outcomes.
- TLR9 rs5743836 polymorphism also showed no significant association with clinical forms of the infection.
- The study suggests other factors, like parasite tropism, may influence disease variability.

## Abstract

Background: The clinical presentation of Leishmania infantum infection ranges from self-resolving cutaneous leishmaniasis (CL) to visceral leishmaniasis (VL). Host genetic factors, particularly polymorphisms in Toll-like receptor (TLR) genes, are suspected to influence disease variability and outcome. This study aimed to investigate the potential association between two specific single-nucleotide polymorphisms (SNPs) in the TLR4 (rs4986790) and TLR9 (rs5743836) genes and susceptibility to different clinical forms of L. infantum leishmaniasis.

Methods: This case-control study genotyped TLR4 rs4986790 and TLR9 rs5743836 in a Tunisian population with 70 patients (50 VL, 20 CL), and 70 controls. PCR-RFLP and BI-PASA methods were used in theTLR9 and TLR4 analysis, respectively. To investigate, we used logistic regression (additive/codominant models).

Results: For TLR4 rs4986790, genotype frequencies were A/A 94.3% and A/G 5.7% in cases vs. A/A 95.7% and A/G 4.3% in controls (no G/G); no significant associations were found (codominant A/G vs. A/A: OR=1.35, 95% CI 0.29-7.09, p=0.698). For TLR9 rs5743836, T/T 30.0% and T/C 70.0% in cases vs. T/T 37.1% and T/C 62.9% in controls (no C/C); no associations were observed (codominant T/C vs. T/T: OR=1.38, 95% CI 0.68-2.81, p=0.371).

Conclusion: These TLR4 and TLR9 polymorphisms are not associated with L. infantum infection outcomes in this Tunisian cohort, suggesting other factors like parasite tropism, drive clinical variability.