TLR3 absence confers increased survival with improved macrophage activity against pneumonia
Madathilparambil V. Suresh, Vladislav A. Dolgachev, Boya Zhang, Sanjay Balijepalli, Samantha Swamy, Jashitha Mooliyil, Georgia Kralovich, Bivin Thomas, David Machado-Aranda, Monita Karmakar, Sanjeev Lalwani, Arulselvi Subramanian, Arun Anantharam, Bethany B. Moore, Krishnan Raghavendran
Madathilparambil V. Suresh, Vladislav A. Dolgachev, Boya Zhang, Sanjay Balijepalli, Samantha Swamy, Jashitha Mooliyil, Georgia Kralovich, Bivin Thomas, David Machado-Aranda, Monita Karmakar, Sanjeev Lalwani, Arulselvi Subramanian, Arun Anantharam, Bethany B. Moore, Krishnan Raghavendran
View: Text | PDF
Research Article Infectious disease

TLR3 absence confers increased survival with improved macrophage activity against pneumonia

Abstract

Toll-like receptor 3 (TLR3) is a pathogen recognition molecule associated with viral infection with double-stranded RNA (dsRNA) as its ligand. We evaluated the role of TLR3 in bacterial pneumonia using Klebsiella pneumoniae (KP). WT and TLR3–/– mice were subjected to a lethal model of KP. Alveolar macrophage polarization, bactericidal activity, and phagocytic capacity were compared. RNA-sequencing was performed on alveolar macrophages from the WT and TLR3–/– mice. Adoptive transfers of alveolar macrophages from TLR3–/– mice to WT mice with KP were evaluated for survival. Expression of TLR3 in postmortem human lung samples from patients who died from gram-negative pneumonia and pathological grading of pneumonitis was determined. Mortality was significantly lower in TLR3–/–, and survival improved in WT mice following antibody neutralization of TLR3 and with TLR3/dsRNA complex inhibitor. Alveolar macrophages from TLR3–/– mice demonstrated increased bactericidal and phagocytic capacity. RNA-sequencing showed an increased production of chemokines in TLR3–/– mice. Adoptive transfer of alveolar macrophages from the TLR3–/– mice restored the survival in WT mice. Human lung samples demonstrated a good correlation between the grade of pneumonitis and TLR3 expression. These data represent a paradigm shift in understanding the mechanistic role of TLR3 in bacterial pneumonia.

Authors

Madathilparambil V. Suresh, Vladislav A. Dolgachev, Boya Zhang, Sanjay Balijepalli, Samantha Swamy, Jashitha Mooliyil, Georgia Kralovich, Bivin Thomas, David Machado-Aranda, Monita Karmakar, Sanjeev Lalwani, Arulselvi Subramanian, Arun Anantharam, Bethany B. Moore, Krishnan Raghavendran

×

Figure 5

WT mice show increased inflammation following LPS administration.

Options: View larger image (or click on image) Download as PowerPoint
WT mice show increased inflammation following LPS administration. PV cur...
PV curves after established combined injury with LPS. PV curves at 24 hours (A) and PV curves at 48 hours (B). Using a SCIREQ FlexiVent quasistatic PV curves with maximal inflation to 30 cmH2O were generated from over 4000 data points (n = 6 per group, 2 independent experiments). The bottom half of each loop represents the inspiratory portion of a PV curve perturbation maneuver. Top half represents the expiratory portion of each graph (*P < 0.05 WT vs. TLR3–/– mice). (C) Mouse albumin was measured by ELISA at 24 and 48 hours following LPS administration. WT and TLR3–/– mice BAL cytokines IL-1β (D), MIP-2/CXCL-2 (E), and KC/CXCL-1 (F) were measured by ELISA following LPS (n = 6 per group, 2 independent experiments) (*P < 0.05, and **P < 0.01, WT vs. TLR3–/– mice). (G) WT and TLR3 mice were inoculated with LPS, and lungs were collected at 24- and 48-hour time points and stained with H&E. Shown are representative sections (n = 3 per group) from each condition (original magnification, ×200). Statistical analysis was performed at each time point. Samples were analyzed using 2-tailed unpaired t test with Welch’s correction (*P < 0.05 WT vs. TLR3–/– mice). The box plots depict the minimum and maximum values (whiskers), the upper and lower quartiles, and the median. The length of the box represents the interquartile range.