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CSF-1R blockade to alleviate azithromycin mediated immunosuppression in a mouse model of intracellular infection
Shivani Yadav1, Sharath Gowda1, Reena Agrawal-Rajput1
1Department of Biotechnology and Bioengineering, Immunology Lab, Indian Institute of Advanced Research, Gandhinagar 382421, Gujarat, India.
Abstract:
Colony Stimulating Factor-1 Receptor (CSF-1R) signalling plays an important role in maturation, differentiation and activation of macrophages. Apposite generation and activation of macrophage phenotypes and subsequent adaptive immune response against any infection is decisive for a positive disease outcome. Antibiotic therapy is imperative for treating bacterial infections however antibiotics have off-target effects on host immune-cells. These effects could either be contextually beneficial or harmful and could potentially aid generation of infection persistence and antimicrobial resistance (AMR) via host immunosuppression. We had recently reported the immunosuppressive-mechanism of azithromycin-induced increased CSF-1R expression on murine-macrophages and bacterial-persistence in Balb/c model of intracellular infection. We further wanted to explore the molecular-mechanism behind these observations and tested GW2580-mediated CSF-1R blockade before azithromycin treatment during S. flexneri induced intracellular infection. In the presented study, we report that the azithromycin alters the protein expression or phosphorylation of transcription-factors ERK1/2, P38, AKT1, STAT3, STAT6, and EGR2 that are involved in macrophage polarisatoin and also take part in CSF-1R signalling pathways. Intrestingly, CSF-1R blockade using GW2580 abrogated or reversed the azithromycin-induced up- or down-regulated expression or phosphorylation of ERK1/2, P38, AKT1, STAT3, STAT6, and EGR2. We further validated our results in Balb/c model of S. flexneri infection. Intrestingly, the CSF-1R blocker and azithromycin treated mice showed batter recovery than the azithromycin alone treated mice and hence we report the aftermath of GW2580 with azithromycin treatment on disease and immunological outcome of an intracellular infection caused by Shigella flexneri.
Insights
Blocking Colony Stimulating Factor-1 Receptor (CSF-1R) with GW2580 reversed azithromycin
Area of Science:
- Immunology
- Microbiology
- Pharmacology
Background:
- Colony Stimulating Factor-1 Receptor (CSF-1R) signaling is crucial for macrophage function and immune response.
- Antibiotics like azithromycin can have unintended effects on immune cells, potentially leading to infection persistence and antimicrobial resistance (AMR).
- Previous research indicated azithromycin increases CSF-1R expression on macrophages, contributing to immunosuppression and bacterial persistence.
Purpose of the Study:
- To investigate the molecular mechanisms behind azithromycin's effects on macrophage polarization and CSF-1R signaling.
- To determine if blocking CSF-1R with GW2580 can mitigate azithromycin's immunosuppressive effects during intracellular infection.
- To evaluate the combined therapeutic effect of GW2580 and azithromycin on disease outcome in a Shigella flexneri infection model.
Main Methods:
- Azithromycin treatment was assessed in conjunction with GW2580-mediated CSF-1R blockade in vitro.
- Protein expression and phosphorylation of key transcription factors (ERK1/2, P38, AKT1, STAT3, STAT6, EGR2) involved in macrophage polarization were analyzed.
- The in vivo efficacy was evaluated in a Balb/c mouse model of Shigella flexneri infection, comparing azithromycin alone versus combined treatment.
Main Results:
- Azithromycin altered the expression and phosphorylation of transcription factors critical for macrophage polarization and CSF-1R signaling.
- GW2580 blockade abrogated or reversed these azithromycin-induced changes in transcription factor activity.
- Mice treated with both GW2580 and azithromycin showed improved recovery compared to those treated with azithromycin alone.
Conclusions:
- Azithromycin impacts macrophage polarization pathways through modulation of CSF-1R signaling.
- Blocking CSF-1R with GW2580 counteracts the immunosuppressive effects of azithromycin on macrophages.
- Combined CSF-1R blockade and azithromycin treatment offer a potential therapeutic strategy for intracellular infections like Shigella flexneri, improving disease outcomes.
