Natural Anti-Inflammatory Compounds Modulate FOXP3, C5aR1, and LIF for Sinusitis Treatment
Background
Chronic rhinosinusitis (CRS), affecting 12% of the Western population, represents a significant healthcare burden. Current therapies primarily target downstream inflammatory mediators, failing to address the underlying immune-regulatory abnormalities that drive disease recurrence. A critical immune-regulatory axis involving forkhead box P3 (FOXP3) + regulatory T cells (Tregs), complement component 5a receptor 1 (C5aR1), and leukemia inhibitory factor (LIF) is crucial for maintaining immune tolerance in sinonasal tissues. Modulating this axis presents a promising, yet largely overlooked, therapeutic strategy.
Study Design
Researchers conducted a comprehensive literature review across PubMed, Scopus, and Web of Science databases, covering the period from 2000-2026. The search aimed to identify research articles on the molecular mechanisms, preclinical evidence, and clinical application of natural compounds in inflammatory disorders, specifically focusing on the sinonasal inflammatory pathway. The review synthesized findings related to the modulation of the FOXP3, C5aR1, and LIF axis by various natural anti-inflammatory products.
Results
The review revealed that FOXP3+ Tregs are significantly depleted in CRS patients with nasal polyps, indicating a breakdown in immune tolerance. Furthermore, complement signaling via C5aR1 actively prevents the induction of Tregs by activating the PI3K-AKT-mTOR pathway, thereby exacerbating inflammation. Conversely, LIF enhances the expression of FOXP3 and effectively counteracts Th17 polarization, which is often driven by IL-6 and contributes to chronic inflammation. Natural products such as epigallocatechin-3-gallate, curcumin, and rosmarinic acid demonstrate the ability to regulate these pathways by inhibiting DNA methyltransferases, the complement cascade, and JAK-STAT signaling, respectively. > Bromelain and cineole have shown clinical evidence of efficacy in acute sinusitis, with other natural compounds exhibiting emerging evidence for their therapeutic potential in CRS.
Key Findings
- FOXP3+ regulatory T cells are highly depleted in chronic rhinosinusitis (CRS) with nasal polyps.
- C5aR1 signaling inhibits Treg induction by activating the PI3K-AKT-mTOR pathway, promoting inflammation.
- LIF enhances FOXP3 expression and opposes pro-inflammatory Th17 polarization.
- Natural compounds like epigallocatechin-3-gallate, curcumin, and rosmarinic acid modulate key inflammatory pathways.
- Bromelain and cineole show clinical efficacy in acute sinusitis, suggesting broader potential in CRS.
Why It Matters
This review highlights that natural compounds offer a multi-target, upstream immune-modulating strategy for CRS, addressing the underlying immune-regulatory abnormalities rather than just symptoms. By targeting the FOXP3-C5aR1-LIF axis, these compounds could provide novel therapeutic avenues that current biologics often overlook. This approach suggests a shift towards treatments with potentially favorable safety profiles and the ability to restore immune balance. While promising, further well-designed trials are needed to study phenotype-based CRS populations and optimize bioavailability for clinical translation.
chronic rhinosinusitis
inflammation
immune regulation
natural compounds
foxp3
c5ar1