LL-37 induced cystitis and the receptor for advanc... - LL-37 Study

LL-37 induced cystitis and the receptor for advanced glycation end-products (RAGE) pathway.

Roundy. Lindsi McCoard LM; Jia. Wanjian W; Zhang. Jianxing J; Ye. Xiangyang X; Prestwich. Glenn D GD; Oottamasathien. Siam S

Key Findings

LL-37 instillation induces bladder inflammation in mice

RAGE expression drops at both mRNA and protein levels after LL-37 exposure

HMGB1 shows a moderate increase in LL-37‑treated tissue

NF‑κB‑dependent inflammatory genes (IL‑6, IL‑1β, GM‑CSF, COX‑2) are substantially up‑regulated, while TNF‑α is not

Practical Outcomes

The work suggests that LL-37 can irritate bladder tissue and activate inflammatory pathways, so any self‑experimentation involving LL-37 in the urinary tract may carry risk. No dosage or safety guidance is provided, and more research is needed before considering practical use.

Summary

Scientists put the peptide LL-37 into mouse bladders and saw it cause inflammation. They checked several inflammation‑related proteins and genes and found that the RAGE receptor went down, the danger signal HMGB1 went up a bit, and most NF‑κB‑controlled inflammatory genes were strongly increased. This shows LL-37 can trigger bladder inflammation through these pathways.

Abstract

To elucidate pathways in bladder inflammation, we employed our physiologically relevant LL-37 induced cystitis model. Based on inflammatory studies involving other organ systems implicating the receptor for advanced glycation end-products (RAGE), we first hypothesized that RAGE is critically involved in LL-37 induced cystitis. We further hypothesized a common RAGE ligand - high mobility group box 1 (HMGB1) is up-regulated in bladders challenged with LL-37. Finally, we hypothesized NF-κB dependent inflammatory genes are activated in LL-37 induced cystitis. Testing our first hypothesis, C57Bl/6 mice were challenged with either saline (control) or 320 μM of LL-37 intravesically for 1 hr. After 12 or 24 hours, tissues were examined with immunohistochemistry (IHC) for RAGE, and both mRNA and protein isolation for respective qRT-PCR and Western Blot analysis. Our second hypothesis was tested by employing HMGB1 IHC. Testing our final hypothesis, qRT-PCR was performed investigating five genes: TNFα, IL-6, IL-1β, GM-CSF, COX-2. In control and LL-37 challenged tissues, IHC for RAGE revealed similar qualitative expression. Evaluation with qRT-PCR and Western Blot for RAGE revealed diminished expression at the mRNA and protein level within LL-37 challenged bladders. IHC for HMGB1 revealed a moderate qualitative increase within LL-37 challenged tissues. Finally, with the exception of TNF α, all NF- κB dependent inflammatory genes yielded substantial up-regulation. We have employed our LL-37 induced cystitis model to gain insight towards a possible mechanistic pathway involved in bladder inflammation. This work provides data for future studies involving the inflammatory ligand HMGB1, RAGE, and receptor pathways that activate NF-κB.

Study Information

Provider

pubmed

Year

2013

Date

2013-08-01T00:00:00.000Z

DOI

10.4236/abb.2013.48a2001