Targeting CIRP and IL-6R-mediated microglial inflammation to improve outcomes in intracerebral hemorrhage

Abstract

Introduction

Cold-inducible RNA-binding protein (CIRP) is an emerging inflammatory mediator implicated in neuronal injury following intracerebral hemorrhage (ICH). However, the underlying mechanisms by which CIRP contributes to neuroinflammation remain unclear.

Objectives

To investigate the role of neuron-derived CIRP in activating microglial inflammation via IL-6 receptor (IL-6R) signaling after ICH and to evaluate the therapeutic potential of targeting CIRP and IL-6R using a designed peptide inhibitor.

Methods

Single-cell RNA sequencing was performed to identify key genes and pathways involved in microglial responses post-ICH. A peptide inhibitor, Tat-CIRP-CMA (TCC), was designed to target CIRP and IL-6R and tested in both in vitro (oxygen-glucose deprivation model) and in vivo (rat ICH model) systems. The effects of TCC on neuronal CIRP release, microglial activation, inflammation, and phagocytic function were assessed. A microglia-specific IL-6Rα knockout mouse model was used to further validate the functional relevance of the IL-6R/ signal transducer and activator of transcription 3 (STAT3) pathway. Clinical analysis of human ICH patients evaluated the correlation between peripheral CIRP expression and infarct volume.

Results

Neuron-derived CIRP activates microglia through IL-6R and downstream STAT3 signaling, driving pro-inflammatory responses in ICH. TCC treatment significantly reduced neuronal CIRP release, suppressed microglial activation, and decreased inflammatory cytokine levels. TCC inhibited the IL-6R /STAT3 pathway and enhanced microglial phagocytosis of red blood cells. Microglia-specific IL-6Rα deletion mirrored the anti-inflammatory and neuroprotective effects observed with TCC, reducing hematoma volume and improving sensory and behavioral outcomes. In human ICH patients, elevated peripheral CIRP expression positively correlated with infarct volume, supporting its value as a biomarker for ICH severity and prognosis.

Conclusion

CIRP plays a pivotal role in post-ICH neuroinflammation by acting on IL-6R in microglia. The TCC peptide inhibitor effectively reduces CIRP-IL-6R mediated inflammation and supports neuroprotection. CIRP represents a promising therapeutic target and biomarker for ICH.