Dynamics of clusterin protein expression in the brain and plasma following experimental traumatic brain injury

Shalini Das Gupta,Anssi Lipponen,Asla Pitkänen,Noora Puhakka,Kaisa M A Paldanius

doi:10.1038/s41598-019-56683-6

Shalini Das Gupta, Anssi Lipponen + Show 3 more

Open Access

https://doi.org/10.1038/s41598-019-56683-6

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Journal: Scientific Reports	Publication Date: Dec 1, 2019
Citations: 11	License type: open-access

Affiliation: University of Eastern Finland

Abstract

Progress in the preclinical and clinical development of neuroprotective and antiepileptogenic treatments for traumatic brain injury (TBI) necessitates the discovery of prognostic biomarkers for post-injury outcome. Our previous mRNA-seq data revealed a 1.8–2.5 fold increase in clusterin mRNA expression in lesioned brain areas in rats with lateral fluid-percussion injury (FPI)-induced TBI. On this basis, we hypothesized that TBI leads to increases in the brain levels of clusterin protein, and consequently, increased plasma clusterin levels. For evaluation, we induced TBI in adult male Sprague-Dawley rats (n = 80) by lateral FPI. We validated our mRNA-seq findings with RT-qPCR, confirming increased clusterin mRNA levels in the perilesional cortex (FC 3.3, p < 0.01) and ipsilateral thalamus (FC 2.4, p < 0.05) at 3 months post-TBI. Immunohistochemistry revealed a marked increase in extracellular clusterin protein expression in the perilesional cortex and ipsilateral hippocampus (7d to 1 month post-TBI), and ipsilateral thalamus (14d to 12 months post-TBI). In the thalamus, punctate immunoreactivity was most intense around activated microglia and mitochondria. Enzyme-linked immunoassays indicated that an acute 15% reduction, rather than an increase in plasma clusterin levels differentiated animals with TBI from sham-operated controls (AUC 0.851, p < 0.05). Our findings suggest that plasma clusterin is a candidate biomarker for acute TBI diagnosis.

Highlights

Progress in the preclinical and clinical development of neuroprotective and antiepileptogenic treatments for traumatic brain injury (TBI) necessitates the discovery of prognostic biomarkers for post-injury outcome
At 2 d post-TBI, no clusterin-ir was detected in the perilesional cortex, hippocampus, or thalamus
From 1 wk to 12 months post-TBI, prolonged spatio-temporally regulated clusterin-ir was observed in the ipsilateral cortex, dentate gyrus, and thalamus (Fig. 1A)

Summary

Introduction

Progress in the preclinical and clinical development of neuroprotective and antiepileptogenic treatments for traumatic brain injury (TBI) necessitates the discovery of prognostic biomarkers for post-injury outcome. Our previous mRNA-seq data revealed a 1.8–2.5 fold increase in clusterin mRNA expression in lesioned brain areas in rats with lateral fluid-percussion injury (FPI)-induced TBI. Our previous mRNA-seq studies revealed increased clusterin mRNA levels in the perilesional cortex and thalamus at 3 months after lateral fluid-percussion injury (FPI)-induced TBI in rats[36]. We observed elevated clusterin mRNA levels in the perilesional cortex and thalamus of both wild-type C57BL/6J and the APP/PS1 mouse model of AD after severe controlled cortical impact (CCI)-induced brain injury[37] Based on these initial findings, we hypothesised that an increase in clusterin protein levels could indicate injury in the lateral FPI model of TBI, and that the increased brain levels of clusterin would lead to elevated plasma clusterin levels, making it a potential non-invasive prognostic biomarker for TBI-induced brain injury. We investigated whether the levels of secreted plasma clusterin distinguish TBI rats from naïve or sham-operated controls

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