# Phosphoglucose isomerase directs the inflammatory response, calcium influx and fibroblast migration in keloids

## TL;DR

This study shows that phosphoglucose isomerase (PGI) controls inflammation, calcium levels, and fibroblast movement in keloids, suggesting PGI inhibition could be a treatment.

## Contribution

First study to show PGI regulates keloid fibroblast migration via calcium influx and inflammation.

## Key findings

- PGI expression is upregulated in keloid tissues and fibroblasts.
- Blocking PGI reduces fibroblast migration and inflammatory signaling.
- PGI regulates fibrotic activity and calcium influx in keloid fibroblasts.

## Abstract

Keloids are regarded as an inflammatory skin disease with altered metabolic demands. Calcium ions are known to regulate cell movement. Phosphoglucose isomerase (PGI) not only balances glucose metabolism but also acts as a multifunctional cytokine, as those calcium ions do. Here, for the first time, we aimed to explore the intracellular calcium level controlled by PGI in keloid fibroblasts (KFs) and normal fibroblasts (NFs). In addition, whether PGI regulates the biological functions of KFs via the inflammatory status was investigated.

The inflammatory status, fibrotic activity, and migration ability of KFs and NFs were evaluated via RT–PCR, western blot analysis, and scratch assay. We inhibited PGI with erythrose 4-phosphate (ER4P) to determine whether PGI regulates KF migration.

The upregulation of PGI expression was measured in both KFs and keloid tissues. Suppressing PGI inhibited SMA and type I collagen expression, and cell migration in KFs. Indeed, PGI regulated inflammation and calcium influx in KFs.

Our study is the first to show that PGI regulates the migration of KFs via a calcium influx-dependent inflammatory response and that blocking PGI might be a therapeutic strategy for keloids.

Keloids are a pathological scar with altered metabolic demands. With increasing capacity to synthesize collagen, keloid fibroblasts continuously have high metabolic demands. To overcome energetic consumption, keloid fibroblasts undergo metabolic reprogramming with reduced oxidative phosphorylation and augmented glycolysis.Keloids are also regarded as an inflammatory skin disease. Excessive and prolonged inflammatory responses tend to lead to the development of pathological scars. The inflammation intensity is positively associated with the scar size.Free calcium ions are important for cellular activities including cell proliferation, differentiation, movement and death.Phosphoglucose isomerase (PGI) not only balances glucose metabolism but also acts as a multifunctional cytokine to induce cell proliferation, differentiation, or metastasis.PGI expression was increased in hyperfibrotic regions in keloid tissues and keloid fibroblasts (KFs).PGI controls fibrotic activity in KFs by regulating the synthesis of α-SMA, collagen I and the release of TGF-β.PGI regulated inflammatory activity in KFs such as IL-33, NK-κB, TNF-α, IL-1 and IL-6.Blocking PGI decreased enhanced cytosolic Ca2+ signaling in KFs.Blocking PGI inhibits fibroblast migration in KFs.Our study is the first to show that PGI regulates the migration of KFs via a calcium influx-dependent inflammatory response. Blocking PGI might be a therapeutic strategy for keloids.

Keloids are a pathological scar with altered metabolic demands. With increasing capacity to synthesize collagen, keloid fibroblasts continuously have high metabolic demands. To overcome energetic consumption, keloid fibroblasts undergo metabolic reprogramming with reduced oxidative phosphorylation and augmented glycolysis.

Keloids are also regarded as an inflammatory skin disease. Excessive and prolonged inflammatory responses tend to lead to the development of pathological scars. The inflammation intensity is positively associated with the scar size.

Free calcium ions are important for cellular activities including cell proliferation, differentiation, movement and death.

Phosphoglucose isomerase (PGI) not only balances glucose metabolism but also acts as a multifunctional cytokine to induce cell proliferation, differentiation, or metastasis.

PGI expression was increased in hyperfibrotic regions in keloid tissues and keloid fibroblasts (KFs).

PGI controls fibrotic activity in KFs by regulating the synthesis of α-SMA, collagen I and the release of TGF-β.

PGI regulated inflammatory activity in KFs such as IL-33, NK-κB, TNF-α, IL-1 and IL-6.

Blocking PGI decreased enhanced cytosolic Ca2+ signaling in KFs.

Blocking PGI inhibits fibroblast migration in KFs.

Our study is the first to show that PGI regulates the migration of KFs via a calcium influx-dependent inflammatory response. Blocking PGI might be a therapeutic strategy for keloids.