CXCR2 Is Deregulated in ALS Spinal Cord and Its Activation Triggers Apoptosis in Motor Neuron-Like Cells Overexpressing hSOD1-G93A

Abstract

Amyotrophic lateral sclerosis (ALS) is a multifactorial neurodegenerative disease characterized by progressive depletion of motor neurons (MNs). Recent evidence suggests a role in ALS pathology for the C-X-C motif chemokine receptor 2 (CXCR2), whose expression was found increased at both mRNA and protein level in cortical neurons of sporadic ALS patients. Previous findings also showed that the receptor inhibition is able to prevent iPSC-derived MNs degeneration in vitro and improve neuromuscular function in SOD1-G93A mice. Here, by performing transcriptional analysis and immunofluorescence studies, we detailed the increased expression and localization of CXCR2 and its main ligand CXCL8 in the human lumbar spinal cord of sporadic ALS patients. We further investigated the functional role of CXCR2/ligands axis in NSC-34 motor neuron-like cells expressing human wild-type (WT) or mutant (G93A) SOD1. A significant expression of CXCR2 was found in doxycycline-induced G93A-SOD1-expressing cells, but not in WT cells. In vitro assays showed CXCR2 activation by GROα and MIP2α, two murine endogenous ligands and functional homologs of CXCL8, reduces cellular viability and triggers apoptosis in a dose dependent manner, while treatment with reparixin, a non-competitive allosteric CXCR2 inhibitor, effectively counteracts GROα and MIP2α toxicity, significantly inhibiting the chemokine-induced cell death. Altogether, data further support a role of CXCR2 axis in ALS etiopathogenesis and confirm its pharmacological modulation as a candidate therapeutic strategy.

The ε-Isozyme of Protein Kinase C (PKCε) Is Impaired in ALS Motor Cortex and Its Pulse Activation by Bryostatin-1 Produces Long Term Survival in Degenerating SOD1-G93A Motor Neuron-like Cells

“…Based on the observed PKCε downregulation in the ALS condition, we wondered about the downstream pharmacological effects of PKCε agonism in vitro and examined the biological outcomes of PKCε pulse activation by Bryostatin-1 in WT and G93A NSC-34 cells in two different paradigms of cell death models. Induction to apoptosis in both WT and G93A doxy-activated cells was prompted by: (i) serum starvation at either 24 or 48 h, or (ii) co-incubation with toxic chemokines (i.e., MIP2α and GROα) for 48 h. This second apoptosis model derives from previous observations conducted in our laboratories [ 40 ], which highlighted the vulnerability of G93A cells to MIP2α and GROα ligand treatment. Indeed, in the chemokines-induced cell death paradigm, the G93A NSC-34 cells displayed more sensitivity to apoptosis compared to the WT NSC-34, showing a peculiar significant reduction of cell viability in the presence of GROα and MIP2α ( Figure 6 b).…”

Endogenous TDP-43 mislocalization in a novel knock-in mouse model reveals DNA repair impairment, inflammation, and neuronal senescence

“…Furthermore, there is an important crosstalk between cellular senescence and neuroinflammation. C-X-C motif chemokine receptor 2 (CXCR2) was found to increase significantly triggering neuronal apoptosis in sporadic ALS [83]. On the other hand, senescent cells activate CXCR2-mediated selfamplifying secretory network which promotes growth arrest [84].…”

Emerging diagnostic markers and therapeutic targets in post-stroke hemorrhagic transformation and brain edema

“…CXCL2 (MIP-2α) can promote the disruption of the BBB by inducing endothelial cell activation and neutrophil recruitment, potentially leading to the extravasation of blood components and water, culminating in HT and vasogenic brain edema ( Chen et al, 2021 ). While CXCL2 primarily acts on immune cells, there is the potential for direct effects on brain cells like neurons, astrocytes, and microglia ( De Paola et al, 2007 ; La Cognata et al, 2023 ). Activated astrocytes and microglia can produce inflammatory mediators that can contribute to cytotoxic edema and neuroinflammation.…”