A necroptosis-independent function of RIPK3 promotes immune dysfunction and prevents control of chronic LCMV infection

Neuronal DAMPs exacerbate neurodegeneration via astrocytic RIPK3 signaling

Astrocyte activation is a common feature of neurodegenerative diseases. However, the ways in which dying neurons influence the activity of astrocytes is poorly understood. Receptor interacting protein kinase-3 (RIPK3) signaling has recently been described as a key regulator of neuroinflammation, but whether this kinase mediates astrocytic responsiveness to neuronal death has not yet been studied. Here, we used the 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine model of Parkinson's disease to show that activation of astrocytic RIPK3 drives dopaminergic cell death and axon damage. Transcriptomic profiling revealed that astrocytic RIPK3 promoted gene expression associated with neuroinflammation and movement disorders, and this coincided with significant engagement of damage-associated molecular pattern signaling. In mechanistic experiments, we showed that factors released from dying neurons signaled through receptor for advanced glycation endproducts to induce astrocytic RIPK3 signaling, which conferred inflammatory and neurotoxic functional activity. These findings highlight a mechanism of neuron-glia crosstalk in which neuronal death perpetuates further neurodegeneration by engaging inflammatory astrocyte activation via RIPK3.

Cell death proteins in sepsis: key players and modern therapeutic approaches

Cell death proteins play a central role in host immune signaling during sepsis. These interconnected mechanisms trigger cell demise via apoptosis, necroptosis, and pyroptosis while also driving inflammatory signaling. Targeting cell death mediators with novel therapies may correct the dysregulated inflammation seen during sepsis and improve outcomes for septic patients.

Neuronal DAMPs exacerbate neurodegeneration via astrocytic RIPK3 signaling

Astrocyte activation is a common feature of neurodegenerative diseases. However, the ways in which dying neurons influence the activity of astrocytes is poorly understood. RIPK3 signaling has recently been described as a key regulator of neuroinflammation, but whether this kinase mediates astrocytic responsiveness to neuronal death has not yet been studied. Here, we used the MPTP model of Parkinson's disease to show that activation of astrocytic RIPK3 drives dopaminergic cell death and axon damage. Transcriptomic profiling revealed that astrocytic RIPK3 promoted gene expression associated with neuroinflammation and movement disorders, and this coincided with significant engagement of DAMP signaling. Using human cell culture systems, we show that factors released from dying neurons signal through RAGE to induce RIPK3-dependent astrocyte activation. These findings highlight a mechanism of neuron-glia crosstalk in which neuronal death perpetuates further neurodegeneration by engaging inflammatory astrocyte activation via RIPK3.

Oxidative Stress Initiates Receptor-Interacting Protein Kinase-3/Mixed Lineage Kinase Domain-Like-Mediated Corneal Epithelial Necroptosis and Nucleotide-Binding Oligomerization Domain-Like Receptor Protein 3 Inflammasome Signaling during Fungal Keratitis

Fungal keratitis remains a major cause of severe visual loss in developing countries because of limited choices of therapy. The progression of fungal keratitis is a race between the innate immune system and the outgrowth of fungal conidia. Programmed necrosis (necroptosis), a type of proinflammatory cell death, has been recognized as a critical pathologic change in several diseases. However, the role and potential regulatory mechanisms of necroptosis have not been investigated in corneal diseases. The current study showed, for the first time, that fungal infection triggered significant corneal epithelial necroptosis in human/mouse/in vitro models. Moreover, a reduction in excessive reactive oxygen species release effectively prevented necroptosis. NLRP3 knockout did not affect necroptosis in vivo. In contrast, ablation of necroptosis via RIPK3 knockout significantly delayed migration and inhibited the nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome in macrophages, which enhanced the progression of fungal keratitis. Taking these findings together, the study indicated that overproduction of reactive oxygen species in fungal keratitis leads to significant necroptosis in the corneal epithelium. Furthermore, the necroptotic stimuli-mediated NLRP3 inflammasome serves as a driving force in host defense against fungal infection.