Cell stress and death liberate the autophagy-inhibitory tissue stress hormone DBI/ACBP into the circulation.
Source: PubMed, NCBI / U.S. National Library of Medicine
Autophagy constitutes a major adaptive response that preserves cellular and organismal homeostasis during stress. However, stress responses also engage systemic communication pathways that may either maintain resilience or propagate pathology. We previously identified acyl-CoA-binding protein, also known as diazepam-binding inhibitor (DBI/ACBP), as a phylogenetically conserved extracellular factor secreted by stressed cells through an unconventional autophagy-dependent pathway. Once released, extracellular DBI/ACBP acts as a feedback inhibitor of autophagy and promotes metabolic and inflammatory alterations. In our most recent work, we identify regulated cell death as an additional major mechanism responsible for extracellular DBI/ACBP accumulation. Plasma DBI/ACBP concentrations correlate with markers of inflammation, senescence and multiorgan dysfunction in hospitalized patients. Experimentally induced injury to liver, kidney, pancreas or skeletal muscle indistinguishably causes rapid increases in circulating DBI/ACBP. Mechanistically, apoptosis, ferroptosis and necroptosis all provoke loss of intracellular DBI/ACBP together with its extracellular release following plasma membrane permeabilization. Pharmacological inhibition of these death pathways suppresses DBI/ACBP liberation. Across large human cohorts, elevated plasma DBI/ACBP is associated with aging, systemic inflammation, multiorgan dysfunction and future morbidity. We propose that DBI/ACBP is not merely a biomarker
Abstract
Autophagy constitutes a major adaptive response that preserves cellular and organismal homeostasis during stress. However, stress responses also engage systemic communication pathways that may either maintain resilience or propagate pathology. We previously identified acyl-CoA-binding protein, also known as diazepam-binding inhibitor (DBI/ACBP), as a phylogenetically conserved extracellular factor secreted by stressed cells through an unconventional autophagy-dependent pathway. Once released, extracellular DBI/ACBP acts as a feedback inhibitor of autophagy and promotes metabolic and inflammatory alterations. In our most recent work, we identify regulated cell death as an additional major mechanism responsible for extracellular DBI/ACBP accumulation. Plasma DBI/ACBP concentrations correlate with markers of inflammation, senescence and multiorgan dysfunction in hospitalized patients. Experimentally induced injury to liver, kidney, pancreas or skeletal muscle indistinguishably causes rapid increases in circulating DBI/ACBP. Mechanistically, apoptosis, ferroptosis and necroptosis all provoke loss of intracellular DBI/ACBP together with its extracellular release following plasma membrane permeabilization. Pharmacological inhibition of these death pathways suppresses DBI/ACBP liberation. Across large human cohorts, elevated plasma DBI/ACBP is associated with aging, systemic inflammation, multiorgan dysfunction and future morbidity. We propose that DBI/ACBP is not merely a biomarker of tissue damage but rather a systemic autophagy-inhibitory stress signal contributing to maladaptive interorgan communication during aging and disease.