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Membrane damage and repair in primary monocytes exposed to human ?-defensin-3.

ABSTRACT: Interactions of AMPs with plasma membranes of primary human immune cells are poorly characterized. Analysis of PI exclusion as a measure of membrane integrity indicated that hBD-3 caused membrane perturbations in monocytes but not T or B cells at concentrations typically used to kill bacteria or to induce activation of APCs. Bleb-like structures were observed in monocytes exposed to hBD-3. These cells also increased surface expression of LAMP1, a membrane repair marker after exposure to hBD-3. Furthermore, cell death was enhanced by adding an inhibitor of membrane repair. Removal of cholesterol from membranes resulted in greater susceptibility of cells to hBD-3, but cholesterol content was not different between the cell types, as assessed by filipin staining. Freshly isolated monocytes expressed higher levels of the negatively charged phospholipid, PS, on their outer leaflet compared with B or T cells. Preincubation of monocytes with molecules that bind PS protected these cells from hBD-3-induced membrane damage, suggesting that outer-membrane PS expression can at least partially explain monocyte susceptibility to hBD-3. The potential for membrane disruption caused by AMPs should be evaluated in various cell types when considering these molecules for therapeutic applications in humans.

SUBMITTER: Lioi AB

PROVIDER: S-EPMC4050522 | biostudies-literature | 2012 Nov

REPOSITORIES: biostudies-literature

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Membrane damage and repair in primary monocytes exposed to human β-defensin-3.

Lioi Anthony B AB Rodriguez Angel L Reyes AL Funderburg Nicholas T NT Feng Zhimin Z Weinberg Aaron A Sieg Scott F SF

Journal of leukocyte biology 20120726 5

Interactions of AMPs with plasma membranes of primary human immune cells are poorly characterized. Analysis of PI exclusion as a measure of membrane integrity indicated that hBD-3 caused membrane perturbations in monocytes but not T or B cells at concentrations typically used to kill bacteria or to induce activation of APCs. Bleb-like structures were observed in monocytes exposed to hBD-3. These cells also increased surface expression of LAMP1, a membrane repair marker after exposure to hBD-3. F ...[more]

PMID: 22837529

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Project description:BackgroundThe coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a worldwide pandemic with over 627 million cases and over 6.5 million deaths. It was reported that smoking-related chronic obstructive pulmonary disease (COPD) might be a crucial risk for COVID-19 patients to develop severe condition. As cigarette smoke (CS) is the major risk factor for COPD, we hypothesize that barrier dysfunction and an altered cytokine response in CS-exposed airway epithelial cells may contribute to increased SARS-CoV-2-induced immune response that may result in increased susceptibility to severe disease. The aim of this study was to evaluate the role of CS on SARS-CoV-2-induced immune and inflammatory responses, and epithelial barrier integrity leading to airway epithelial damage.MethodsPrimary human airway epithelial cells were differentiated under air-liquid interface culture. Cells were then exposed to cigarette smoke medium (CSM) before infection with SARS-CoV-2 isolated from a local patient. The infection susceptibility, morphology, and the expression of genes related to host immune response, airway inflammation and damages were evaluated.ResultsCells pre-treated with CSM significantly caused higher replication of SARS-CoV-2 and more severe SARS-CoV-2-induced cellular morphological alteration. CSM exposure caused significant upregulation of long form angiotensin converting enzyme (ACE)2, a functional receptor for SARS-CoV-2 viral entry, transmembrane serine protease (TMPRSS)2 and TMPRSS4, which cleave the spike protein of SARS-CoV-2 to allow viral entry, leading to an aggravated immune response via inhibition of type I interferon pathway. In addition, CSM worsened SARS-CoV-2-induced airway epithelial cell damage, resulting in severe motile ciliary disorder, junctional disruption and mucus hypersecretion.ConclusionSmoking led to dysregulation of host immune response and cell damage as seen in SARS-CoV-2-infected primary human airway epithelia. These findings may contribute to increased disease susceptibility with severe condition and provide a better understanding of the pathogenesis of SARS-CoV-2 infection in smokers.

Project description:Several intracellular pathogens, such as Mycobacterium tuberculosis, damage endomembranes to access the cytosol and subvert innate immune responses. The host counteracts endomembrane damage by recruiting repair machineries that retain the pathogen inside the vacuole. Here, we show that the endoplasmic reticulum (ER)-Golgi protein oxysterol-binding protein (OSBP) and its Dictyostelium discoideum homolog OSBP8 are recruited to the Mycobacterium-containing vacuole (MCV) dependent on the presence of the ESX-1 secretion system, suggesting that their mobilization is associated with membrane damage. Lack of OSBP8 causes a hyperaccumulation of phosphatidylinositol-4-phosphate (PI4P) on the MCV and decreased cell viability. OSBP8-depleted cells had reduced lysosomal and degradative capabilities of their vacuoles that favored mycobacterial growth. In agreement with a potential role of OSBP8 in membrane repair, human macrophages infected with M. tuberculosis recruited OSBP in an ESX-1-dependent manner. These findings identified an ER-dependent repair mechanism for restoring MCVs in which OSBP8 functions to equilibrate PI4P levels on damaged membranes. IMPORTANCE Tuberculosis still remains a global burden and is one of the top infectious diseases from a single pathogen. Mycobacterium tuberculosis, the causative agent, has perfected many ways to replicate and persist within its host. While mycobacteria induce vacuole damage to evade the toxic environment and eventually escape into the cytosol, the host recruits repair machineries to restore the MCV membrane. However, how lipids are delivered for membrane repair is poorly understood. Using advanced fluorescence imaging and volumetric correlative approaches, we demonstrate that this involves the recruitment of the endoplasmic reticulum (ER)-Golgi lipid transfer protein OSBP8 in the Dictyostelium discoideum/Mycobacterium marinum system. Strikingly, depletion of OSBP8 affects lysosomal function accelerating mycobacterial growth. This indicates that an ER-dependent repair pathway constitutes a host defense mechanism against intracellular pathogens such as M. tuberculosis.

Dataset Information

Membrane damage and repair in primary monocytes exposed to human ?-defensin-3.

Publications

Membrane damage and repair in primary monocytes exposed to human β-defensin-3.

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