RESUMEN
In chronic obstructive pulmonary disease (COPD), lung natural killer cells (NKs) lyse autologous lung epithelial cells in vitro, but underlying mechanisms and their relationship to epithelial cell apoptosis in vivo are undefined. Although this cytolytic capacity of lung NKs depends on priming by dendritic cells (DCs), whether priming correlates with DC maturation or is limited to a specific DC subset is also unknown. We recruited ever-smokers (≥10 pack-years; n = 96) undergoing clinically indicated lung resections. We analyzed lung NKs for cytotoxic molecule transcripts and for cytotoxicity, which we correlated with in situ detection of activated Caspase-3/7+ airway epithelial cells. To investigate DC priming, we measured lung DC expression of CCR2, CCR7, and CX3CR1 and cocultured peripheral blood NKs with autologous lung DCs, either matured using lipopolysaccharide (LPS) (nonobstructed smokers) or separated into conventional dendritic cell type-1 (cDC1) versus cDC type-2 (cDC2) (COPD). Lung NKs in COPD expressed more perforin (P < 0.02) and granzyme B (P < 0.03) transcripts; inhibiting perforin blocked in vitro killing by lung NKs. Cytotoxicity in vitro correlated significantly (Sr = 0.68, P = 0.0043) with numbers of apoptotic epithelial cells per airway. In nonobstructed smokers, LPS-induced maturation enhanced DC-mediated priming of blood NKs, reflected by greater epithelial cell death. Although CCR7 expression was greater in COPD in both cDC1 (P < 0.03) and cDC2 (P = 0.009), only lung cDC1 primed NK killing. Thus, rather than being intrinsic to those with COPD, NK priming is a capacity of human lung DCs that is inducible by recognition of bacterial (and possibly other) danger signals and restricted to the cDC1 subset.
Asunto(s)
Células Dendríticas/inmunología , Células Epiteliales/patología , Regulación de la Expresión Génica/efectos de los fármacos , Células Asesinas Naturales/inmunología , Pulmón/patología , Perforina/efectos adversos , Enfermedad Pulmonar Obstructiva Crónica/patología , Estudios de Casos y Controles , Citotoxinas/efectos adversos , Células Dendríticas/efectos de los fármacos , Células Dendríticas/metabolismo , Células Dendríticas/patología , Células Epiteliales/efectos de los fármacos , Células Epiteliales/inmunología , Células Epiteliales/metabolismo , Femenino , Granzimas/genética , Granzimas/metabolismo , Humanos , Células Asesinas Naturales/metabolismo , Células Asesinas Naturales/patología , Pulmón/efectos de los fármacos , Pulmón/inmunología , Pulmón/metabolismo , Masculino , Persona de Mediana Edad , Enfermedad Pulmonar Obstructiva Crónica/inducido químicamente , Enfermedad Pulmonar Obstructiva Crónica/inmunología , Enfermedad Pulmonar Obstructiva Crónica/metabolismo , Fumar/efectos adversosRESUMEN
Severe malaria caused by Plasmodium falciparum poses a major global health problem with high morbidity and mortality. P. falciparum harbors a family of pore-forming proteins (PFPs), known as perforin like proteins (PLPs), which are structurally equivalent to prokaryotic PFPs. These PLPs are secreted from the parasites and, they contribute to disease pathogenesis by interacting with host cells. The severe malaria pathogenesis is associated with the dysfunction of various barrier cells, including endothelial cells (EC). Several factors, including PLPs secreted by parasites, contribute to the host cell dysfunction. Herein, we have tested the hypothesis that PLPs mediate dysfunction of barrier cells and might have a role in disease pathogenesis. We analyzed various dysfunctions in barrier cells following rPLP2 exposure and demonstrate that it causes an increase in intracellular Ca2+ levels. Additionally, rPLP2 exposed barrier cells displayed features of cell death, including Annexin/PI positivity, depolarized the mitochondrial membrane potential, and ROS generation. We have further performed the time-lapse video microscopy of barrier cells and found that the treatment of rPLP2 triggers their membrane blebbing. The cytoplasmic localization of HMGB1, a marker of necrosis, further confirmed the necrotic type of cell death. This study highlights the role of parasite factor PLP in endothelial dysfunction and provides a rationale for the design of adjunct therapies against severe malaria.