title: The oxidation of HSP70 is associated with functional impairment and lack of stimulatory capacity.
abstract: Expression of intracellular HSP70 is associated with cytoprotective effects against a wide range of stressful stimuli, such as inflammation, oxidative stress, hypoxia, endotoxins, infections, and fever. This cytoprotective effect is mainly attributed to their ability to stabilize protein structures through chaperone-like reversible interactions. HSP70 was recently detected in the extracellular medium, and its presence in serum is commonly associated with pathological situations, where it exerts modulatory effects on cells of the immune system. Previously, we have described the relationship between serum HSP70 levels, oxidant status, and clinical outcome of septic patients; the group of patients with higher prooxidant status and higher serum HSP70 had also higher mortality. To investigate the possible association between oxidized HSP70 and cytoprotection or cell death, we incubated RAW 264.7 macrophages with oxidized HSP70 and evaluated nitrite production, cell proliferation, cell viability, TNF-α release, and phagocytic activity. We also evaluated structural modifications caused by oxidation in purified HSP70. Oxidation of HSP70 altered its protein structure; besides, the modulatory effect of oxidized HSP70 on RAW264.7 cells was different from that of native HSP70. Macrophages treated with oxidized HSP70 presented lower proliferation and viability, lower phagocytic activity, and lower TNF-α release. These results indicate that oxidation of extracellular HSP70 modified its signaling properties, causing alterations on its modulatory effects on macrophage function and viability.
authors.affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600, Porto Alegre, Rio Grande do Sul, CEP 90035-003, Brazil, marcelo.sartori@yahoo.com.br.
authors.forename: Marcelo Sartori
authors.initials: MS
authors.lastname: Grunwald
authors.forename: André Simões
authors.initials: AS
authors.lastname: Pires
authors.forename: Alfeu
authors.initials: A
authors.lastname: Zanotto-Filho
authors.forename: Juciano
authors.initials: J
authors.lastname: Gasparotto
authors.forename: Daniel Pens
authors.initials: DP
authors.lastname: Gelain
authors.forename: Diogo Ribeiro
authors.initials: DR
authors.lastname: Demartini
authors.forename: Cinthia Maria
authors.initials: CM
authors.lastname: Schöler
authors.forename: Paulo Ivo Homem
authors.initials: PI
authors.lastname: de Bittencourt
authors.forename: José Cláudio Fonseca
authors.initials: JC
authors.lastname: Moreira
mesh_terms: D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation; D002470:Cell Survival; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D018836:Inflammation Mediators / Q000378:metabolism; D008262:Macrophage Activation; D008264:Macrophages / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D009573:Nitrites / Q000378:metabolism; D010084:Oxidation-Reduction; D010587:Phagocytosis; D011487:Protein Conformation; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D018840:HSP70 Heat-Shock Proteins; D018836:Inflammation Mediators; D009573:Nitrites; D014409:Tumor Necrosis Factor-alpha