Monocyte activation drives preservation of membrane thiols by promoting release of oxidised membrane moieties via extracellular vesicles.
The redox state of cellular exofacial molecules is reflected by the amount of available thiols. Furthermore, surface thiols can be considered as indicators of immune cell activation. One group of thiol containing proteins, peroxiredoxins, in particular, have been associated with inflammation. In this study, we assessed surface thiols of the U937 and Thp1 monocyte cell lines and primary monocytes in vitro upon inflammatory stimulation by irreversibly labelling the cells with a fluorescent derivative of maleimide. We also investigated exofacial thiols on circulating blood mononuclear cells in patients with rheumatoid arthritis and healthy controls. When analysing extracellular vesicles, we combined thiol labelling with the use of antibodies to specific CD markers to exclude extracellular vesicle mimicking signals from thiol containing protein aggregates. Furthermore, differential detergent lysis was applied to confirm the vesicular nature of the detected extracellular events in blood plasma. We found an increase in exofacial thiols on monocytes upon in vitro stimulation by LPS or TNF, both in primary monocytes and monocytic cell lines (p<0.0005). At the same time, newly released extracellular vesicles showed a decrease in their exofacial thiols compared with those from unstimulated cells (p<0.05). We also found a significant elevation of surface thiols on circulating monocytes in rheumatoid arthritis patients (p<0.05) and newly released extracellular vesicles of isolated CD14+cells from rheumatoid arthritis patients had decreased thiol levels compared with healthy subjects (p<0.01). Exofacial peroxiredoxin 1 was demonstrated on the surface of primary and cultured monocytes, and the number of peroxiredoxin 1 positive extracellular vesicles was increased in rheumatoid arthritis blood plasma (p<0.05). Furthermore, an overoxidised form of peroxiredoxin was detected in extracellular vesicle-enriched preparations from blood plasma. Our data show that cell surface thiols play a protective role and reflect oxidative stress resistance state in activated immune cells. Furthermore, they support a role of extracellular vesicles in the redox regulation of human monocytes, possibly representing an antioxidant mechanism.
Semmelweis University, Department of Genetics, Cell, and Immunobiology, Nagyvárad tér 4, 1089 Budapest, Hungary. Electronic address: szabo-taylor.katalin@med.semmelweis-univ.hu.
K É
KÉ
Szabó-Taylor
Semmelweis University, Department of Genetics, Cell, and Immunobiology, Nagyvárad tér 4, 1089 Budapest, Hungary.
E Á
EÁ
Tóth
Semmelweis University, Department of Genetics, Cell, and Immunobiology, Nagyvárad tér 4, 1089 Budapest, Hungary.
A M
AM
Balogh
Semmelweis University, Department of Genetics, Cell, and Immunobiology, Nagyvárad tér 4, 1089 Budapest, Hungary.
B W
BW
Sódar
Semmelweis University, Department of Genetics, Cell, and Immunobiology, Nagyvárad tér 4, 1089 Budapest, Hungary.
L
L
Kádár
Semmelweis University, Department of Genetics, Cell, and Immunobiology, Nagyvárad tér 4, 1089 Budapest, Hungary.
K
K
Pálóczi
Semmelweis University, Department of Genetics, Cell, and Immunobiology, Nagyvárad tér 4, 1089 Budapest, Hungary.
N
N
Fekete
Semmelweis University, Department of Genetics, Cell, and Immunobiology, Nagyvárad tér 4, 1089 Budapest, Hungary.
A
A
Németh
Semmelweis University, Department of Genetics, Cell, and Immunobiology, Nagyvárad tér 4, 1089 Budapest, Hungary.
X
X
Osteikoetxea
Semmelweis University, Department of Genetics, Cell, and Immunobiology, Nagyvárad tér 4, 1089 Budapest, Hungary.
K V
KV
Vukman
Semmelweis University, Department of Genetics, Cell, and Immunobiology, Nagyvárad tér 4, 1089 Budapest, Hungary.
M
M
Holub
Semmelweis University, Department of Genetics, Cell, and Immunobiology, Nagyvárad tér 4, 1089 Budapest, Hungary.
É
É
Pállinger
Semmelweis University, Department of Genetics, Cell, and Immunobiology, Nagyvárad tér 4, 1089 Budapest, Hungary; Semmelweis University, Department of Rheumatology, 3rd Department of Internal Medicine, 1023 Budapest, Hungary.
Gy
G
Nagy
University of Exeter Medical School, St Luke's Campus, Heavitree Road, Exeter EX1 2LU, United Kingdom.
P G
PG
Winyard
Semmelweis University, Department of Genetics, Cell, and Immunobiology, Nagyvárad tér 4, 1089 Budapest, Hungary.
E I
EI
Buzás
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D000067128:Extracellular Vesicles / Q000378:metabolism*; D005260:Female; D006801:Humans; D007249:Inflammation / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000276:immunology; D008297:Male; D008301:Maleimides; D008875:Middle Aged; D009000:Monocytes / Q000502:physiology*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D013438:Sulfhydryl Compounds / Q000737:chemistry / Q000378:metabolism*; D000074084:THP-1 Cells; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D020298:U937 Cells
D008070:Lipopolysaccharides; D008301:Maleimides; D013438:Sulfhydryl Compounds; D014409:Tumor Necrosis Factor-alpha; C043592:maleimide
Exofacial thiols; Extracellular vesicle; Inflammation; Maleimide; Peroxiredoxin 1