SARS-CoV-2 Spike protein is not pro-inflammatory in human primary macrophages: endotoxin contamination and lack of protein glycosylation as possible confounders.
Cell Biol Toxicol
; 38(4): 667-678, 2022 08.
Article
in English
| MEDLINE | ID: covidwho-1616182
ABSTRACT
INTRODUCTION:
The inflammatory potential of SARS-CoV-2 Spike S1 (Spike) has never been tested in human primary macrophages (MΦ). Different recombinant Spikes might display different effects in vitro, according to protein length and glycosylation, and endotoxin (lipopolysaccharide, LPS) contamination.OBJECTIVES:
To assess (1) the effects of different Spikes on human primary MΦ inflammation; (2) whether LPS contamination of recombinant Spike is (con)cause in vitro of increased MΦ inflammation.METHODS:
Human primary MΦ were incubated in the presence/absence of several different Spikes (10 nM) or graded concentrations of LPS. Pro-inflammatory marker expression (qPCR and ELISA) and supernatant endotoxin contamination (LAL test) were the main readouts.RESULTS:
LPS-free, glycosylated Spike (the form expressed in infected humans) caused no inflammation in human primary MΦ. Two (out of five) Spikes were contaminated with endotoxins ≥ 3 EU/ml and triggered inflammation. A non-contaminated non-glycosylated Spike produced in E. coli induced MΦ inflammation.CONCLUSIONS:
Glycosylated Spike per se is not pro-inflammatory for human MΦ, a feature which may be crucial to evade the host innate immunity. In vitro studies with commercially available Spike should be conducted with excruciating attention to potential LPS contamination.Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Endotoxins
/
Spike Glycoprotein, Coronavirus
/
Macrophages
Limits:
Humans
Language:
English
Journal:
Cell Biol Toxicol
Journal subject:
Toxicology
Year:
2022
Document Type:
Article
Affiliation country:
S10565-021-09693-y
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