Elevated serum nitric oxide levels in patients with inflammatory arthritis associated with co-expression of inducible nitric oxide synthase and protein kinase C-eta in peripheral blood monocyte-derived macrophages.
OBJECTIVE
To quantify circulating nitric oxide (NO) levels and inducible NO synthase (iNOS) expression in peripheral blood monocyte-derived macrophages (PB-MDM) from patients with inflammatory arthritis (IA) as a measure of disease activity, and to determine if there is a correlation between expression of iNOS and protein kinase C-eta (PKC-eta).


METHODS
PB-MDM were isolated from whole blood of 20 patients with IA (14 rheumatoid arthritis and 6 peripheral spondyloarthropathies). Thirteen patients with osteoarthritis (OA) and 9 healthy individuals were controls. Serum NO levels were measured by indirect determination of nitrite and nitrate. Expression of PKC-eta and iNOS was investigated by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis.


RESULTS
Serum NO (189.9 +/- 49.7 microM) was significantly higher (p < 0.0028) in IA patients than in controls (131.1 +/- 18.5 microM) or patients with OA (126.9 +/- 37.1 microM). IA patients with severe inflammation had highest levels of NO, while those with mild inflammation had normal levels of NO. RT-PCR showed that PB-MDM from IA patients with active disease co-expressed iNOS and PKC-eta. This was observed in 15 out of 16 cases. All other groups with normal plasma NO expressed neither gene.


CONCLUSIONS
Our findings show that elevated plasma NO levels were only present in IA patients with severe disease activity. We show for the first time a positive correlation between PKC-eta and iNOS expression in arthritis, supporting our earlier in vitro findings that PKC-eta expression was essential for lipopolysaccharide-mediated iNOS induction and NO production in human monocytes. PKC-eta may be important for the development of IA-induced iNOS positive phenotype in human PB-MDM.
Pham
Tram N Q
TN
Faculty of Medicine, Memorial University of Newfoundland and Rheumatology Research, St. Clare's Mercy Hospital, St. John's, Newfoundland A1B 3V6, Canada.
Rahman
Proton
P
Tobin
Yvonne M
YM
Khraishi
Majed M
MM
Hamilton
Sean F
SF
Alderdice
Catherine
C
Richardson
Vernon J
VJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000473:pathology; D006801:Humans; D007596:Joints / Q000473:pathology; D008264:Macrophages / Q000201:enzymology* / Q000473:pathology; D008875:Middle Aged; D009569:Nitric Oxide / Q000097:blood*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D010003:Osteoarthritis / Q000097:blood / Q000473:pathology; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger; D020133:Reverse Transcriptase Polymerase Chain Reaction
D012333:RNA, Messenger; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C119190:protein kinase C nu; D011493:Protein Kinase C