Oral glucosamine modulates the response of the liver and lymphocytes of the mesenteric lymph nodes in a papain-induced model of joint damage and repair.
OBJECTIVE
To assess whether glucosamine (GlcN), an oral supplement commonly taken to relieve the symptoms of osteoarthritis, modulates the immune and inflammatory responses to joint injury in organs proximal to GlcN absorption; namely, the liver and the gut-draining lymph nodes.


METHODS
Using a papain-injected knee mouse model, standard histological methods were used to validate our model and document the impact of GlcN (100mg/kg/day) on groups of C57BL/6 mice (n=5). Circulating inflammatory cytokines were assessed by Luminex-based immunoassays and the relevance of this cytokine profile on proteoglycan biosynthesis evaluated using a patellar-cartilage assay. Real-time PCR was used to document the role of the liver in cytokine production. Finally, we appraised the activation of mesenteric lymph nodes (MLNs) lymphocytes by flow cytometry.


RESULTS
Papain significantly degraded the proteoglycans in the injected knees by 2 days. Cartilage proteoglycan content was significantly higher in GlcN-treated, papain-injected knees at Day 14. The peak concentration of serum pro-inflammatory cytokines occurred earlier and decreased sooner in the injected, GlcN-supplemented mice; this trend was in agreement with the expression of these factors by the liver. GlcN did not alter the percentage of MLN populations but accelerated their activation.


CONCLUSIONS
Oral GlcN alters the physiology of the liver and MLNs, which in turn, could indirectly alter the biology of the injured joint.
Panicker
S
S
Department of Biochemistry, Rush University Medical Center, 1653 West Congress Parkway, Chicago, IL 60612, United States.
Borgia
J
J
Fhied
C
C
Mikecz
K
K
Oegema
T R
TR
D000818:Animals; D001169:Arthritis, Experimental / Q000276:immunology / Q000473:pathology*; D002358:Cartilage, Articular / Q000276:immunology / Q000473:pathology*; D005260:Female; D005944:Glucosamine / Q000378:metabolism*; D007719:Knee Joint / Q000187:drug effects / Q000473:pathology; D008099:Liver / Q000187:drug effects / Q000473:pathology*; D008214:Lymphocytes / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D010003:Osteoarthritis / Q000276:immunology / Q000473:pathology*
D005944:Glucosamine