Joint Disease

Question 1

Possible value of synovial SAA measurement

Answer 1

Its concentrations are not affected by repeated arthrocenteses, intra-articular administration of amikacin, arthroscopic lavage [Sanchez-Terrna VS 2016] or through-and- through joint lavage in healthy joints.

In healthy horses, SAA concentrations in both blood and synovial fluid are generally less than 1 mg/L [51]. A rise in SAA concentration has been proposed as useful to differentiate between septic or nonseptic intrasynovial pathology, with a cut-off value of 60.7 mg/L for septic condition (Robinson Vet Rec 2017)

Question 2

Main pro and anti-inflammatory cytokines in OA

Answer 2

PRO

• IL-1β
• TNF-α (these are the major top 2 players)
• IL-6
• PGE2
• MMPs 1, 3, 8 and 13 (collagenases)
• ADAMTS 4,5 (aggrecanases)

ANTI

• IGF-1
• TIMP 1,2 (tissue inhibitor of metalloproteinase)
• TGFβ
• BMPs are part of the TGFβ superfamily and BMP2 and 7 have anti-degradative effects

Question 3

4 layers of articular (hyaline cartilage)

Answer 3

Transitions are gradual rather than abrupt, apart from the last layer.

1) Superficial zone - flattened chondrocytes, densely packed type II collagen fibrils running parallel to the surface, a relatively small amount of PGs, and high water content.
2) Intermediate zone - lower water content, more PG, and a lower density of collagen with rounded chondrocytes dispersed irregularly in the ECM.
3) Deep zone, which together form the hyaline part of the cartilage. Lowest % water and highest % PG. Chondrocytes are arranged in columns perpendicular to the subchondral bone. Separated from calcified cartilage layer by the ‘tidemark’
4) Distinct layer of calcified cartilage that forms the interface between the resilient hyaline cartilage and the rigid subchondral bone