Occurrence of Leu-Lys-bradykinin and histidine-rich peptide in high-molecular-weight kininogen isolated from horse plasma

Arthrogenic lameness of the fetlock: synovial fluid markers of inflammation and cartilage turnover in relation to clinical joint pain

REASONS FOR PERFORMING THE STUDY

Joint pain is one of the most common causes of lameness in the horse but its pathogenesis is poorly understood.

OBJECTIVES

To investigate which synovial fluid markers may be related to the presence of clinically detectable joint pain in the horse.

METHODS

Concentrations of structural (CPII, C2C, GAG) and inflammatory markers (PGE2, LTB4, CysLTs, bradykinin and substance P) were measured in fetlock joint fluid from 22 horses in which lameness was localised to the fetlock region by perineural anaesthesia. Levels of these markers were then compared in horses that responded (n = 15) to those that did not (n = 7) to subsequent intra-articular anaesthesia (IAA).

RESULTS

Of all markers analysed, only substance P levels were significantly higher (P = 0.0358) in synovial fluid of horses that showed a positive response to IAA compared to those with a negative response to IAA. Notably, while PGE2 levels were found to be elevated in all 22 lame horses compared to sound controls (P = 0.0025), they were not related to the response to IAA.

CONCLUSIONS

While levels of PGE2 are elevated in synovial fluid of lame horses that respond to perineural anaesthesia, only substance P is related to joint pain as detected by the response to intra-articular anaesthesia.

POTENTIAL RELEVANCE

Substance P is associated with clinically detectable joint pain in the horse. Elevated levels of PGE2 in fetlock-lame horses, regardless of their response to IAA, indicate that either this mediator does not reflect intra-articular pain or that IAA might have limitations in differentiating between intra- and peri-articular sources of pain. Either way, a negative response to IAA may not exclude intra-articular pathology.

Partial purification and characterization of cysteine proteinase inhibitor from chicken plasma

A high-molecular-weight cysteine proteinase inhibitor (CPI) was purified from chicken (Gallus gallus) plasma using polyethylene glycol (PEG) fractionation and affinity chromatography on carboxymethyl-papain-Sepharose-4B. The CPI was purified 96.8-fold with a yield of 28.9%. Based on inhibitory activity staining for papain, CPI was shown to have an apparent molecular mass of 122 kDa. No inhibitory activity was obtained under reducing condition, indicating that CPI from chicken plasma was stabilized by disulfide bonds. CPI was stable in temperature ranges from 40 to 70 degrees C for 10 min; however, more than 50% of the inhibitory activity towards papain was lost within 30 min of heating at 90 degrees C. CPI was stable in the presence of salt up to 3%. The purified CPI exhibited the inhibitory activity toward autolysis of arrowtooth flounder (Atheresthes stomias) and Pacific whiting (Merluccius productus) natural actomyosin (NAM) in a concentration-dependent manner.

Studies on porcine high molecular weight kininogen. An improved method for the purification of porcine high molecular weight kininogen and cleavage of the kininogen by the action of porcine plasma kallikrein

By introduction of stepwise DEAE Sephadex A-50 and copper-Chelating Sepharose 6B column chromatographies, about 18.5 mg of high molecular weight kininogen (HK) composed of a single polypeptide chain was obtained from 500 ml of porcine plasma. Molecular weights of reduced or non-reduced preparation were estimated to be 110 kDa and 116 kDa, respectively, by SDS-PAGE. Using the preparation, cleavage of HK by porcine plasma kallikrein (KK) was investigated. A single polypeptide HK was cleaved into two chains cross-linked by disulfide bond(s), accompanying the release of kinin. Further degradation was not observed. Molecular weights of heavy-chain (H-chain) and light-chain (L-chain) were estimated to be 61 kDa and 56 kDa, respectively, by SDS-PAGE. The amino- (N-) terminal sequences of intact HK, reduced and carboxymethylated- (RCM-) H-chain, RCM-L-chain and the peptide around the kinin moiety obtained by BrCN digestion were determined. Their sequences were highly homologous with those of bovine or human HK. These results indicate that plasma KK first cleaved the Arg-Ser bond of HK, and formed nicked HK. The second cleavage yielded bradykinin (BK) and kinin-free protein, which was apparently of equal size to the nicked HK. The structure of HK was from the N-terminus to the carboxy- (C-) terminus, H-chain-BK-L-chain.

Isolation and structure of T-kinin

T-kinin, a previously undescribed peptide containing bradykinin, has been isolated following treatment of rat plasma with trypsin (1 mg/ml). The liberated T-kinin, which contracts the rat uterus, was isolated by procedures including OM-cellulose, Biogel P-4 and reverse-phase high-performance liquid chromatography. The final material had a single N-terminal isoleucine and was shown by amino acid analysis and sequence determination to have the structure of the undecapeptide Ile-Ser-Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg (isoleucyl-seryl-bradykinin). The relationships of the protein from which T-kinin is cleaved (T-kininogen) to other known kininogens is discussed.