Development and validation of novel enzyme activity methods to assess inhibition of matrix metalloproteinases (MMPs) in human serum by antibodies against enzyme therapeutics.

This paper summarizes the development and validation of five enzyme activity methods to assess the specific inhibition of human endogenous matrix metalloproteinases MMP-1 (interstitial collagenase), MMP-2 (gelatinase A), MMP-3 (stromelysin 1), MMP-8 (collagenase 2) and MMP-13 (collagenase 3) by anti-Collagenase Clostridium histolyticum (CCH) antibodies in human serum. These MMPs are of interest since antibodies against a therapeutic enzyme may cross-react with, and inactivate, the MMPs. The validated methods utilize spiked exogenous individual MMPs added to serum to determine if the serum inhibits MMP enzyme activity. Factors evaluated and optimized during development include pH, reaction time and temperature, inhibitor concentration for the positive control, and substrate and serum concentration. Characteristics established during validation for each MMP activity inhibition method included intra- and inter-assay precision and recovery, recovery in the pooled normal human serum samples, bench-top stability at room temperature and on wet ice, and assay cut-point determination. Precision results ranged from ~1 to 12% CV, recoveries of the activities of the exogenous MMPs ranged from ~84 to 90% and cut-point values ranged from 67 to 91%.

Assessment of potential cross-reactivity of human endogenous matrix metalloproteinases with collagenase Clostridium histolyticum antibodies in human sera obtained from patients with Dupuytren's contracture.

Collagenase Clostridium histolyticum (CCH) contains a fixed ratio of class I (AUX-I) and class II (AUX-II) collagenases and is used as treatment for Dupuytren's contracture. These two Zn-dependent enzymes, produced by the Gram-positive bacterium Clostridium histolyticum, are related functionally to matrix metalloproteinases (MMPs) which, among other functions, degrade the extracellular matrix. Since AUX-I and AUX-II exhibit sequence similarities to human MMPs, we assessed MMP-1 (interstitial collagenase), MMP-2 (gelatinase A), MMP-3 (stromelysin 1), MMP-8 (collagenase 2), and MMP-13 (collagenase 3) for cross-reactivity with anti-AUX-I and anti-AUX-II antibodies in patient serum. Serum samples from 71 subjects enrolled in a long-term clinical study (58 males and 13 females; 63 ± 10 years old [mean ± standard error]) were evaluated for cross-reactivity with the five MMPs using the two validated enzyme-linked immunosorbent assays (ELISAs). Inhibition cutoff points for anti-AUX-I and anti-AUX-II antibodies were based on assay inhibition obtained with a nonspecific protein, bovine gamma globulin, which was tested for each clinical sample. No MMP cross-reactivity was found for any of the 71 clinical antibody-positive sera evaluated. Sequence identity assessments indicated minimal, nonmeaningful alignments of the MMPs and AUX-I/AUX-II. Furthermore, clinical adverse event assessments indicated no safety signals related to MMP inhibition. The bioanalytical results, sequence identity, and clinical assessments consistently did not demonstrate cross-reactivity between CCH antidrug antibodies and endogenous human matrix metalloproteinases. The results presented here suggest that treatment of Dupuytren's contracture patients with CCH does not lead to any clinical adverse events associated with MMP inhibition.

Purification and characterization of plasma membrane-associated human sperm alpha-L-fucosidase.

Detergent and salt extraction studies, as well as cytochemical localization with fluorescein isothiocyanate-bovine serum albumin-L-fucose, have provided further evidence for the plasma membrane association of a novel human sperm, alpha-L-fucosidase. This alpha-L-fucosidase has been solubilized and purified 8600-fold to high specific activity (35 000 U/mg protein) by affinity chromatography on agarose-C(24)-fucosylamine. To our knowledge, this is the first report concerning the purification and characterization of a mammalian plasma membrane-associated alpha-L-fucosidase. Both SDS-PAGE and Western blot analysis indicated the alpha-L-fucosidase is highly purified and contains a single subunit with a molecular mass of 51 kDa. N-glycanase studies indicated the subunit contains N-glycans, and lectin blot analysis detected the presence of mannose, but no terminal galactose or sialic acid residues. Isoelectric focusing indicated the presence of two major alpha-L-fucosidase isoforms (pIs 6.5 and 6.7) and a possible minor isoform (pI 6.3). Treatment of alpha-L-fucosidase with neuraminidase did not change its isoform profile, providing further evidence for the enzyme's lack of sialic acid residues. Kinetic analysis with 4-methylumbelliferyl alpha-L-fucopyranoside indicated that sperm alpha-L-fucosidase has a pH optimum near 7, an apparent K(m) of 0.08 mM, and a V(max) of 6.8 micro mol/min/mg protein. The unusual properties of human sperm alpha-L-fucosidase argue in support of a potentially important, but presently unknown, role for this enzyme in human reproduction.

Purification and characterization of human seminal plasma alpha-L-fucosidase.

Human seminal plasma alpha-L-fucosidase (EC 3.2.1.51) has been purified 7100-fold to very high purity and specific activity (83,000 nmol/min/mg protein) by affinity chromatography on agarose-epsilon-aminocaproyl-fucopyranosylamine. The purified alpha-L-fucosidase appeared to contain a single subunit of 56-57 kDa (as determined by SDS-PAGE and Western analysis). Lectin blotting and N-glycanase treatment studies indicated that this subunit is N-glycosylated and contains sialic acid residues. Human seminal plasma alpha-L-fucosidase was shown to contain three multimeric forms of 110, 236 and 314 kDa respectively (as determined by Sephadex G-200 chromatography) and therefore probably exists in dimeric, tetrameric and hexameric forms. Kinetic analysis with the 4-methylumbelliferyl-alpha-L-fucopyranoside (4MU-Fuc) substrate indicated a broad acidic optimum (pH 4.0-4.5) with a second neutral optimum (pH 6.4-7.4) with 60-80% of maximal activity. Apparent K(M) and V(max) values for the 4MU-Fuc substrate were determined to be 0.06 mmol/l and 92 micromol/min/mg protein respectively, using Lineweaver-Burk double reciprocal plots. Isoelectric focusing and neuraminidase treatment studies provided further evidence that the purified seminal plasma alpha-L-fucosidase is a sialoglycoprotein with several isoforms between pI values 5-7. The acidic isoforms between pI values 5-6 appear to be related chemically to the more neutral isoforms by sialic acid residues since neuraminidase treatment converted the former into the latter isoforms.