We use vertebroplasty for patients with the most severe pain caused by osteoporotic vertebral fractures less than 6 weeks old, and have observed dramatic pain relief in this acute setting. A recent editorial in the Journal, written by the authors of two recent vertebroplasty trials, suggested that vertebroplasty is not an effective therapy for acute osteoporotic vertebral fractures. The trials described in the editorial sampled a very different patient cohort to the one that we treat with vertebroplasty. Our clinical experience and most of the published literature relating to the benefits of vertebroplasty are in striking contrast to the opinions presented in that editorial.

Tryptases are neutral serine proteases selectively expressed in mast cells and have been implicated in the development of a number of inflammatory diseases including asthma. It has recently been established that the number of genes encoding human mast cell tryptases is much larger than originally believed, but it is not clear how many of these genes are expressed. A recent report suggested that the transcript for at least one of these genes, originally named mMCP-7-like tryptase, is not expressed. To further address this question, we screened tissue-specific RNA samples by RT-PCR, using primers designed to match the putative exonic sequence of this gene. We successfully generated and cloned the correctly sized RT-PCR product from mRNA isolated from the human mast cell-I cell line. Two distinct clones were identified whose nucleotide sequence matched the published sequence of the mMCP-7-like I and mMCP-7-like II genes. Transcripts were detected in a wide variety of human tissues including lung, heart, stomach, spleen, skin, and colon. A polyclonal antipeptide Ab that specifically recognizes the translated product of this transcript was used to demonstrate its expression in mast cells that reside in the colon, lung, and inflamed synovium. A recombinant form of this protein expressed in bacterial cells was able to cleave a synthetic trypsin-sensitive substrate, d-Ile-Phe-Lys pNA. These results suggest that the range of functional tryptases is larger than previously recognized. For simplicity, we suggest that the gene, transcripts, and corresponding protein product be named δ tryptase.

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