Anti-PPAT monoclonal antibody

Clostridium perfringens type D strains are usually associated with diseases of livestock, and their virulence requires the production of epsilon toxin (ETX). We previously showed (J. Li, S. Sayeed, S. Robertson, J. Chen, and B. A. McClane, PLoS Pathog 7:e1002429, 2011, http://dx.doi.org/10.1371/journal.ppat.1002429) that BMC202, a nanI null mutant of type D strain CN3718, produces less ETX than wild-type CN3718 does. The current study proved that the lower ETX production by strain BMC202 is due to nanI gene disruption, since both genetic and physical (NanI or sialic acid) complementation increased ETX production by BMC202. Furthermore, a sialidase inhibitor that interfered with NanI activity also reduced ETX production by wild-type CN3718. The NanI effect on ETX production was shown to involve reductions in codY and ccpA gene transcription levels in BMC202 versus wild-type CN3718. Similar to CodY, CcpA was found to positively control ETX production. A double codY ccpA null mutant produced even less ETX than a codY or ccpA single null mutant. CcpA bound directly to sequences upstream of the etx or codY start codon, and bioinformatics identified putative CcpA-binding cre sites immediately upstream of both the codY and etx start codons, suggesting possible direct CcpA regulatory effects. A ccpA mutation also decreased codY transcription, suggesting that CcpA effects on ETX production can be both direct and indirect, including effects on codY transcription. Collectively, these results suggest that NanI, CcpA, and CodY work together to regulate ETX production, with NanI-generated sialic acid from the intestines possibly signaling type D strains to upregulate their ETX production and induce disease. IMPORTANCE Clostridium perfringens NanI was previously shown to increase ETX binding to, and cytotoxicity for, MDCK host cells. The current study demonstrates that NanI also regulates ETX production via increased transcription of genes encoding the CodY and CcpA global regulators. Results obtained using single ccpA or codY null mutants and a ccpA codY double null mutant showed that codY and ccpA regulate ETX production independently of one another but that ccpA also affects codY transcription. Electrophoretic mobility shift assays and bioinformatic analyses suggest that both CodY and CcpA may directly regulate etx transcription. Collectively, results of this study suggest that sialic acid generated by NanI from intestinal sources signals ETX-producing C. perfringens strains, via CcpA and CodY, to upregulate ETX production and cause disease.

Purpose: Menopause-related changes may affect regional but also morphological characteristics of adipose tissue. We sought to assess the clinical value of echogenicity of subcutaneous adipose tissue (SAT) and preperitoneal adipose tissue (pPAT) in postmenopausal women without cardiovascular disease. Methods: In 244 consecutively recruited postmenopausal women, subclinical atherosclerosis was assessed in the femoral and carotid arteries by intima-media thickness (IMT) and atheromatous plaques using high-resolution ultrasonography. In 41 women with a second visit (median followup 41.5 months), carotid atherosclerosis was re-evaluated. Images of SAT and pPAT were ultrasonographically acquired, and their echogenicity was evaluated by grayscale mean (GSMn) using a dedicated software. A control group of 20 healthy premenopausal women was used for comparisons in fat echogenicity. Results: SAT GSMn but not pPAT was higher in postmenopausal as compared with healthy premenopausal women and was independently associated with metabolic markers of adiposity including body mass index (BMI) and waist circumference (WC). SAT GSMn was associated with carotid IMT and the presence and number of atheromatous plaques [adjusted OR 2.44 and 2.32 per 1-SD increase in GSMn (95% Cls 1.55 to 3.93 and 1.55 to 3.45), respectively]. SAT GSMn conferred incremental value over traditional risk factors, insulin resistance, BMI, and WC for the detection of subclinical atherosclerosis. Increased baseline SAT GSMn was associated with increased rate of progression in carotid IMT. Conclusions: SAT echogenicity may serve as a qualitative marker of adiposity, conferring incremental clinical value over BMI and WC in postmenopausal women. Further investigation is warranted to assess the utility of ultrasonography-derived fat echogenicity as a screening method for morbid obesity.