Characterization of alginate lyase gene using a metagenomic library constructed from the gut microflora of abalone.

A metagenomic fosmid library was constructed using a genomic DNA mixture extracted from the gut microflora of abalone. The library gave an alginate lyase positive clone (AlyDW) harboring a 31.7-kbp insert. The AlyDW insert consisted of 22 open reading frames (ORFs). The deduced amino acid sequences of ORFs 11-13 were similar to those of known alginate lyase genes, which are found adjacent in the genome of Klebsiella pneumoniae subsp. aerogenes, Vibrio splendidus, and Vibrio sp. belonging to the phylum Gammaproteobacteria. Among the three recombinant proteins expressed from the three ORFs, alginate lyase activity was only observed in the recombinant protein (AlyDW11) coded by ORF 11. The expressed protein (AlyDW11) had the highest alginate lyase activity at pH 7.0 and 45°C in the presence of 1 mM AgNO(3). The alginate lyase activity of ORF 11 was confirmed to be endolytic by thin-layer chromatography. AlyDW11 preferred poly(ß-D: -mannuronate) as a substrate over poly(α-L: -guluronate). AlyDW11 contained three highly conserved regions, RSEL, QIH, and YFKAGVYNQ, which may act to stabilize the three-dimensional conformation and function of the alginate lyase.

Polymorphic Region-Specific Antibody for Evaluation of Affinity-Associated Profile of Chimeric Antigen Receptor.

Antibody applications in cancer immunotherapy involve diverse strategies, some of which redirect T cell-mediated immunity via engineered antibodies. Affinity is a trait that is crucial for these strategies, as optimal affinity reduces unwanted side effects while retaining therapeutic function. Antibody-antigen pairs possessing a broad affinity range are required to define optimal affinity and to investigate the affinity-associated functional profiles of T cell-engaging strategies such as bispecific antibodies and chimeric antigen receptor-engineered T cells. Here, we demonstrate the unique binding characteristic of the developed antibody clone MVR, which exhibits robust binding to B-lymphoid cell lines. Intriguingly, MVR specifically recognizes the highly polymorphic human leukocyte antigen (HLA)-DR complex and exhibits varying affinities that are dependent upon the HLA-DRB1 allele type. Remarkably, MVR binds to the conformational epitope that consists of two hypervariable regions. As an application of MVR, we demonstrate an MVR-engineered chimeric antigen receptor (CAR) that elicits affinity-dependent function in response to a panel of target cell lines that express different HLA-DRB1 alleles. This tool evaluates the effect of affinity on cytotoxic killing, polyfunctionality, and activation-induced cell death of CAR-engineered T cells. Collectively, MVR exhibits huge potential for the evaluation of the affinity-associated profile of T cells that are redirected by engineered antibodies.

Desensitized chimeric antigen receptor T cells selectively recognize target cells with enhanced antigen expression.

Chimeric antigen receptor (CAR) T cell therapy is an effective method for treating specific cancers. CARs are normally designed to recognize antigens, which are highly expressed on malignant cells but not on T cells. However, when T cells are engineered with CARs that recognize antigens expressed on the T cell surface, CAR T cells exhibit effector function on other T cells, which results in fratricide, or killing of neighboring T cells. Here, using human leukocyte antigen-DR (HLA-DR)-targeted CAR T cells, we show that weak affinity between CAR and HLA-DR reduces fratricide and induces sustained CAR downregulation, which consequently tunes the avidity of CAR T cells, leading to desensitization. We further demonstrate that desensitized CAR T cells selectively kill Epstein-Barr virus-transformed B cells with enhanced HLA-DR expression, while sparing normal B cells. Our study supports an avidity-tuning strategy that permits sensing of antigen levels by CAR T cells.

Effect of weight reduction on metabolic syndrome in Korean obese patients.

The Third Report of the National Cholesterol Education Program Adult Treatment Panel III emphasized the importance of management of the metabolic syndrome. However, little information is available about the effect of weight reduction on the metabolic syndrome in obese patients among Koreans. A longitudinal clinical intervention study from the 12-week of weight reduction program, including life style modification and adjuvant appetite suppressants, in 78 obese persons was performed. Anthropometry and metabolic risk factors were measured before and after weight reduction. Visceral (VAT), subcutaneous (SAT), and total adipose tissue (TAT) on abdomen were determined by CT scan. Moderate decrease in weight (9.3%) induced significant reduction of waist circumference, systolic and diastolic blood pressure, and triglyceride. Weight reduction also resulted in significant decrease in total cholesterol, LDL-C, uric acid, fasting insulin, and HOMA score. The subjects with metabolic syndrome showed more improvements of metabolic components than those without metabolic syndrome through weight reduction. The reductions of visceral-subcutaneous fat ratio (VSR) and waist circumference were observed as for the predictable variables related to the improvement of metabolic component and insulin resistance in Korean obese patients.