Efficient production of recombinant secretory IgA against Clostridium difficile toxins in CHO-K1 cells.

Despite the essential role secretory IgAs play in the defense against pathogenic invasion and the proposed value of recombinant secretory IgAs as novel therapeutics, currently there are no IgA-based therapies in clinics. Secretory IgAs are complex molecules and the major bottleneck limiting their therapeutic potential is a reliable recombinant production system. In this report, we addressed this issue and established a fast and robust production method for secretory IgAs in CHO-K1 cells using BAC-based expression vectors. As a proof of principle, we produced IgAs against Clostridium difficile toxins TcdA and TcdB. Recombinant secretory IgAs produced using our expression system showed comparable titers to IgGs, widely used as therapeutic biologicals. Importantly, secretory IgAs produced using our method were functional and could efficiently neutralize Clostridium difficile toxins TcdA and TcdB. These results show that recombinant secretory IgAs can be efficiently produced, thus opening the possibility to use them as therapeutic agents in clinics.

Inhibiting cellular uptake of mutant huntingtin using a monoclonal antibody: Implications for the treatment of Huntington's disease.

Huntington's disease (HD) is caused by a highly polymorphic CAG trinucleotide expansion in the gene encoding for the huntingtin protein (HTT). The resulting mutant huntingtin protein (mutHTT) is ubiquitously expressed but also exhibits the ability to propagate from cell-to-cell to disseminate pathology; a property which may serve as a new therapeutic focus. Accordingly, we set out to develop a monoclonal antibody (mAB) targeting a particularly exposed region close to the aa586 caspase-6 cleavage site of the HTT protein. This monoclonal antibody, designated C6-17, effectively binds mutHTT and is able to deplete the protein from cell culture supernatants. Using cell-based assays, we demonstrate that extracellular secretion of mutHTT into cell culture media and its subsequent uptake in recipient HeLa cells can be almost entirely blocked by mAB C6-17. Immunohistochemical stainings of post-mortem HD brain tissue confirmed the specificity of mAB C6-17 to human mutHTT aggregates. These findings demonstrate that mAB C6-17 not only successfully engages with its target, mutHTT, but also inhibits cell uptake suggesting that this antibody could interfere with the pathological processes of mutHTT spreading in vivo.

Predictors and reproducibility of exercise-induced bronchoconstriction in cold air.

BACKGROUND: Physical activity is an important part of life, and hence exercise-induced bronchoconstriction (EIB) can reduce the quality of life. A standardized test is needed to diagnose EIB. The American Thoracic Society (ATS) guidelines recommend an exercise challenge in combination with dry air. We investigated the feasibility of a new, ATS guidelines conform exercise challenge in a cold chamber (ECC) to detect EIB. The aim of this study was to investigate the surrogate marker reaction to methacholine, ECC and exercise challenge in ambient temperature for the prediction of a positive reaction and to re-evaluate the reproducibility of the response to an ECC. METHODS: Seventy-eight subjects aged 6 to 40 years with suspected EIB were recruited for the study. The subjects performed one methacholine challenge, two ECCs, and one exercise challenge at an ambient temperature. To define the sensitivity and specificity of the predictor, a receiver-operating characteristic curve was plotted. The repeatability was evaluated using the method described by Bland and Altman (95% Limits of agreement). RESULTS: The following cut-off values showed the best combination of sensitivity and specificity: the provocation dose causing a 20% decrease in the forced expiratory volume in 1 s (PD20FEV1) of methacholine: 1.36 mg (AUC 0.69, p < 0.05), the maximal decrease in FEV1 during the ECC: 8.5% (AUC 0.78, p < 0.001) and exercise challenges at ambient temperatures: FEV1 5.2% (AUC 0.64, p = 0.13). The median decline in FEV1 was 14.5% (0.0-64.2) during the first ECC and 10.7% (0.0-52.5) during the second ECC. In the comparison of both ECCs, the Spearman rank correlation of the FEV1 decrease was r = 0.58 (p < 0.001). The 95% limits of agreement (95% LOAs) for the FEV1 decrease were - 17.7 to 26.4%. CONCLUSIONS: The surrogate markers PD20FEV1 of methacholine and maximal decrease in FEV1 during ECC can predict a positive reaction in another ECC, whereas the maximal FEV1 decrease in an exercise challenge at an ambient temperature was not predictive. Compared with previous studies, we can achieve a similar reproducibility with an ECC. CLINICAL TRIAL REGISTRATION: NCT02026492 (retrospectively registered 03/Jan/2014).