Manipulating gene expression levels in mammalian cell factories: An outline of synthetic molecular toolboxes to achieve multiplexed control.

Mammalian cells have developed dedicated molecular mechanisms to tightly control expression levels of their genes where the specific transcriptomic signature across all genes eventually determines the cell's phenotype. Modulating cellular phenotypes is of major interest to study their role in disease or to reprogram cells for the manufacturing of recombinant products, such as biopharmaceuticals. Cells of mammalian origin, for example Chinese hamster ovary (CHO) and Human embryonic kidney 293 (HEK293) cells, are most commonly employed to produce therapeutic proteins. Early genetic engineering approaches to alter their phenotype have often been attempted by "uncontrolled" overexpression or knock-down/-out of specific genetic factors. Many studies in the past years, however, highlight that rationally regulating and fine-tuning the strength of overexpression or knock-down to an optimum level, can adjust phenotypic traits with much more precision than such "uncontrolled" approaches. To this end, synthetic biology tools have been generated that enable (fine-)tunable and/or inducible control of gene expression. In this review, we discuss various molecular tools used in mammalian cell lines and group them by their mode of action: transcriptional, post-transcriptional, translational and post-translational regulation. We discuss the advantages and disadvantages of using these tools for each cell regulatory layer and with respect to cell line engineering approaches. This review highlights the plethora of synthetic toolboxes that could be employed, alone or in combination, to optimize cellular systems and eventually gain enhanced control over the cellular phenotype to equip mammalian cell factories with the tools required for efficient production of emerging, more difficult-to-express biologics formats.

Process-wide control and automation of an integrated continuous manufacturing platform for antibodies.

Integrated continuous manufacturing is entering the biopharmaceutical industry. The main drivers range from improved economics, manufacturing flexibility, and more consistent product quality. However, studies on fully integrated production platforms have been limited due to the higher degree of system complexity, limited process information, disturbance, and drift sensitivity, as well as difficulties in digital process integration. In this study, we present an automated end-to-end integrated process consisting of a perfusion bioreactor, CaptureSMB, virus inactivation (VI), and two polishing steps to produce an antibody from an instable cell line. A supervisory control and data acquisition (SCADA) system was developed, which digitally integrates unit operations and analyzers, collects and centrally stores all process data, and allows process-wide monitoring and control. The integrated system consisting of bioreactor and capture step was operated initially for 4 days, after which the full end-to-end integrated run with no interruption lasted for 10 days. In response to decreasing cell-specific productivity, the supervisory control adjusted the loading duration of the capture step to obtain high capacity utilization without yield loss and constant antibody quantity for subsequent operations. Moreover, the SCADA system coordinated VI neutralization and discharge to enable constant loading conditions on the polishing unit. Lastly, the polishing was sufficiently robust to cope with significantly increased aggregate levels induced on purpose during virus inactivation. It is demonstrated that despite significant process disturbances and drifts, a robust process design and the supervisory control enabled constant (optimum) process performance and consistent product quality.

Celiac disease and non-organ-specific autoantibodies in patients with chronic hepatitis C virus infection.

OBJECTIVE: Considering that celiac disease (CD) is an autoimmune-based entity and the hepatitis C virus is suspected of being able to trigging autoimmune reactions, it has been hypothesized that hepatitis C virus infection might predispose to CD. The aim of this study was to investigate CD-related antibodies in a large series of hepatitis C virus-infected subjects that were also tested for non-organ-specific autoantibodies (NOSA) as indirect marker of autoimmune disorders. METHODS: Two hundred and forty-four patients with chronic hepatitis C virus infection (HCV-patients) and 121 patients with HCV-negative liver disease (non-HCV-patients) underwent NOSA determination and celiac serology (firstly, anti-tissue transglutaminase antibodies, then the cases which tested positive were subsequently evaluated for the presence of antiendomysial antibodies). Serum samples from 42 of the HCV-patients who underwent interferon-alpha therapy after enrollment were tested for celiac antibodies and NOSA even after stopping treatment. Additionally, sera from 1,230 blood donors were assayed for celiac serology as healthy control population. RESULTS: Positive anti-endomysial antibodies (AEA) were found in 5/244 (2%) HCV-patients, 1/121 (0.8%) non-HCV-patients and 2/1,230 (0.16%) blood donors, with a significant difference between HCV-patients and blood donors (P = 0.02; Odds ratio 12.8; 95% Confidence Interval 2.4-66). NOSA were found in 51 HCV-patients but only one of them had positive AEA. Eight out of 42 HCV-patients treated with interferon-alpha developed NOSA under therapy and none of them had CD antibodies. CONCLUSIONS: AEA occur in 2% of HCV-patients and their presence is independent of other patterns of autoimmunity.

Chryseobacterium indologenes bacteraemia in a diabetic child.

Chryseobacterium indologenes is a non-fermentative Gram-negative bacillus that is a rare pathogen in humans. Its occurrence in diabetic children has not been previously reported. In this report, a case is described of C. indologenes bacteraemia possibly associated with the use of a peripheral venous catheter. A 2-year-old boy with type I diabetes mellitus was admitted due to a coma caused by cerebral oedema and was successfully treated for his neurological condition but presented on the tenth day after admission with fever of 40 degrees C, agitation, restlessness, lack of appetite, somnolence and fatigue. His pulse rate was 90 min(-1) and his respiratory rate was 20 min(-1). Laboratory studies revealed a white blood cell count of 4900 mm(-3) with 67% neutrophils and 27% lymphocytes. Two separate blood cultures yielded C. indologenes. Treatment with ceftriaxone was started before the culture results were obtained, and was continued after susceptibility test results were obtained. The patient became afebrile after 48 h, and his general condition improved within 36 h. The infection did not recur. This is believed to be the third case of bacteraemia outside of Asia due to C. indologenes and the first in a diabetic child not otherwise immunocompromised. This case indicates that C. indologenes infection can occur in diabetic children without ventilator or central venous catheter and might be treated with a single agent after in vitro susceptibility tests have been performed.

Hearing loss in congenital hypothalamic hypothyroidism: a wide therapeutic window.

In this study, which aims to investigate for the first time auditoty sensitivity in congenital central hypothyroidism (CH), we concluded that: (1) permanent sensorineural hearing loss may be observed not only in congenital primary disorders of thyroid function, as reported hitherto; (2) it may also be found in patients with congenital CH, at least when substitutive treatment is started many years after thyroid failure presentation; (3) the concept of a 'critical therapeutic window' in preventing hearing impairment also holds true for children with congenital CH; (4) the therapeutic window in CH is wider than in primary hypothyroidism; (5) this is probably due to the less severe thyroid impairment in the cases with a central origin of hypothyroidism. These conclusions were suggested by the following data obtained in a cohort of 10 patients with congenital CH who were euthyroid at the time of audiological evaluation thanks to long-standing substitutive therapy: (a) four out of 10 patients exhibited a bilateral sensorineural hearing loss; (b) hearing impaired patients were the oldest of the entire series at diagnosis of hypothyroidism and none of them was aged less than 7 years at the time of the start of replacement therapy; (c) a strong positive relationship was found between age at therapy start and hearing loss.