Whole Blood Profiling of T-cell-Derived microRNA Allows the Development of Prognostic models in Inflammatory Bowel Disease

BACKGROUND

MicroRNAs [miRNAs] are cell-specific small non-coding RNAs that can regulate gene expression and have been implicated in inflammatory bowel disease [IBD] pathogenesis. Here we define the cell-specific miRNA profiles and investigate its biomarker potential in IBD.

METHODS

In a two-stage prospective multi-centre case control study, next generation sequencing was performed on a discovery cohort of immunomagnetically separated leukocytes from 32 patients (nine Crohn's disease [CD], 14 ulcerative colitis [UC], eight healthy controls) and differentially expressed signals were validated in whole blood in 294 patients [97 UC, 98 CD, 98 non-IBD, 1 IBDU] using quantitative PCR. Correlations were analysed with phenotype, including need for early treatment escalation as a marker of progressive disease using Cox proportional hazards.

RESULTS

In stage 1, each leukocyte subset [CD4+ and CD8+ T-cells and CD14+ monocytes] was analysed in IBD and controls. Three specific miRNAs differentiated IBD from controls in CD4+ T-cells, including miR-1307-3p [p = 0.01], miR-3615 [p = 0.02] and miR-4792 [p = 0.01]. In the extension cohort, in stage 2, miR-1307-3p was able to predict disease progression in IBD (hazard ratio [HR] 1.98, interquartile range [IQR]: 1.20-3.27; logrank p = 1.80 × 10-3), in particular CD [HR 2.81; IQR: 1.11-3.53, p = 6.50 × 10-4]. Using blood-based multimarker miRNA models, the estimated chance of escalation in CD was 83% if two or more criteria were met and 90% for UC if three or more criteria are met.

INTERPRETATION

We have identified and validated unique CD4+ T-cell miRNAs that are differentially regulated in IBD. These miRNAs may be able to predict treatment escalation and have the potential for clinical translation; further prospective evaluation is now indicated.

Renal transplantation in a 14-year-old girl with vitamin B12-responsive cblA-type methylmalonic acidaemia

Renal tubular dysfunction and chronic renal failure are well recognised complications of methylmalonic acidaemia (MMA) and can occur even in the context of optimal medical metabolic management. Organ transplantation, such as renal and combined liver and renal transplants, have been utilised in the past for children whose disease cannot be managed by conservative medical practices and those with end stage renal disease. Our patient was diagnosed with B(12)-responsive MMA (subsequently proven to be cblA-type MMA) in the postoperative period following renal transplantation for idiopathic chronic renal failure. She remains well, with excellent graft function and metabolic control 4 years after transplantation. This patient highlights the importance of testing for the inborn errors of metabolism in patients presenting with recurrent acidosis and progressive renal impairment.

Differentiated chondrocytes for cartilage tissue engineering

Trauma to the articular cartilage surface of the joint represents a challenging clinical problem due to the very limited ability of this tissue to self-repair. Moreover, repair techniques such as microfracture, which introduce cells into the joint, have unpredictable clinical outcomes as they produce a fibrocartilage tissue that degenerates with time. Alternative treatments include tissue reconstruction with autograft and allograft tissue. However, these procedures are restricted by the availability of suitable donor tissue. These limitations have been the driving force behind the emerging field of articular cartilage tissue engineering. This paper will highlight and contrast the key challenges associated with the tissue engineering of this neo-tissue using differentiated adult cells. The various components of the tissue engineering process will be described including the choice of donor cell/tissue type and the selection of scaffolds that guide the formation of tissue. The ability of the tissue engineered implants to stimulate the repair of defects in vivo will also be discussed. Tissue engineering approaches may, in the future, provide an ideal alternative to the current surgical treatments for cartilage repair.

Relationship between cell proliferation, cell-cycle phase, and retroviral vector production in FLYRD18 human packaging cells

The relatively low concentrations of retroviral vectors produced by most packaging cells requires the optimization and intensification of their production to make a commercially viable product for gene therapy. While a number of reports exist concerning target cell-cycle effects on retroviral vector infection efficiency, no studies have been reported on the effects of packaging cell cycle on vector production. We have studied the effect of proliferation of the human packaging cell line, FLYRD18, on vector production. In addition, the titer levels of vector produced by cells in each phase of the cell cycle were compared. Numerous studies suggested progression of the cells through the cell cycle to be essential for vector production. However, vector release was found not to be predominant in any particular phase of the cell cycle. These findings indicate that packaging cell proliferation is important for optimal virus production and that arrest of the cells in any particular phase of the cell cycle affords no benefits in retroviral vector production. In contrast to previous reports (using other cell lines), we observed no temporary inhibition of cell cycle progression after detachment of cells from their substratum and that virus production occurred immediately after re-plating of the cells. The findings in this report are important for determining the optimal culture conditions for vector production by packaging cells in vitro.

Effects of culture parameters on the production of retroviral vectors by a human packaging cell line

The use of retroviral vectors for human gene therapy requires the production of large quantities of high titer vector stocks. Maintaining high titers during the prolonged culture of packaging cells will require that critical parameters be controlled. The aim of this study was to determine which culture parameters critically affect the production/decay of retroviral vectors produced by the human packaging cell line FLYRD18/LNC-hB7. The stability of retroviral vectors released by this cell line was found to be temperature dependent (half-life of 6.9, 11.0, and 64.3 h when incubated at 37, 32, and 0 degrees C, respectively). Titers increased up to 10-fold when the packaging cells were cultured at 32 degrees C, compared to 37 degrees C, despite a decrease in cell yield (cell-specific titers were 20-fold higher). Virus titers were also over 10-fold higher when the packaging cells were cultured in a reduced serum concentration (1%) compared to 5%. Retrovirus production at a range of pH levels revealed a significant decrease in virus titer at pH levels below 6.8 and above 7.2, optimum titers being achieved in cultures at pH 7.2. Dissolved oxygen levels in the range 20-80% did not significantly affect titers under the conditions tested. Finally, a packed bed system containing the packaging cells immobilized on porous microcarriers was shown to sustain the production of active retroviral vectors for over 1 month, in relatively large volumes.

Monoclonal antibodies to high-incidence Kell epitopes: characterization and application in automated screening of donor samples

Monoclonal antibodies, LM313/706 and LM357/828, recognize high-frequency epitopes which are absent on red cells of Ko phenotype. Both antibodies have proved suitable for automated screening of blood donor samples, with 5 ml of each culture supernatant sufficient to screen 3,000 donor samples. In a screen of 45,545 samples, LM313/706 revealed 11 samples (1:3686) of Kp(a+b-) phenotype. Thirty-seven samples of K+k- phenotype were identified in 15,235 samples screened with LM357/828 antibody (0.24%). The epitope recognized by LM313/706 was inactivated by 2 mM DTT suggesting a possible association with the Jsa/Jsb antigen structure. The expression of the k-like epitope detected by LM357/828 antibody was found to be influenced by pH change.

Heart rate during breath-holding and diving in the unrestrained harbor seal (Phoco vitulina richardi)

Heart rate and breathing movements have been monitored in three unrestrained harbor seals. On voluntary submergence heart rate fell markedly in all seals, and after 2–3 s submergence stabilized at about 40–50% of the predive level. Heart rate increased before the animals broke surface at the end of the dive and, when breathing began again, a postdive tachycardia was observed. Two of the three seals frequently showed anticipation of the dive as judged from their heart-rate response. Heart rate during feeding dives was generally more variable; in fact one seal exhibited no bradycardia in 20% of its feeding dives, although another seal showed a significantly greater bradycardia than was seen in routine dives. When breathing rate was low (less than five breaths min−1) respiratory variations in the heart rate occurred, although the onset of bradycardia was much more rapid during diving than during breath-holding. Because of the flexibility of the response it is concluded that the generation of diving bradycardia in the seal is a complex phenomenon which, aside from any responses set in train by peripheral receptors, must also involve some form of associative learning.