Tacrolimus (FK506) Prevents Early Stages of Ethanol Induced Hepatic Fibrosis by Targeting LARP6 Dependent Mechanism of Collagen Synthesis.

Tacrolimus (FK506) Prevents Early Stages of Ethanol Induced Hepatic Fibrosis by Targeting LARP6 Dependent Mechanism of Collagen Synthesis.

PLoS One. 2013; 8(6): e65897
Manojlovic Z, Blackmon J, Stefanovic B

Tacrolimus (FK506) is a widely used immunosuppressive drug. Its effects on hepatic fibrosis have been controversial and attributed to immunosuppression. We show that in vitro FK506, inhibited synthesis of type I collagen polypeptides, without affecting expression of collagen mRNAs. In vivo, administration of FK506 at a dose of 4 mg/kg completely prevented development of alcohol/carbon tetrachloride induced liver fibrosis in rats. Activation of hepatic stellate cells (HSCs) was absent in the FK506 treated livers and expression of collagen ?2(I) mRNA was at normal levels. Collagen ?1(I) mRNA was increased in the FK506 treated livers, but this mRNA was not translated into ?1(I) polypeptide. No significant inflammation was associated with the fibrosis model used. FK506 binding protein 3 (FKBP3) is one of cellular proteins which binds FK506 with high affinity. We discovered that FKBP3 interacts with LARP6 and LARP6 is the major regulator of translation and stability of collagen mRNAs. In the presence of FK506 the interaction between FKBP3 and LARP6 is weakened and so is the pull down of collagen mRNAs with FKBP3. We postulate that FK506 inactivates FKBP3 and that lack of interaction of LARP6 and FKBP3 results in aberrant translation of collagen mRNAs and prevention of fibrosis. This is the first report of such activity of FK506 and may renew the interest in using this drug to alleviate hepatic fibrosis. HubMed – drug


Polyamines inhibit porin-mediated fluoroquinolone uptake in mycobacteria.

PLoS One. 2013; 8(6): e65806
Sarathy JP, Lee E, Dartois V

Polyamines decrease the permeability of the outer membrane of Escherichia coli to fluoroquinolones and ?-lactams. In this study, we tested the effect of four polyamines (spermidine, spermine, cadaverine and putrescine) on fluoroquinolone uptake in Mycobacterium bovis BCG. Our results show that polyamines are also capable of reducing the permeability of the mycobacterial outer membrane to fluoroquinolones. Spermidine was most effective and demonstrated reversible dose- and pH-dependent inhibition of ciprofloxacin accumulation. The extent of this inhibition was demonstrated across the fluoroquinolone compound class to varying degrees. Furthermore, we have shown that the addition of spermidine increases the survival of M. bovis BCG after a 5-day exposure to ciprofloxacin by up to 25 times. The treatment of actively-replicating Mycobacterium tuberculosis with spermidine reduced ciprofloxacin accumulation by half while non-replicating nutrient-starved M. tuberculosis cultures lacked similar sensitivity to polyamines. Gene expression studies showed that several outer membrane proteins are significantly down-regulated during the shift to non-replication. Collectively, these characteristics of fluoroquinolone uptake in M. bovis BCG are consistent with facilitated transport by porin-like proteins and suggest that a reduction in intracellular uptake contributes to the phenotypic drug resistance demonstrated by M. tuberculosis in the non-replicating state. HubMed – drug


Increased risk of sudden cardiac arrest in obstructive pulmonary disease: a case-control study.

PLoS One. 2013; 8(6): e65638
Warnier MJ, Blom MT, Bardai A, Berdowksi J, Souverein PC, Hoes AW, Rutten FH, de Boer A, Koster RW, De Bruin ML, Tan HL

We aimed to determine whether (1) patients with obstructive pulmonary disease (OPD) have an increased risk of sudden cardiac arrest (SCA) due to ventricular tachycardia or fibrillation (VT/VF), and (2) the SCA risk is mediated by cardiovascular risk-profile and/or respiratory drug use.A community-based case-control study was performed, with 1310 cases of SCA of the ARREST study and 5793 age, sex and SCA-date matched non-SCA controls from the PHARMO database. Only incident SCA cases, age older than 40 years, that resulted from unequivocal cardiac causes with electrocardiographic documentation of VT/VF were included. Conditional logistic regression analysis was used to assess the association between SCA and OPD. Pre-specified subgroup analyses were performed regarding age, sex, cardiovascular risk-profile, disease severity, and current use of respiratory drugs.A higher risk of SCA was observed in patients with OPD (n?=?190 cases [15%], 622 controls [11%]) than in those without OPD (OR adjusted for cardiovascular risk-profile 1.4 [1.2-1.6]). In OPD patients with a high cardiovascular risk-profile (OR 3.5 [2.7-4.4]) a higher risk of SCA was observed than in those with a low cardiovascular risk-profile (OR 1.3 [0.9-1.9]) The observed SCA risk was highest among OPD patients who received short-acting ?2-adrenoreceptor agonists (SABA) or anticholinergics (AC) at the time of SCA (SABA OR: 3.9 [1.7-8.8], AC OR: 2.7 [1.5-4.8] compared to those without OPD).OPD is associated with an increased observed risk of SCA. The most increased risk was observed in patients with a high cardiovascular risk-profile, and in those who received SABA and, possibly, those who received AC at the time of SCA. HubMed – drug