Limits...
Preclinical Evaluations To Identify Optimal Linezolid Regimens for Tuberculosis Therapy.

Brown AN, Drusano GL, Adams JR, Rodriquez JL, Jambunathan K, Baluya DL, Brown DL, Kwara A, Mirsalis JC, Hafner R, Louie A - MBio (2015)

Bottom Line: However, long-term use of linezolid has shown to be toxic in patients, often resulting in thrombocytopenia.We examined therapeutic linezolid regimens in an in vitro model to characterize the exposure-toxicity relationship.These findings can provide valuable insight for designing optimal dosage regimens for linezolid that are part of the long combination courses used to treat multidrug-resistant M. tuberculosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Institute for Therapeutic Innovation, University of Florida, Orlando, Florida, USA Ashley.Brown@medicine.ufl.edu.

No MeSH data available.


Related in: MedlinePlus

OXPHOS mitochondrial protein levels for complexes 1, 3, 4, and 5 from K562 cells treated with linezolid in the HFIM system. The effects of linezolid on the production of OXPHOS protein complexes 1 (A), 3 (B), 4 (C), and 5 (D) in K562 cells harvested from the HFIM system were assessed. Cell pellets were lysed, and OXPHOS mitochondrial protein levels were quantified by ELISA.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4631805&req=5

fig2: OXPHOS mitochondrial protein levels for complexes 1, 3, 4, and 5 from K562 cells treated with linezolid in the HFIM system. The effects of linezolid on the production of OXPHOS protein complexes 1 (A), 3 (B), 4 (C), and 5 (D) in K562 cells harvested from the HFIM system were assessed. Cell pellets were lysed, and OXPHOS mitochondrial protein levels were quantified by ELISA.

Mentions: Mitochondrial toxicity of K562 cells was evaluated by assessing two characterized mitochondrial toxicity biomarkers: energy metabolism disruption and altered apoptosis. Disruption of cellular energy metabolism was determined by quantifying oxidative-phosphorylation (OXPHOS) protein complexes 1, 3, 4, and 5 and measuring ATP production. Linezolid therapy had little effect on the protein synthesis of OXPHOS complex 1, 3, or 5 proteins (Fig. 2A, B, and D). In contrast, OXPHOS complex 4 proteins were markedly inhibited in the linezolid treatment arms relative to the no-treatment control, and protein levels were suppressed in a clearly exposure-dependent manner for the once-daily (q24h) regimens (Fig. 2C). At day 9 (when maximal protein inhibition was observed), complex 4 protein levels were 36.36% for the 342-mg q24h regimen, 33.33% for the 600-mg q24h regimen, 15.15% for the 858-mg q24h regimen, and 9.09% for the 1,116-mg q24h regimen relative to the no-treatment control arm (Fig. 2C). Interestingly, the twice-daily regimen (300 mg q12h) resulted in the lowest levels of complex 4 proteins (6.06% relative to the no-treatment control at day 9), indicating that mitochondrial protein synthesis is sensitive to linezolid dosing interval. Cellular ATP production was not influenced by linezolid, as an exposure-response relationship was not observed over time for linezolid-treated K562 cells (Fig. 3A). Finally, mitochondrial toxicity was evaluated by assessing the induction of apoptosis (a mitochondrial toxicity biomarker) in K562 cells treated with linezolid by measuring caspase 3 activation. Caspase 3 activity levels increased in all treatment arms throughout the duration of the 16-day study (Fig. 3B). The degree of apoptosis did not correlate with different exposures of linezolid (Fig. 3B), suggesting that linezolid-induced mitochondrial toxicity is not the result of altered apoptosis in treated K562 cells.


Preclinical Evaluations To Identify Optimal Linezolid Regimens for Tuberculosis Therapy.

Brown AN, Drusano GL, Adams JR, Rodriquez JL, Jambunathan K, Baluya DL, Brown DL, Kwara A, Mirsalis JC, Hafner R, Louie A - MBio (2015)

OXPHOS mitochondrial protein levels for complexes 1, 3, 4, and 5 from K562 cells treated with linezolid in the HFIM system. The effects of linezolid on the production of OXPHOS protein complexes 1 (A), 3 (B), 4 (C), and 5 (D) in K562 cells harvested from the HFIM system were assessed. Cell pellets were lysed, and OXPHOS mitochondrial protein levels were quantified by ELISA.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4631805&req=5

fig2: OXPHOS mitochondrial protein levels for complexes 1, 3, 4, and 5 from K562 cells treated with linezolid in the HFIM system. The effects of linezolid on the production of OXPHOS protein complexes 1 (A), 3 (B), 4 (C), and 5 (D) in K562 cells harvested from the HFIM system were assessed. Cell pellets were lysed, and OXPHOS mitochondrial protein levels were quantified by ELISA.
Mentions: Mitochondrial toxicity of K562 cells was evaluated by assessing two characterized mitochondrial toxicity biomarkers: energy metabolism disruption and altered apoptosis. Disruption of cellular energy metabolism was determined by quantifying oxidative-phosphorylation (OXPHOS) protein complexes 1, 3, 4, and 5 and measuring ATP production. Linezolid therapy had little effect on the protein synthesis of OXPHOS complex 1, 3, or 5 proteins (Fig. 2A, B, and D). In contrast, OXPHOS complex 4 proteins were markedly inhibited in the linezolid treatment arms relative to the no-treatment control, and protein levels were suppressed in a clearly exposure-dependent manner for the once-daily (q24h) regimens (Fig. 2C). At day 9 (when maximal protein inhibition was observed), complex 4 protein levels were 36.36% for the 342-mg q24h regimen, 33.33% for the 600-mg q24h regimen, 15.15% for the 858-mg q24h regimen, and 9.09% for the 1,116-mg q24h regimen relative to the no-treatment control arm (Fig. 2C). Interestingly, the twice-daily regimen (300 mg q12h) resulted in the lowest levels of complex 4 proteins (6.06% relative to the no-treatment control at day 9), indicating that mitochondrial protein synthesis is sensitive to linezolid dosing interval. Cellular ATP production was not influenced by linezolid, as an exposure-response relationship was not observed over time for linezolid-treated K562 cells (Fig. 3A). Finally, mitochondrial toxicity was evaluated by assessing the induction of apoptosis (a mitochondrial toxicity biomarker) in K562 cells treated with linezolid by measuring caspase 3 activation. Caspase 3 activity levels increased in all treatment arms throughout the duration of the 16-day study (Fig. 3B). The degree of apoptosis did not correlate with different exposures of linezolid (Fig. 3B), suggesting that linezolid-induced mitochondrial toxicity is not the result of altered apoptosis in treated K562 cells.

Bottom Line: However, long-term use of linezolid has shown to be toxic in patients, often resulting in thrombocytopenia.We examined therapeutic linezolid regimens in an in vitro model to characterize the exposure-toxicity relationship.These findings can provide valuable insight for designing optimal dosage regimens for linezolid that are part of the long combination courses used to treat multidrug-resistant M. tuberculosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Institute for Therapeutic Innovation, University of Florida, Orlando, Florida, USA Ashley.Brown@medicine.ufl.edu.

No MeSH data available.


Related in: MedlinePlus