Research Spotlight

Srivastava, S., Chapagain, M., van Zyl, J., Deshpande, D. and Gumbo, T. (2021). “Vancomycin’s potency against Mycobacterium tuberculosis in the hollow fiber system model.” J Glob Antimicrob Resist Jan 25;S2213-7165(21)00017-5. [Epub ahead of print].

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OBJECTIVE: To determine if inhaled vancomycin formulation, that allow deposition of high intrapulmonary 0-24hr area under the concentration-time curve [AUC(0-24)], could be optimized for treatment of tuberculosis. We also explored vancomycin synergy and antagonism with D-cycloserine and benzylpenicillin. METHODS: First, we determined MIC of the Mycobacterium tuberculosis [Mtb] laboratory strains H37Ra, and H37Rv, two drug susceptible and nine multidrug resistant clinical strains. Second, in the hollow fiber system model of TB [HFS-TB] using Mtb H37Ra strain, we recapitulated vancomycin intrapulmonary pharmacokinetics of eight different doses administered twice daily over 28 days, mimicking 6 hr half-life. Third, using the HFS-TB, vancomycin was tested in combination with D-cycloserine and benzylpenicillin to determine the synergy or antagonism between the drugs having the target in the same pathway. RESULTS: Vancomycin MICs in drug susceptible Mtb clinical isolates was 12 and 48 mg/L, but >96 mg/L in all MDR isolates. In the HFS-TB, vancomycin killed 3.9 ± 0.6 log(10) CFU/mL Mtb. Concentration mediating 50% kill [EC(50)] was calculated as AUC(0-24)/MIC of 184.6 ± 106.5. Compared to day 0 bacterial burden, 1.0 and 2.0 log(10) CFU/mL kill was achieved by an AUC(0-24)/MIC of 168 and 685, respectively. Acquired-vancomycin resistance developed to all vancomycin doses tested in the HFS-TB. In the HFS-TB, vancomycin was antagonistic to benzylpenicillin, which works downstream to glycopeptides in peptidoglycan synthesis, but was synergistic with D-cycloserine, which inhibits upstream D-Ala-D-Ala ligase and alanine racemase. CONCLUSION: Our proof-of-concept studies show that vancomycin optimal exposure target for Mtb kill could be achieved via the inhalational route drug delivery. Addition of drugs such as D-cycloserine that are synergistic with vancomycin may lower the vancomycin concentrations required to kill Mtb.

Gumbo, T., Sherman, C.M., Deshpande, D., Alffenaar, J.W. and Srivastava, S. (2021). “Mycobacterium tuberculosis sterilizing activity of faropenem, pyrazinamide and linezolid combination and failure to shorten the therapy duration.” Int J Infect Dis Feb 5;104:680-684. [Epub ahead of print].

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BACKGROUND: Faropenem (F), an orally bioavailable β-lactam, kills Mycobacterium tuberculosis (Mtb) without the help of a β-lactamase inhibitor. This study explored the sterilizing effect of adding F once or twice daily to a linezolid (L) plus pyrazinamide (Z) backbone regimen. METHODS: In vitro studies were performed using the hollow fiber model of tuberculosis (HFS-TB) to compare the kill rates of: 1) ZL two-drug combination; 2) F administered once daily plus ZL (F(1)ZL); 3) F administered twice-daily plus once daily ZL (F(2)ZL); 4) F(2)ZL with high-dose Z (F(2)Z(hi)L); 5) standard therapy of isoniazid, rifampin and Z; and 6) non-treated controls. The study was performed over 56 days with three HFS-TB replicates for each regimen. RESULTS: Mtb in the non-treated HFS-TB grew at a rate of 0.018 ± 0.007 log(10) CFU/mL/day. The exponential kill rates for standard therapy were 6.6-13.2-fold higher than ZL dual therapy. The F(1)ZL and F(2)ZL regimens ranked third. The pre-existing isoniazid-resistant sub-population in the inoculum (1.34 ± 0.57 log(10) CFU/mL) grew to 4.21 ± 0.58 log(10) CFU/mL in 56 days in non-treated HFS-TB. However, no isoniazid-resistant sub-population was recorded in any of the FZL combination regimens. CONCLUSION: Due to the slow kill rate compared to standard therapy, FZL regimens are unlikely to shorten therapy duration. Efficacy of these regimens against drug-resistant tuberculosis needs to be determined.

Stavniichuk, R., DeLaForest, A., Thompson, C.A., Miller, J., Souza, R.F. and Battle, M.A. (2021). “GATA4 blocks squamous epithelial cell gene expression in human esophageal squamous cells.” Sci Rep 11(1): 3206.

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GATA4 promotes columnar epithelial cell fate during gastric development. When ectopically expressed in the developing mouse forestomach, the tissue emerges as columnar-like rather than stratified squamous with gene expression changes that parallel those observed in the pre-malignant squamous to columnar metaplasia known as Barrett’s esophagus (BE). GATA4 mRNA up-regulation and gene amplification occur in BE and its associated cancer, esophageal adenocarcinoma (EAC), and GATA4 gene amplification correlates with poor patient outcomes. Here, we explored the effect of ectopic expression of GATA4 in mature human esophageal squamous epithelial cells. We found that GATA4 expression in esophageal squamous epithelial cells compromised squamous cell marker gene expression and up-regulated expression of the canonical columnar cell cytokeratin KRT8. We observed GATA4 occupancy in the p63, KRT5, and KRT15 promoters, suggesting that GATA4 directly represses expression of squamous epithelial cell marker genes. Finally, we verified GATA4 protein expression in BE and EAC and found that exposure of esophageal squamous epithelial cells to acid and bile, known BE risk factors, induced GATA4 mRNA expression. We conclude that GATA4 suppresses expression of genes marking the stratified squamous epithelial cell lineage and that this repressive action by GATA4 may have implications in BE and EAC.

Pelletier, F., Perrier, S., Cayami, F.K., Mirchi, A., Saikali, S., Tran, L.T., Ulrick, N., Guerrero, K., Rampakakis, E., van Spaendonk, R.M.L., Naidu, S., Pohl, D., Gibson, W.T., Demos, M., Goizet, C., Tejera-Martin, I., Potic, A., Fogel, B.L., Brais, B., Sylvain, M., Sébire, G., Lourenço, C.M., Bonkowsky, J.L., Catsman-Berrevoets, C., Pinto, P.S., Tirupathi, S., Strømme, P., de Grauw, T., Gieruszczak-Bialek, D., Krägeloh-Mann, I., Mierzewska, H., Philippi, H., Rankin, J., Atik, T., Banwell, B., Benko, W.S., Blaschek, A., Bley, A., Boltshauser, E., Bratkovic, D., Brozova, K., Cimas, I., Clough, C., Corenblum, B., Dinopoulos, A., Dolan, G., Faletra, F., Fernandez, R., Fletcher, J., Garcia Garcia, M.E., Gasparini, P., Gburek-Augustat, J., Gonzalez Moron, D., Hamati, A., Harting, I., Hertzberg, C., Hill, A., Hobson, G.M., Innes, A.M., Kauffman, M., Kirwin, S.M., Kluger, G., Kolditz, P., Kotzaeridou, U., La Piana, R., Liston, E., McClintock, W., McEntagart, M., McKenzie, F., Melançon, S., Misbahuddin, A., Suri, M., Monton, F.I., Moutton, S., Murphy, R.P.J., Nickel, M., Onay, H., Orcesi, S., Özkınay, F., Patzer, S., Pedro, H., Pekic, S., Pineda Marfa, M., Pizzino, A., Plecko, B., Poll-The, B.T., Popovic, V., Rating, D., Rioux, M.F., Rodriguez Espinosa, N., Ronan, A., Ostergaard, J.R., Rossignol, E., Sanchez-Carpintero, R., Schossig, A., Senbil, N., Sønderberg Roos, L.K., Stevens, C.A., Synofzik, M., Sztriha, L., Tibussek, D., Timmann, D., Tonduti, D., van de Warrenburg, B.P., Vázquez-López, M., Venkateswaran, S., Wasling, P., Wassmer, E., Webster, R.I., Wiegand, G., Yoon, G., Rotteveel, J., Schiffmann, R., van der Knaap, M.S., Vanderver, A., Martos-Moreno, G., Polychronakos, C., Wolf, N.I. and Bernard, G. (2021). “Endocrine and Growth Abnormalities in 4H Leukodystrophy Caused by Variants in POLR3A, POLR3B, and POLR1C.” J Clin Endocrinol Metab 106(2): e660-e674.

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CONTEXT: 4H or POLR3-related leukodystrophy is an autosomal recessive disorder typically characterized by hypomyelination, hypodontia, and hypogonadotropic hypogonadism, caused by biallelic pathogenic variants in POLR3A, POLR3B, POLR1C, and POLR3K. The endocrine and growth abnormalities associated with this disorder have not been thoroughly investigated to date. OBJECTIVE: To systematically characterize endocrine abnormalities of patients with 4H leukodystrophy. DESIGN: An international cross-sectional study was performed on 150 patients with genetically confirmed 4H leukodystrophy between 2015 and 2016. Endocrine and growth abnormalities were evaluated, and neurological and other non-neurological features were reviewed. Potential genotype/phenotype associations were also investigated. SETTING: This was a multicenter retrospective study using information collected from 3 predominant centers. PATIENTS: A total of 150 patients with 4H leukodystrophy and pathogenic variants in POLR3A, POLR3B, or POLR1C were included. MAIN OUTCOME MEASURES: Variables used to evaluate endocrine and growth abnormalities included pubertal history, hormone levels (estradiol, testosterone, stimulated LH and FSH, stimulated GH, IGF-I, prolactin, ACTH, cortisol, TSH, and T4), and height and head circumference charts. RESULTS: The most common endocrine abnormalities were delayed puberty (57/74; 77% overall, 64% in males, 89% in females) and short stature (57/93; 61%), when evaluated according to physician assessment. Abnormal thyroid function was reported in 22% (13/59) of patients. CONCLUSIONS: Our results confirm pubertal abnormalities and short stature are the most common endocrine features seen in 4H leukodystrophy. However, we noted that endocrine abnormalities are typically underinvestigated in this patient population. A prospective study is required to formulate evidence-based recommendations for management of the endocrine manifestations of this disorder.

Ilardi, F., Santoro, C., Maréchal, P., Dulgheru, R., Postolache, A., Esposito, R., Giugliano, G., Sannino, A., Avvedimento, M., Leone, A., Cirillo, P., Stabile, E., Lancellotti, P. and Esposito, G. (2021). “Accuracy of global and regional longitudinal strain at peak of dobutamine stress echocardiography to detect significant coronary artery disease.” Int J Cardiovasc Imaging Jan 12;1-11. [Epub ahead of print]. 1-11.

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Dobutamine stress echocardiography (DSE) is sensitive but subjective diagnostic tool to detect inducible ischemia. Nowadays, speckle tracking allows an objective quantification of regional wall function. We aimed to investigate the feasibility and accuracy of global (GLS) and regional longitudinal strain (RLS) during DSE to detect significant coronary stenosis (SCS). We conducted a prospective observational multicenter study including patients undergoing DSE for suspected SCS. 50 patients with positive DSE underwent coronary angiography. Besides visual regional wall motion score index (WMSI), GLS and RLS were determined at rest and at peak stress by Automated Function Imaging. DSE GLS feasibility was 96%. Among 35 patients with SCS, 12 patients were affected by multivessel disease, 18 had stenosis of left anterior descending artery (LAD), 18 of left circumflex (LCX) and 15 of right coronary artery (RCA). At peak stress, both GLS reduction (p = 0.037) and WMSI worsening (p = 0.04) showed significant agreement with coronary angiography for detecting SCS. When single lesion was considered, peak stress GLS and LAD RLS were lower in the obstructed LAD regions than in normo-perfused territories (17.4 ± 5.5 vs. 20.5 ± 4.4%, p = 0.03; 17.1 ± 7.6 vs. 21.6 ± 5.5%, p < 0.02, respectively). Furthermore, the addition of RLS to regional WMSI was able to improve accuracy in LAD SCS prediction (AUC 0.68, p = 0.037). Conversely, in presence of LCX or RCA SCS, LS was less accurate than WMSI at peak stress. In conclusion, DSE strain analysis is feasible and may improve prediction of LAD SCS, whereas regional WMSI assessment performs better in presence of SCS of LCX and RCA.