Philana Ling Lin

Texas Children's Hospital, Houston, Texas, United States

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Publications (34)208.42 Total impact

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    ABSTRACT: While active tuberculosis (TB) is a treatable disease, many complex factors prevent its global elimination. Part of the difficulty in developing optimal therapies is the large design space of antibiotic doses, regimens and combinations. Computational models that capture the spatial and temporal dynamics of antibiotics at the site of infection can aid in reducing the design space of costly and time-consuming animal pre-clinical and human clinical trials. The site of infection in TB is the granuloma, a collection of immune cells and bacteria that form in the lung, and new data suggest that penetration of drugs throughout granulomas is problematic. Here we integrate our computational model of granuloma formation and function with models for plasma pharmacokinetics, lung tissue pharmacokinetics and pharmacodynamics for two first line anti-TB antibiotics. The integrated model is calibrated to animal data. We make four predictions. First, antibiotics are frequently below effective concentrations inside granulomas, leading to bacterial growth between doses and contributing to the long treatment periods required for TB. Second, antibiotic concentration gradients form within granulomas, with lower concentrations toward their centers. Third, during antibiotic treatment, bacterial subpopulations shift from mostly intracellular to mostly extracellular. These extracellular bacteria are located in areas non-permissive for replication (hypoxic areas), presenting a changing target population over time. Finally, we find that on an individual granuloma basis, pre-treatment infection severity (including bacterial burden, host cell activation and host cell death) is predictive of treatment outcome. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Journal of Theoretical Biology 12/2014; · 2.35 Impact Factor
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    ABSTRACT: Oxazolidinone antibiotics such as linezolid have shown significant therapeutic effects in patients with extensively drug-resistant (XDR) tuberculosis (TB) despite modest effects in rodents and no demonstrable early bactericidal activity in human phase 2 trials. We show that monotherapy with either linezolid or AZD5847, a second-generation oxazolidinone, reduced bacterial load at necropsy in Mycobacterium tuberculosis-infected cynomolgus macaques with active TB. This effect coincided with a decline in 2-deoxy-2-[(18)F]-fluoro-d-glucose positron emission tomography (FDG PET) imaging avidity in the lungs of these animals and with reductions in pulmonary pathology measured by serial computed tomography (CT) scans over 2 months of monotherapy. In a parallel phase 2 clinical study of linezolid in patients infected with XDR-TB, we also collected PET/CT imaging data from subjects receiving linezolid that had been added to their failing treatment regimens. Quantitative comparisons of PET/CT imaging changes in these human subjects were similar in magnitude to those observed in macaques, demonstrating that the therapeutic effect of these oxazolidinones can be reproduced in this model of experimental chemotherapy. PET/CT imaging may be useful as an early quantitative measure of drug efficacy against TB in human patients. Copyright © 2014, American Association for the Advancement of Science.
    Science translational medicine 12/2014; 6(265):265ra167. · 10.76 Impact Factor
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    ABSTRACT: Background: Invasive pneumococcal infections (IPI) due to Streptococcus pneumoniae serotype (ST) 3 have not declined as dramatically in children as other vaccine STs since the introduction in 2010 of the 13-valent pneumococcal conjugate vaccine, PCV13. While persistence of ST 3 isolates is likely due to capsule characteristics, genotypes with greater fitness may also emerge. We analyzed molecular characteristics of S. pneumoniae ST 3 isolates that were obtained from children with IPI. Methods: IPI cases at 8 children’s hospitals in the United States were prospectively identified from 2008-2013. ST 3 isolates were selected from the associated database. Isolates were typed by multilocus sequence typing (MLST). Select patient information was analyzed and antibiotic susceptibility patterns were compared. Statistical analysis included Wilcoxon rank-sum and Fisher's exact tests. Results: Sixty-three patients with 62 isolates were identified from the database (Table); 36 were male. Median age was 3.7y (0.1-17.6y). Disease presentations were pneumonia (n=33), meningitis (n=9), bacteremia (n=7), mastoiditis (n=6), cellulitis/abscess (n=7), and peritonitis (n=1). Twelve (19%) patients had an underlying condition. The MLSTs were 180 (n=58), 260, 338, 433 and 1116. The MLST distribution did not change over time. All isolates were penicillin and ceftriaxone susceptible. Only 3 were resistant to erythromycin and 2 were resistant to clindamycin. Table. Characteristics of pediatric serotype 3 infections, 2008-2013 Year Total invasive SPN Serotype 3 (% of total) MLST 180 Pneumonia (% of total serotype 3) Mean Age (years) 2008 197 11 (6%) 11 8 (73%) 3.1 2009 219 22 (10%) 20 7 (32%) 5.6 2010 165 8 (5%) 7 5 (63%) 3.4 2011 128 5 (4%) 4 1 (20%) 6.2 2012 112 6 (5%) 5 4 (67%) 5.7 2013 104 11 (11%) 11 8 (73%) 6.2 Total 925 63 58 33 5.0 Conclusion: ST 3 isolates chiefly caused pneumonia in this patient population and were mainly MLST180. MLST distribution did not change following introduction of PCV13. No statistical differences in distribution, age, disease presentation, age or, antibiotic susceptibility were observed. A modified vaccine, potentially including non-capsular antigens, is likely required to optimally reduce IPI due to ST 3 in children.
    IDWeek 2014 Meeting of the Infectious Diseases Society of America; 10/2014
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    ABSTRACT: Background: After the introduction of PCV7 the incidence of pediatric pneumococcal meningitis (PM) decreased significantly. The impact of PCV13 on PM in children is unknown. We compared the serotype (ST) distribution, antibiotic susceptibility and outcomes of children with PM 3 yrs before and 3 yrs after the introduction of PCV13. Methods: We identified patients ≤18 years with PM at 8 children's hospitals in the US (1/1/2007 - 12/31/2013). Pneumococcal isolates were collected prospectively. Serotyping and antibiotic susceptibility were performed in a central laboratory. Clinical and laboratory data were collected retrospectively. Patients were divided into 3 subgroups: pre-PCV13 (2007-2009), transitional year (2010) and post-PCV13 (2011-2013). Dichotomous variables were analyzed by Χ2 test and continuous variables with parametric/non-parametric tests. Results: During the study period, 173 of 1158 (15%) children with invasive pneumococcal disease (IPD) had PM; 76 of 644 (12%) during 2007-2009 and 69 of 344 (20%) during 2011-2013 (+8%, p<0.001) (Figure). We obtained clinical data from 125 patients (72%), of those 7 pneumococcal isolates were not viable for serotyping. In 2010, 22 cases were identified. 2007-2009 2011-2013 p N=103 56 47 Age, mo median (IQR) 16.8 (5-81) 16.3 (6-84) 0.9 Underlying condition (%) 16(29) 17(36) 0.4 CSF WBC (x103/mm3), median (IQR) 1.1 (0.1-2.9) 0.9 (0.1-2.8) 0.9 PCV13 ST 26/54 (48) 12/45 (27) 0.03 ST 19A 10/54 (19) 10/45 (22) 0.7 Penicillin MIC ≥0.12g/ml 13/54 (24) 14/45 (31) 0.4 Ceftriaxone MIC ≥0.5g/ml* 9/54 (17) 9/45 (20) 0.7 Death 1 (1.8) 5 (10.6) 0.08 Intensive care 33 (59) 38(81) 0.02 Fever after admission, days 3.22.4 4.73.7 0.02 *All ST 19A and 35B ST 7F decreased by 13% (p=0.02). The most common non-PCV13 STs during 2011-2013 were 33F (n=5; increased by 11%, p=0.02), 22F and 35B (n=4 each). Other measures of severity were similar during 2007-2009 and 2011-2013. Of all survivors, 46% had neurologic sequelae and 24% had sensorineural hearing loss. Rates of sequelae were similar among PCV13 and non-PCV13 ST cases; and during 2007-2009 and 2011-2013. Conclusion: After the introduction of PCV13, the number of cases of PM per year in children has remained unchanged, but with an increasing proportion of PM among children with IPD. ST 19A continues to be the most common ST in 2011-2013. Rates of morbidity and mortality remain substantial.
    IDWeek 2014 Meeting of the Infectious Diseases Society of America; 10/2014
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    ABSTRACT: Background: Following routine use of the 13-valent pneumococcal conjugate vaccine (PCV13, contains PCV7 serotypes [STs] + STs 1, 3, 5, 6A, 7F , 19A), invasive pneumococcal infections (IPI) declined over 40% in 2011 compared to the average number of cases in 2007 to 2009 at 8 children's hospitals in the United States. The most common STs causing IPI in 2011 were 19A, 7F and 33F (Pediatr Infect Dis J 2013;32:203-7). We now report findings for 2012 and 2013. Methods: IPI have been prospectively identified by investigators at 8 children's hospitals in the US since 1993. Demographic and clinical data are collected on case report forms and isolates are sent to a central laboratory where serotyping and antibiotic susceptibilities are performed. Dichotomous variables were analyzed by chi-square. Results: The total number of IPI, most common STs and % of children under 60 months old for each year is shown in the table. The total number of IPI has continued to decrease each year primarily related to declines in ST 19A (P=0.003) and 7F (P=0.02) isolates. However, ST 3 isolates remained at pre-PCV13 numbers. 9 children with ST 19A isolates and 4 children with ST 3 isolates had received 2 or more doses of PCV13 prior to IPI. In 2013, 3 of 12 children had received 4 PCV13 doses prior to ST19A IPI. Only 3 ST 1, 7 ST 19F, and 0 ST 5 isolates were encountered over these 3 years. STs 33F, 22F, 35B, 10, and 15C were the most common non-PCV13 STs. In 2012 and 2013, almost 75% of isolates were non-PCV13 STs. The % of children with underlying conditions was 45-46% each year. The most common conditions were malignancies (n=41), cardiovascular (n=15), genetic (n=14), renal (n=13) and central nervous system (n=10). Non-PCV13 STs accounted for 78% (32/144) of IPI isolates from children with underlying conditions. Isolates 2011 2012 2013 Total 128 112 104 19A 34 (2)* 16 (2) 12 (5) 3 5 (1) 6 (1) 11 (2) 7F 11 3 2 6C 5 3 5 33F 8 10 10 22F 5 9 8 35B 6 4 8 10 3 9 4 15C 3 8 3 23B 2 5 6 23A 4 6 2 12F 3 5 4 % non PCV13 54 73 74 % < 60 mon. 60 63 55 *() number of children who received ≥ 2 doses of PCV13 Conclusion: IPIs among 8 children's hospital continued to decline 2 and 3 years after full implementation of PCV13. STs 19A and 7F cases declined markedly whereas ST3 cases remained unchanged compared with pre-PCV13 findings. The number of non-PCV13 ST isolates has remained steady with STs 33F and 22F being the most common non-PCV13 STs in 2011 to 2013.
    IDWeek 2014 Meeting of the Infectious Diseases Society of America; 10/2014
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    ABSTRACT: Pneumonia remains a leading cause of morbidity and mortality despite advances in treatment and therapy. The "Pneumonia: Treatment and Diagnosis" session of the Pittsburgh International Lung Conference examined topics related to improving care of patients with pneumonia. These topics included the process and quality of care for community-acquired pneumonia (CAP), diagnosis and treatment of emerging fungal pathogens, an overview of the strengths and weaknesses of different diagnostic modalities, and an example of how basic science is exploring immunomodulatory strategies for pneumonia treatment. Systematic health care provider and institutional improvements can decrease mortality rates in CAP, particularly in patients with increasingly complex comorbidities. Aspects of current guidelines for the diagnosis and treatment of fungal pneumonia were reviewed through a series of case presentations. Proper treatment of pneumonia hinges on correct pathogen identification but is complicated by the variety of diagnostic assays with variable specificity, sensitivity, and interpretation. In addressing this topic, Dr. Patrick Murray, Ph.D., discussed a range of diagnostic tests for a variety of pathogens and guidelines for their use. In addition to the current state of CAP treatment, Bill (Beibei) Chen, M.D., Ph.D., presented a new potential therapeutic agent called forsythin, an immunomodulatory compound derived from a plant used in traditional Chinese medicine. These topics, ranging from institution-sized policy to interactions at the molecular scale, paint a broad perspective of the efforts against pneumonia.
    Annals of the American Thoracic Society. 08/2014; 11(Supplement 4):S189-S192.
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    ABSTRACT: Rationale: Cynomolgus macaques infected with low dose M. tuberculosis develop both active tuberculosis and latent infection similar to humans, providing an opportunity to study the clinically silent early events in infection. (18)Fluorodeoxyglucose radiotracer with positron emission tomography co-registered with computed tomography (FDG PET/CT) provides a non-invasive method to measure disease progression.Objectives: We sought to determine temporal patterns of granuloma evolution that distinguished active and latent outcomes.Methods and measurements: Macaques (n=10) were infected with low dose M. tuberculosis with FDG PET/CT performed during infection. At 24 weeks post infection, animals were classified as having active disease (n=3) or latent infection (n=6), with one "percolator" monkey (1). Imaging characteristics (e.g., lesion number, metabolic activity, size, mineralization, distribution of lesions) were compared among active and latent groups.Results: As early as 3 weeks post-infection, more pulmonary granulomas were observed in animals that would later develop active disease compared to those that would develop latent infection. Over time, new lesions developed in active disease animals, but not in latent animals. Granulomas and mediastinal lymph nodes from active disease but not latent animals consistently increased in metabolic activity at early time points.Conclusions: The presence of fewer lesions at 3 weeks and the lack of new lesion development in animals with latent infection suggest that innate and rapid adaptive responses are critical to preventing active tuberculosis. A greater emphasis on innate responses and/or rapid recruitment of adaptive responses, especially in the airway, should be emphasized in newer vaccine strategies.
    Infection and immunity 03/2014; · 4.21 Impact Factor
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    ABSTRACT: Over 30% of the world's population is infected with Mycobacterium tuberculosis (Mtb), yet only ∼5-10% will develop clinical disease. Despite considerable effort, researchers understand little about what distinguishes individuals whose infection progresses to active tuberculosis (TB) from those whose infection remains latent for decades. The variable course of disease is recapitulated in cynomolgus macaques infected with Mtb. Active disease occurs in ∼45% of infected macaques and is defined by clinical, microbiologic and immunologic signs, whereas the remaining infected animals are clinically asymptomatic. Here, we use individually marked Mtb isolates and quantitative measures of culturable and cumulative bacterial burden to show that most lung lesions are probably founded by a single bacterium and reach similar maximum burdens. Despite this observation, the fate of individual lesions varies substantially within the same host. Notably, in active disease, the host sterilizes some lesions even while others progress. Our data suggest that lesional heterogeneity arises, in part, through differential killing of bacteria after the onset of adaptive immunity. Thus, individual lesions follow diverse and overlapping trajectories, suggesting that critical responses occur at a lesional level to ultimately determine the clinical outcome of infection. Defining the local factors that dictate outcome will be useful in developing effective interventions to prevent active TB.
    Nature medicine 12/2013; · 27.14 Impact Factor
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    ABSTRACT: Trials to test new drugs currently in development against tuberculosis in humans are impractical. All animal models to prioritize new regimens are imperfect but non-human primates (NHP) infected with Mtb develop active tuberculosis (TB) disease with a full spectrum of lesion types seen in humans. Serial 2-deoxy -2-[(18)F]-D-deoxyglucose (FDG) positron emission tomography (PET) with computed tomography (CT) imaging was performed on cynomolgus macaques during infection and chemotherapy with individual agents or the four-drug combination therapy most widely used globally. Size and metabolic activity of lung granulomas varied among animals, and even within a single animal, during development of disease. Individual granulomas within untreated animals had highly local and independent outcomes, some progressing in size and FDG uptake while others waned, illustrating the highly dynamic nature of active TB. At necropsy even untreated animals were found to have a proportion of sterile lesions consistent with the dynamics of this infection. A more marked reduction in overall metabolic activity in the lungs (decreased FDG uptake) was associated with effective treatment. Reduction in size of individual lesions correlated with lower bacterial burden at necropsy. Isoniazid treatment was associated with a transient increase in metabolic activity in individual lesions whereas a net reduction occurred in most lesions from rifampin-treated animals. Quadruple-drug therapy resulted in the highest decrease in FDG uptake. PET/CT may be an important early correlate of efficacy of novel combinations of new drugs that can be directly translated to human clinical trials.
    Antimicrobial Agents and Chemotherapy 06/2013; · 4.57 Impact Factor
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    ABSTRACT: Macrophages in granulomas are both antimycobacterial effector and host cell for Mycobacterium tuberculosis, yet basic aspects of macrophage diversity and function within the complex structures of granulomas remain poorly understood. To address this, we examined myeloid cell phenotypes and expression of enzymes correlated with host defense in macaque and human granulomas. Macaque granulomas had upregulated inducible and endothelial NO synthase (iNOS and eNOS) and arginase (Arg1 and Arg2) expression and enzyme activity compared with nongranulomatous tissue. Immunohistochemical analysis indicated macrophages adjacent to uninvolved normal tissue were more likely to express CD163, whereas epithelioid macrophages in regions where bacteria reside strongly expressed CD11c, CD68, and HAM56. Calprotectin-positive neutrophils were abundant in regions adjacent to caseum. iNOS, eNOS, Arg1, and Arg2 proteins were identified in macrophages and localized similarly in granulomas across species, with greater eNOS expression and ratio of iNOS/Arg1 expression in epithelioid macrophages as compared with cells in the lymphocyte cuff. iNOS, Arg1, and Arg2 expression in neutrophils was also identified. The combination of phenotypic and functional markers support that macrophages with anti-inflammatory phenotypes localized to outer regions of granulomas, whereas the inner regions were more likely to contain macrophages with proinflammatory, presumably bactericidal, phenotypes. Together, these data support the concept that granulomas have organized microenvironments that balance antimicrobial anti-inflammatory responses to limit pathology in the lungs.
    The Journal of Immunology 06/2013; · 5.52 Impact Factor
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    ABSTRACT: Existing small animal models of tuberculosis (TB) rarely develop cavitary disease limiting their value for assessing the biology and dynamics of this highly important feature of human disease. To develop a smaller primate model with pathology similar to that seen in humans, we experimentally infected the common marmoset (Callithrix jacchus) with diverse strains of Mycobacterium tuberculosis (Mtb) of varying pathogenic potential. These included recent isolates of the modern Beijing lineage, the Euro-American X lineage, and M. africanum (Maf). All three strains produced fulminant disease in this animal with a spectrum of progression rates and clinical sequellae that could be monitored in real time using 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) positron emission tomography (PET)/computed tomography (CT). Lesion pathology at sacrifice revealed the entire spectrum of lesions observed in human TB patients. The three strains produced different rates of progression to disease, varying extents of extrapulmonary dissemination and varying degrees of cavitation. The majority of live births in this species are twins and comparison of results from siblings with different infecting strains allowed us to establish that the infection was highly reproducible and that the differential virulence of strains was not simply host variation. Quantitative assessment of disease burden by FDG-PET/CT provided an accurate reflection of the pathology findings at necropsy. These results suggest that the marmoset offers an attractive small animal model of human disease that recapitulates both the complex pathology and spectrum of disease observed in humans infected with various Mtb strain clades.
    Infection and immunity 05/2013; · 4.21 Impact Factor
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    ABSTRACT: BACKGROUND: Mycobacterial interspersed repetitive units (MIRUs) are minisatellites within the Mycobacterium tuberculosis (Mtb) genome. Copy number variation (CNV) in MIRU loci is used for epidemiological typing, making the rate of variation important for tracking the transmission of Mtb strains. In this study, we developed and assessed a whole-genome sequencing (WGS) approach to detect MIRU CNV in Mtb. We applied this methodology to a panel of Mtb strains isolated from the macaque model of tuberculosis (TB), the animal model that best mimics human disease. From these data, we have estimated the rate of MIRU variation in the host environment, providing a benchmark rate for future epidemiologic work. RESULTS: We assessed variation at the 24 MIRU loci used for typing in a set of Mtb strains isolated from infected cynomolgus macaques. We previously performed WGS of these strains and here have applied both read depth (RD) and paired-end mapping (PEM) metrics to identify putative copy number variants. To assess the relative power of these approaches, all MIRU loci were resequenced using Sanger sequencing. We detected two insertion/deletion events both of which could be identified as candidates by PEM criteria. With these data, we estimate a MIRU mutation rate of 2.70 x 10-03 (95% CI: 3.30 x 10-04- 9.80 x 10-03) per locus, per year. CONCLUSION: Our results represent the first experimental estimate of the MIRU mutation rate in Mtb. This rate is comparable to the highest previous estimates gathered from epidemiologic data and meta-analyses. Our findings allow for a more rigorous interpretation of data gathered from MIRU typing.
    BMC Genomics 03/2013; 14(1):145. · 4.40 Impact Factor
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    ABSTRACT: BACKGROUND:: The 13-valent pneumococcal conjugate vaccine (PCV13) was introduced for routine administration to infants and children in 2010 in the United States. We have monitored clinical and microbiologic features of invasive pneumococcal infections among children before and after PCV13 use. METHODS:: Infants and children cared for at 8 children hospitals in the United States with culture-proven invasive infections caused by S. pneumoniae were identified in an ongoing prospective surveillance study. Demographic and clinical data were recorded on a standard case report form. Serotype and antimicrobial susceptibilities of isolates were determined. RESULTS:: Since routine PCV13 immunization in 2010, invasive pneumococcal infections decreased 42% overall and 53% for children <24 months of age in 2011 compared with the average number of cases for 2007 to 2009. PCV13 serotype isolates decreased 57% during these same time periods; 19A, 7F and 3 decreased by 58%, 54% and 68%, respectively. The number of infections caused by serotypes 1 and 6C also decreased in 2011. The most common non-PCV13 serotypes encountered in 2010 and 2011 combined were 33F, 22F, 12, 15B, 15C, 23A and 11. Bacteremia, pneumonia and mastoiditis cases decreased more than meningitis cases. CONCLUSIONS:: After the introduction of PCV13, invasive pneumococcal infections decreased among 8 children hospitals compared with the 3 years before PCV13 use. Slight increases in some non-PCV13 serotype isolates were noted in 2011. Continued surveillance is necessary to determine the effectiveness of PCV13 including herd protection as well as any emerging invasive serotypes.
    The Pediatric Infectious Disease Journal 03/2013; 32(3):203-207. · 3.57 Impact Factor
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    ABSTRACT: Among 594 Streptococcus pneumoniae serotype 19A invasive pneumococcal disease (IPD) isolates from 1993-2011, we identified 85 sequence types (ST) by multilocus sequence typing (MLST). CC320 was associated with multidrug resistance and reduced susceptibility to penicillin and ceftriaxone and still predominated among declining serotype 19A IPD isolates following PCV13 introduction.
    Journal of clinical microbiology 02/2013; · 4.16 Impact Factor
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    ABSTRACT: Targeting Mycobacterium tuberculosis bacilli in low-oxygen microenvironments, such as caseous granulomas, has been hypothesized to have the potential to shorten therapy for active tuberculosis (TB) and prevent reactivation of latent infection. We previously reported that upon low-dose M. tuberculosis infection, equal proportions of cynomolgus macaques develop active disease or latent infection and that latently infected animals reactivated upon neutralization of TNF. Using this model we now show that chemoprophylaxis of latently infected cynomolgus macaques with 6 mo of isoniazid (INH) effectively prevented anti-TNF antibody-induced reactivation. Similarly, 2-mo treatment of latent animals with a combination of INH and rifampicin (RIF) was highly effective at preventing reactivation disease in this model. Metronidazole (MTZ), which has activity only against anaerobic, nonreplicating bacteria, was as effective as either of these treatments in preventing reactivation of latent infection. Because hypoxic lesions also occur during active TB, we further showed that addition of MTZ to INH/RIF effectively treated animals with active TB within 2 mo. Healing lesions were associated with distinct changes in cellular pathology, with a shift toward increasingly fibrotic and calcified lesions. Our data in the nonhuman primate model of active and latent TB supports targeting bacteria in hypoxic environments for preventing reactivation of latent infection and possibly shortening the duration of therapy in active TB.
    Proceedings of the National Academy of Sciences 07/2012; 109(35):14188-93. · 9.81 Impact Factor
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    ABSTRACT: Abstract CD4 T cells are believed to be important in protection against Mycobacterium tuberculosis, but the relative contribution to control of initial or latent infection is not known. Antibody-mediated depletion of CD4 T cells in M. tuberculosis-infected cynomolgus macaques was used to study the role of CD4 T cells during acute and latent infection. Anti-CD4 antibody severely reduced levels of CD4 T cells in blood, airways, and lymph nodes. Increased pathology and bacterial burden were observed in CD4-depleted monkeys during the first 8 weeks of infection compared to controls. CD4-depleted monkeys had greater interferon (IFN)-γ expression and altered expression of CD8 T cell activation markers. During latent infection, CD4 depletion resulted in clinical reactivation in only three of six monkeys. Reactivation was associated with lower CD4 T cells in the hilar lymph nodes. During both acute and latent infection, CD4 depletion was associated with reduced percentages of CXCR3(+) expressing CD8 T cells, reported to be involved in T cell recruitment, regulatory function, and effector and memory T cell maturation. CXCR3(+) CD8 T cells from hilar lymph nodes had more mycobacteria-specific cytokine expression and greater coexpression of multiple cytokines compared to CXCR3(-) CD8 T cells. CD4 T cells are required for protection against acute infection but reactivation from latent infection is dependent on the severity of depletion in the draining lymph nodes. CD4 depletion influences CD8 T cell function. This study has important implications for human HIV-M. tuberculosis coinfection.
    AIDS research and human retroviruses 04/2012; · 2.18 Impact Factor
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    ABSTRACT: It is estimated that one-third of the world's population is infected with Mycobacterium tuberculosis. Infection typically remains latent, but it can reactivate to cause clinical disease. The only vaccine, Mycobacterium bovis bacillus Calmette-Guérin (BCG), is largely ineffective, and ways to enhance its efficacy are being developed. Of note, the candidate booster vaccines currently under clinical development have been designed to improve BCG efficacy but not prevent reactivation of latent infection. Here, we demonstrate that administering a multistage vaccine that we term H56 in the adjuvant IC31 as a boost to vaccination with BCG delays and reduces clinical disease in cynomolgus macaques challenged with M. tuberculosis and prevents reactivation of latent infection. H56 contains Ag85B and ESAT-6, which are two of the M. tuberculosis antigens secreted in the acute phase of infection, and the nutrient stress-induced antigen Rv2660c. Boosting with H56/IC31 resulted in efficient containment of M. tuberculosis infection and reduced rates of clinical disease, as measured by clinical parameters, inflammatory markers, and improved survival of the animals compared with BCG alone. Boosted animals showed reduced pulmonary pathology and extrapulmonary dissemination, and protection correlated with a strong recall response against ESAT-6 and Rv2660c. Importantly, BCG/H56-vaccinated monkeys did not reactivate latent infection after treatment with anti-TNF antibody. Our results indicate that H56/IC31 boosting is able to control late-stage infection with M. tuberculosis and contain latent tuberculosis, providing a rationale for the clinical development of H56.
    The Journal of clinical investigation 12/2011; 122(1):303-14. · 15.39 Impact Factor
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    ABSTRACT: Tuberculosis poses a global health emergency, which has been compounded by the emergence of drug-resistant Mycobacterium tuberculosis (Mtb) strains. We used whole-genome sequencing to compare the accumulation of mutations in Mtb isolated from cynomolgus macaques with active, latent or reactivated disease. We sequenced 33 Mtb isolates from nine macaques with an average genome coverage of 93% and an average read depth of 117×. Based on the distribution of SNPs observed, we calculated the mutation rates for these disease states. We found a similar mutation rate during latency as during active disease or in a logarithmically growing culture over the same period of time. The pattern of polymorphisms suggests that the mutational burden in vivo is because of oxidative DNA damage. We show that Mtb continues to acquire mutations during disease latency, which may explain why isoniazid monotherapy for latent tuberculosis is a risk factor for the emergence of isoniazid resistance.
    Nature Genetics 05/2011; 43(5):482-6. · 35.21 Impact Factor
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    ABSTRACT: Streptococcus pneumoniae serotype 6C, which was described in 2007, causes invasive disease in adults and children. We investigated the prevalence of 6C among pediatric isolates obtained from eight children's hospitals in the United States. S. pneumoniae isolates were identified from a prospective multicenter study (1993 to 2009). Fifty-seven serotype 6C isolates were identified by multiplex PCR and/or Quellung reaction. Five were isolated before 2000, and the prevalence increased over time (P < 0.000001). The median patient age was 2.1 years (range, 0.2 to 22.5 years). Clinical presentations included bacteremia (n = 24), meningitis (n = 7), pneumonia (n = 4), abscess/wound (n = 3), mastoiditis (n = 2), cellulitis (n = 2), peritonitis (n = 1), septic arthritis (n = 1), otitis media (n = 10), and sinusitis (n = 3). By broth microdilution, 43/44 invasive serotype 6C isolates were susceptible to penicillin (median MIC, 0.015 μg/ml; range, 0.008 to 2 μg/ml); all were susceptible to ceftriaxone (median MIC, 0.015 μg/ml; range, 0.008 to 1 μg/ml). By disk diffusion, 16/44 invasive isolates (36%) were nonsusceptible to erythromycin, 19 isolates (43%) were nonsusceptible to trimethoprim-sulfamethoxazole (TMP-SMX), and all isolates were clindamycin susceptible. Multilocus sequence typing (MLST) revealed 24 sequence types (STs); 9 were new to the MLST database. The two main clonal clusters (CCs) were ST473 and single-locus variants (SLVs) (n = 13) and ST1292 and SLVs (n = 23). ST1292 and SLVs had decreased antibiotic susceptibility. Serotype 6C causes disease in children in the United States. Emerging CC1292 expressed TMP-SMX resistance and decreased susceptibility to penicillin and ceftriaxone. Continued surveillance is needed to monitor changes in serotype prevalence and possible emergence of antibiotic resistance in pediatric pneumococcal disease.
    Journal of clinical microbiology 03/2011; 49(6):2097-101. · 4.16 Impact Factor
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    ABSTRACT: Understanding the early immunologic events accompanying reactivated tuberculosis (TB) in HIV-infected individuals may yield insight into causes of reactivation and improve treatment modalities. We used the cynomolgus macaque (Macaca fascicularis) model of HIV-Mycobacterium tuberculosis coinfection to investigate the dynamics of multifunctional T cell responses and granuloma T cell phenotypes in reactivated TB. CD4(+) and CD8(+) T cells expressing Th1 cytokines (IFN-γ, IL-2, TNF) and Th2 cytokines (IL-4 and IL-10) were followed from latent M. tuberculosis infection to reactivation after coinfection with a pathogenic SIV. Coinfected animals experienced increased Th1 cytokine responses to M. tuberculosis Ags above the latent-response baseline 3-5 wk post-SIV infection that corresponded with peak plasma viremia. Th2 cytokine expression was not Ag specific, but strong, transient IL-4 expression was noted 4-7 wk post-SIV infection. Animals reactivating <17 wk post-SIV infection had significantly more multifunctional CD4(+) T cells 3-5 wk post-SIV infection and more Th2-polarized and fewer Th0-, Th1-polarized CD8(+) T cells during weeks 1-10 post-SIV infection than animals reactivating >26 wk post-SIV infection. Granuloma T cells included Th0-, Th1-, and Th2-polarized phenotypes but were particularly rich in cytolytic (CD107(+)) T cells. When combined with the changes in peripheral blood T cells, these factors indicate that events during acute HIV infection are likely to include distortions in proinflammatory and anti-inflammatory T cell responses within the granuloma that have significant effects on reactivation of latent TB. Moreover, it appears that mycobacteria-specific multifunctional T cells are better correlates of Ag load (i.e., disease status) than of protection.
    The Journal of Immunology 02/2011; 186(6):3527-37. · 5.52 Impact Factor

Publication Stats

943 Citations
208.42 Total Impact Points

Institutions

  • 2013
    • Texas Children's Hospital
      Houston, Texas, United States
  • 2004–2013
    • University of Pittsburgh
      • • Department of Microbiology and Molecular Genetics
      • • Department of Pediatrics
      • • Division of Pediatric Pathology at Children's Hospital of Pittsburgh of UPMC
      Pittsburgh, PA, United States
  • 2003–2013
    • Childrens Hospital of Pittsburgh
      • • Department of Pediatrics
      • • Division of Pediatric Infectious Diseases
      Pittsburgh, Pennsylvania, United States
  • 2010
    • Riley Hospital for Children
      Indianapolis, Indiana, United States
  • 2008
    • Hospital of the University of Pennsylvania
      Philadelphia, Pennsylvania, United States