51
|
Mitchell AP, Dey P, Ohn JA, Tabatabai SM, Curry MA, Bach PB. The Accuracy and Usefulness of the National Comprehensive Cancer Network Evidence Blocks Affordability Rating. PHARMACOECONOMICS 2020; 38:737-745. [PMID: 32201922 PMCID: PMC8357422 DOI: 10.1007/s40273-020-00901-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
BACKGROUND The National Comprehensive Cancer Network (NCCN) Guidelines' Evidence Blocks has the broadest scope of the several oncology value assessment frameworks. The Evidence Blocks includes the Affordability criterion, which reflects the financial cost of each treatment on a 1-5 scale. The accuracy of Affordability is unknown. METHODS We calculated Medicare costs for all first-line and maintenance treatments for the 30 cancers with the highest incidence in the USA that had published NCCN Evidence Blocks as of 31 December 2018. We assessed the accuracy and consistency of Affordability across different treatments and cancer types. Among different treatments for the same indication, we determined the frequency with which the Affordability assessment was consistent with calculated treatment costs. RESULTS There were a total of 1386 treatments in our sample. Lower Affordability scores were associated with higher costs. There was significant variation in cost at each level of Affordability; for treatments with Affordability = 1 (very expensive), costs ranged from $US4551 to $US43,794 per month for treatments administered over an undefined time period and from $US2865 to $US500,982 per course of therapy for treatments administered over a defined time period. Among treatments for the same indication, Affordability was discrepant with calculated treatment costs in 7.9% of pairwise comparisons, identifying the higher-cost treatment as being more affordable. Discrepancies were reduced when we reassigned Affordability scores based on calculated treatment costs. CONCLUSIONS Evidence Blocks Affordability generally correlated with treatment costs but contained discrepancies, which may limit its usefulness to clinicians in comparing costs. This study suggests that the Affordability score may be improved by indexing more directly to specified dollar value thresholds.
Collapse
|
52
|
Lanni F, Lagree K, Huang MY, Yan L, Woolford CA, Mitchell AP. Clarifying and Imaging Candida albicans Biofilms. J Vis Exp 2020. [PMID: 32202525 DOI: 10.3791/60718] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The microbial fungus Candida albicans can undergo a change from commensal colonization to virulence that is strongly correlated with its ability to switch from yeast-form growth to hyphal growth. Cells initiating this process become adherent to surfaces as well as to each other, with the resulting development of a biofilm colony. This commonly occurs not only on mucosal tissue surfaces in yeast infections, but also on medical implants such as catheters. It is well known that biofilm cells are resistant to antifungal drugs, and that cells that shed from the biofilm can lead to dangerous systemic infections. Biofilms range from heavily translucent to opaque due to refractive heterogeneity. Therefore, fungal biofilms are difficult to study by optical microscopy. To visualize internal structural, cellular, and subcellular features, we clarify fixed intact biofilms by stepwise solvent exchange to a point of optimal refractive index matching. For C. albicans biofilms, sufficient clarification is attained with methyl salicylate (n = 1.537) to enable confocal microscopy from apex to base in 600 µm biofilms with little attenuation. In this visualization protocol we outline phase contrast refractometry, the growth of laboratory biofilms, fixation, staining, solvent exchange, the setup for confocal fluorescence microscopy, and representative results.
Collapse
|
53
|
Mitchell AP, Rotter JS, Patel E, Richardson D, Wheeler SB, Basch E, Goldstein DA. Association Between Reimbursement Incentives and Physician Practice in Oncology: A Systematic Review. JAMA Oncol 2020; 5:893-899. [PMID: 30605222 DOI: 10.1001/jamaoncol.2018.6196] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Importance Significant controversy exists regarding whether physicians factor personal financial considerations into their clinical decision making. Within oncology, several reimbursement policies may incentivize physicians to increase health care use. Objective To evaluate whether the financial incentives presented by oncology reimbursement policies affect physician practice patterns. Evidence Review Studies evaluating an association between reimbursement incentives and changes in reimbursement policy on oncology care delivery were reviewed. Articles were identified systematically by searching PubMed/MEDLINE, Web of Science, Proquest Health Management, Econlit, and Business Source Premier. English-language articles focused on the US health care system that made empirical estimates of the association between a measurement of physician reimbursement/compensation and a measurement of delivery of cancer treatment services were included. The Risk of Bias in Non-Randomized Studies of Interventions tool was used to assess risk of bias. There were no date restrictions on the publications, and literature searches were finalized on February 14, 2018. Findings Eighteen studies were included. All were observational cohort studies, and most had a moderate risk of bias. Heterogeneity of reimbursement policies and outcomes precluded meta-analysis; therefore, a qualitative synthesis was performed. Most studies (15 of 18 [83%]) reported an association between reimbursement and care delivery consistent with physician responsiveness to financial incentives, although such an association was not identified in all studies. Findings consistently suggested that self-referral arrangements may increase use of radiotherapy and that profitability of systemic anticancer agents may affect physicians' choice of drug. Findings were less conclusive as to whether profitability of systemic anticancer therapy affects the decision of whether to use any systemic therapy. Conclusions and Relevance To date, this study is the first systematic review of reimbursement policy and clinical care delivery in oncology. The findings suggest that some oncologists may, in certain circumstances, alter treatment recommendations based on personal revenue considerations. An implication of this finding is that value-based reimbursement policies may be a useful tool to better align physician incentives with patient need and increase the value of oncology care.
Collapse
|
54
|
Lagree K, Woolford CA, Huang MY, May G, McManus CJ, Solis NV, Filler SG, Mitchell AP. Roles of Candida albicans Mig1 and Mig2 in glucose repression, pathogenicity traits, and SNF1 essentiality. PLoS Genet 2020; 16:e1008582. [PMID: 31961865 PMCID: PMC6994163 DOI: 10.1371/journal.pgen.1008582] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 01/31/2020] [Accepted: 12/20/2019] [Indexed: 12/16/2022] Open
Abstract
Metabolic adaptation is linked to the ability of the opportunistic pathogen Candida albicans to colonize and cause infection in diverse host tissues. One way that C. albicans controls its metabolism is through the glucose repression pathway, where expression of alternative carbon source utilization genes is repressed in the presence of its preferred carbon source, glucose. Here we carry out genetic and gene expression studies that identify transcription factors Mig1 and Mig2 as mediators of glucose repression in C. albicans. The well-studied Mig1/2 orthologs ScMig1/2 mediate glucose repression in the yeast Saccharomyces cerevisiae; our data argue that C. albicans Mig1/2 function similarly as repressors of alternative carbon source utilization genes. However, Mig1/2 functions have several distinctive features in C. albicans. First, Mig1 and Mig2 have more co-equal roles in gene regulation than their S. cerevisiae orthologs. Second, Mig1 is regulated at the level of protein accumulation, more akin to ScMig2 than ScMig1. Third, Mig1 and Mig2 are together required for a unique aspect of C. albicans biology, the expression of several pathogenicity traits. Such Mig1/2-dependent traits include the abilities to form hyphae and biofilm, tolerance of cell wall inhibitors, and ability to damage macrophage-like cells and human endothelial cells. Finally, Mig1 is required for a puzzling feature of C. albicans biology that is not shared with S. cerevisiae: the essentiality of the Snf1 protein kinase, a central eukaryotic carbon metabolism regulator. Our results integrate Mig1 and Mig2 into the C. albicans glucose repression pathway and illuminate connections among carbon control, pathogenicity, and Snf1 essentiality. All organisms tailor genetic programs to the available nutrients, such as sources of carbon. Here we define two key regulators of the genetic programs for carbon source utilization in the fungal pathogen Candida albicans. The two regulators have many shared roles, yet are partially specialized to control carbon acquisition and metabolism, respectively. In addition, the regulators together control traits associated with pathogenicity, an indication that carbon regulation is integrated into the pathogenicity program. Finally, the regulators help to explain a long-standing riddle—that the central carbon regulator Snf1 is essential for C. albicans viability.
Collapse
|
55
|
Mitchell AP, Kinlaw AC, Peacock‐Hinton S, Dusetzina SB, Sanoff HK, Lund JL. Use of High-Cost Cancer Treatments in Academic and Nonacademic Practice. Oncologist 2020; 25:46-54. [PMID: 31611329 PMCID: PMC6964140 DOI: 10.1634/theoncologist.2019-0338] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 08/21/2019] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Academic physicians, such as those affiliated with National Cancer Institute (NCI)-designated Comprehensive Cancer Centers, may have different practice patterns regarding the use of high-cost cancer drugs than nonacademic physicians. MATERIALS AND METHODS For this cohort study, we linked cancer registry, administrative, and demographic data for patients with newly diagnosed cancer in North Carolina from 2004 to 2011. We selected cancer types with multiple U.S. Food and Drug Administration-approved, National Comprehensive Cancer Network-recommended treatment options and large differences in reimbursement between higher-priced and lower-priced options (stage IV colorectal, stage IV lung, and stage II-IV head-and-neck cancers). We assessed whether provider's practice setting-NCI-designated Comprehensive Cancer Center ("NCI") versus other location ("non-NCI")-was associated with use of higher-cost treatment options. We used inverse probability of exposure weighting to control for patient characteristics. RESULTS Of 800 eligible patients, 79.6% were treated in non-NCI settings. Patients treated in non-NCI settings were more likely to receive high-cost treatment than patients treated in NCI settings (36.0% vs. 23.2%), with an unadjusted prevalence difference of 12.7% (95% confidence interval [CI], 5.1%-20.0%). After controlling for potential confounding factors, non-NCI patients remained more likely to receive high-cost treatment, although the strength of association was attenuated (adjusted prevalence difference, 9.6%; 95% CI -0.1%-18.7%). Exploratory analyses suggested potential heterogeneity across cancer type and insurance status. CONCLUSION Use of higher-cost cancer treatments may be more common in non-NCI than NCI settings. This may reflect differential implementation of clinical evidence, local practice variation, or possibly a response to the reimbursement incentives presented by chemotherapy billing. IMPLICATIONS FOR PRACTICE Oncology care delivery and practice patterns may vary between care settings. By comparing otherwise similar patients treated in National Cancer Institute (NCI)-designated Comprehensive Cancer Centers with those treated elsewhere, this study suggests that patients may be more likely to receive treatment with certain expensive cancer drugs if treated in the non-NCI setting. These practice differences may result in differences in patient costs and outcomes as a result of where they receive treatment.
Collapse
|
56
|
Witchley JN, Penumetcha P, Abon NV, Woolford CA, Mitchell AP, Noble SM. Candida albicans Morphogenesis Programs Control the Balance between Gut Commensalism and Invasive Infection. Cell Host Microbe 2019; 25:432-443.e6. [PMID: 30870623 DOI: 10.1016/j.chom.2019.02.008] [Citation(s) in RCA: 140] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 11/11/2018] [Accepted: 02/21/2019] [Indexed: 01/12/2023]
Abstract
Candida albicans is a gut commensal and opportunistic pathogen. The transition between yeast and invasive hyphae is central to virulence but has unknown functions during commensal growth. In a mouse model of colonization, yeast and hyphae co-occur throughout the gastrointestinal tract. However, competitive infections of C. albicans homozygous gene disruption mutants revealed an unanticipated, inhibitory role for the yeast-to-hypha morphogenesis program on commensalism. We show that the transcription factor Ume6, a master regulator of filamentation, inhibits gut colonization, not by effects on cell shape, but by activating the expression of a hypha-specific pro-inflammatory secreted protease, Sap6, and a hyphal cell surface adhesin, Hyr1. Like a ume6 mutant, strains lacking SAP6 exhibit enhanced colonization fitness, whereas SAP6-overexpression strains are attenuated in the gut. These results reveal a tradeoff between fungal programs supporting commensalism and virulence in which selection against hypha-specific markers limits the disease-causing potential of this ubiquitous commensal-pathogen.
Collapse
|
57
|
Huang MY, Woolford CA, May G, McManus CJ, Mitchell AP. Circuit diversification in a biofilm regulatory network. PLoS Pathog 2019; 15:e1007787. [PMID: 31116789 PMCID: PMC6530872 DOI: 10.1371/journal.ppat.1007787] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 04/23/2019] [Indexed: 11/18/2022] Open
Abstract
Genotype-phenotype relationships can vary extensively among members of a species. One cause of this variation is circuit diversification, the alteration of gene regulatory relationships among members of a species. Circuit diversification is thought to be a starting point for the circuit divergence or rewiring that occurs during speciation. How widespread is circuit diversification? Here we address this question with the fungal pathogen Candida albicans, which forms biofilms rich in distinctive hyphal cells as a prelude to infection. Our understanding of the biofilm/hyphal regulatory network comes primarily from studies of one clinical isolate, strain SC5314, and its marked derivatives. We used CRISPR-based methods to create mutations of four key biofilm transcription factor genes–BCR1, UME6, BRG1, and EFG1 –in SC5314 and four additional clinical isolates. Phenotypic analysis revealed that mutations in BCR1 or UME6 have variable impact across strains, while mutations in BRG1 or EFG1 had uniformly severe impact. Gene expression, sampled with Nanostring probes and examined comprehensively for EFG1 via RNA-Seq, indicates that regulatory relationships are highly variable among isolates. Our results suggest that genotype-phenotype relationships vary in this strain panel in part because of differences in control of BRG1 by BCR1, a hypothesis that is supported through engineered constitutive expression of BRG1. Overall, the data show that circuit diversification is the rule, not the exception, in this biofilm/hyphal regulatory network. Much of what we know about microbial pathogens is derived from in-depth analysis of one or a few standard laboratory strains. This statement is especially true for the fungal pathogen Candida albicans, because most studies have centered on strain SC5314 and its genetically marked derivatives. Here we examine the functional impact of mutations of four key biofilm regulators across five different clinical isolates. We observe that functional impact of the mutations, based on biological phenotypes and gene expression effects, varies extensively among the isolates. Our results support the idea that gene function should be validated with multiple strain isolates. In addition, our results indicate that a core regulatory network, which comprises regulatory relationships common to multiple isolates, may be enriched for functionally relevant genes.
Collapse
|
58
|
Mitchell AP, Winn AN, Lund JL, Dusetzina SB. Evaluating the Strength of the Association Between Industry Payments and Prescribing Practices in Oncology. Oncologist 2019; 24:632-639. [PMID: 30728276 DOI: 10.1634/theoncologist.2018-0423] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 11/30/2018] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Financial relationships between physicians and the pharmaceutical industry are common, but factors that may determine whether such relationships result in physician practice changes are unknown. MATERIALS AND METHODS We evaluated physician use of orally administered cancer drugs for four cancers: prostate (abiraterone, enzalutamide), renal cell (axitinib, everolimus, pazopanib, sorafenib, sunitinib), lung (afatinib, erlotinib), and chronic myeloid leukemia (CML; dasatinib, imatinib, nilotinib). Separate physician cohorts were defined for each cancer type by prescribing history. The primary exposure was the number of calendar years during 2013-2015 in which a physician received payments from the manufacturer of one of the studied drugs; the outcome was relative prescribing of that drug in 2015, compared with the other drugs for that cancer. We evaluated whether practice setting at a National Cancer Institute (NCI)-designated Comprehensive Cancer Center, receipt of payments for purposes other than education or research (compensation payments), maximum annual dollar value received, and institutional conflict-of-interest policies were associated with the strength of the payment-prescribing association. We used modified Poisson regression to control confounding by other physician characteristics. RESULTS Physicians who received payments for a drug in all 3 years had increased prescribing of that drug (compared with 0 years), for renal cell (relative risk [RR] 1.81, 95% confidence interval [CI] 1.58-2.07), CML (RR 1.22, 95% CI 1.08-1.39), and lung (RR 1.69, 95% CI 1.58-1.82), but not prostate (RR 0.97, 95% CI 0.93-1.02). Physicians who received compensation payments or >$100 annually had increased prescribing compared with those who did not, but NCI setting and institutional conflict-of-interest policies were not consistently associated with the direction of prescribing change. CONCLUSION The association between industry payments and cancer drug prescribing was greatest among physicians who received payments consistently (within each calendar year). Receipt of payments for compensation purposes, such as for consulting or travel, and higher dollar value of payments were also associated with increased prescribing. IMPLICATIONS FOR PRACTICE Financial payments from pharmaceutical companies are common among oncologists. It is known from prior work that oncologists tend to prescribe more of the drugs made by companies that have given them money. By combining records of industry gifts with prescribing records, this study identifies the consistency of payments over time, the dollar value of payments, and payments for compensation as factors that may strengthen the association between receiving payments and increased prescribing of that company's drug.
Collapse
|
59
|
Lagree K, Mon HH, Mitchell AP, Ducker WA. Impact of surface topography on biofilm formation by Candida albicans. PLoS One 2018; 13:e0197925. [PMID: 29912894 PMCID: PMC6005505 DOI: 10.1371/journal.pone.0197925] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 05/10/2018] [Indexed: 11/27/2022] Open
Abstract
Candida albicans is a fungal pathogen that causes serious biofilm-based infections. Here we have asked whether surface topography may affect C. albicans biofilm formation. We tested biofilm growth of the prototypical wild-type strain SC5314 on a series of polydimethylsiloxane (PDMS) solids. The surfaces were prepared with monolayer coatings of monodisperse spherical silica particles that were fused together into a film using silica menisci. The surface topography was varied by varying the diameter of the silica particles that were used to form the film. Biofilm formation was observed to be a strong function of particle size. In the particle size range 4.0-8.0 μm, there was much more biofilm than in the size range 0.5-2.0 μm. The behavior of a clinical isolate from a clade separate from SC5314, strain p76067, showed results similar to that of SC5314. Our results suggest that topographic coatings may be a promising approach to reduce C. albicans biofilm infections.
Collapse
|
60
|
Mitchell AP, Winn AN, Dusetzina SB. Pharmaceutical Industry Payments and Oncologists' Selection of Targeted Cancer Therapies in Medicare Beneficiaries. JAMA Intern Med 2018; 178:854-856. [PMID: 29630687 PMCID: PMC6145757 DOI: 10.1001/jamainternmed.2018.0776] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
This study examines the association between oncologists’ receipt of payments from pharmaceutical manufacturers and drug selection in 2 situations where there are multiple treatment options.
Collapse
|
61
|
Dominguez E, Zarnowski R, Sanchez H, Covelli AS, Westler WM, Azadi P, Nett J, Mitchell AP, Andes DR. Conservation and Divergence in the Candida Species Biofilm Matrix Mannan-Glucan Complex Structure, Function, and Genetic Control. mBio 2018; 9:e00451-18. [PMID: 29615504 PMCID: PMC5885036 DOI: 10.1128/mbio.00451-18] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 03/01/2018] [Indexed: 01/18/2023] Open
Abstract
Candida biofilms resist the effects of available antifungal therapies. Prior studies with Candida albicans biofilms show that an extracellular matrix mannan-glucan complex (MGCx) contributes to antifungal sequestration, leading to drug resistance. Here we implement biochemical, pharmacological, and genetic approaches to explore a similar mechanism of resistance for the three most common clinically encountered non-albicansCandida species (NAC). Our findings reveal that each Candida species biofilm synthesizes a mannan-glucan complex and that the antifungal-protective function of this complex is conserved. Structural similarities extended primarily to the polysaccharide backbone (α-1,6-mannan and β-1,6-glucan). Surprisingly, biochemical analysis uncovered stark differences in the branching side chains of the MGCx among the species. Consistent with the structural analysis, similarities in the genetic control of MGCx production for each Candida species also appeared limited to the synthesis of the polysaccharide backbone. Each species appears to employ a unique subset of modification enzymes for MGCx synthesis, likely accounting for the observed side chain diversity. Our results argue for the conservation of matrix function among Candida spp. While biogenesis is preserved at the level of the mannan-glucan complex backbone, divergence emerges for construction of branching side chains. Thus, the MGCx backbone represents an ideal drug target for effective pan-Candida species biofilm therapy.IMPORTANCECandida species, the most common fungal pathogens, frequently grow as a biofilm. These adherent communities tolerate extremely high concentrations of antifungal agents, due in large part, to a protective extracellular matrix. The present studies define the structural, functional, and genetic similarities and differences in the biofilm matrix from the four most common Candida species. Each species synthesizes an extracellular mannan-glucan complex (MGCx) which contributes to sequestration of antifungal drug, shielding the fungus from this external assault. Synthesis of a common polysaccharide backbone appears conserved. However, subtle structural differences in the branching side chains likely rely upon unique modification enzymes, which are species specific. Our findings identify MGCx backbone synthesis as a potential pan-Candida biofilm therapeutic target.
Collapse
|
62
|
Liu H, Xu W, Solis NV, Woolford C, Mitchell AP, Filler SG. Functional convergence of gliP and aspf1 in Aspergillus fumigatus pathogenicity. Virulence 2018; 9:1062-1073. [PMID: 30052103 PMCID: PMC6086310 DOI: 10.1080/21505594.2018.1482182] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 05/25/2018] [Indexed: 10/28/2022] Open
Abstract
Gliotoxin contributes to the virulence of the fungus Aspergillus fumigatus in non-neutropenic mice that are immunosuppressed with corticosteroids. To investigate how the absence of gliotoxin affects both the fungus and the host, we used a nanoString nCounter to analyze their transcriptional responses during pulmonary infection of a non-neutropenic host with a gliotoxin-deficient ΔgliP mutant. We found that the ΔgliP mutation led to increased expression of aspf1, which specifies a secreted ribotoxin. Prior studies have shown that aspf1, like gliP, is not required for virulence in a neutropenic infection model, but its role in a non-neutropenic infection model has not been fully investigated. To investigate the functional significance of this up-regulation of aspf1, a Δaspf1 single mutant and a Δaspf1 ΔgliP double mutant were constructed. Both Δaspf1 and ΔgliP single mutants had reduced lethality in non-neutropenic mice, and a Δaspf1 ΔgliP double mutant had a greater reduction in lethality than either single mutant. Analysis of mice infected with these mutants indicated that the presence of gliP is associated with massive apoptosis of leukocytes at the foci of infection and inhibition of chemokine production. Also, the combination of gliP and aspf1 is associated with suppression of CXCL1 chemokine expression. Thus, aspf1 contributes to A. fumigatus pathogenicity in non-neutropenic mice and its up-regulation in the ΔgliP mutant may partially compensate for the absence of gliotoxin. ABBREVIATIONS PAS: periodic acid-Schiff; PBS: phosphate buffered saline; ROS: reactive oxygen species; TUNEL: terminal deoxynucleotidyl transferase dUTP nick-end labeling.
Collapse
|
63
|
Mitchell AP, Boggan JC, Lau K, Simel DL. Splenectomy as a Destination: Improving Quality of Care Among Asplenic Veterans Through a Travel Clinic. Am J Med 2017; 130:856-861. [PMID: 28213046 DOI: 10.1016/j.amjmed.2017.01.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 09/28/2016] [Accepted: 01/24/2017] [Indexed: 11/30/2022]
Abstract
BACKGROUND Asplenic patients are at risk for severe infections, but adherence to recommended preventive education and vaccination is poor. The goal of this study was to demonstrate that a targeted intervention can improve vaccination rates in a population of asplenic veterans. METHODS Surgically asplenic patients actively receiving care in our health care system were identified via a database search. Patients were contacted via mailed letters and encouraged to attend an existing travel clinic with a new process designed for asplenic patients. In the clinic, patients were educated on the risks of asplenia and proper preventive precautions, a vaccination history was taken, and patients were administered any additional indicated vaccines. RESULTS The database search yielded 113 patients; an additional 14 asplenic patients were identified and referred to the clinic by providers, and 2 were referred prior to planned splenectomy. Among all asplenic patients, the first-year referral rate to clinic was 38/129 (29%). During the first year of the intervention, there were increases in the rates of 3 of 4 recommended vaccinations: pneumococcal conjugate, 19% to 55% (P <.001); Haemophilus influenzae type B, 19% to 35% (P = .007); and meningococcal vaccine, 24% to 43% (P = .002). The pneumococcal polysaccharide vaccination rate increased from 91% to 93% (P = .62). CONCLUSIONS Targeted interventions can improve guideline-based care for asplenic patients. The creation of a clinic designed for asplenic patients led to increases in 3 of 4 recommended vaccinations. This strategy may be applicable to other health care systems with similar numbers of asplenic patients.
Collapse
|
64
|
Cuevas RA, Eutsey R, Kadam A, West-Roberts JA, Woolford CA, Mitchell AP, Mason KM, Hiller NL. A novel streptococcal cell-cell communication peptide promotes pneumococcal virulence and biofilm formation. Mol Microbiol 2017; 105:554-571. [PMID: 28557053 DOI: 10.1111/mmi.13721] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2017] [Indexed: 12/29/2022]
Abstract
Streptococcus pneumoniae (pneumococcus) is a major human pathogen. It is a common colonizer of the human respiratory track, where it utilizes cell-cell communication systems to coordinate population-level behaviors. We reasoned that secreted peptides that are highly expressed during infection are pivotal for virulence. Thus, we used in silico pattern searches to define a pneumococcal secretome and analyzed the transcriptome of the clinically important PMEN1 lineage to identify which peptide-encoding genes are highly expressed in vivo. In this study, we characterized virulence peptide 1 (vp1), a highly expressed Gly-Gly peptide-encoding gene in chinchilla middle ear effusions. The vp1 gene is widely distributed across pneumococcus as well as encoded in related species. Studies in the chinchilla model of middle ear infection demonstrated that VP1 is a virulence determinant. The vp1 gene is positively regulated by a transcription factor from the Rgg family and its cognate SHP (short hydrophobic peptide). In vitro data indicated that VP1 promotes increased thickness and biomass for biofilms grown on chinchilla middle ear epithelial cells. Furthermore, the wild-type biofilm is restored with the exogenous addition of synthetic VP1. We conclude that VP1 is a novel streptococcal regulatory peptide that controls biofilm development and pneumococcal pathogenesis.
Collapse
|
65
|
Kadam A, Eutsey RA, Rosch J, Miao X, Longwell M, Xu W, Woolford CA, Hillman T, Motib AS, Yesilkaya H, Mitchell AP, Hiller NL. Promiscuous signaling by a regulatory system unique to the pandemic PMEN1 pneumococcal lineage. PLoS Pathog 2017; 13:e1006339. [PMID: 28542565 PMCID: PMC5436883 DOI: 10.1371/journal.ppat.1006339] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 04/07/2017] [Indexed: 01/03/2023] Open
Abstract
Streptococcus pneumoniae (pneumococcus) is a leading cause of death and disease in children and elderly. Genetic variability among isolates from this species is high. These differences, often the product of gene loss or gene acquisition via horizontal gene transfer, can endow strains with new molecular pathways, diverse phenotypes, and ecological advantages. PMEN1 is a widespread and multidrug-resistant pneumococcal lineage. Using comparative genomics we have determined that a regulator-peptide signal transduction system, TprA2/PhrA2, was acquired by a PMEN1 ancestor and is encoded by the vast majority of strains in this lineage. We show that TprA2 is a negative regulator of a PMEN1-specific gene encoding a lanthionine-containing peptide (lcpA). The activity of TprA2 is modulated by its cognate peptide, PhrA2. Expression of phrA2 is density-dependent and its C-terminus relieves TprA2-mediated inhibition leading to expression of lcpA. In the pneumococcal mouse model with intranasal inoculation, TprA2 had no effect on nasopharyngeal colonization but was associated with decreased lung disease via its control of lcpA levels. Furthermore, the TprA2/PhrA2 system has integrated into the pneumococcal regulatory circuitry, as PhrA2 activates TprA/PhrA, a second regulator-peptide signal transduction system widespread among pneumococci. Extracellular PhrA2 can release TprA-mediated inhibition, activating expression of TprA-repressed genes in both PMEN1 cells as well as another pneumococcal lineage. Acquisition of TprA2/PhrA2 has provided PMEN1 isolates with a mechanism to promote commensalism over dissemination and control inter-strain gene regulation. Streptococcus pneumoniae (pneumococcus), an important human pathogen, exhibits a dual lifestyle featuring asymptomatic colonization of the host on the one hand as well as infliction of severe local and systemic disease on the other. In pneumococcal strains, differences in gene possession often lead to varied phenotypic outcomes. Epidemiologically, pandemic strains of the PMEN1 lineage show high prevalence in disease as well as carriage, posing an interesting question on the composition and function of the genomic toolkit that leads to their widespread success. Here, we characterize TprA2/PhrA2 sensory system, a genomic region acquired exclusively by the PMEN1 strains. The system consists of a regulator-peptide pair that was horizontally acquired into PMEN1 along with its regulatory circuitry. The regulatory peptide PhrA2 is receptive to cell density of PMEN1 cells and is an example of elegant communication signaling between bacterial cells. The regulatory influence of PhrA2 extends beyond PMEN1 cells such that it controls genes of a widespread signaling system and virulence regulon in non-PMEN1 strains. This work contributes to the knowledge of peptide-communication signals in pneumococcus and further adds a novel mechanism by which an ecologically successful linage may modify the transcriptomic and functional landscape of a multi-strain pneumococcal community.
Collapse
|
66
|
Woolford CA, Lagree K, Aleynikov T, Mitchell AP. Negative control of Candida albicans filamentation-associated gene expression by essential protein kinase gene KIN28. Curr Genet 2017; 63:1073-1079. [PMID: 28501989 DOI: 10.1007/s00294-017-0705-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 04/25/2017] [Accepted: 05/10/2017] [Indexed: 12/31/2022]
Abstract
The fungus Candida albicans can grow as either yeast or filaments, which include hyphae and pseudohyphae, depending on environmental conditions. Filamentous growth is of particular interest because it is required for biofilm formation and for pathogenesis. Environmentally induced filamentous growth is associated with expression of filamentation-associated genes, and both filamentous growth and associated gene expression depend upon several well-characterized transcription factors. Surprisingly, strains with reduced expression of many essential genes display filamentous growth under non-inducing conditions-those in which the wild type grows as yeast. We found recently that diminished expression of several essential protein kinase genes leads to both filamentous cell morphology and filamentation-associated gene expression under non-inducing conditions. Reduced expression of the essential protein kinase gene CAK1 promoted filamentation-associated gene expression and biofilm formation in strains that lacked key transcriptional activators of these processes, thus indicating that CAK1 expression is critical for both environmental and genetic control of filamentation. In this study, we extend our genetic interaction analysis to a second essential protein kinase gene, KIN28. Reduced expression of KIN28 also permits filamentation-associated gene expression, though not biofilm formation, in the absence of several key transcriptional activators. Our results argue that impairment of several essential cellular processes can alter the regulatory requirements for filamentation-associated gene expression. Our results also indicate that levels of filamentation-associated gene expression are not fully predictive of biofilm formation ability.
Collapse
|
67
|
Mitchell AP, Sanoff HK. Anti-EGFR and Anti-VEGF Agents in First-Line Therapy for Advanced Colorectal Cancer. CURRENT COLORECTAL CANCER REPORTS 2017. [DOI: 10.1007/s11888-017-0372-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
68
|
Abstract
We focus this article on turning a biofilm inside out. The "inside" of the biofilm comprises the individual biofilm-related phenotypes, their environmental drivers and genetic determinants, and the coordination of gene functions through transcriptional regulators. Investigators have viewed the inside of the biofilm through diverse approaches, and this article will attempt to capture the essence of many. The ultimate goal is to connect the inside to the "outside," which we view as biofilm structure, development, pharmacological attributes, and medical impact.
Collapse
|
69
|
|
70
|
Mitchell AP, Basch EM, Dusetzina SB. Financial Relationships With Industry Among National Comprehensive Cancer Network Guideline Authors. JAMA Oncol 2017; 2:1628-1631. [PMID: 27561170 DOI: 10.1001/jamaoncol.2016.2710] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Importance Financial conflicts of interest (FCOIs) among authors of clinical practice guidelines have the potential to influence treatment recommendations. Objective To quantify FCOIs with industry among authors of the National Comprehensive Cancer Network (NCCN) guidelines. Design, Setting, and Participants We assessed FCOIs occurring during 2014 among NCCN guideline authors in the United States. All were physician members of the NCCN guideline committees for lung, breast, prostate, and colorectal cancer as of the end of 2014. The data source for FCOIs was Open Payments, which is publically reported by the Centers for Medicare and Medicaid Services. This study was cross-sectional. Main Outcomes and Measures The proportion of NCCN authors having FCOIs with industry; the average amount received from industry sources per author. Results Of 125 guideline authors, 108 (86%) had at least 1 reported FCOI. Authors received an average of $10 011 (range, $0-$106 859) in general payments (GPs), which include consulting, meals, lodging, and similar transfers of value, and $236 066 (range $0-$2 756 713) in industry research payments (RPs), including funding associated with clinical trials. Approximately 84% of authors received GPs, while 47% received RPs. Eight (6%) had FCOIs in excess of the $50 000 net and/or $20 000 single-company maximums stipulated by NCCN. Conclusions and Relevance Among NCCN guideline authors, FCOIs involving RPs were of greater value, while those involving GPs were more prevalent. Although FCOIs may result from engaging in important scholarship, FCOIs may still influence guideline authors in counterproductive ways. Research is needed to understand how best to manage author FCOIs during guideline creation.
Collapse
|
71
|
Woolford CA, Lagree K, Xu W, Aleynikov T, Adhikari H, Sanchez H, Cullen PJ, Lanni F, Andes DR, Mitchell AP. Bypass of Candida albicans Filamentation/Biofilm Regulators through Diminished Expression of Protein Kinase Cak1. PLoS Genet 2016; 12:e1006487. [PMID: 27935965 PMCID: PMC5147786 DOI: 10.1371/journal.pgen.1006487] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 11/15/2016] [Indexed: 12/17/2022] Open
Abstract
Biofilm formation on implanted medical devices is a major source of lethal invasive infection by Candida albicans. Filamentous growth of this fungus is tied to biofilm formation because many filamentation-associated genes are required for surface adherence. Cell cycle or cell growth defects can induce filamentation, but we have limited information about the coupling between filamentation and filamentation-associated gene expression after cell cycle/cell growth inhibition. Here we identified the CDK activating protein kinase Cak1 as a determinant of filamentation and filamentation-associated gene expression through a screen of mutations that diminish expression of protein kinase-related genes implicated in cell cycle/cell growth control. A cak1diminished expression (DX) strain displays filamentous growth and expresses filamentation-associated genes in the absence of typical inducing signals. In a wild-type background, expression of filamentation-associated genes depends upon the transcription factors Bcr1, Brg1, Efg1, Tec1, and Ume6. In the cak1 DX background, the dependence of filamentation-associated gene expression on each transcription factor is substantially relieved. The unexpected bypass of filamentation-associated gene expression activators has the functional consequence of enabling biofilm formation in the absence of Bcr1, Brg1, Tec1, Ume6, or in the absence of both Brg1 and Ume6. It also enables filamentous cell morphogenesis, though not biofilm formation, in the absence of Efg1. Because these transcription factors are known to have shared target genes, we suggest that cell cycle/cell growth limitation leads to activation of several transcription factors, thus relieving dependence on any one. The ability of the pathogen Candida albicans to grow on surfaces as biofilms is a determinant of infection ability, because biofilms on implanted medical devices seed infections. Biofilm formation by this organism requires growth in the form of filamentous cells and the expression of filamentation-associated genes. Inhibition of cell proliferation can induce filamentous cell formation, as we find here for strains that express greatly reduced levels of the cell cycle regulator Cak1. Surprisingly, biofilm formation occurs independently of many central biofilm regulatory genes when Cak1 levels are reduced. This response to proliferation inhibition may reflect the activation of numerous biofilm regulators, thus relieving the dependence on any one regulator. The stimulation of biofilm formation by proliferation inhibition, a property of many bacterial pathogens as well, may contribute to the limited effectiveness of antimicrobials against biofilms.
Collapse
|
72
|
Banos G, Winters M, Mrode R, Mitchell AP, Bishop SC, Woolliams JA, Coffey MP. Genetic evaluation for bovine tuberculosis resistance in dairy cattle. J Dairy Sci 2016; 100:1272-1281. [PMID: 27939547 DOI: 10.3168/jds.2016-11897] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Accepted: 10/17/2016] [Indexed: 11/19/2022]
Abstract
Genetic evaluations for resistance to bovine tuberculosis (bTB) were calculated based on British national data including individual animal tuberculin skin test results, postmortem examination (presence of bTB lesions and bacteriological culture for Mycobacterium bovis), animal movement and location information, production history, and pedigree records. Holstein cows with identified sires in herds with bTB breakdowns (new herd incidents) occurring between the years 2000 and 2014 were considered. In the first instance, cows with a positive reaction to the skin test and a positive postmortem examination were defined as infected. Values of 0 and 1 were assigned to healthy and infected animal records, respectively. Data were analyzed with mixed models. Linear and logit function heritability estimates were 0.092 and 0.172, respectively. In subsequent analyses, breakdowns were split into 2-mo intervals to better model time of exposure and infection in the contemporary group. Intervals with at least one infected individual were retained and multiple intervals within the same breakdown were included. Healthy animal records were assigned values of 0, and infected records a value of 1 in the interval of infection and values reflecting a diminishing probability of infection in the preceding intervals. Heritability and repeatability estimates were 0.115 and 0.699, respectively. Reliabilities and across time stability of the genetic evaluation were improved with the interval model. Subsequently, 2 more definitions of "infected" were analyzed with the interval model: (1) all positive skin test reactors regardless of postmortem examination, and (2) all positive skin test reactors plus nonreactors with positive postmortem examination. Estimated heritability was 0.085 and 0.089, respectively; corresponding repeatability estimates were 0.701 and 0.697. Genetic evaluation reliabilities and across time stability did not change. Correlations of genetic evaluations for bTB with other traits in the current breeding goal were mostly not different from zero. Correlation with the UK Profitable Lifetime Index was moderate, significant, and favorable. Results demonstrated the feasibility of a national genetic evaluation for bTB resistance. Selection for enhanced resistance will have a positive effect on profitability and no antagonistic effects on current breeding goal traits. Official genetic evaluations are now based on the interval model and the last bTB trait definition.
Collapse
|
73
|
Ichikawa Y, Morohashi N, Tomita N, Mitchell AP, Kurumizaka H, Shimizu M. Sequence-directed nucleosome-depletion is sufficient to activate transcription from a yeast core promoter in vivo. Biochem Biophys Res Commun 2016; 476:57-62. [PMID: 27208777 DOI: 10.1016/j.bbrc.2016.05.063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 05/12/2016] [Indexed: 11/18/2022]
Abstract
Nucleosome-depleted regions (NDRs) (also called nucleosome-free regions or NFRs) are often found in the promoter regions of many yeast genes, and are formed by multiple mechanisms, including the binding of activators and enhancers, the actions of chromatin remodeling complexes, and the specific DNA sequences themselves. However, it remains unclear whether NDR formation per se is essential for transcriptional activation. Here, we examined the relationship between nucleosome organization and gene expression using a defined yeast reporter system, consisting of the CYC1 minimal core promoter and the lacZ gene. We introduced simple repeated sequences that should be either incorporated in nucleosomes or excluded from nucleosomes in the site upstream of the TATA boxes. The (CTG)12, (GAA)12 and (TGTAGG)6 inserts were incorporated into a positioned nucleosome in the core promoter region, and did not affect the reporter gene expression. In contrast, the insertion of (CGG)12, (TTAGGG)6, (A)34 or (CG)8 induced lacZ expression by 10-20 fold. Nucleosome mapping analyses revealed that the inserts that induced the reporter gene expression prevented nucleosome formation, and created an NDR upstream of the TATA boxes. Thus, our results demonstrated that NDR formation dictated by DNA sequences is sufficient for transcriptional activation from the core promoter in vivo.
Collapse
|
74
|
|
75
|
Xu W, Solis NV, Filler SG, Mitchell AP. Gene Expression Profiling of Infecting Microbes Using a Digital Bar-coding Platform. J Vis Exp 2016:e53460. [PMID: 26863547 PMCID: PMC4781349 DOI: 10.3791/53460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
For most mammalian pathogens, gene expression profiling studies have been limited by technical difficulties to accurately quantify pathogen gene transcripts from infected tissues. Pathogen RNA constitutes a tiny portion of the total RNA isolated from infected tissue samples. Both microarray and RNAseq technologies have difficulties in generating reliable reads for weakly expressed pathogen genes. Mutant pathogen strains with reduced in vivo proliferation pose an even bigger challenge. Here we describe an in vivo gene expression profiling protocol that is very fast, extremely sensitive and highly reproducible. We developed this protocol during our investigation of the fungal pathogen Candida albicans in a murine model of hematogenously disseminated candidiasis. Using this protocol, we have documented time courses of dynamically regulated C. albicans gene expression during kidney infection, and discovered unexpected features of gene expression responses to antifungal drug treatment in vivo.
Collapse
|