New business models for antibiotic innovation.

The increase in antibiotic resistance and the dearth of novel antibiotics have become a growing concern among policy-makers. A combination of financial, scientific, and regulatory challenges poses barriers to antibiotic innovation. However, each of these three challenges provides an opportunity to develop pathways for new business models to bring novel antibiotics to market. Pull-incentives that pay for the outputs of research and development (R&D) and push-incentives that pay for the inputs of R&D can be used to increase innovation for antibiotics. Financial incentives might be structured to promote delinkage of a company's return on investment from revenues of antibiotics. This delinkage strategy might not only increase innovation, but also reinforce rational use of antibiotics. Regulatory approval, however, should not and need not compromise safety and efficacy standards to bring antibiotics with novel mechanisms of action to market. Instead regulatory agencies could encourage development of companion diagnostics, test antibiotic combinations in parallel, and pool and make transparent clinical trial data to lower R&D costs. A tax on non-human use of antibiotics might also create a disincentive for non-therapeutic use of these drugs. Finally, the new business model for antibiotic innovation should apply the 3Rs strategy for encouraging collaborative approaches to R&D in innovating novel antibiotics: sharing resources, risks, and rewards.

Practices and outcomes of self-treatment with helminths based on physicians' observations.

The successful use of helminths as therapeutic agents to resolve inflammatory disease was first recorded 40 years ago. Subsequent work in animal models and in humans has demonstrated that the organisms might effectively treat a wide range of inflammatory diseases, including allergies, autoimmune disorders and inflammation-associated neuropsychiatric disorders. However, available information regarding the therapeutic uses and effects of helminths in humans is limited. This study probes the practices and experiences of individuals 'self-treating' with helminths through the eyes of their physicians. Five physicians monitoring more than 700 self-treating patients were interviewed. The results strongly support previous indications that helminth therapy can effectively treat a wide range of allergies, autoimmune conditions and neuropsychiatric disorders, such as major depression and anxiety disorders. Approximately 57% of the self-treating patients observed by physicians in the study had autism. Physicians reported that the majority of patients with autism and inflammation-associated co-morbidities responded favourably to therapy with either of the two most popular organisms currently used by self-treaters, Hymenolepis diminuta and Trichuris suis. However, approximately 1% of paediatric patients experienced severe gastrointestinal pains with the use of H. diminuta, although the symptoms were resolved with an anti-helminthic drug. Further, exposure to helminths apparently did not affect the impaired comprehension of social situations that is the hallmark of autism. These observations point toward potential starting points for clinical trials, and provide further support for the importance of such trials and for concerted efforts aimed at probing the potential of helminths, and perhaps other biologicals, for therapeutic use.

Enhanced de novo alloantibody and antibody-mediated injury in rhesus macaques.

Chronic allograft rejection is a major impediment to long-term transplant success. Humoral immune responses to alloantigens are a growing clinical problem in transplantation, with mounting evidence associating alloantibodies with the development of chronic rejection. Nearly a third of transplant recipients develop de novo antibodies, for which no established therapies are effective at preventing or eliminating, highlighting the need for a nonhuman primate model of antibody-mediated rejection. In this report, we demonstrate that depletion using anti-CD3 immunotoxin (IT) combined with maintenance immunosuppression that included tacrolimus with or without alefacept reliably prolonged renal allograft survival in rhesus monkeys. In these animals, a preferential skewing toward CD4 repopulation and proliferation was observed, particularly with the addition of alefacept. Furthermore, alefacept-treated animals demonstrated increased alloantibody production (100%) and morphologic features of antibody-mediated injury. In vitro, alefacept was found to enhance CD4 effector memory T cell proliferation. In conclusion, alefacept administration after depletion and with tacrolimus promotes a CD4+memory T cell and alloantibody response, with morphologic changes reflecting antibody-mediated allograft injury. Early and consistent de novo alloantibody production with associated histological changes makes this nonhuman primate model an attractive candidate for evaluating targeted therapeutics.

Interleukin-15 receptor blockade in non-human primate kidney transplantation.

BACKGROUND: Interleukin (IL)-15 is a chemotactic factor to T cells. It induces proliferation and promotes survival of activated T cells. IL-15 receptor blockade in mouse cardiac and islet allotransplant models has led to long-term engraftment and a regulatory T-cell environment. This study investigated the efficacy of IL-15 receptor blockade using Mut-IL-15/Fc in an outbred non-human primate model of renal allotransplantation. METHODS: Male cynomolgus macaque donor-recipient pairs were selected based on ABO typing, major histocompatibility complex class I typing, and carboxy-fluorescein diacetate succinimidyl ester-based mixed lymphocyte responses. Once animals were assigned to one of six treatment groups, they underwent renal transplantation and bilateral native nephrectomy. Serum creatinine level was monitored twice weekly and as indicated, and protocol biopsies were performed. Rejection was defined as a increase in serum creatinine to 1.5 mg/dL or higher and was confirmed histologically. Complete blood counts and flow cytometric analyses were performed periodically posttransplant; pharmacokinetic parameters of Mut-IL-15/Fc were assessed. RESULTS: Compared with control animals, Mut-IL-15/Fc-treated animals did not demonstrate increased graft survival despite adequate serum levels of Mut-IL-15/Fc. Flow cytometric analysis of white blood cell subgroups demonstrated a decrease in CD8 T-cell and natural killer cell numbers, although this did not reach statistical significance. Interestingly, two animals receiving Mut-IL-15/Fc developed infectious complications, but no infection was seen in control animals. Renal pathology varied widely. CONCLUSIONS: Peritransplant IL-15 receptor blockade does not prolong allograft survival in non-human primate renal transplantation; however, it reduces the number of CD8 T cells and natural killer cells in the peripheral blood.

A model of sequential heart and composite tissue allotransplant in rats.

BACKGROUND: Some of the 600,000 patients with solid organ allotransplants need reconstruction with a composite tissue allotransplant, such as the hand, abdominal wall, or face. The aim of this study was to develop a rat model for assessing the effects of a secondary composite tissue allotransplant on a primary heart allotransplant. METHODS: Hearts of Wistar Kyoto rats were harvested and transplanted heterotopically to the neck of recipient Fisher 344 rats. The anastomoses were performed between the donor brachiocephalic artery and the recipient left common carotid artery, and between the donor pulmonary artery and the recipient external jugular vein. Recipients received cyclosporine A for 10 days only. Heart rate was assessed noninvasively. The sequential composite tissue allotransplant consisted of a 3 x 3-cm abdominal musculocutaneous flap harvested from Lewis rats and transplanted to the abdomen of the heart allotransplant recipients. The abdominal flap vessels were connected to the femoral vessels. No further immunosuppression was administered following the composite tissue allotransplant. Ten days after composite tissue allotransplantation, rejection of the heart and abdominal flap was assessed histologically. RESULTS: The rat survival rate of the two-stage transplant surgery was 80 percent. The transplanted heart rate decreased from 150 +/- 22 beats per minute immediately after transplant to 83 +/- 12 beats per minute on day 20 (10 days after stopping immunosuppression). CONCLUSIONS: This sequential allotransplant model is technically demanding. It will facilitate investigation of the effects of a secondary composite tissue allotransplant following primary solid organ transplantation and could be useful in developing future immunotherapeutic strategies.

Coordination of platinum therapeutic agents to met-rich motifs of human copper transport protein1.

Platinum therapeutic agents are widely used in the treatment of several forms of cancer. Various mechanisms for the transport of the drugs have been proposed including passive diffusion across the cellular membrane and active transport via proteins. The copper transport protein Ctr1 is responsible for high affinity copper uptake but has also been implicated in the transport of cisplatin into cells. Human hCtr1 contains two methionine-rich Mets motifs on its extracellular N-terminus that are potential platinum-binding sites: the first one encompasses residues 7-14 with amino acid sequence Met-Gly-Met-Ser-Tyr-Met-Asp-Ser and the second one spans residues 39-46 with sequence Met-Met-Met-Met-Pro-Met-Thr-Phe. In these studies, we use liquid chromatography and mass spectrometry to compare the binding interactions between cisplatin, carboplatin and oxaliplatin with synthetic peptides corresponding to hCtr1 Mets motifs. The interactions of cisplatin and carboplatin with Met-rich motifs that contain three or more methionines result in removal of the carrier ligands of both platinum complexes. In contrast, oxaliplatin retains its cyclohexyldiamine ligand upon platinum coordination to the peptide.

Minding metals: tailoring multifunctional chelating agents for neurodegenerative disease.

Neurodegenerative diseases like Alzheimer's and Parkinson's disease are associated with elevated levels of iron, copper, and zinc and consequentially high levels of oxidative stress. Given the multifactorial nature of these diseases, it is becoming evident that the next generation of therapies must have multiple functions to combat multiple mechanisms of disease progression. Metal-chelating agents provide one such function as an intervention for ameliorating metal-associated damage in degenerative diseases. Targeting chelators to adjust localized metal imbalances in the brain, however, presents significant challenges. In this perspective, we focus on some noteworthy advances in the area of multifunctional metal chelators as potential therapeutic agents for neurodegenerative diseases. In addition to metal chelating ability, these agents also contain features designed to improve their uptake across the blood-brain barrier, increase their selectivity for metals in damage-prone environments, increase antioxidant capabilities, lower Abeta peptide aggregation, or inhibit disease-associated enzymes such as monoamine oxidase and acetylcholinesterase.

Prenatal protease inhibitor use and risk of preterm birth among HIV-infected women initiating antiretroviral drugs during pregnancy.

BACKGROUND: Conflicting results have been reported among studies of protease inhibitor (PI) use during pregnancy and preterm birth. Uncontrolled confounding by indication may explain some of the differences among studies. METHODS: In total, 777 human immunodeficiency virus (HIV)-infected pregnant women in a prospective cohort who were not receiving antiretroviral (ARV) treatment at conception were studied. Births <37 weeks gestation were reviewed, and deliveries due to spontaneous labor and/or rupture of membranes were identified. Risk of preterm birth and low birth weight (<2500 g) were evaluated by using multivariable logistic regression. RESULTS: Of the study population, 558 (72%) received combination ARV with PI during pregnancy, and a total of 130 preterm births were observed. In adjusted analyses, combination ARV with PI was not significantly associated with spontaneous preterm birth, compared to ARV without PI (odds ratio [OR], 1.22; 95% confidence interval [CI], 0.70-2.12). Sensitivity analyses that included women who received ARV prior to pregnancy also did not identify a significant association (OR, 1.34; 95% CI, 0.84-2.16). Low birth weight results were similar. CONCLUSIONS: No evidence of an association between use of combination ARV with PI during pregnancy and preterm birth was found. Our study supports current guidelines that promote consideration of combination ARV for all HIV-infected pregnant women.

High-throughput identification of chemical inhibitors of E. coli Group 2 capsule biogenesis as anti-virulence agents.

Rising antibiotic resistance among Escherichia coli, the leading cause of urinary tract infections (UTIs), has placed a new focus on molecular pathogenesis studies, aiming to identify new therapeutic targets. Anti-virulence agents are attractive as chemotherapeutics to attenuate an organism during disease but not necessarily during benign commensalism, thus decreasing the stress on beneficial microbial communities and lessening the emergence of resistance. We and others have demonstrated that the K antigen capsule of E. coli is a preeminent virulence determinant during UTI and more invasive diseases. Components of assembly and export are highly conserved among the major K antigen capsular types associated with UTI-causing E. coli and are distinct from the capsule biogenesis machinery of many commensal E. coli, making these attractive therapeutic targets. We conducted a screen for anti-capsular small molecules and identified an agent designated "C7" that blocks the production of K1 and K5 capsules, unrelated polysaccharide types among the Group 2-3 capsules. Herein lies proof-of-concept that this screen may be implemented with larger chemical libraries to identify second-generation small-molecule inhibitors of capsule biogenesis. These inhibitors will lead to a better understanding of capsule biogenesis and may represent a new class of therapeutics.

Patterns in blood pressure medication use in US incident dialysis patients over the first 6 months.

BACKGROUND: Several observational studies have evaluated the effect of a single exposure window with blood pressure (BP) medications on outcomes in incident dialysis patients, but whether BP medication prescription patterns remain stable or a single exposure window design is adequate to evaluate effect on outcomes is unclear. METHODS: We described patterns of BP medication prescription over 6 months after dialysis initiation in hemodialysis and peritoneal dialysis patients, stratified by cardiovascular comorbidity, diabetes, and other patient characteristics. The cohort included 13,072 adult patients (12,159 hemodialysis, 913 peritoneal dialysis) who initiated dialysis in Dialysis Clinic, Inc., facilities January 1, 2003-June 30, 2008, and remained on the original modality for at least 6 months. We evaluated monthly patterns in BP medication prescription over 6 months and at 12 and 24 months after initiation. RESULTS: Prescription patterns varied by dialysis modality over the first 6 months; substantial proportions of patients with prescriptions for beta-blockers, renin angiotensin system agents, and dihydropyridine calcium channel blockers in month 6 no longer had prescriptions for these medications by month 24. Prescription of specific medication classes varied by comorbidity, race/ethnicity, and age, but little by sex. The mean number of medications was 2.5 at month 6 in hemodialysis and peritoneal dialysis cohorts. CONCLUSIONS: This study evaluates BP medication patterns in both hemodialysis and peritoneal dialysis patients over the first 6 months of dialysis. Our findings highlight the challenges of assessing comparative effectiveness of a single BP medication class in dialysis patients. Longitudinal designs should be used to account for changes in BP medication management over time, and designs that incorporate common combinations should be considered.

The role of B cells in solid organ transplantation.

The role of antibodies in chronic injury to organ transplants has been suggested for many years, but recently emphasized by new data. We have observed that when immunosuppressive potency decreases either by intentional weaning of maintenance agents or due to homeostatic repopulation after immune cell depletion, the threshold of B cell activation may be lowered. In human transplant recipients the result may be donor-specific antibody, C4d+ injury, and chronic rejection. This scenario has precise parallels in a rhesus monkey renal allograft model in which T cells are depleted with CD3 immunotoxin, or in a CD52-T cell transgenic mouse model using alemtuzumab to deplete T cells. Such animal models may be useful for the testing of therapeutic strategies to prevent DSA. We agree with others who suggest that weaning of immunosuppression may place transplant recipients at risk of chronic antibody-mediated rejection, and that strategies to prevent this scenario are needed if we are to improve long-term graft and patient outcomes in transplantation. We believe that animal models will play a crucial role in defining the pathophysiology of antibody-mediated rejection and in developing effective therapies to prevent graft injury. Two such animal models are described herein.

Early clopidogrel versus prasugrel use among contemporary STEMI and NSTEMI patients in the US: insights from the National Cardiovascular Data Registry.

BACKGROUND: P2Y12 antagonist therapy improves outcomes in acute myocardial infarction (MI) patients. Novel agents in this class are now available in the US. We studied the introduction of prasugrel into contemporary MI practice to understand the appropriateness of its use and assess for changes in antiplatelet management practices. METHODS AND RESULTS: Using ACTION Registry-GWTG (Get-with-the-Guidelines), we evaluated patterns of P2Y12 antagonist use within 24 hours of admission in 100 228 ST elevation myocardial infarction (STEMI) and 158 492 Non-ST elevation myocardial infarction (NSTEMI) patients at 548 hospitals between October 2009 and September 2012. Rates of early P2Y12 antagonist use were approximately 90% among STEMI and 57% among NSTEMI patients. From 2009 to 2012, prasugrel use increased significantly from 3% to 18% (5% to 30% in STEMI; 2% to 10% in NSTEMI; P for trend <0.001 for all). During the same period, we observed a decrease in use of early but not discharge P2Y12 antagonist among NSTEMI patients. Although contraindicated, 3.0% of patients with prior stroke received prasugrel. Prasugrel was used in 1.9% of patients ≥75 years and 4.5% of patients with weight <60 kg. In both STEMI and NSTEMI, prasugrel was most frequently used in patients at the lowest predicted risk for bleeding and mortality. Despite lack of supporting evidence, prasugrel was initiated before cardiac catheterization in 18% of NSTEMI patients. CONCLUSIONS: With prasugrel as an antiplatelet treatment option, contemporary practice shows low uptake of prasugrel and delays in P2Y12 antagonist initiation among NSTEMI patients. We also note concerning evidence of inappropriate use of prasugrel, and inadequate targeting of this more potent therapy to maximize the benefit/risk ratio.

Mental Health and Substance Use Among Patients in a North Carolina HIV Clinic.

BACKGROUND: The HIV/AIDS epidemic is a significant public health concern in North Carolina, and previous research has pointed to elevated mental health distress and substance use among HIV-infected populations, which may impact patients' adherence to medications. The aims of this study were to describe the prevalence of mental health and substance use issues among patients of a North Carolina HIV clinic, to examine differences by demographic characteristics, and to examine factors associated with suboptimal adherence to HIV medications. METHODS: This study was a secondary analysis of clinical data routinely collected through a health behavior questionnaire at a large HIV clinic in North Carolina. We analyzed data collected from February 2011 to August 2012. RESULTS: The sample included 1,398 patients. Overall, 12.2% of patients endorsed current symptomology indicative of moderate or severe levels of depression, and 38.6% reported receiving a psychiatric diagnosis at some point in their life. Additionally, 19.1% had indications of current problematic drinking, and 8.2% reported problematic drug use. Nearly one-quarter (22.1%) reported suboptimal adherence to HIV medications. Factors associated with poor adherence included racial/ethnic minority, age less than 35 years, and indications of moderate or severe depression. LIMITATIONS: The questionnaire was not completed systematically in the clinic, which may limit generalizability, and self-reported measures may have introduced social desirability bias. CONCLUSION: Patients were willing to disclose mental health distress, substance use, and suboptimal medication adherence to providers, which highlights the importance of routinely assessing these behaviors during clinic visits. Our findings suggest that treating depression may be an effective strategy to improve adherence to HIV medications.

In vivo small animal micro-CT using nanoparticle contrast agents.

Computed tomography (CT) is one of the most valuable modalities for in vivo imaging because it is fast, high-resolution, cost-effective, and non-invasive. Moreover, CT is heavily used not only in the clinic (for both diagnostics and treatment planning) but also in preclinical research as micro-CT. Although CT is inherently effective for lung and bone imaging, soft tissue imaging requires the use of contrast agents. For small animal micro-CT, nanoparticle contrast agents are used in order to avoid rapid renal clearance. A variety of nanoparticles have been used for micro-CT imaging, but the majority of research has focused on the use of iodine-containing nanoparticles and gold nanoparticles. Both nanoparticle types can act as highly effective blood pool contrast agents or can be targeted using a wide variety of targeting mechanisms. CT imaging can be further enhanced by adding spectral capabilities to separate multiple co-injected nanoparticles in vivo. Spectral CT, using both energy-integrating and energy-resolving detectors, has been used with multiple contrast agents to enable functional and molecular imaging. This review focuses on new developments for in vivo small animal micro-CT using novel nanoparticle probes applied in preclinical research.

Live Imaging of Host-Parasite Interactions in a Zebrafish Infection Model Reveals Cryptococcal Determinants of Virulence and Central Nervous System Invasion.

UNLABELLED: The human fungal pathogen Cryptococcus neoformans is capable of infecting a broad range of hosts, from invertebrates like amoebas and nematodes to standard vertebrate models such as mice and rabbits. Here we have taken advantage of a zebrafish model to investigate host-pathogen interactions of Cryptococcus with the zebrafish innate immune system, which shares a highly conserved framework with that of mammals. Through live-imaging observations and genetic knockdown, we establish that macrophages are the primary immune cells responsible for responding to and containing acute cryptococcal infections. By interrogating survival and cryptococcal burden following infection with a panel of Cryptococcus mutants, we find that virulence factors initially identified as important in causing disease in mice are also necessary for pathogenesis in zebrafish larvae. Live imaging of the cranial blood vessels of infected larvae reveals that C. neoformans is able to penetrate the zebrafish brain following intravenous infection. By studying a C. neoformans FNX1 gene mutant, we find that blood-brain barrier invasion is dependent on a known cryptococcal invasion-promoting pathway previously identified in a murine model of central nervous system invasion. The zebrafish-C. neoformans platform provides a visually and genetically accessible vertebrate model system for cryptococcal pathogenesis with many of the advantages of small invertebrates. This model is well suited for higher-throughput screening of mutants, mechanistic dissection of cryptococcal pathogenesis in live animals, and use in the evaluation of therapeutic agents. IMPORTANCE: Cryptococcus neoformans is an important opportunistic pathogen that is estimated to be responsible for more than 600,000 deaths worldwide annually. Existing mammalian models of cryptococcal pathogenesis are costly, and the analysis of important pathogenic processes such as meningitis is laborious and remains a challenge to visualize. Conversely, although invertebrate models of cryptococcal infection allow high-throughput assays, they fail to replicate the anatomical complexity found in vertebrates and, specifically, cryptococcal stages of disease. Here we have utilized larval zebrafish as a platform that overcomes many of these limitations. We demonstrate that the pathogenesis of C. neoformans infection in zebrafish involves factors identical to those in mammalian and invertebrate infections. We then utilize the live-imaging capacity of zebrafish larvae to follow the progression of cryptococcal infection in real time and establish a relevant model of the critical central nervous system infection phase of disease in a nonmammalian model.