Toxic and drug-induced peripheral neuropathies: updates on causes, mechanisms and management.

PURPOSE OF REVIEW: This review discusses publications highlighting current research on toxic, chemotherapy-induced peripheral neuropathies (CIPNs), and drug-induced peripheral neuropathies (DIPNs). RECENT FINDINGS: The emphasis in clinical studies is on the early detection and grading of peripheral neuropathies, whereas recent studies in animal models have given insights into molecular mechanisms, with the discovery of novel neuronal, axonal, and Schwann cell targets. Some substances trigger inflammatory changes in the peripheral nerves. Pharmacogenetic techniques are underway to identify genes that may help to predict individuals at higher risk of developing DIPNs. Several papers have been published on chemoprotectants; however, to date, this approach has not been shown effective in clinical trials. SUMMARY: Both length and nonlength-dependent neuropathies are encountered, including small-fiber involvement. The introduction of new diagnostic techniques, such as excitability studies, skin laser Doppler flowmetry, and pharmacogenetics, holds promise for early detection and to elucidate underlying mechanisms. New approaches to improve functions and quality of life in CIPN patients are discussed. Apart from developing less neurotoxic anticancer therapies, there is still hope to identify chemoprotective agents (erythropoietin and substances involved in the endocannabinoid system are promising) able to prevent or correct painful CIPNs.

Simulation of amoxicillin pharmacokinetics in humans for the prevention of streptococcal endocarditis in rats.

The pharmacokinetic determinants of successful antibiotic prophylaxis of endocarditis are not precisely known. Differences in half-lives of antibiotics between animals and humans preclude extrapolation of animal results to human situations. To overcome this limitation, we have mimicked in rats the amoxicillin kinetics in humans following a 3-g oral dose (as often used for prophylaxis of endocarditis) by delivering the drug through a computerized pump. Rats with catheter-induced vegetations were challenged with either of two strains of antibiotic-tolerant viridans group streptococci. Antibiotics were given either through the pump (to simulate the whole kinetic profile during prophylaxis in humans) or as an intravenous bolus which imitated only the peak level of amoxicillin (18 mg/liter) in human serum. Prophylaxis by intravenous bolus was inoculum dependent and afforded a limited protection only in rats challenged with the minimum inoculum size infecting > or = 90% of untreated controls. In contrast, simulation of kinetics in humans significantly protected animals challenged with 10 to 100 times the inoculum of either of the test organisms infecting > or = 90% of untreated controls. Thus, simulation of the profiles of amoxicillin prophylaxis in human serum was more efficacious than mere imitation of the transient peak level in rats. This confirms previous studies suggesting that the duration for which the serum amoxicillin level remained detectable (not only the magnitude of the peak) was an important parameter in successful prophylaxis of endocarditis. The results also suggest that single-dose prophylaxis with 3 g of amoxicillin in humans might be more effective than predicted by conventional animal models in which only peak levels of antibiotic in human serum were stimulated.

Lymphoid follicles in chronic lung diseases.

Lymphoid follicles (LFs) can be induced in the lung on infection or chronic inflammation; however, their relevance and contribution to protective immunity or pathogenesis is poorly understood. Recent advances from clinical studies and animal models have shed some light on the mechanisms that trigger and facilitate the development of LFs. As we grasp a better understanding of their development and their relevance to disease, the potential value in targeting pulmonary LFs with novel therapeutics will become evident.

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This chapter explores the progress and various approaches toward identifying genes important for an understanding of sleep and sleep-related traits in rodents. Until the functions of sleep are more clearly defined, it may be difficult to uncover the core genetic basis for sleep and the core molecular events that underlie this fundamental behavior in most, if not all, animal species. However, similar to other areas of medicine, an understanding of the underlying genetics will become increasingly important in sleep medicine. At this time, rodents represent the best animal models for such studies, especially the many genetically modified mouse lines that have been created and the mouse strains that form important genetic reference populations for a wide range of biomedical research. Given the similarities in physiology and genetics across eutherian mammals, it is likely that genes influencing sleep ...

The human immunodeficiency virus preventive vaccine research at the French National Agency for acquired immunodeficiency syndrome research

The human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic is of unprecedented gravity and is spreading rapidly, notably in the most disadvantaged regions of the world. The search for a preventive vaccine is thus an absolute priority. For over 10 years the French National Agency for AIDS research (ANRS) has been committed to an original program combining basic science and clinical research. The HIV preventive vaccine research program run by the ANRS covers upstream research for the definition of immunogens, animal models, and clinical research to evaluate candidate vaccines. Most researchers in 2004 believe that it should be possible to obtain partial vaccine protection through the induction of a strong and multiepitopic cellular response. Since 1992, the ANRS has set up 15 phases I and II clinical trials in order to evaluate the safety and the capacity of the candidate vaccines for inducing cellular immune responses. The tested candidate vaccines were increasingly complex recombinant canarypox viruses (Alvac) containing sequences coding for certain viral proteins, utilized alone or combined with other immunogens (whole or truncated envelope proteins). ANRS has also been developing an original strategy based on the utilization of lipopeptides. These comprise synthetic fragments of viral proteins associated with lipids that facilitate the induction of a cellular immune response. These approaches promptly allowed the assessment of a prime-boost strategy combining a viral vector and lipopeptides.

Macrophage elastase (MMP-12): a pro-inflammatory mediator?

As many metalloproteinases (MMPs), macrophage elastase (MMP-12) is able to degrade extracellular matrix components such as elastin and is involved in tissue remodeling processes. Studies using animal models of acute and chronic pulmonary inflammatory diseases, such as pulmonary fibrosis and chronic obstrutive pulmonary disease (COPD), have given evidences that MMP-12 is an important mediator of the pathogenesis of these diseases. However, as very few data regarding the direct involvement of MMP-12 in inflammatory process in the airways were available, we have instilled a recombinant form of human MMP-12 (rhMMP-12) in mouse airways. Hence, we have demonstrated that this instillation induced a severe inflammatory cell recruitment characterized by an early accumulation of neutrophils correlated with an increase in proinflammatory cytokines and in gelatinases and then by a relatively stable recruitment of macrophages in the lungs over a period of ten days. Another recent study suggests that resident alveolar macrophages and recruited neutrophils are not involved in the delayed macrophage recruitment. However, epithelial cells could be one of the main targets of rhMMP-12 in our model. We have also reported that a corticoid, dexamethasone, phosphodiesterase 4 inhibitor, rolipram and a non-selective MMP inhibitor, marimastat could reverse some of these inflammatory events. These data indicate that our rhMMP-12 model could mimic some of the inflammatory features observed in COPD patients and could be used for the pharmacological evaluation of new anti-inflammatory treatment. In this review, data demonstrating the involvement of MMP-12 in the pathogenesis of pulmonary fibrosis and COPD as well as our data showing a pro-inflammatory role for MMP-12 in mouse airways will be summarized.

Effects of Brazilian propolis on Leishmania amazonensis

Leishmaniasis, an endemic parasitosis that leads to chronic cutaneous, mucocutaneous or visceral lesions, is part of those diseases, which still requires improved control tools. Propolis has shown activities against different bacteria, fungi, and parasites. In this study we investigated the effect of four ethanolic extracts of typified propolis collected in different Brazilian states, on Leishmania amazonensis performing assays with promastigote forms, extracellular amastigotes, and on infected peritoneal macrophages. Ethanolic extracts of all propolis samples (BRG, BRPG, BRP-1, and BRV) were capable to reduce parasite load as monitored by the percentage of infected macrophages and the number of intracellular parasites. BRV sample called red propolis, collected in the state of Alagoas, and containing high concentration of prenylated and benzophenones compounds, was the most active extract against L. amazonensis. The anti-Leishmania effect of BRV sample was increased in a concentration and time dependent manner. BRV treatment proved to be non-toxic to macrophage cultures. Since BRV extract at the concentration of 25 µg/ml reduced the parasite load of macrophages while presented no direct toxic to promastigotes and extracellular amastigotes, it was suggested that constituents of propolis intensify the mechanism of macrophage activation leading to killing of L. amazonensis. Our results demonstrate, for the first time, that ethanolic extracts of Brazilian propolis reduce L. amazonensis infection in macrophages, and encourage further studies of this natural compound in animal models of leishmaniasis.

Mice Transgenic For Human Dominant Mutations Of The GUCY2D Gene

Purpose: Animal models are essential to study pathological mechanisms and to test new therapeutic strategies. Many mouse models mimic human rod loss but only a limited number simulate cone dystrophies. The importance of cone function for human vision highlights the need to engineer a model for cone degeneration. An approach of lentiviral-directed transgenesis was tested in mice to express a dominant mutant gene described in a human cone dystrophy.Methods: Lentiviral vectors (LV) encoding either hrGFPII or the human double mutant GUCY2DE837D/R838S cDNA under the control of a region of the pig arrestin-3 promoter (Arr3) were produced and used for lentiviral-derived transgenesis. PCR-genotyping determined the transgenic mouse ratio. The expression of GFP was then analyzed both in vivo and by immunohistochemistry in Arr3-GFPII mice. Functional analysis was performed by ERG at 5, 9, 16 and 24 weeks for Arr3-GUCY2DE837D/R838S mice. Mice were sacrificed at 10 months of age for both histological analysis and RNA extraction.Results: While all the newborns from the transgenesis using the LV-Arr3-GFPII were transgenic, one third of the newborns from the LV-Arr3-GUCY2DE837D/R838S transgenesis were positive. Expression of GFPII was demonstrated by in vivo imaging, while expression of the mutant GUCY2D transcript was detetected using RT-PCR. No severe alteration of the functional response was observed up to 24 weeks of age in the transgenic mice. No obvious modification of the retinal morphology was identified either.Conclusions: Lentiviral-directed transgenesis is a rapid and straightforward method to engineer transgenic mice. Protein expression can be specifically targeted to the retina and thus could help to study the effect of expression of dominant mutant proteins. In our case, Arr3-GUCY2DE837D/R838S mice have a less severe phenotype than that described for human patients. Further analyses are required to understand this difference but several modifications of the expression cassette might also help to increase the expression of the mutant protein and reinforce the phenotype. Interestingly, the same construct is less effective in mouse versus pig retina (see Arsenijevic et al. ARVO 2011 abstract).

Vaccines against Toxoplasma gondii: challenges and opportunities

Development of vaccines against Toxoplasma gondii infection in humans is of high priority, given the high burden of disease in some areas of the world like South America, and the lack of effective drugs with few adverse effects. Rodent models have been used in research on vaccines against T. gondii over the past decades. However, regardless of the vaccine construct, the vaccines have not been able to induce protective immunity when the organism is challenged with T. gondii, either directly or via a vector. Only a few live, attenuated T. gondii strains used for immunization have been able to confer protective immunity, which is measured by a lack of tissue cysts after challenge. Furthermore, challenge with low virulence strains, especially strains with genotype II, will probably be insufficient to provide protection against the more virulent T. gondii strains, such as those with genotypes I or II, or those genotypes from South America not belonging to genotype I, II or III. Future studies should use animal models besides rodents, and challenges should be performed with at least one genotype II T. gondii and one of the more virulent genotypes. Endpoints like maternal-foetal transmission and prevention of eye disease are important in addition to the traditional endpoint of survival or reduction in numbers of brain cysts after challenge.

Notch signaling in the pigmented epithelium of the anterior eye segment promotes ciliary body development at the expense of iris formation.

The ciliary body and iris are pigmented epithelial structures in the anterior eye segment that function to maintain correct intra-ocular pressure and regulate exposure of the internal eye structures to light, respectively. The cellular and molecular factors that mediate the development of the ciliary body and iris from the ocular pigmented epithelium remain to be fully elucidated. Here, we have investigated the role of Notch signaling during the development of the anterior pigmented epithelium by using genetic loss- and gain-of-function approaches. Loss of canonical Notch signaling results in normal iris development but absence of the ciliary body. This causes progressive hypotony and over time leads to phthisis bulbi, a condition characterized by shrinkage of the eye and loss of structure/function. Conversely, Notch gain-of-function results in aniridia and profound ciliary body hyperplasia, which causes ocular hypertension and glaucoma-like disease. Collectively, these data indicate that Notch signaling promotes ciliary body development at the expense of iris formation and reveals novel animal models of human ocular pathologies.

Perspectives of vaccination in Chagas disease revisited

The perspectives for a Chagas Disease vaccine 30 years ago and today are compared. Antigens and adjuvants have improved, but logistic problems remain the same. Sterilizing vaccines have not been produced and animal models for chronic Chagas have not been developed. Vector control has been successful and Chagas incidence has come to a halt. We do not have a population candidate to vaccination now in Brazil. And if we had, we would not know how to evaluate the success of vaccination in a short time period. A vaccine may not seem important at the moment. However, scientific reasons and incertitudes about the future recommend that a search for a vaccine be continued.

Protective immunity against Trypanosoma cruzi

Upon infection, Trypanosoma cruzi triggers a strong immune response that has both protective and pathological consequences. In this work, several important questions regarding protective immunity are reviewed. Emphasis is placed on recent studies of the important protective role of CD8+ T cells and on previous studies of immunisation of domestic T. cruzi reservoirs that sought to address practical vaccination problems. Research on the maturation of memory cells and studies indicating that the prevalence of T. cruzi-specific T-cell responses and a high frequency of committed CD8+ T cells are associated with better clinical outcomes are also reviewed. Additionally, animal models in which protection was achieved without immunopathological consequences are discussed.

Evolution of gene expression changes in newborn rats after mechanical ventilation with reversible intubation.

Mechanical ventilation (MV) is life-saving but potentially harmful for lungs of premature infants. So far, animal models dealt with the acute impact of MV on immature lungs, but less with its delayed effects. We used a newborn rodent model including non-surgical and therefore reversible intubation with moderate ventilation and hypothesized that there might be distinct gene expression patterns after a ventilation-free recovery period compared to acute effects directly after MV. Newborn rat pups were subjected to 8 hr of MV with 60% oxygen (O(2) ), 24 hr after injection of lipopolysaccharide (LPS), intended to create a low inflammatory background as often recognized in preterm infants. Animals were separated in controls (CTRL), LPS injection (LPS), or full intervention with LPS and MV with 60% O(2) (LPS + MV + O(2) ). Lungs were recovered either directly following (T:0 hr) or 48 hr after MV (T:48 hr). Histologically, signs of ventilator-induced lung injury (VILI) were observed in LPS + MV + O(2) lungs at T:0 hr, while changes appeared similar to those known from patients with chronic lung disease (CLD) with fewer albeit larger gas exchange units, at T:48 hr. At T:0 hr, LPS + MV + O(2) increased gene expression of pro-inflammatory MIP-2. In parallel anti-inflammatory IL-1Ra gene expression was increased in LPS and LPS + MV + O(2) groups. At T:48 hr, pro- and anti-inflammatory genes had returned to their basal expression. MMP-2 gene expression was decreased in LPS and LPS + MV + O(2) groups at T:0 hr, but no longer at T:48 hr. MMP-9 gene expression levels were unchanged directly after MV. However, at T:48 hr, gene and protein expression increased in LPS + MV + O(2) group. In conclusion, this study demonstrates the feasibility of delayed outcome measurements after a ventilation-free period in newborn rats and may help to further understand the time-course of molecular changes following MV. The differences obtained from the two time points could be interpreted as an initial transitory increase of inflammation and a delayed impact of the intervention on structure-related genes. Pediatr Pulmonol. 2012; 47:1204-1214. © 2012 Wiley Periodicals, Inc.

Current status and perspectives of cell therapy in Chagas disease

One century after its discovery, Chagas disease, caused by the protozoan, Trypanosoma cruzi, remains a major health problem in Latin America. Mortality and morbidity are mainly due to chronic processes that lead to dysfunction of the cardiac and digestive systems. About one third of the chronic chagasic individuals have or will develop the symptomatic forms of the disease, with cardiomyopathy being the most common chronic form. This is a progressively debilitating disease for which there are no currently available effective treatments other than heart transplantation. Like in other cardiac diseases, tissue engineering and cell therapy have been investigated in the past few years as a means of recovering the heart function lost as a consequence of chronic damage caused by the immune-mediated pathogenic mechanisms elicited in individuals with chronic chagasic cardiomyopathy. Here we review the studies of cell therapy in animal models and patients with chronic Chagas disease and the perspectives of the recovery of the heart function lost due to infection with T. cruzi.

The ALK-F1174L activating mutation is tumorigenic in MONC-1 neural crest stem cells in an orthotopic murine model of neuroblastoma

Background: Activating mutations of the anaplastic lymphoma receptor tyrosine kinase gene (ALK) were identified in both somatic and familial neuroblastoma. The most common somatic mutation, F1174L, is associated with NMYC amplification and displayed an efficient transforming activity in vivo. In addition, both AKL-F1174L and NMYC were shown cooperate in neuroblastoma tumorigenesis in animal models. To analyse the role of ALK mutations in the oncogenesis of neuroblastoma, ALK wt and various ALK mutants were transduced in murine neural crest stem cells (MONC1). Methods: ALK-wt, and F1174L, and R1275Q mutants were stably expressed by retroviral infection using the pMIGR1 vector in the murine neural crest stem cell line MONC-1, previously immortalised with v-myc, and further implanted subcutaneously or orthotopically in nude mice. Results: Both MONC1-ALK-F1174L and -R1275Q cells displayed a rapid tumour forming capacity upon subcutaneous injection in nude mice compared to control MONC1-MIGR or MONC1 cells. Interestingly, the transforming capacity of the F1174L mutant was much more potent compared to that of R1275Q mutant in murine neural crest stem cells, while ALK-wt was not tumorigenic. In addition, mice implanted orthotopically in the left adrenal gland with MONC1-ALK-F1174L cells developed highly aggressive tumours in 100% of mice within three weeks, while MONC1-Migr or MONC1 derived tumours displayed a longer latency and a reduced tumour take. Conclusions: The activating ALK-F1174L mutant is highly tumorigenic in neural crest stem cells. Nevertheless, we cannot exclude a functional implication of the v-myc oncogene used for MONC1 cells immortalisation. Indeed, the control MONC1-Migr and MONC1 cells were also able to derive subcutaneous and orthotopic tumours, although with considerable reduced efficiency. Further investigations using neural crest stem cell lacking exogenous myc expression are currently on way to assess the exclusive role of ALK mutations in NB oncogenesis.