Low dose dietary contamination with deoxynivalenol mycotoxin exacerbates enteritis and colorectal cancer in mice

BACKGROUND

The mycotoxin deoxynivalenol (DON) is a frequent contaminant of grain and cereal products worldwide. Exposure to DON can cause gastrointestinal inflammation, disturb gut barrier function, and induce gut dysbiosis in vivo under basal conditions, but little is known about the effects of DON ingestion in individuals with pre-existing gastrointestinal disease.

OBJECTIVES

Mice were orally exposed to 10 and 100 μg/kg bw/day of DON, corresponding to 10 to 100-fold human tolerable daily intake concentrations, and to the translation in mice of current human daily intake. The effects of DON exposure were explored under steady-state conditions, and in murine models of enteritis and colorectal cancer (CRC).

RESULTS

After 8 days of DON exposure, an increase of histomorphological and molecular parameters of epithelial proliferation were observed in normal mice, from the duodenum to the colon. The same exposure in a murine model of indomethacin-induced enteritis led to exacerbation of lesion development and induction of ileal cytokines. DON exposure also worsened the development of colitis-associated CRC in mice as shown by increases in endoscopic and histological colitis scores, tumor grades, and histological hyperplasia. In colon of DON-exposed mice, upstream and downstream ERK signaling genes were upregulated including Mapk1, Mapk3, Map 2k1, Map2k2 core ERK pathway effectors, and Bcl2 and Bcl2l1 antiapoptotic genes. The effects observed in the CRC model were associated with alterations in cecal microbiota taxonomic composition and metabolism of bacterial fucose and rhamnose. Strong Spearman's correlations were revealed between the relative abundance of the changed bacterial genera and CRC-related variables.

DISCUSSION

Ingestion of DON mycotoxin at concentrations representative of human real-world exposure worsened the development of indomethacin-induced enteritis and colitis-associated CRC in mice. Our results suggest that even at low doses, which are currently tolerated in the human diet, DON could promote the development of intestinal inflammatory diseases and CRC.

Oral exposure to polyethylene microplastics induces inflammatory and metabolic changes and promotes fibrosis in mouse liver

Accumulating evidence shows widespread contamination of water sources and food with microplastics. Although the liver is one of the main sites of bioaccumulation within the human body, it is still unclear whether microplastics produce damaging effects. In particular, the hepatic consequences of ingesting polyethylene (PE) microplastics in mammals are unknown. In this study, female mice were fed with food contaminated with 36 and 116 µm diameter PE microbeads at a dosage of 100 µg/g of food for 6 and 9 weeks. Mice were exposed to each type of microbead, or co-exposed to the 2 types of microbeads. Mouse liver showed altered levels of genes involved in uptake, synthesis, and β-oxidation of fatty acids. Ingestion of PE microbeads disturbed the detoxification response, promoted oxidative imbalance, increased inflammatory foci and cytokine expression, and enhanced proliferation in liver. Since relative expression of the hepatic stellate cell marker Pdgfa and collagen deposition were increased following PE exposure, we assessed the effect of PE ingestion in a mouse model of CCl4-induced fibrosis and showed that PE dietary exposure exacerbated liver fibrogenesis. These findings provide the first demonstration of the adverse hepatic effects of PE ingestion in mammals and highlight the need for further health risk assessment in humans.

Gene/environment interaction in the susceptibility of Crohn's disease patients to aluminum

BACKGROUND & AIM

The key role of environmental factors in the pathogenesis of Inflammatory Bowel Diseases (IBD) is recognized. Aluminum is suspected to be a risk factor for IBD. However, mechanisms linking aluminum exposure to disease development are unknown. We examined the role of aluminum transport and subcellular localisation on human colon susceptibility to aluminum-induced inflammation.

METHODS

Human colon biopsies isolated from Crohn's disease (CD) or control patients and Caco-2 cells were incubated with aluminum. The effects of aluminum were evaluated on cytokine secretion and transporter expression. The role of aluminum kinetics parameters was studied in Caco-2 using transport inhibitors and in human colon biopsies by assessing genetic polymorphisms of transporters.

RESULTS

Aluminum exposure was shown to induce cytokine secretion in colon of CD but not healthy patients. In Caco-2 cells, aluminum internalisation was correlated with inflammatory status. In human colon, analysis of genetic polymorphisms and expression of ABCB1 and SLC26A3 transporters showed that their decreased activity was involved in aluminum-induced inflammation.

CONCLUSIONS

We hypothesize that alteration in detoxifying response would lead to a deregulation of intestinal homeostasis and to the expression of IBD. Our study emphasizes the complexity of gene/environment interaction for aluminum adverse health effect, highlighting at risk populations or subtypes of patients. A better understanding of correlations between gene expression or SNP and xenobiotic kinetics parameters would shift the medical paradigm to more personalized disease management and treatment.

Oral exposure to polyethylene microplastics alters gut morphology, immune response, and microbiota composition in mice

The ubiquitous and growing presence of microplastics (MPs) in all compartments of the environment raises concerns about their possible harmful effects on human health. Human exposure to MPs occurs largely through ingestion. Polyethylene (PE) is widely employed for reusable bags and food packaging and found to be present in drinking water and food. It is also one of the major polymers detected in human stool. The aim of this study was to characterize the effects of intestinal exposure to PE MPs on gut homeostasis. Mice were orally exposed for 6 weeks to PE microbeads of 2 different sizes, 36 and 116 μm, that correspond to those found in human stool. They were administrated either individually or as a mixture at a dose of 100 μg/g of food. Both PE microbead sizes were detected in mouse stool. Different parameters related to major intestinal functions were compared between control mice, mice exposed to each type of microbead, or co-exposed to the 2 types of microbeads. Intestinal disturbances were observed after individual exposure to each size of PE microbead, and the most marked deleterious effects were found in co-exposed mice. At the histomorphological level, crypt depth was increased throughout the intestinal tissues. Significant variations of gene expression related to epithelial, permeability, and inflammatory biomarkers were quantified. Defective recruitment of some intestinal immune cells was observed from the proximal portion of the small intestine to the colon. Several bacterial taxa at the order level were found to be affected by exposure to the MPs by metagenomic analysis of cecal microbiota. These results show that ingestion of PE microbeads induces significant alterations of crucial intestinal markers in mice and underscores the need to further study the health impact of MP exposure in humans.

Murine in utero exposure to simulated complex urban air pollution disturbs offspring gut maturation and microbiota during intestinal suckling-to-weaning transition in a sex-dependent manner

Background

Emerging data indicate that prenatal exposure to air pollution may lead to higher susceptibility to several non-communicable diseases. Limited research has been conducted due to difficulties in modelling realistic air pollution exposure. In this study, pregnant mice were exposed from gestational day 10–17 to an atmosphere representative of a 2017 pollution event in Beijing, China. Intestinal homeostasis and microbiota were assessed in both male and female offspring during the suckling-to-weaning transition.

Results

Sex-specific differences were observed in progeny of gestationally-exposed mice. In utero exposed males exhibited decreased villus and crypt length, vacuolation abnormalities, and lower levels of tight junction protein ZO-1 in ileum. They showed an upregulation of absorptive cell markers and a downregulation of neonatal markers in colon. Cecum of in utero exposed male mice also presented a deeply unbalanced inflammatory pattern. By contrast, in utero exposed female mice displayed less severe intestinal alterations, but included dysregulated expression of Lgr5 in colon, Tjp1 in cecum, and Epcam, Car2 and Sis in ileum. Moreover, exposed female mice showed dysbiosis characterized by a decreased weighted UniFrac β-diversity index, a higher abundance of Bacteroidales and Coriobacteriales orders, and a reduced Firmicutes/Bacteroidetes ratio.

Conclusion

Prenatal realistic modelling of an urban air pollution event induced sex-specific precocious alterations of structural and immune intestinal development in mice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00481-y.

Exposure to atmospheric Ag, TiO2, Ti and SiO2 engineered nanoparticles modulates gut inflammatory response and microbiota in mice

The development of nanotechnologies is leading to greater abundance of engineered nanoparticles (EN) in the environment, including in the atmospheric air. To date, it has been shown that the most prevalent EN found in the air are silver (Ag), titanium dioxide (TiO₂), titanium (Ti), and silicon dioxide (SiO₂). As the intestinal tract is increasingly recognized as a target for adverse effects induced by inhalation of air particles, the aim of this study was to assess the impact of these 4 atmospheric EN on intestinal inflammation and microbiota. We assessed the combined toxicity effects of Ag, Ti, TiO₂, and SiO₂ following a 28-day inhalation protocol in male and female mice. In distal and proximal colon, and in jejunum, EN mixture inhalation did not induce overt histological damage, but led to a significant modulation of inflammatory cytokine transcript abundance, including downregulation of Tnfα, Ifnγ, Il1β, Il17a, Il22, IL10, and Cxcl1 mRNA levels in male jejunum. A dysbiosis was observed in cecal microbiota of male and female mice exposed to the EN mixture, characterized by sex-dependent modulations of specific bacterial taxa, as well as sex-independent decreased abundance of the Eggerthellaceae family. Under dextran sodium sulfate-induced inflammatory conditions, exposure to the EN mixture increased the development of colitis in both male and female mice. Moreover, the direct dose-response effects of individual and mixed EN on gut organoids was studied and Ag, TiO₂, Ti, SiO₂, and EN mixture were found to generate specific inflammatory responses in the intestinal epithelium. These results indicate that the 4 most prevalent atmospheric EN could have the ability to disturb intestinal homeostasis through direct modulation of cytokine expression in gut epithelium, and by altering the inflammatory response and microbiota composition following inhalation.

Review article: Epidemiological and animal evidence for the role of air pollution in intestinal diseases

BACKGROUND

Ambient air pollution is recognized as one of the leading causes of global burden of disease. Involvement of air pollution in respiratory and cardiovascular diseases was first recognized, and then cumulative data has indicated that the intestinal tract could be also damaged.

AIM

To review and discuss the current epidemiological and animal data on the effects of air pollution on intestinal homeostasis.

METHODS

An extensive literature search was conducted using Google Scholar and Pubmed to gather relevant human and animal studies that have reported the effects of any air pollutant on the intestine.

RESULTS

Exposure to several gaseous and particulate matter components of air pollution have been associated either positively or negatively with the onset of various intestinal diseases including appendicitis, gastroenteric disorders, irritable bowel syndrome, inflammatory bowel diseases, and peptic ulcers. Several atmospheric pollutants have been associated with modifications of gut microbiota in humans. Animal studies have showed that inhalation of atmospheric particulate matter can lead to modifications of gut microbiota, impairments of oxidative and inflammatory intestinal balances, and disruption of gut epithelial permeability.

CONCLUSIONS

Overall, the literature appears to indicate that the gut is an underestimated target of adverse health effects induced by air pollution. It is therefore important to develop additional studies that aim to better understand the link between air pollutants and gastro-intestinal diseases.

Fine-scale geographical distribution and ecological risk factors for Crohn's disease in France (2007-2014)

BACKGROUND

Geographical variations in Crohn's disease (CD) suggest that the environment has a role in the pathogenesis of this condition.

AIMS

To describe the spatial distribution and the clustering of CD cases in France, and to assess the relationship between the prevalence of CD and environmental risk factors.

METHODS

We identified all patients with CD included in the French hospital discharge database from 2007 to 2014. Age- and gender-smoothed standardised prevalence ratios over this period were computed for 5610 spatial units. An ecological regression analysis was used to assess the relationship between the risk of CD and ecological variables (health care, latitude, socio-economic deprivation, urbanisation, proportion of agricultural surfaces and density of industries). Local spatial clusters of high-CD prevalence were searched for using elliptic spatial scan statistics and characterised in a hierarchical ascendant classification based on the same ecological variables.

RESULTS

About 129 089 patients with CD were identified, yielding a crude prevalence of 203 per 100 000 inhabitants. The overall spatial heterogeneity was statistically significant (P < .001). An elevated risk of CD was found to be significantly associated with high-social deprivation (relative risk [95% confidence interval] = 1.05 [1.02-1.08]) and high urbanisation (1.09 [1.04-1.14]). Sixteen significant spatial clusters of high-CD prevalence were identified; there were no common ecological variables.

CONCLUSIONS

The geographical distribution of CD prevalence in France is not uniform, and is associated with high levels of social deprivation and urbanisation. Larger ecological databases integrating more detailed environmental and clinical information are needed.

[Raxone in the Leber optical neuropathy: Parisian experience]

INTRODUCTION

Leber's Hereditary Optic Neuropathy (LHON) causes a rapid and severe decrease in visual acuity. Raxone^® (Idebenone, Santhera) is the only drug to have a European Marketing Authorization for the treatment of this optic neuropathy. It can be proposed in the first months after the onset of this optic neuropathy, according to an international consensus meeting.

PATIENTS AND METHODS

Retrospective study of the efficacy of Raxone^® on the visual acuity of patients with genetically confirmed LHON who were followed in four Parisian hospitals. The primary endpoint is the best recovery of LogMar visual acuity between baseline and the end of follow-up. The secondary endpoints are the evolution of LogMar visual acuity of the best eye at baseline and change in LogMar visual acuity for each eye considered separately.

RESULTS

Seventeen patients, three women and 14 men, mean age 34.2 years, naive to treatment with Raxone^® were included in this study. The mean duration of treatment was 11.0±6.6 months. A mitochondrial DNA mutation was found in all patients. Only 2 had the 14484 mutation. A recovery of better LogMar visual acuity was found at the end of the treatment for 4 eyes (23.5 %), and a deterioration was observed for 8 (47.0 %). Only 2 eyes (11.7 %) with the best visual acuity at baseline improved. On the other hand, 17.6 % of the eyes considered separately had an improvement in their LogMar visual acuity at the end of the treatment.

CONCLUSION

The results confirm the trend of Raxone^® treatment to improve patients' visual acuity. Given the recommendations of a consensus conference, this treatment should be started early after the onset of LHON. It is therefore important to look for this diagnosis in the presence of any hereditary optic neuropathy, in order to be able to initiate this treatment.

Aluminum Ingestion Promotes Colorectal Hypersensitivity in Rodents

Background & Aims

Irritable bowel syndrome (IBS) is a multifactorial disease arising from a complex interplay between genetic predisposition and environmental influences. To date, environmental triggers are not well known. Aluminum is commonly present in food, notably by its use as food additive. We investigated the effects of aluminum ingestion in rodent models of visceral hypersensitivity, and the mechanisms involved.

Methods

Visceral hypersensitivity was recorded by colorectal distension in rats administered with oral low doses of aluminum. Inflammation was analyzed in the colon of aluminum-treated rats by quantitative PCR for cytokine expression and by immunohistochemistry for immune cells quantification. Involvement of mast cells in the aluminum-induced hypersensitivity was determined by cromoglycate administration of rats and in mast cell-deficient mice (KitW-sh/W-sh). Proteinase-activated receptor-2 (PAR2) activation in response to aluminum was evaluated and its implication in aluminum-induced hypersensitivity was assessed in PAR2 knockout mice.

Results

Orally administered low-dose aluminum induced visceral hypersensitivity in rats and mice. Visceral pain induced by aluminum persisted over time even after cessation of treatment, reappeared and was amplified when treatment resumed. As observed in humans, female animals were more sensitive than males. Major mediators of nociception were up-regulated in the colon by aluminum. Activation of mast cells and PAR2 were required for aluminum-induced hypersensitivity.

Conclusions

These findings indicate that oral exposure to aluminum at human dietary level reproduces clinical and molecular features of IBS, highlighting a new pathway of prevention and treatment of visceral pain in some susceptible patients.

High carriage of adherent invasive E. coli in wildlife and healthy individuals

BACKGROUND

Adherent invasive Escherichia coli (AIEC) are suspected to be involved in the pathogenesis of inflammatory bowel diseases. Since AIEC was first described in 1999, despite important progress on its genomic and immune characterizations, some crucial questions remain unanswered, such as whether there exists a natural reservoir, or whether there is asymptomatic carriage. The ECOR collection, including E. coli strains isolated mainly from the gut of healthy humans and animals, constitutes an ideal tool to investigate AIEC prevalence in healthy condition. A total of 61 E. coli strains were examined for characteristics of AIEC.

METHODS

The adhesion, invasion and intramacrophage replication capabilities (AIEC phenotype) of 61 intestinal E. coli strains were determined. The absence of virulence-associated diarrheagenic E. coli pathotypes (EPEC, ETEC, EIEC, EHEC, DAEC, EAEC), and uropathogenic E. coli was checked.

RESULTS

Out of 61 intestinal strains, 13 (21%) exhibit the AIEC phenotype, 7 are from human origin and 6 are from animal origin. Prevalence of AIEC strains is about 24 and 19% in healthy humans and animals respectively. These strains are highly genetically diverse as they are distributed among the main described phylogroups. Among E. coli strains from the ECOR collection, we also detected strains able to detach I-407 cells.

CONCLUSIONS

Our study described for the first time AIEC strains isolated from the feces of healthy humans and animals.

Chronic ingestion of deoxynivalenol at human dietary levels impairs intestinal homeostasis and gut microbiota in mice

The mycotoxin deoxynivalenol (DON) is a frequent contaminant of cereals and their by-products in areas with a moderate climate. Produced by Fusarium species, it is one of the most prevalent mycotoxins in cereal crops worldwide, and the most frequently occurring type B trichothecene in Europe. Due to its toxic properties, high stability and prevalence, the presence of DON in the food chain could represent a major public health risk. However, despite its well-known acute toxicological effects, information on the adverse effects of realistic exposure remains limited. We orally exposed mice during 9 months to DON at doses relevant for currently estimated human intake and explored the impact on various gut health parameters. DON exposure induced recruitment of regulatory B cells, and activation of regulatory T cells and dendritic cells in mesenteric lymph nodes. Several inflammatory parameters were increased in colon of DON-exposed mice, whereas inversely inflammatory markers were decreased in ileum. Histomorphological impairments were observed from the duodenum to the colon. Both colon and jejunum presented a hyperproliferation of epithelial cells and an increased expression of mature absorptive cells markers. Finally, DON exposure reshaped gut microbial structure and drastically disturbed the abundance of several bacterial phyla, families, and genera, leading to dysbiosis. Chronic oral exposure to human relevant doses of DON induces several disturbances of gut homeostasis with likely pathological implications for susceptible individuals.

Stress-induced flexibility and individuality in female and male zebra finch distance calls

Vocal recognition is central to the coordination and organization of behavior in pair-bonding species such as zebra finches. Zebra finches' vocalizations are individualized and support acoustic discrimination processes. Physiological states - such as the ones involved in emotional stress - can modify vocal production and consequently the structure of vocalizations. These modifications might signal the state of the caller but also impair individual recognition processes. This may represent a signaling trade-off, especially in contexts where both pieces of information can be critically important, for example when mates use calls to reunite after social isolation. Here we study the impact of a stress on the individual vocal signature in both female and male zebra finch distance calls. We built a manually curated database of distance calls of several individuals (both females and males) recorded in control and stress conditions. The stress was induced either by social isolation of the bird or using exogenous corticosterone. We developed a machine learning approach to assess the impact of stress on the individual characterization of calls. We show that while calls' spectral structure is significantly modified by stress, it still allows for the correct classification of calls to the caller. Moreover, we also show that the stress-induced modification of calls' structure is not a 'general feature signal' that can be detected as a 'stress' signal regardless of identity. Thus, female and male zebra finch calls' structure show stress-induced flexibility that stays within the range of individual vocal signatures.

Effects of urban coarse particles inhalation on oxidative and inflammatory parameters in the mouse lung and colon

Background

Air pollution is a recognized aggravating factor for pulmonary diseases and has notably deleterious effects on asthma, bronchitis and pneumonia. Recent studies suggest that air pollution may also cause adverse effects in the gastrointestinal tract. Accumulating experimental evidence shows that immune responses in the pulmonary and intestinal mucosae are closely interrelated, and that gut-lung crosstalk controls pathophysiological processes such as responses to cigarette smoke and influenza virus infection. Our first aim was to collect urban coarse particulate matter (PM) and to characterize them for elemental content, gastric bioaccessibility, and oxidative potential; our second aim was to determine the short-term effects of urban coarse PM inhalation on pulmonary and colonic mucosae in mice, and to test the hypothesis that the well-known antioxidant N-acetyl-L-cysteine (NAC) reverses the effects of PM inhalation.

Results

The collected PM had classical features of urban particles and possessed oxidative potential partly attributable to their metal fraction. Bioaccessibility study confirmed the high solubility of some metals at the gastric level. Male mice were exposed to urban coarse PM in a ventilated inhalation chamber for 15 days at a concentration relevant to episodic elevation peak of air pollution. Coarse PM inhalation induced systemic oxidative stress, recruited immune cells to the lung, and increased cytokine levels in the lung and colon. Concomitant oral administration of NAC reversed all the observed effects relative to the inhalation of coarse PM.

Conclusions

Coarse PM-induced low-grade inflammation in the lung and colon is mediated by oxidative stress and deserves more investigation as potentiating factor for inflammatory diseases.

Electronic supplementary material

The online version of this article (10.1186/s12989-017-0227-z) contains supplementary material, which is available to authorized users.

Gut: An underestimated target organ for Aluminum

Since World War II, several factors such as an impressive industrial growth, an enhanced environmental bioavailability and intensified food consumption have contributed to a significant amplification of human exposure to aluminum. Aluminum is particularly present in food, beverages, some drugs and airbone dust. In our food, aluminum is superimposed via additives and cooking utensils. Therefore, the tolerable intake of aluminum is exceeded for a significant part of the world population, especially in children who are more vulnerable to toxic effects of pollutants than adults. Faced with this oral aluminum influx, intestinal tract is an essential barrier, especially as 38% of ingested aluminum accumulates at the intestinal mucosa. Although still poorly documented to date, the impact of oral exposure to aluminum in conditions relevant to real human exposure appears to be deleterious for gut homeostasis. Aluminum ingestion affects the regulation of the permeability, the microflora and the immune function of intestine. Nowadays, several arguments are consistent with an involvement of aluminum as an environmental risk factor for inflammatory bowel diseases.

Open-angle glaucoma and paraoptic cyst: first description of a series of 11 patients

We report 11 patients who were referred to our institution for severe open-angle glaucoma who had a paraoptic cyst on MR imaging. All cysts were extraoptic and retrolaminar; most were deforming the adjacent optic nerve. Cysts had a high signal on T2 and FLAIR sequences, and a variable signal on T1 and variable echogenicity, suggesting different proteinaceous content. Arterial vascularization of the optic nerve was normal. Cyst volumes were inversely correlated with the severity of glaucoma on the same eye (P < .01-.05, Spearman correlation coefficient). We hypothesized that such cysts may reflect a valve mechanism, which would allow preservation of the translamina cribrosa pressure and thus could preserve visual function. The rarity of this association, together with the frequent mass effect of the cyst on the optic nerve, stresses the necessity of long-term follow-up in these patients.

[Epidemiology, risk factors and factors associated with disabling course in inflammatory bowel disease]

Inflammatory bowel diseases (IBD) are not rare and would affect near of 5 million of patients in the world (including 2.5 in North America and 2.5 in Europe with at least 200,000 in France). These are chronic relapsing disorders affecting young patients (peak of incidence in patients aged from 20 to 30 years), particularly the young females (sex ratio F/M: 1.3). Their cause is unknown and there is no curative treatment. Although many research studies have isolated more than 160 genes whose variants are associated with these diseases, the weight of genetics remains low in their occurrence. Significant time and space variations in incidence of IBD have been reported. Firstly, an increase of IBD incidence has been reported overtime worldwide. Secondly, a space variation in IBD incidence has been noted with a dramatic increase in emerging countries. Even within a same geographical area through a prospective population-based dataset since 27 years (EPIMAD Registry), a spatial heterogeneity of incidence has been reported, suggesting the important role of the environment in the occurrence of these diseases. Smoking and appendectomy are the only environmental factors clearly involved in the development and progression of IBD and cannot explain spatial and temporal heterogeneity in the IBD observed incidence worldwide. New multidisciplinary basic and epidemiological studies are needed to identify the factors involved in the onset of IBD.

Optic neuritis revealing Kikuchi-Fujimoto disease

Kikuchi-Fujimoto disease is a rare systemic disease with uncommon neurological involvement. We report the case of a 30-year-old Asian woman who presented a rapidly progressive loss of vision. Magnetic resonance imaging (MRI) of the optic nerve revealed an inflammation of the left optic nerve with chiasmatic involvement, without any encephalic or medullar lesion. Thoracic computed tomography scan showed bilateral axillary lymphadenopathy. Analysis of a biopsy of the axillary lymph node showed typical histological findings of Kikuchi-Fujimoto disease. There was no clinical or biological sign of associated systemic lupus erythematosus. The patient spontaneously recovered normal visual acuity in 4 weeks, with resolution of MRI abnormalities. No optic neuritis relapse or neurological event occurred in a 3-year follow-up. To our knowledge this is the first case of optic neuritis associated with Kikuchi-Fujimoto disease.

AIEC colonization and pathogenicity: influence of previous antibiotic treatment and preexisting inflammation

BACKGROUND

Inflammatory bowel diseases (IBD) patients are abnormally colonized by adherent-invasive Escherichia coli (AIEC). NOD2 gene mutations impair intracellular bacterial clearance. We evaluated the impact of antibiotic treatment on AIEC colonization in wildtype (WT) and NOD2 knockout mice (NOD2KO) and the consequences on intestinal inflammation.

METHODS

After 3 days of antibiotic treatment, mice were infected for 2 days with 10⁹ CFU AIEC and sacrificed 1, 5, and 60 days later. In parallel, mice were challenged with AIEC subsequent to a dextran sodium sulfate (DSS) treatment and sacrificed 9 days later. Ileum, colon, and mesenteric tissues were sampled for AIEC quantification and evaluation of inflammation.

RESULTS

Without antibiotic treatment, AIEC was not able to colonize WT and NOD2KO mice. Compared with nontreated animals, antibiotic treatment led to a significant increase in ileal and colonic colonization of AIEC in WT and/or NOD2KO mice. Persistent AIEC colonization was observed until day 5 only in NOD2KO mice, disappearing at day 60. Mesenteric translocation of AIEC was observed only in NOD2KO mice. No inflammation was observed in WT and NOD2KO mice treated with antibiotics and infected with AIEC. During DSS-induced colitis, colonization and persistence of AIEC was observed in the colon. Moreover, a dramatic increase in clinical, histological, and molecular parameters of colitis was observed in mice infected with AIEC but not with a commensal E. coli strain.

CONCLUSIONS

Antibiotic treatment was necessary for AIEC colonization of the gut and mesenteric tissues and persistence of AIEC was dependent on NOD2. AIEC exacerbated a preexisting DSS-induced colitis in WT mice.

Social experience affects neuronal responses to male calls in adult female zebra finches

Plasticity studies have consistently shown that behavioural relevance can change the neural representation of sounds in the auditory system, but what occurs in the context of natural acoustic communication where significance could be acquired through social interaction remains to be explored. The zebra finch, a highly social songbird species that forms lifelong pair bonds and uses a vocalization, the distance call, to identify its mate, offers an opportunity to address this issue. Here, we recorded spiking activity in females while presenting distance calls that differed in their degree of familiarity: calls produced by the mate, by a familiar male, or by an unfamiliar male. We focused on the caudomedial nidopallium (NCM), a secondary auditory forebrain region. Both the mate's call and the familiar call evoked responses that differed in magnitude from responses to the unfamiliar call. This distinction between responses was seen both in single unit recordings from anesthetized females and in multiunit recordings from awake freely moving females. In contrast, control females that had not heard them previously displayed responses of similar magnitudes to all three calls. In addition, more cells showed highly selective responses in mated than in control females, suggesting that experience-dependent plasticity in call-evoked responses resulted in enhanced discrimination of auditory stimuli. Our results as a whole demonstrate major changes in the representation of natural vocalizations in the NCM within the context of individual recognition. The functional properties of NCM neurons may thus change continuously to adapt to the social environment.

Sphenoid and optic nerve sheath meningioma revealed by recurrent brain infarctions

Meningioma, though benign, may invade adjacent structures such as bone, soft tissues, dural sinuses and arteries. However brain infarctions secondary to meningioma involving the cavernous sinus and encasing and narrowing the intracranial carotid artery are rare. We report the case of a young man with recurrent left carotid artery infarctions due to a left sphenoid meningioma infiltrating the posterior optic nerve sheath through the optic canal and circumscribing the intracranial carotid artery. The patient had a gradually progressive occlusion of the middle cerebral artery, the distal internal carotid artery and finally the anterior cerebral artery ipsilateral to the sphenoid meningioma.

Ophthalmoplegia as the presenting muscle-related manifestation of myotonic dystrophy

INTRODUCTION

Myotonic dystrophy type 1 (DM1) is a genetic disorder caused by expanded CTG repeats within the 3' untranslated region of the dystrophia myotonia protein kinase (DMPK) gene on chromosome 19. Diplopia is rare in this disease and has only been reported in patients with diffuse neuromuscular disorders.

OBSERVATION

We report here on the case of a 58-year-old woman in whom ophthalmoplegia was the first neuromuscular manifestation of DM1 and led to the diagnosis. Among the multisystem abnormalities associated with DM1, muscle-related symptoms are prominent, and usually involve the facial and neck muscles early on in the disease. This case provides additional evidence of oculomotor muscle involvement in DM1.

CONCLUSION

DM1 should, therefore, be considered during the diagnostic workup of any unexplained ophthalmoplegia of muscle origin, especially if there has been a previous history of cataract, even in the absence of typical muscle-related features.

Toll-like receptor 2 is critical for induction of Reg3 beta expression and intestinal clearance of Yersinia pseudotuberculosis

OBJECTIVE

Yersinia pseudotuberculosis causes ileitis and mesenteric lymphadenitis by mainly invading the Peyer's patches that are positioned in the terminal ileum. Whereas toll-like-receptor 2 (TLR2) controls mucosal inflammation by detecting certain microbiota-derived signals, its exact role in protecting Peyer's patches against bacterial invasion has not been defined.

DESIGN

Wild-type, Tlr2-, Nod2- and MyD88-deficient animals were challenged by Y pseudotuberculosis via the oral or systemic route. The role of microbiota in conditioning Peyer's patches against Yersinia through TLR2 was assessed by delivering, ad libitum, exogenous TLR2 agonists in drinking water to germ-free and streptomycin-treated animals. Bacterial eradication from Peyer's patches was measured by using a colony-forming unit assay. Expression of cryptdins and the c-type lectin Reg3 beta was quantified by quantitative reverse transcriptase polymerase chain reaction analysis.

RESULTS

Our data demonstrated that Tlr2-deficient mice failed to limit Yersinia dissemination from the Peyer's patches and succumbed to sepsis independently of nucleotide-binding and oligomerisation domain 2 (NOD2). Recognition of both microbiota-derived and myeloid differentiation factor 88 (MyD88)-mediated elicitors was found to be critically involved in gut protection against Yersinia-induced lethality, while TLR2 was dispensable to systemic Yersinia infection. Gene expression analyses revealed that optimal epithelial transcript level of the anti-infective Reg3 beta requires TLR2 activation. Consistently, Yersinia infection triggered TLR2-dependent Reg3 beta expression in Peyer's patches. Importantly, oral treatment with exogenous TLR2 agonists in germ-free animals was able to further enhance Yersinia-induced expression of Reg3 beta and to restore intestinal resistance to Yersinia. Lastly, genetic ablation of Reg3 beta resulted in impaired clearance of the bacterial load in Peyer's patches.

CONCLUSIONS

TLR2/REG3 beta is thus an essential component in conditioning epithelial defence signalling pathways against bacterial invasion.

Idiopathic intracranial hypertension: a comparison between French and North-American white patients

OBJECTIVE

To compare French and American white patients with idiopathic intracranial hypertension (IIH), and to determine prognostic factors associated with visual loss.

METHODS

Medical records of all consecutive white patients with definite IIH seen between 2001 and 2006 in three French tertiary care medical centers and one American tertiary medical center were reviewed. Demographics, associated clinical features, and visual function at presentation and follow-up were collected. French white patients were compared to American white patients.

RESULTS

One hundred and thirty-four patients (66 French, 68 American) were included. American patients were 8.7 times more likely than French patients to have visual acuity 20/60 or worse or visual field constriction (95% CI: 2.1-36.1, p=0.0001). American patients were treated more aggressively than French patients. French patients were older (31 vs. 28 years, p=0.02) and more likely to have anemia (20 vs. 2%, p<0.001). American patients had a longer duration of symptoms prior to diagnosis (12 vs. 4 weeks, p=0.01) and longer follow-up than French patients (26 vs. 11 months, p=0.001). Multivariable analysis found that nationality was an independent risk factor for visual loss. French and American patients did not differ regarding gender proportion, frequency of obesity, sleep apnea, endocrine diseases, or systemic hypertension. Cerebrospinal fluid (CSF) opening pressures were similar in both groups.

CONCLUSION

American patients with IIH had worse visual outcomes than French patients despite more aggressive treatment. These differences are not explained by differences in previously known risk factors.

The Drosophila peptidoglycan recognition protein PGRP-LF blocks PGRP-LC and IMD/JNK pathway activation

Eukaryotic peptidoglycan recognition proteins (PGRPs) are related to bacterial amidases. In Drosophila, PGRPs bind peptidoglycan and function as central sensors and regulators of the innate immune response. PGRP-LC/PGRP-LE constitute the receptor complex in the immune deficiency (IMD) pathway, which is an innate immune cascade triggered upon Gram-negative bacterial infection. Here, we present the functional analysis of the nonamidase, membrane-associated PGRP-LF. We show that PGRP-LF acts as a specific negative regulator of the IMD pathway. Reduction of PGRP-LF levels, in the absence of infection, is sufficient to trigger IMD pathway activation. Furthermore, normal development is impaired in the absence of functional PGRP-LF, a phenotype mediated by the JNK pathway. Thus, PGRP-LF prevents constitutive activation of both the JNK and the IMD pathways. We propose a model in which PGRP-LF keeps the Drosophila IMD pathway silent by sequestering circulating peptidoglycan.

Measuring brain hemodynamic changes in a songbird: responses to hypercapnia measured with functional MRI and near-infrared spectroscopy

Songbirds have been evolved into models of choice for the study of the cerebral underpinnings of vocal communication. Nevertheless, there is still a need for in vivo methods allowing the real-time monitoring of brain activity. Functional Magnetic Resonance Imaging (fMRI) has been applied in anesthetized intact songbirds. It relies on blood oxygen level-dependent (BOLD) contrast revealing hemodynamic changes. Non-invasive near-infrared spectroscopy (NIRS) is based on the weak absorption of near-infrared light by biological tissues. Time-resolved femtosecond white laser NIRS is a new probing method using real-time spectral measurements which give access to the local variation of absorbing chromophores such as hemoglobins. In this study, we test the efficiency of our time-resolved NIRS device in monitoring physiological hemodynamic brain responses in a songbird, the zebra finch (Taeniopygia guttata), using a hypercapnia event (7% inhaled CO(2)). The results are compared to those obtained using BOLD fMRI. The NIRS measurements clearly demonstrate that during hypercapnia the blood oxygen saturation level increases (increase in local concentration of oxyhemoglobin, decrease in deoxyhemoglobin concentration and total hemoglobin concentration). Our results provide the first correlation in songbirds of the variations in total hemoglobin and oxygen saturation level obtained from NIRS with local BOLD signal variations.

Nod-like receptors: cytosolic watchdogs for immunity against pathogens

In mammals, tissue-specific sets of pattern-recognition molecules, including Nod-like receptors (NLR), enable concomitant and sequential detection of microbial-associated molecular patterns from both the extracellular and intracellular microenvironment. Repressing and de-repressing the cytosolic surveillance machinery contributes to vital immune homeostasis and protective responses within specific tissues. Conversely, defective biology of NLR drives the development of recurrent infectious, autoimmune and/or inflammatory diseases by failing to mount barrier functions against pathogens, to tolerate commensals, and/or to instruct the adaptive immune response against microbes. Better decoding microbial strategies that are evolved to circumvent NLR sensing will provide clues for the development of rational therapies aimed at curing and/or preventing common and emerging immunopathologies.

Diagnosis and treatment of dural carotid-cavernous fistulas: a consecutive series of 27 patients

OBJECTIVES

To report clinical characteristics, angiographical findings and results of endovascular treatment of patients presenting with dural carotid-cavernous fistulas (DCCFs).

METHOD

Retrospective analysis of 27 consecutive patients with DCCF referred to a specialised interventional neuroradiology department.

RESULTS

Orbital and neuro-ophthalmological symptoms were the most common clinical presentation at diagnosis (n = 25). The venous drainage of the fistula involved the ipsilateral superior ophthalmic vein in 24 patients, the contralateral cavernous sinus in 6 and a leptomeningeal vein in 5 patients. Thrombosis of at least one petrosal sinus was found in 23 patients. 7 patients did not receive endovascular treatment: 3 had spontaneous DCCF obliteration, and 4 had only minor clinical symptoms and no leptomeningeal venous drainage on an angiogram. 20 patients received endovascular treatment via either a transvenous (n = 16) or a transarterial approach (n = 4). Complete occlusion of the fistula was obtained in 14 of 16 (87%) patients treated by the transvenous approach and in 1 of 4 (25%) patients treated by the transarterial approach. 16 patients had early clinical improvement after endovascular treatment. One patient had a cerebral haemorrhage after transvenous embolisation of a DCCF with leptomeningeal drainage. On follow-up, all patients treated by the transarterial route remained symptomatic, whereas 10 of 14 (71%) patients cured by the transvenous route were asymptomatic.

CONCLUSIONS

Transvenous embolisation is a safe and efficient endovascular approach to treat patients with DCCF. However, this technique requires a long learning curve.

NODs in defence: from vulnerable antimicrobial peptides to chronic inflammation

Defensins and cathelicidins are prevalent and essential gastrointestinal cationic antimicrobial peptides (CAPs). However, these defensive peptides are not infallible because certain enteropathogens can overcome their protective function. Furthermore, impaired defensin synthesis has been linked to the occurrence of Crohn's disease (CD), a chronic inflammatory bowel disease. Recently, defective bacterial sensing through NOD1 and NOD2 has been related to reduced defensin production, CD predisposition and susceptibility to enteric infection. Hence, we propose that microbial sensors at the gut interface monitor the levels of these effector peptides, which might function as "danger" signals to confer tolerance and alert immunocytes. Further work is required to clarify how gastrointestinal CAPs are regulated and to assess their role in maintaining epithelial homeostasis and triggering adaptive immunity.

Downregulation of the Drosophila immune response by peptidoglycan-recognition proteins SC1 and SC2

Peptidoglycan-recognition proteins (PGRPs) are evolutionarily conserved molecules that are structurally related to bacterial amidases. Several Drosophila PGRPs have lost this enzymatic activity and serve as microbe sensors through peptidoglycan recognition. Other PGRP family members, such as Drosophila PGRP-SC1 or mammalian PGRP-L, have conserved the amidase function and are able to cleave peptidoglycan in vitro. However, the contribution of these amidase PGRPs to host defense in vivo has remained elusive so far. Using an RNA-interference approach, we addressed the function of two PGRPs with amidase activity in the Drosophila immune response. We observed that PGRP-SC1/2–depleted flies present a specific over-activation of the IMD (immune deficiency) signaling pathway after bacterial challenge. Our data suggest that these proteins act in the larval gut to prevent activation of this pathway following bacterial ingestion. We further show that a strict control of IMD-pathway activation is essential to prevent bacteria-induced developmental defects and larval death.

It has long been known that the mammalian immune response needs to be kept under tight control. Responses that are delayed or of insufficient vigor can lead to a failure to control infection. However, excessive or inappropriate inflammation can be harmful or event fatal. Using the fruit fly as a model, evidence is presented that such an immuno-modulation is also essential in invertebrates and is mediated by peptidoglycan-recognition proteins (PGRPs). PGRPs are evolutionarily conserved molecules derived from enzymes that cleave bacterial peptidoglycan. It has been shown previously that some PGRPs have lost this enzymatic activity and function as sensors of bacteria upstream of the Drosophila immune pathways. The contribution of PGRPs which have maintained enzymatic activity to host defense has remained elusive so far. Here, the authors investigate in vivo data on the role of Drosophila PGRPs with enzymatic activity. Their results suggest that these proteins are required in the larval gut to negatively regulate the immune response, thus preventing bacterially induced developmental defects and death.

Function of the drosophila pattern-recognition receptor PGRP-SD in the detection of Gram-positive bacteria

The activation of an immune response requires recognition of microorganisms by host receptors. In drosophila, detection of Gram-positive bacteria is mediated by cooperation between the peptidoglycan-recognition protein-SA (PGRP-SA) and Gram-negative binding protein 1 (GNBP1) proteins. Here we show that some Gram-positive bacterial species activate an immune response in a PGRP-SA- and GNBP1-independent manner, indicating that alternative receptors exist. Consistent with this, we noted that PGRP-SD mutants were susceptible to some Gram-positive bacteria and that a loss-of-function mutation in PGRP-SD severely exacerbated the PGRP-SA and GNBP1 mutant phenotypes. These data indicate that PGRP-SD can function as a receptor for Gram-positive bacteria and shows partial redundancy with the PGRP-SA-GNBP1 complex.

Lipomannans, but not lipoarabinomannans, purified from Mycobacterium chelonae and Mycobacterium kansasii induce TNF-alpha and IL-8 secretion by a CD14-toll-like receptor 2-dependent mechanism

Lipoarabinomannans (LAMs) are glycolipids from the mycobacterial cell wall that exhibit various biological activities, including proinflammatory and anti-inflammatory responses. However, little is known about the properties of lipomannans (LMs), considered to be precursors of LAMs. In this study, we provide evidence that LMs purified from Mycobacterium chelonae and a clinical strain of Mycobacterium kansasii stimulated mRNA expression and secretion of TNF-alpha and IL-8 from human macrophage-like differentiated THP-1 cells. In contrast to LMs, LAMs were not able to induce a significant cytokine-inducing effect. The mechanism of activation by LMs was investigated using various Abs raised against surface receptors for multiple bacterial products. The presence of anti-CD14 or anti-Toll-like receptor 2 (TLR2) Abs profoundly affected production of TNF-alpha and IL-8, suggesting that both CD14 and TLR2 participate in the LM-mediated activation process. Furthermore, stimulation of cells was dependent on the presence of the LPS-binding protein, a plasma protein that transfers glycolipids to CD14. Chemical degradation of the arabinan domain of mannose-capped LAM from M. kansasii, which presented no cytokine-eliciting effect, restored the cytokine-inducing activity at a level similar to those of LMs. These results support the hypothesis that the presence of an arabinan in LAMs prevents the interaction of these glycolipids with TLR2/CD14 receptors. In addition, we found that phosphatidylinositol dimannosides isolated from M. kansasii did not induce cytokine secretion. This study suggests that LMs isolated from different mycobacterial species participate in the immunomodulation of the infected host and that the D-mannan core of this glycolipid is essential for this function.

The complication of retained intraocular recipient corneal button after penetrating keratoplasty

PURPOSE

To describe the complication of retained intraocular recipient corneal button after penetrating keratoplasty.

METHOD

Case report. A 27-year-old man was referred to us because of complications after penetrating keratoplasty on the right eye. Slit-lamp examination disclosed a clear graft with a second clear corneal button behind.

RESULTS

A second penetrating keratoplasty was performed successfully on the right eye. Histologic examination showed an intact epithelium and stroma vascularization of the recipient corneal button. Immunochemistry of the recipient corneal button and the first donor corneal button was performed.

CONCLUSION

Although the recipient corneal button remained inside the anterior chamber for 5 months, no epithelial ingrowth occurred.