Awareness and agreement with neurofibromatosis care guidelines among U.S. neurofibromatosis specialists.

INTRODUCTION: The neurofibromatoses (NF) are a group of rare, genetic diseases sharing a predisposition to develop multiple benign nervous system tumors. Given the wide range of NF symptoms and medical specialties involved in NF care, we sought to evaluate the level of awareness of, and agreement with, published NF clinical guidelines among NF specialists in the United States. METHODS: An anonymous, cross-sectional, online survey was distributed to U.S.-based NF clinicians. Respondents self-reported demographics, practice characteristics, awareness of seven NF guideline publications, and level of agreement with up to 40 individual recommendations using a 5-point Likert scale. We calculated the proportion of recommendations that each clinician rated "strongly agree", and assessed for differences in guideline awareness and agreement by respondent characteristics. RESULTS: Sixty-three clinicians (49% female; 80% academic practice) across > 8 medical specialties completed the survey. Awareness of each guideline publication ranged from 53%-79% of respondents; specialists had higher awareness of publications endorsed by their medical professional organization (p < 0.05). The proportion of respondents who "strongly agree" with individual recommendations ranged from 17%-83%; for 16 guidelines, less than 50% of respondents "strongly agree". There were no significant differences in overall agreement with recommendations based on clinicians' gender, race, specialty, years in practice, practice type (academic/private practice/other), practice location (urban/suburban/rural), or involvement in NF research (p > 0.05 for all). CONCLUSIONS: We identified wide variability in both awareness of, and agreement with, published NF care guidelines among NF experts. Future quality improvement efforts should focus on evidence-based, consensus-driven methods to update and disseminate guidelines across this multi-specialty group of providers. Patients and caregivers should also be consulted to proactively anticipate barriers to accessing and implementing guideline-driven care. These recommendations for improving guideline knowledge and adoption may also be useful for other rare diseases requiring multi-specialty care coordination.

The impact of the COVID-19 pandemic on neurofibromatosis clinical care and research.

PURPOSE: The coronavirus disease 2019 (COVID-19) pandemic has had unprecedented impact on the provision of medical care for genetic disorders. The purpose of this study was to assess the effects of the pandemic on neurofibromatosis (NF) care and research. METHODS: Sixty-three United States NF clinics were surveyed to identify the impact of the pandemic on clinician role, patient volume, continuity of guideline-driven surveillance, research protocols, and use of (and satisfaction with) telehealth for the delivery of NF care. RESULTS: Fifty-two clinic directors or their representatives completed the survey (83% response rate). About 2/3 of the clinics reported a greater than 50% decrease in the number of available patient appointments, and modified clinical surveillance and research protocols. Fifty-one clinics (98%) newly instituted telehealth during the pandemic. Barriers to telehealth prior to the pandemic were insurance reimbursement concerns and lack of infrastructure. Since telehealth was initiated, high provider satisfaction was reported with ease of use. The most common area of concern was related to inability to perform a physical examination. CONCLUSION: Results show marked impacts on NF care and research since the beginning of the pandemic, with potential long-term changes related to the introduction (or adoption) of telehealth for clinical care.

Phenotypic heterogeneity of neurofibromatosis type 1 in a large international registry.

Neurofibromatosis type 1 (NF1) is a rare genetic disorder, characterized by the development of benign and malignant nerve tumors. Although all individuals with NF1 harbor genetic alterations in the same gene, the clinical manifestations of NF1 are extremely heterogeneous even among individuals who carry identical genetic defects. In order to deepen the understanding of phenotypic manifestations in NF1, we comprehensively characterized the prevalence of 18 phenotypic traits in 2051 adults with NF1 from the Children's Tumor Foundation's NF1 registry. We further investigated the coassociation of traits and found positive correlations between spinal neurofibromas and pain, spinal neurofibromas and scoliosis, spinal neurofibromas and optic gliomas, and optic gliomas and sphenoid wing dysplasia. Furthermore, with increasing numbers of cutaneous neurofibromas, the odds ratio of malignant peripheral nerve sheath tumor increased. Phenotypic clustering revealed 6 phenotypic patient cluster subtypes: mild, freckling predominant, neurofibroma predominant, skeletal predominant, late-onset neural severe, and early-onset neural severe, highlighting potential phenotypic subtypes within NF1. Together, our results support potential shared molecular pathogenesis for certain clinical manifestations and illustrate the utility of disease registries for understanding rare diseases.

The Use of MEK Inhibitors in Neurofibromatosis Type 1-Associated Tumors and Management of Toxicities.

Early-phase clinical trials using oral inhibitors of MEK, the mitogen-activated protein kinase kinase, have demonstrated benefit for patients with neurofibromatosis type 1 (NF1)-associated tumors, particularly progressive low-grade gliomas and plexiform neurofibromas. Given this potential of MEK inhibition as an effective medical therapy, the use of targeted agents in the NF1 population is likely to increase substantially. For clinicians with limited experience prescribing MEK inhibitors, concern about managing these treatments may be a barrier to use. In this manuscript, the Clinical Care Advisory Board of the Children's Tumor Foundation reviews the published experience with MEK inhibitors in NF1 and outlines recommendations for side-effect management, as well as monitoring guidelines. These recommendations can serve as a beginning framework for NF providers seeking to provide the most effective treatments for their patients. IMPLICATIONS FOR PRACTICE: Neurofibromatosis type 1 (NF1) clinical care is on the cusp of a transformative shift. With the success of recent clinical trials using MEK inhibitors, an increasing number of NF1 patients are being treated with MEK inhibitors for both plexiform neurofibromas and low-grade gliomas. The use of MEK inhibitors is likely to increase substantially in NF1. Given these changes, the Clinical Care Advisory Board of the Children's Tumor Foundation has identified a need within the NF1 clinical community for guidance for the safe and effective use of MEK inhibitors for NF1-related tumors. This article provides a review of the published experience of MEK inhibitors in NF1 and provides recommendations for monitoring and management of side effects.

Increasing access to specialty care for rare diseases: a case study using a foundation sponsored clinic network for patients with neurofibromatosis 1, neurofibromatosis 2, and schwannomatosis.

BACKGROUND: Our primary aim was to assess the ability of a non-profit foundation-sponsored clinic network to facilitate access to specialized care for patients with neurofibromatoses (NF), a group of neurogenetic disorders including NF1, NF2, and schwannomatosis (SWN). Our secondary aim was to identify how our findings in NF could be applied more broadly to other rare diseases. METHODS: We retrospectively reviewed aggregate data on patient volume reported by specialty NF clinics in a nonprofit network from 2008 to 2015. We classified clinics as high or low volume for disease type (NF1 and NF2/schwannomatosis) and pediatric/adult care. We compared clinic-level data to self-reported patient-level data from a large online patient registry. RESULTS: Between 2008 and 2015, the number of certified NF clinics grew from 32 to 50, and annual patient volume rose from 6776 to 10,245 patients (13% of the total estimated U.S. NF patient population). For patient registry participants (n = 4476), the median driving distance to the nearest network clinic was 51.3 miles. Driving distances to reach high-volume centers were elevated for adults compared to children (295.8 vs. 67.9 miles), and schwannomatosis and NF2 patients compared to NF1 patients (310.9 vs. 368.1 vs. 161.7 miles). Of registry participants reporting their location of care (n = 2271), only 43.2% received care in a network specialty clinic, with especially low rates of attendance in the Southwest and Far West. CONCLUSIONS: While the number of certified NF clinics and volume of patients seen in these clinics has increased, many NF patients still do not attend specialty clinics and/or travel a significant distance for care. Geographic access to care is more limited for adults, patients with rarer conditions, and patients in the Western U.S. Potential measures to improve access to specialty care for people living with NF and other rare diseases are discussed.

Cutaneous neurofibromas in the genomics era: current understanding and open questions.

Cutaneous neurofibromas (cNF) are a nearly ubiquitous symptom of neurofibromatosis type 1 (NF1), a disorder with a broad phenotypic spectrum caused by germline mutation of the neurofibromatosis type 1 tumour suppressor gene (NF1). Symptoms of NF1 can include learning disabilities, bone abnormalities and predisposition to tumours such as cNFs, plexiform neurofibromas, malignant peripheral nerve sheath tumours and optic nerve tumours. There are no therapies currently approved for cNFs aside from elective surgery, and the molecular aetiology of cNF remains relatively uncharacterised. Furthermore, whereas the biallelic inactivation of NF1 in neoplastic Schwann cells is critical for cNF formation, it is still unclear which additional genetic, transcriptional, epigenetic, microenvironmental or endocrine changes are important. Significant inroads have been made into cNF understanding, including NF1 genotype-phenotype correlations in NF1 microdeletion patients, the identification of recurring somatic mutations, studies of cNF-invading mast cells and macrophages, and clinical trials of putative therapeutic targets such as mTOR, MEK and c-KIT. Despite these advances, several gaps remain in our knowledge of the associated pathogenesis, which is further hampered by a lack of translationally relevant animal models. Some of these questions may be addressed in part by the adoption of genomic analysis techniques. Understanding the aetiology of cNF at the genomic level may assist in the development of new therapies for cNF, and may also contribute to a greater understanding of NF1/RAS signalling in cancers beyond those associated with NF1. Here, we summarise the present understanding of cNF biology, including the pathogenesis, mutational landscape, contribution of the tumour microenvironment and endocrine signalling, and the historical and current state of clinical trials for cNF. We also highlight open access data resources and potential avenues for future research that leverage recently developed genomics-based methods in cancer research.

Malignant Peripheral Nerve Sheath Tumors in Neurofibromatosis: Impact of Family History.

OBJECTIVE: The main objective of this study was to determine if family history of malignant peripheral nerve sheath tumor (MPNST) increases risk of developing an MPNST in patients with neurofibromatosis-1 (NF-1). MATERIALS AND METHODS: Individuals with NF-1 registered with the Children's Tumor Foundation's Neurofibromatosis Registry were emailed an anonymous 15-minute survey with regard to personal and family history of NF-1, MPNST, ages of onset, and symptomatology. Participation was voluntary and information was self-reported. RESULTS: The survey was sent to 4801 registrants, 878 responded. Presence of a family history of MPNST was found to be a risk factor for the development of MPNST; 19.4% of respondents confirming a family history of MPNST developed MPNST compared with 7.5% of respondents with no family history (odds ratio, 2.975; 95% confidence interval, 1.232-7.187; P=0.021). NF-1 patients with a positive family history developed MPNST at a younger age than those with no family history (8.3% vs. 0.5% P=0.003 and 13.9% vs. 2.4% P=0.003, for onset before 10 and 20, respectively). In the MPNST population with a known family history, onset prior to age 10 was significantly more prevalent (42.9% vs. 7% P=0.029). CONCLUSIONS: These results suggest a positive family history of MPNST represents a risk factor for the development and early onset of MPNST in individuals with NF-1.

Characterization and utilization of an international neurofibromatosis web-based, patient-entered registry: An observational study.

The neurofibromatoses (neurofibromatosis type 1, neurofibromatosis type 2 and schwannomatosis) are rare disorders having clinical manifestations that vary greatly from patient to patient. The rarity and variability of these disorders has made it challenging for investigators to identify sufficient numbers of patients with particular clinical characteristics or specific germline mutations for participation in interventional studies. Similarly, because the natural history of all types of neurofibromatosis (NF) is variable and unique for each individual, it is difficult to identify meaningful clinical outcome measures for potential therapeutic interventions. In 2012, the Children's Tumor Foundation created a web-based patient-entered database, the NF Registry, to inform patients of research opportunities for which they fit general eligibility criteria and enable patients to contact investigators who are seeking to enroll patients in approved trials. Registrants were recruited through CTF-affiliated NF clinics and conferences, through its website, and by word-of-mouth and social media. Following online consent, demographic information and details regarding manifestations of NF were solicited on the Registry website. Statistical analyses were performed on data from a cohort of 4680 registrants (the number of registrants as of October 9, 2015) who met diagnostic criteria for one of the 3 NF conditions. The analyses support our hypothesis that patient-reported symptom incidences in the NF Registry are congruent with published clinician-sourced data. Between April 26, 2013 and July 8, 2016, the registry has been useful to investigators in recruitment, particularly for observational trials, especially those for development of patient-reported outcomes.

A high-throughput molecular data resource for cutaneous neurofibromas.

Neurofibromatosis type 1 (NF1) is a genetic disorder with a range of clinical manifestations such as widespread growth of benign tumours called neurofibromas, pain, learning disorders, bone deformities, vascular abnormalities and even malignant tumours. With the establishment of the Children's Tumour Foundation biobank, neurofibroma samples can now be collected directly from patients to be analysed by the larger scientific community. This work describes a pilot study to characterize one class of neurofibroma, cutaneous neurofibromas, by molecularly profiling of ~40 cutaneous neurofibromas collected from 11 individual patients. Data collected from each tumour includes (1) SNP Arrays, (2) Whole genome sequencing (WGS) and (3) RNA-Sequencing. These data are now freely available for further analysis at http://www.synapse.org/cutaneousNF.

Neurofibromatosis as a gateway to better treatment for a variety of malignancies.

The neurofibromatoses (NF) are a group of rare genetic disorders that can affect all races equally at an incidence from 1:3000 (NF1) to a log unit lower for NF2 and schwannomatosis. Since the research community is reporting an increasing number of malignant cancers that carry mutations in the NF genes, the general interest of both the research and pharma community is increasing and the authors saw an opportunity to present a novel, fresh approach to drug discovery in NF. The aim of the paper is to challenge the current drug discovery approach to NF, whereby existing targeted therapies that are either in the clinic or on the market for other disease indications are repurposed for NF. We offer a suggestion for an alternative drug discovery approach. In the new approach, selective and tolerable targeted therapies would be developed for NF and later expanded to patients with more complex diseases such as malignant cancer in which the NF downstream pathways are deregulated. The Children's Tumor Foundation, together with some other major NF funders, is playing a key role in funding critical initiatives that will accelerate the development of better targeted therapies for NF patients, while these novel, innovative treatments could potentially be beneficial to molecularly characterized cancer patients in which NF mutations have been identified.

Current status and recommendations for biomarkers and biobanking in neurofibromatosis.

OBJECTIVE: Clinically validated biomarkers for neurofibromatosis 1 (NF1), neurofibromatosis 2 (NF2), and schwannomatosis (SWN) have not been identified to date. The biomarker working group's goals are to (1) define biomarker needs in NF1, NF2, and SWN; (2) summarize existing data on biomarkers in NF1, NF2, and SWN; (3) outline recommendations for sample collection and biomarker development; and (4) standardize sample collection and methodology protocols where possible to promote comparison between studies by publishing standard operating procedures (SOPs). METHODS: The biomarker group reviewed published data on biomarkers in NF1, NF2, and SWN and on biobanking efforts outside these diseases via literature search, defined the need for biomarkers in NF, and developed recommendations in a series of consensus meetings. RESULTS: We describe existing biomarkers in NF and report consensus recommendations for SOP and a minimal clinical dataset to accompany samples derived from patients with NF1, NF2, and SWN in decentralized biobanks. CONCLUSIONS: These recommendations are intended to provide clinicians and researchers with a common set of guidelines to collect and store biospecimens and for establishment of biobanks for NF1, NF2, and SWN.

Tailored drug release from biodegradable stent coatings based on hybrid polyurethanes.

Highly adjustable and precisely controllable drug release from a biodegradable stent coating was achieved using a unique family of nanostructured hybrid polyurethanes. These polyurethanes are polyhedral oligosilsesquioxane thermoplastic polyurethanes (POSS TPUs) featuring alternating multiblock structures formed by nanostructured hard segments of POSS and biodegradable soft segments of a polylactide/caprolactone copolymer (P(DLLA-co-CL)) incorporating polyethylene glycol (PEG) covalently. POSS aggregated to form crystals serving as physical crosslinks on the nanometer scale, while the soft segments were designed carefully to modulate the drug release rate from the POSS TPU stent coatings in PBS buffer solution, with 90% of the drug releasing from within half a day to about 90 days. In order to interpret the underlying drug release mechanisms, an approximation model capable of describing the entire drug release process was developed. This model is based on Fickian diffusional transport, but also takes into account the polymer degradation and/or swelling of the coating, depending on the dominance of the degradation/swelling behavior compared to that of the diffusion characteristics. A general methodology was utilized for statistically fitting the drug release curves from the POSS TPU stent coatings using the model. We observed that the fitted initial drug release diffusion coefficient covered more than three orders of magnitude, depending on the polymer glass transition temperature (T(g)), according to a modified Williams-Landel-Ferry (WLF) equation. In addition, two additional rate constants describing the impact of degradation and swelling on drug elution were determined and found to be consistent with independent measurements. Our results clearly show that the studied hybrid polyurethane family allows a drug release rate that is effectively manipulated through variation in polymer T(g), degradation rate, and thickness increment rate.

The expression of intelectin in sheep goblet cells and upregulation by interleukin-4.

Upregulation of intelectin (ITLN) transcript and protein has previously been shown in intestinal nematode infections of resistant mice strains with immunolocalisation of protein to goblet cells and paneth cells. In man, intelectin expression has been shown in respiratory tract epithelium, with upregulation occurring in bronchoalveolar lavage fluid of asthmatic individuals. This study describes the expression of intelectin in the respiratory tract of sheep and the immunolocalisation to goblet cells using a novel affinity-purified chicken anti-intelectin peptide antibody. Furthermore we show that when sheep tracheal explants were cultured for 48 h+/- recombinant sheep IL-4, sheep ITLN transcripts were upregulated compared with controls. Putative roles for intelectin have included an antibacterial role and an alteration of the character of mucus. Our data suggest ITLNs may play an important role in the mucosal response in allergy and parasitic infections.

Aberrant mucosal mast cell protease expression in the enteric epithelium of nematode-infected mice lacking the integrin alphavbeta6, a transforming growth factor-beta1 activator.

Infection of mice with the nematode Trichinella spiralis triggers recruitment and differentiation of intraepithelial intestinal mucosal mast cells expressing mouse mast cell protease 1 (Mcpt-1), which contributes to expulsion of the parasite. Expression of Mcpt-1 is transforming growth factor (TGF)-beta1-dependent in vitro. TGF-beta1, which is secreted within tissues as a biologically inactive complex with latency-associated peptide, requires extracellular modification to become functionally active. The integrin-alpha(nu)beta(6) mediates local activation of TGF-beta(1) in association with epithelia. Using T. spiralis-infected beta(6)(-/-) mice, we show accumulation of mucosal mast cells in the lamina propria of the small intestine with minimal recruitment into the epithelial compartment. This was accompanied by a coordinate reduction in expression of both Mcpt-1 and -2 in the jejunum and increased tryptase expression, whereas Mcpt-9 became completely undetectable. In contrast, the cytokine stem cell factor, a regulator of mast cell differentiation and survival, was significantly up-regulated in T. spiralis-infected beta(6)(-/-) mice compared with infected beta(6)(+/+) controls. Despite these changes, beta(6)(-/-) mice still appeared to expel the worms normally. We postulate that compromised TGF-beta(1) activation within the gastrointestinal epithelial compartment is a major, but not the only, contributing factor to the observed changes in mucosal mast cell protease and epithelial cytokine expression in beta(6)(-/-) mice.

The proteome of mouse mucosal mast cell homologues: the role of transforming growth factor beta1.

Mast cells migrate to the mucosal epithelium during intestinal nematode infections in mice, where they express abundant mucosal mast cell-specific proteases, mouse mast cell protease-1 and -2 (MCPT1 and MCPT2). Expression of these proteases is strictly controlled by transforming growth factor-beta1 (TGF-beta1) in the epithelium. In vitro homologues of mucosal mast cells are generated by culturing bone marrow-derived mast cells (BMMC) in the presence of TGF-beta1. We examined the proteome of BMMC cultured either in the presence of TGF-beta1 (n = 5) or of a neutralising anti-TGF-beta1 antibody (n = 5). Cell extracts were examined by 2-DE, and changes in expression levels of protein spots were determined by densitometry. Spots of interest were identified by tryptic peptide mapping. In addition to the up-regulation of MCPT1 and MCPT2, which accounted for approximately 40% of all soluble protein in the TGF-beta1 treated cells, MCPT7 was modestly up-regulated by TGF-beta1, and calnexin was up-regulated fivefold. A 7.6-fold down-regulation of galectin-1 was verified by Western blotting and FACS analysis. Galectin-1 is located on the cell surface where it mediates cellular adhesion to basement membranes. Regulation of its expression by TGF-beta1 may be of relevance to mast cell adhesion within the epithelium.

Regulation of RELM/FIZZ isoform expression by Cdx2 in response to innate and adaptive immune stimulation in the intestine.

Host immune responses to commensal flora and enteric pathogens are known to influence gene expression in the intestinal epithelium. Although the Cdx family of caudal-related transcription factors represents critical regulators of gene expression in the intestinal epithelium, the effect of intestinal immune responses on Cdx expression and function has not been determined. We have shown that bacterial colonization and Th2 immune stimulation by intestinal nematode infection induce expression of the intestinal goblet cell-specific gene RELM beta. In this study, we investigated the transcriptional regulation of resistin-like molecule/found in inflammatory zone (RELM/FIZZ, RELM beta) and its isoforms RELM alpha and RELM gamma to ascertain the role of Cdx in modifying intestinal gene expression associated with innate and adaptive immune responses. Analysis of the RELM beta promoter showed that Cdx2 plays a critical role in basal gene activation in vitro. This was confirmed in vivo using transgenic mice, where ectopic gastric and hepatic expression of Cdx2 induces expression of RELM beta, but not RELM alpha or RELM gamma, exclusively in the stomach. Although there was no quantitative change in colonic Cdx2 mRNA expression, protein distribution, or phosphorylation of Cdx2, bacterial colonization induced expression of RELM beta, but not RELM alpha or RELM gamma. In contrast, parasitic nematode infections activated colonic expression of all three RELM isoforms without alteration in Cdx2 expression. These results demonstrated that Cdx2 participates in directing intestine-specific expression of RELM beta in the presence of commensal bacteria and that adaptive Th2 immune responses to intestinal nematode infections can activate intestinal goblet cell-specific gene expression independent of Cdx2.

Expression profiling reveals novel innate and inflammatory responses in the jejunal epithelial compartment during infection with Trichinella spiralis.

Infection with intestinal nematodes induces profound pathological changes to the gut that are associated with eventual parasite expulsion. We have applied expression profiling as an initial screening process with oligonucleotide microarrays (Affymetrix MG-U74AV2 gene chips) and time course kinetics to investigate gene transcription triggered by the intraepithelial nematode Trichinella spiralis in jejunal epithelium from BALB/c mice. Of the 4,114 genes detected, 2,617 were present in all uninfected and T. spiralis-infected replicates, 8% of which were notably upregulated, whereas 12% were downregulated at the time of worm expulsion (day 14 postinfection). Upregulation of goblet cell mucin gene transcripts intestinal mucin gene 3 (MUC3), calcium chloride channel 5 (CLCA5), and goblet cell gene 4 (GOB4) is consistent with enhanced production and alteration of mucus, whereas a 60- to 70-fold upregulation of transcripts for mast cell proteases 1 and 2 (MCPT-1 and -2) is consistent with intraepithelial mucosal mast cell recruitment. Importantly, there was novel expression of sialyltransferase 4C (SIAT4C), small proline-rich protein 2A (SPRR2A), and resistin-like molecule beta (RELMbeta) on day 14 postinfection. In contrast, DNase I and regenerating protein 3 (REG3) transcripts were substantially downregulated. Time course analyses revealed early (within 48 h of infection) induction of Siat4c, Sprr2A, and Relmbeta and later (within 120 h) induction of Mcpt-1 and -2. The findings demonstrate early innate responses and later inflammatory changes within the epithelium. The early epithelial responses may be associated both with repair (Sprr2A) and with the development of innate immunity (Siat4c and Relmbeta).

RELMbeta/FIZZ2 is a goblet cell-specific immune-effector molecule in the gastrointestinal tract.

Gastrointestinal (GI) nematode infections are an important public health and economic concern. Experimental studies have shown that resistance to infection requires CD4(+) T helper type 2 (Th2) cytokine responses characterized by the production of IL-4 and IL-13. However, despite >30 years of research, it is unclear how the immune system mediates the expulsion of worms from the GI tract. Here, we demonstrate that a recently described intestinal goblet cell-specific protein, RELMbeta/FIZZ2, is induced after exposure to three phylogenetically distinct GI nematode pathogens. Maximal expression of RELMbeta was coincident with the production of Th2 cytokines and host protective immunity, whereas production of the Th1 cytokine, IFN-gamma, inhibited RELMbeta expression and led to chronic infection. Furthermore, whereas induction of RELMbeta was equivalent in nematode-infected wild-type and IL-4-deficient mice, IL-4 receptor-deficient mice showed minimal RELMbeta induction and developed persistent infections, demonstrating a direct role for IL-13 in optimal expression of RELMbeta. Finally, we show that RELMbeta binds to components of the nematode chemosensory apparatus and inhibits chemotaxic function of a parasitic nematode in vitro. Together, these results suggest that intestinal goblet cell-derived RELMbeta may be a novel Th2 cytokine-induced immune-effector molecule in resistance to GI nematode infection.

Expression of integrin-alphaE by mucosal mast cells in the intestinal epithelium and its absence in nematode-infected mice lacking the transforming growth factor-beta1-activating integrin alphavbeta6.

Peak intestinal mucosal mast cell (MMC) recruitment coincides with expulsion of Trichinella spiralis, at a time when the majority of the MMCs are located within the epithelium in BALB/c mice. Although expression of integrin-alpha(E)beta(7) by MMCs has not been formally demonstrated, it has been proposed as a potential mechanism to account for the predominantly intraepithelial location of MMCs during nematode infection. Co-expression of integrin-alpha(E)beta(7) and the MMC chymase mouse mast cell protease-1, by mouse bone marrow-derived mast cells, is strictly regulated by transforming growth factor (TGF)-beta(1). However, TGF-beta(1) is secreted as part of a latent complex in vivo and subsequent extracellular modification is required to render it biologically active. We now show, for the first time, that intraepithelial MMCs express integrin-alpha(E)beta(7) in Trichinella-infected BALB/c and S129 mice. In S129 mice that lack the gene for the integrin-beta(6) subunit and, as consequence, do not express the epithelial integrin-alpha(v)beta(6), integrin-alpha(E) expression is virtually abolished and recruitment of MMCs into the intestinal epithelium is dramatically reduced despite significant overall augmentation of the MMC population. Because a major function of integrin-alpha(v)beta(6) is to activate latent TGF-beta(1,) these findings strongly support a role for TGF-beta(1) in both the recruitment and differentiation of murine MMCs during nematode infection.

Mast cells disrupt epithelial barrier function during enteric nematode infection.

We have investigated the influence of mast cells on the barrier function of intestinal epithelium during nematode infection. Trichinella spiralis infection induces a strong type 2 cytokine-mediated inflammation, resulting in a critical mucosal mastocytosis that is known to mediate expulsion of the parasites from the intestine. The host response to infection is also characterized by an increase in mucosal leakiness. We show here that intestinal epithelial permeability is markedly elevated during infection, with kinetics that mirror the adaptive immune response to primary and secondary infection. Furthermore, we have identified degradation of the tight junction protein, occludin, thereby providing a mechanism for increased paracellular permeability during helminth infection. We further demonstrate by using anti-c-kit antibody and IL-9 transgenic mice that mast cells are directly responsible for increasing epithelial paracellular permeability and that mice deficient in a mast cell-specific protease fail to increase intestinal permeability and fail to expel their parasite burden. These results provide the mechanism whereby mucosal mast cells mediate parasite expulsion from the intestine.