Tight junction defects are seen in the buccal mucosa of patients receiving standard dose chemotherapy for cancer

Oral mucositis is one of the most common and debilitating side effects of chemotherapy treatment. Patients are often unable to eat and drink, which can lead to poor clinical outcomes and extensive resource utilisation. The primary aim of this study was to determine the molecular integrity of oral epithelial tight junctions in patients undergoing chemotherapy. The secondary aim was to correlate these changes with proinflammatory cytokines and matrix metalloproteinase profiles.Patients (n = 23) were recruited from the Royal Adelaide Hospital between 2000 and 2003. Reach patient underwent two oral buccal mucosa biopsies (4 mm): one prior to chemotherapy treatment and a second one after chemotherapy treatment. Oral buccal mucosa biopsies were also taken from seven healthy volunteers with no history of cancer, chemo- or radiotherapy treatment or inflammatory disorders. Routine haematoxylin and eosin staining was performed to determine epithelial thickness. Immunohistochemical staining was performed for claudin-1, zonular occludens-1, occludin, interleukin-1β, tumour necrosis factor, interleukin-6, matrix metalloproteinase-2 and metalloproteinase-9.Patients receiving standard dose chemotherapy had significant epithelial atrophy. Elevations in all cytokines and matrix metalloproteinases were seen, with significant lamina propria staining for interleukin-6 and tumour necrosis factor. Matrix metalloproteinase-2 appeared most upregulated within the oral epithelium. These changes coincided with altered tight junction staining properties. Changes in the staining intensity and localisation were both noted, with clear cytoplasmic staining for zonular occludens-1 and claudin-1 in patients treated with chemotherapy.Chemotherapy causes defects in oral tight junctions, coupled with altered cytokine and matrix metalloproteinase profiles. Tight junction disruption in the epithelium may contribute to ulcer development or lead to poor tissue integrity, and the timing of these events may be a target for preventative treatment.Hannah R. Wardill, Richard M. Logan, Joanne M. Bowen, Ysabella Z. A. Van Sebille, Rachel J. Gibso

A novel in vitro platform for the study of SN38-induced mucosal damage and the development of Toll-like receptor 4-targeted therapeutic options

Tight junction and epithelial barrier disruption is a common trait of many gastrointestinal pathologies, including chemotherapy-induced gut toxicity. Currently, there are no validated in vitro models suitable for the study of chemotherapy-induced mucosal damage that allow paralleled functional and structural analyses of tight junction integrity. We therefore aimed to determine if a transparent, polyester membrane insert supports a polarized T84 monolayer with the phenotypically normal tight junctions. T84 cells (passage 5-15) were seeded into either 0.6 cm(2), 0.4 µm pore mixed-cellulose transwell hanging inserts or 1.12 cm(2), 0.4 µm pore polyester transwell inserts at varying densities. Transepithelial electrical resistance was measured daily to assess barrier formation. Immunofluoresence for key tight junction proteins (occludin, zonular occludens-1, claudin-1) and transmission electron microscopy were performed to assess tight junction integrity, organelle distribution, and polarity. Reverse transcription-polymerase chain reaction was performed to determine expression of toll-like receptor 4 (TLR4). Liquid chromatography was also conducted to assess SN38 degradation in this model. Polyester membrane inserts support a polarized T84 phenotype with functional tight junctions in vitro. Transmission electron microscopy indicated polarity, with apico-laterally located tight junctions. Immunofluorescence showed membranous staining for all tight junction proteins. No internalization was evident. T84 cells expressed TLR4, although this was significantly lower than levels seen in HT29 cells (P = .0377). SN38 underwent more rapid degradation in the presence of cells (-76.04 ± 1.86%) compared to blank membrane (-48.39 ± 4.01%), indicating metabolic processes. Polyester membrane inserts provide a novel platform for paralleled functional and structural analysis of tight junction integrity in T84 monolayers. T84 cells exhibit the unique ability to metabolize SN38 as well as expressing TLR4, making this an excellent platform to study clinically relevant therapeutic interventions for SN38-induced mucosal damage by targeting TLR4.Hannah R Wardill, Rachel J Gibson, Ysabella ZA Van Sebille, Kate R Secombe, Richard M Logan, and Joanne M Bowe

TLR4-dependent claudin-1 internalization and secretagogue-mediated chloride secretion regulate irinotecan-induced diarrhea

Published OnlineFirst August 22, 2016Abstract not availableHannah R.Wardill, Joanne M. Bowen, Ysabella Z.A. Van Sebille, Kate R. Secombe, Janet K. Coller, Imogen A. Ball, Richard M. Logan, and Rachel J Gibso

Routine assessment of the gut microbiome to promote preclinical research reproducibility and transparency

Letter. Published online 9 January 2017Hannah R Wardill, Joanne M Bowen, Ysabella ZA Van Sebille, Rachel J Gibso

Pre-therapy fasting slows epithelial turnover and modulates the microbiota but fails to mitigate methotrexate-induced gastrointestinal mucositis

BACKGROUND: Recent findings by Tang et al. (2020) show dietary restriction (30%, 2 weeks) prevents methotrexate-induced mortality by modulation of the microbiota, specifically the expansion of Lactobacillus. While fundamentally insightful, upscaling this schedule is a major obstacle to clinical uptake. Here, we evaluate a safe and clinically achievable schedule of pre-therapy fasting for 48 h on microbiota composition, body composition and intestinal proliferation, and assess its impact on the severity of methotrexate-induced gastrointestinal mucositis using a validated preclinical rat model. METHODS: Age- and weight-matched male Wistar rats were treated with a sublethal dose of 45 mg/kg methotrexate with or without pre-therapy fasting. The impact of acute fasting on epithelial proliferation, body composition and the microbiota was assessed using plasma citrulline, Ki67 immunohistochemistry, miniSpec and 16S rRNA sequencing. The severity of gastrointestinal mucositis was evaluated using plasma citrulline and body weight. RESULTS: Whilst pre-therapy fasting slowed epithelial proliferation and increased microbial diversity and richness, it also induced significant weight loss and was unable to attenuate the severity of mucositis in both age- and weight-matched groups. In contrast to Tang et al., we saw no expansion of Lactobacillus following acute fasting. CONCLUSIONS: Our findings suggest that the beneficial effects of acute fasting are masked by the detrimental effects on body weight and composition and lacking influence on Lactobacillus. Future studies should consider alternative fasting schedules or aim to induce comparable microbial and mucosal manipulation without compromising body composition using clinically feasible methods of dietary or microbial intervention

Irinotecan-induced gastrointestinal dysfunction and pain are mediated by common TLR4-dependent mechanisms

Published Online First March 29, 2016Abstract not availableHannah R. Wardill, Rachel J. Gibson, Ysabella Z.A. Van Sebille, Kate R. Secombe, Janet K. Coller, Imogen A. White, Jim Manavis, Mark R. Hutchinson, Vasiliki Staikopoulos, Richard M. Logan, and Joanne M. Bowe

Translational model of melphalan-induced gut toxicity reveals drug-host-microbe interactions that drive tissue injury and fever

Published: 20 April 2021PURPOSE: Conditioning therapy with high-dose melphalan (HDM) is associated with a high risk of gut toxicity, fever and infections in haematopoietic stem cell transplant (HSCT) recipients. However, validated preclinical models that adequately reflect clinical features of melphalan-induced toxicity are not available. We therefore aimed to develop a novel preclinical model of melphalan-induced toxicity that reflected well-defined clinical dynamics, as well as to identify targetable mechanisms that drive intestinal injury. METHODS: Male Wistar rats were treated with 4-8 mg/kg melphalan intravenously. The primary endpoint was plasma citrulline. Secondary endpoints included survival, weight loss, diarrhea, food/water intake, histopathology, body temperature, microbiota composition (16S sequencing) and bacterial translocation. RESULTS: Melphalan 5 mg/kg caused self-limiting intestinal injury, severe neutropenia and fever while impairing the microbial metabolome, prompting expansion of enteric pathogens. Intestinal inflammation was characterized by infiltration of polymorphic nuclear cells in the acute phases of mucosal injury, driving derangement of intestinal architecture. Ileal atrophy prevented bile acid reabsorption, exacerbating colonic injury via microbiota-dependent mechanisms. CONCLUSION: We developed a novel translational model of melphalan-induced toxicity, which has excellent homology with the well-known clinical features of HDM transplantation. Application of this model will accelerate fundamental and translational study of melphalan-induced toxicity, with the clinical parallels of this model ensuring a greater likelihood of clinical success.H. R. Wardill, C. E. M. de Mooij, A. R. da Silva Ferreira, I. P. van de Peppel, R. Havinga, H. J. M. Harmsen ... et al

Riboflavin Supplementation Promotes Butyrate Production in the Absence of Gross Compositional Changes in the Gut Microbiota

Aims: We performed a randomized, placebo-controlled trial, RIBOGUT, to study the effect of 2 weeks supplementation with either 50 or 100 mg/d of riboflavin on (i) Faecalibacterium prausnitzii abundance, (ii) gut microbiota composition, (iii) short-chain fatty acid (SCFA) profiles, and (iv) the satiety and gut hormones.Results: Neither dose of riboflavin, analyzed separately, impacted the abundance of F. prausnitzii, and only minor differences in SCFA concentrations were observed. However, combining the results of the 50 and 100 mg/d groups showed a significant increase in butyrate production. While the gut bacterial diversity was not affected by riboflavin supplementation, the complexity and stability of the bacterial network were enhanced. Oral glucose tolerance tests showed a trend of increased plasma insulin concentration and GLP-1 after 100 mg/d supplementation.Innovation: Dietary supplements, such as vitamins, promote health by either directly targeting host physiology or indirectly via gut microbiota modulation. Here, we show for the first time that riboflavin intervention changes the activity of the microbiota. The butyrate production increased after intervention and although the composition did not change significantly, the network of microbial interactions was enforced.Conclusion: This RIBOGUT study suggests that oral riboflavin supplementation promotes butyrate production in the absence of major shifts in gut microbiota composition. ClinicalTrials.gov Identifier: NCT02929459.</p

Optimization of a GCaMP Calcium Indicator for Neural Activity Imaging

Genetically encoded calcium indicators (GECIs) are powerful tools for systems neuroscience. Recent efforts in protein engineering have significantly increased the performance of GECIs. The state-of-the art single-wavelength GECI, GCaMP3, has been deployed in a number of model organisms and can reliably detect three or more action potentials in short bursts in several systems in vivo. Through protein structure determination, targeted mutagenesis, high-throughput screening, and a battery of in vitro assays, we have increased the dynamic range of GCaMP3 by severalfold, creating a family of “GCaMP5” sensors. We tested GCaMP5s in several systems: cultured neurons and astrocytes, mouse retina, and in vivo in Caenorhabditis chemosensory neurons, Drosophila larval neuromuscular junction and adult antennal lobe, zebrafish retina and tectum, and mouse visual cortex. Signal-to-noise ratio was improved by at least 2- to 3-fold. In the visual cortex, two GCaMP5 variants detected twice as many visual stimulus-responsive cells as GCaMP3. By combining in vivo imaging with electrophysiology we show that GCaMP5 fluorescence provides a more reliable measure of neuronal activity than its predecessor GCaMP3. GCaMP5 allows more sensitive detection of neural activity in vivo and may find widespread applications for cellular imaging in general.Molecular and Cellular Biolog

Network adaptation improves temporal representation of naturalistic stimuli in drosophila eye: II Mechanisms

Retinal networks must adapt constantly to best present the ever changing visual world to the brain. Here we test the hypothesis that adaptation is a result of different mechanisms at several synaptic connections within the network. In a companion paper (Part I), we showed that adaptation in the photoreceptors (R1-R6) and large monopolar cells (LMC) of the Drosophila eye improves sensitivity to under-represented signals in seconds by enhancing both the amplitude and frequency distribution of LMCs' voltage responses to repeated naturalistic contrast series. In this paper, we show that such adaptation needs both the light-mediated conductance and feedback-mediated synaptic conductance. A faulty feedforward pathway in histamine receptor mutant flies speeds up the LMC output, mimicking extreme light adaptation. A faulty feedback pathway from L2 LMCs to photoreceptors slows down the LMC output, mimicking dark adaptation. These results underline the importance of network adaptation for efficient coding, and as a mechanism for selectively regulating the size and speed of signals in neurons. We suggest that concert action of many different mechanisms and neural connections are responsible for adaptation to visual stimuli. Further, our results demonstrate the need for detailed circuit reconstructions like that of the Drosophila lamina, to understand how networks process information