Nanofiber-based glaucoma drainage implant improves surgical outcomes by modulating fibroblast behavior

Biomaterials are implanted in millions of individuals worldwide each year. Both naturally derived and synthetic biomaterials induce a foreign body reaction that often culminates in fibrotic encapsulation and reduced functional lifespan. In ophthalmology, glaucoma drainage implants (GDIs) are implanted in the eye to reduce intraocular pressure (IOP) in order to prevent glaucoma progression and vision loss. Despite recent efforts towards miniaturization and surface chemistry modification, clinically available GDIs are susceptible to high rates of fibrosis and surgical failure. Here, we describe the development of synthetic, nanofiber-based GDIs with partially degradable inner cores. We evaluated GDIs with nanofiber or smooth surfaces to investigate the effect of surface topography on implant performance. We observed in vitro that nanofiber surfaces supported fibroblast integration and quiescence, even in the presence of pro-fibrotic signals, compared to smooth surfaces. In rabbit eyes, GDIs with a nanofiber architecture were biocompatible, prevented hypotony, and provided a volumetric aqueous outflow comparable to commercially available GDIs, though with significantly reduced fibrotic encapsulation and expression of key fibrotic markers in the surrounding tissue. We propose that the physical cues provided by the surface of the nanofiber-based GDIs mimic healthy extracellular matrix structure, mitigating fibroblast activation and potentially extending functional GDI lifespan.

A87 PERSPECTIVES ON DIET MODIFICATION TO MANAGE THEIR SYMPTOMS IN PATIENTS WITH INFLAMMATORY BOWEL DISEASE. A SCOPING REVIEW

Background

The link between diet, disease activity and symptoms in IBD patients have recently gained attention and recommendations on dietary interventions to manage symptoms are common. Most studies have explored the correlation between dietary patterns and increased risk of IBD or symptom severity. However, there is limited understanding and no relevant systematic review of IBD patients’ perspectives and barriers to adopt the prescribed diets. We thus conducted a scoping review for this topic.

Purpose

Aim: We performed a scoping review of current evidence to investigate the extent of evidence on IBD adult patients’ perspectives on dietary modification to manage their symptoms and gaps for future research to explore patients' experiences.

Method

We followed the JBI (Joanna Briggs Institute) method for scoping reviews. A systematic search of Ovid Medline, Embase and Cochrane Library was conducted in April 2022 to retrieve published English language qualitative, quantitative and mixed methods studies that report IBD patients’ perspectives, behaviours, beliefs related to diet modification and barriers to diet adoption for managing their symptoms or disease activity. We manually reviewed reference lists of reviews on this topic. Since this is a scoping review, no statistical comparison is needed.

Result(s)

Out of 2822 papers screened, 42 studies met the inclusion criteria. Various methods were used in included studies with heterogenous outcomes reported. Of the 42 studies, 19 reported IBD patients' beliefs and behaviors related to diet as a primary outcome. Most patients reported changing their diet after being diagnosed with IBD, and food avoidance and restrictive diet were commonly reported to prevent relapse. Some studies reported that many patients reduced their opportunities for social life, such as eating out, practicing outdoor sports, having dinner with family in the same household and meeting friends. The dietary modification was more significant among individuals with active than inactive disease. Most studies showed that patients believe food can play a role in causing or preventing relapse, but beliefs are varied regarding the role of diet as initiating factor for IBD. Some patients believe dietary modification could be more important than medication to manage their disease symptoms. Few studies focused on patients' barriers when changing their diet, but financial barriers and limited nutritional guidance were commonly reported acknowledging searching for dietary advice on the internet.

Conclusion(s)

Food avoidance and social restriction for relapse prevention are standard practices by most IBD patients. The belief that nutrition is key in managing IBD is prevalent. This scoping review highlights the need to identify patients' barriers to accessing professional dietary guidance and nutritional interventions and provides direction for clinical studies and systematic reviews of focused research questions.

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Disclosure of Interest

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661 Neoantigen-specific CD4+ T cells in human melanoma have diverse differentiation states and correlate with CD8+ T cell, macrophage, and B cell function

Background

Tumor-antigen specific CD4+ T cells are crucial for the efficacy of antibodies that block immune checkpoint proteins in mouse tumor models, but their activities in human tumor immunity are less clear. CD8+ T cells infiltrating human tumors, including those specific for tumor antigens, have been studied using single cell profiling techniques and exist in a variety of dysfunctional states. The transcriptional states of tumor-specific CD4+ T cells present in tumors and their potential contributions to the tumor microenvironment are less well understood.

Methods

We used targeted single cell RNA sequencing and matching of T cell receptor (TCR) sequences to identify phenotypic signatures that discriminated tumor antigen- and viral antigen-specific CD4+ T cells infiltrating human melanoma tumors in four patients. The presence of CD4+ T cells with these signatures was correlated with the number and phenotype of other immune cells in the tumor microenvironment in an extended cohort of 20 patients.

Results

We identified 259 CD4+ T cells representing 40 different TCR clonotypes specific for 13 neoantigens and 108 cells representing 14 TCR clonotypes specific for self-antigens in four melanoma patients. High expression of CXCL13 defined conventional CD4+ T cells that recognize tumor associated neoantigens and self-antigens from bystander and viral antigen-specific CD4+ T cells. Tumor-reactive CD4+ T cells could be subdivided into clusters expressing memory and T follicular helper markers, and those expressing cytolytic markers and IFN-g. In an extended cohort of 20 patients with melanoma, the frequency of CXCL13+ CD4+ T cells in the tumor microenvironment correlated with the presence and proliferation of CD8+ T cells, the presence and maturation of B cells, the activation of interferon responsive genes in tumor associated macrophages, and patient survival. CD4+ T cells with similar transcriptional signatures were identified in data sets from breast and non-small cell lung cancer, suggesting these markers may enrich for tumor-reactive CD4+ T cells in many cancers.

Conclusions

These results identify a subset of tumor infiltrating conventional CD4+ T cells in melanoma that are enriched for reactivity to tumor antigens and exist in multiple phenotypic states. Correlations of the presence of these cells with the frequency and phenotype of other immune cells suggest roles for these tumor antigen-specific CD4+ T cells in providing CD8+ T cell help, driving recruitment and maturation of B cells, and activating macrophages. Isolating such cells based on their unique phenotype and utilizing them for adoptive therapy could alter the tumor microenvironment for therapeutic benefit.

Ethics Approval

All Patient samples in this study were obtained from patients who signed informed consent in a study approved by the institutional review board of the Fred Hutchinson Cancer Research Center (protocol #2643).

Regional Differences and Physiologic Behaviors in Peripapillary Scleral Fibroblasts

Purpose

The purpose of this study was to describe the cellular architecture of normal human peripapillary sclera (PPS) and evaluate surface topography's role in fibroblast behavior.

Methods

PPS cryosections from nonglaucomatous eyes were labelled for nuclei, fibrillar actin (FA), and alpha smooth muscle actin (αSMA) and imaged. Collagen fibrils were imaged using second harmonic generation. Nuclear density and aspect ratio of the internal PPS (iPPS), outer PPS (oPPS), and peripheral sclera were determined. FA and αSMA fibril alignment with collagen extracellular matrix (ECM) was determined. PPS fibroblasts were cultured on smooth or patterned membranes under mechanical strain and in the presence of TGFβ1 and 2.

Results

The iPPS (7.1 ± 2.0 × 10⁻⁴, P < 0.0001) and oPPS (5.3 ± 1.4 × 10⁻⁴, P = 0.0013) had greater nuclei density (nuclei/µm²) than peripheral sclera (2.5 ± 0.8 × 10⁻⁴). The iPPS (2.0 ± 0.3, P = 0.002) but not oPPS (2.4 ± 0.4, P = 0.45) nuclei had smaller aspect ratios than peripheral (2.7 ± 0.5) nuclei. FA was present throughout the scleral stroma and was more aligned with oPPS collagen (9.6 ± 1.9 degrees) than in the peripheral sclera (15.9 ± 3.9 degrees, P =0.002). The αSMA fibers in the peripheral sclera were less aligned with collagen fibrils (26.4 ± 4.8 degrees) than were FA (15.9 ± 3.9 degrees, P = 0.0002). PPS fibroblasts cultured on smooth membranes shifted to an orientation perpendicular to the direction of cyclic uniaxial strain (1 Hz, 5% strain, 42.2 ± 7.1 degrees versus 62.0 ± 8.5 degrees, P < 0.0001), whereas aligned fibroblasts on patterned membranes were resistant to strain-induced reorientation (5.9 ± 1.4 degrees versus 10 ± 3.3 degrees, P = 0.21). Resistance to re-orientation was reduced by TGFβ treatment (10 ± 3.3 degrees without TGFβ1 compared to 23.1 ± 4.5 degrees with TGFβ1, P < 0.0001).

Conclusions

Regions of the posterior sclera differ in cellular density and nuclear morphology. Topography alters the cellular response to mechanical strain.

A novel bilayered expanded polytetrafluoroethylene glaucoma implant creates a permeable thin capsule independent of aqueous humor exposure

The purpose of these studies was to evaluate clinical, functional, and histopathological features of glaucoma drainage implants (GDIs) fabricated from novel, custom-tailored expanded polytetrafluoroethylene (ePTFE). Implants of matching footprints were fabricated from silicone (Control) and novel, bilayered ePTFE. ePTFE implants included: (a) one that inflated with aqueous humor (AH) (High), (b) one that inflated with a lower profile (Low), (c) an uninflated implant not connected to the anterior chamber (Flat), and (d) one filled with material that did not allow AH flow (Filled). All implants were placed in adult New Zealand White rabbits and followed over 1-3 months with clinical exams and intraocular pressure. The permeability of tissue capsules surrounding GDIs was assessed using constant-flow perfusion with fluoresceinated saline at physiologic flow rates. After sacrifice, quantitative histopathological measures of capsule thickness were compared among devices, along with qualitative assessment of cellular infiltration and inflammation. Capsular thickness was significantly reduced in blebs over ePTFE (61.4 ± 53 μm) versus silicone implants (193.6 ± 53 μm, p = .0086). AH exposure did not significantly alter capsular thickness, as there was no significant difference between High and Filled (50.9 ± 29, p = .34) implants. Capsules around ePTFE implants demonstrated permeability with steady-state pressure: flow relationships at physiologic flow rates and rapid pressure decay with flow cessation, while pressure in control blebs increased even at low flow rates and showed little decay. Perfused fluorescein dye appeared beyond the plate border only in ePTFE implants. ePTFE implants are associated with thinner, more permeable capsules compared to silicone implants simulating presently used devices.

Conserved glycines in the C terminus of MinC proteins are implicated in their functionality as cell division inhibitors

Alignment of 36 MinC sequences revealed four completely conserved C-terminal glycines. As MinC inhibits cytokinesis in Neisseria gonorrhoeae and Escherichia coli, the functional importance of these glycines in N. gonorrhoeae MinC (MinC(Ng)) and E. coli MinC (MinC(Ec)) was investigated through amino acid substitution by using site-directed mutagenesis. Each mutant was evaluated for its ability to arrest cell division and to interact with itself and MinD. In contrast to overexpression of wild-type MinC, overexpression of mutant proteins in E. coli did not induce filamentation, indicating that they lost functionality. Yeast two-hybrid studies showed that MinC(Ec) interacts with itself and MinD(Ec); however, no interactions involving MinC(Ng) were detected. Therefore, a recombinant MinC protein, with the N terminus of MinC(Ec) and the C terminus of MinC(Ng), was designed to test for a MinC(Ng)-MinD(Ng) interaction. Each MinC mutant interacted with either MinC or MinD but not both, indicating the specificity of glycine residues for particular protein-protein interactions. Each glycine was mapped on the C-terminal surfaces (A, B, and C) of the solved Thermotoga maritima MinC structure. We found that MinC(Ec) G161, residing in close proximity to the A surface, is involved in homodimerization, which is essential for MinC function. Glycines corresponding to MinC(Ec) G135, G154, and G171, located within or adjacent to the B-C surface junction, are critical for MinC-MinD interactions. Circular dichroism revealed no gross structural perturbations of the mutant proteins, although the contribution of glycines to protein flexibility and stability cannot be discounted. Using molecular modeling, we propose that exposed conserved MinC glycines interact with exposed residues of the alpha-7 helix of MinD.

Gonococcal MinD affects cell division in Neisseria gonorrhoeae and Escherichia coli and exhibits a novel self-interaction

The Min proteins are involved in determining cell division sites in bacteria and have been studied extensively in rod-shaped bacteria. We have recently shown that the gram-negative coccus Neisseria gonorrhoeae contains a min operon, and the present study investigates the role of minD from this operon. A gonococcal minD insertional mutant, CJSD1, was constructed and exhibited both grossly abnormal cell division and morphology as well as altered cell viability. Western blot analysis verified the absence of MinD from N. gonorrhoeae (MinD(Ng)) in this mutant. Hence, MinD(Ng) is required for maintaining proper cell division and growth in N. gonorrhoeae. Immunoblotting of soluble and insoluble gonococcal cell fractions revealed that MinD(Ng) is both cytosolic and associated with the insoluble membrane fraction. The joint overexpression of MinC(Ng) and MinD(Ng) from a shuttle vector resulted in a significant enlargement of gonococcal cells, while cells transformed with plasmids encoding either MinC(Ng) or MinD(Ng) alone did not display noticeable morphological changes. These studies suggest that MinD(Ng) is involved in inhibiting gonococcal cell division, likely in conjunction with MinC(Ng). The alignment of MinD sequences from various bacteria showed that the proteins are highly conserved and share several regions of identity, including a conserved ATP-binding cassette. The overexpression of MinD(Ng) in wild-type Escherichia coli led to cell filamentation, while overexpression in an E. coli minD mutant restored a wild-type morphology to the majority of cells; therefore, gonococcal MinD is functional across species. Yeast two-hybrid studies and gel-filtration and sedimentation equilibrium analyses of purified His-tagged MinD(Ng) revealed a novel MinD(Ng) self-interaction. We have also shown by yeast two-hybrid analysis that MinD from E. coli interacts with itself and with MinD(Ng). These results indicate that MinD(Ng) is required for maintaining proper cell division and growth in N. gonorrhoeae and suggests that the self-interaction of MinD may be important for cell division site selection across species.

Deletion of the cell-division inhibitor MinC results in lysis of Neisseria gonorrhoeae

The minCDE genes involved in division site selection in Neisseria gonorrhoeae were identified using raw data from the N. gonorrhoeae genome project and are part of a cluster of 27 genes. When gonococcal min genes were heterologously expressed as a cluster in Escherichia coli, minicells and filaments were produced, indicating that gonococcal min genes disrupted cell division in other genera. The insertional inactivation of the minC gene of N. gonorrhoeae CH811 resulted in a strain (CSRC1) with decreased viability and grossly abnormal cell division as observed by phase-contrast and electron microscopy analysis. Western blot analysis of N. gonorrhoeae CSRC1 confirmed that MinC(Ng) was not produced. Complementation of CSRC1 by integrating a minC-6xHis tag fusion at the proAB locus by homologous recombination restored viability and 1.9 times wild-type levels of MinC(Ng) expression. This slight increase of expression caused a small percentage of the complemented cells to divide aberrantly. This suggested that the 6xHis tag has partially affected the stability of MinC, or that the chromosomal position of minC is critical to its regulation. Comparison of MinC proteins from different bacteria showed a homologous region corresponding to residues 135-230 with five conserved amino acids. Overexpression of MinC(Ng) in wild-type E. coli cells induced filamentation and an E. coli minC mutant was successfully complemented with minC(Ng). Therefore, the evidence indicates that MinC from N. gonorrhoeae acts as a cell-division inhibitor and that its role is essential in maintaining proper division in cocci.

Genetic diversity and relationships among Streptococcus pyogenes strains expressing serotype M1 protein: recent intercontinental spread of a subclone causing episodes of invasive disease

Chromosomal diversity and relationships among 126 Streptococcus pyogenes strains expressing M1 protein from 13 countries on five continents were analyzed by multilocus enzyme electrophoresis and restriction fragment profiling by pulsed-field gel electrophoresis. All isolates were studied for the presence of the gene encoding streptococcal pyrogenic exotoxin A by PCR. Strain subsets were also examined by automated DNA sequencing for allelic polymorphism in genes encoding M protein (emm), streptococcal pyrogenic exotoxin A (speA), streptokinase (ska), pyrogenic exotoxin B (interleukin-1 beta convertase) (speB), and C5a peptidase (scp). Seven distinct emm1 alleles that encode M proteins differing at one or more amino acids in the N-terminal variable region were identified. Although substantial levels of genetic diversity exist among M1-expressing organisms, most invasive disease episodes are caused by two subclones marked by distinctive multilocus enzyme electrophoretic profiles and pulsed-field gel electrophoresis restriction fragment length polymorphism (RFLP) types. One of these subclones (ET 1/RFLP pattern 1a) has the speA gene and was recovered worldwide. Identity of speA, emm1, speB, and ska alleles in virtually all isolates of ET 1/RFLP type 1a means that these organisms share a common ancestor and that global dispersion of this M1-expressing subclone has occurred very recently. The occurrence of the same emm and ska alleles in strains that are well differentiated in overall chromosomal character demonstrates that horizontal transfer and recombination play a fundamental role in diversifying natural populations of S. pyogenes.

Cloning of novel Wilms tumor gene (WT1) cDNAs; evidence for antisense transcription of WT1

WT1 is a tumor suppressor gene that has been implicated in Wilms tumor, and is expressed in cells of mesodermal origin. The Wit-1 gene is located approximately 2 kb from the WT1 gene, and is expressed coordinately with WT1. WT1 and Wit-1 are bi-directionally transcribed from the same promoter region. We have screened a human fetal kidney cDNA library to identify novel WT1 cDNA clones. Here we report the cloning of cDNA clones which span part of intron 1 of WT1, exon 1, upstream sequences between WT1 and Wit-1 and part of the Wit-1 gene. Northern blot and RNAase protection analysis using subcloned fragments of the cDNAs corresponding to regions from within intron 1 of WT1 suggest that a 7-10 Kb RNA is expressed in human fetal kidney, which overlaps with WT1 and is transcribed in the same direction as Wit-1.

Relaxation of insulin-like growth factor II gene imprinting implicated in Wilms' tumour

Genomic imprinting has been implicated in the onset of several embryonal tumours but the mechanism is not well understood. Maternal chromosome 11p15 loss of heterozygosity and paternal chromosome 11 isodisomy suggest that imprinted genes are involved in the onset of Wilms' tumour and the Beckwith-Wiedemann syndrome. The insulin-like growth factor II (IGF2) gene located at 11p15.5 has been put forward as a candidate gene as it is maternally imprinted (paternally expressed) in the mouse, and is expressed at high levels in Wilms' tumours. We report here that the IGF2 gene is expressed from the paternal allele in human fetal tissue, but that in Wilms' tumour expression can occur biallelically. These results provide, to our knowledge, the first evidence that relaxation of imprinting may play a role in the onset of disease and suggest a new genetic mechanism involved in the development of cancer.