Inflammatory bowel disease (IBD) is characterized by chronic remitting and relapsing inflammation of the lower gastrointestinal tract. The etiology underlying IBD remains unknown, but it is thought to involve a hypersensitive immune response to environmental antigens, including the microbiota. Diagnosis and monitoring of IBD is heavily reliant on endoscopy, which is invasive and does not provide information regarding specific mediators. This review describes recent developments in imaging of IBD with a focus on positron emission tomography (PET) and single-photon emission computed tomography (SPECT) of inflammatory mediators, and how these developments may be applied to the microbiota.
Inflammatory bowel disease (IBD) is a chronic relapsing and remitting inflammatory disease of the gastrointestinal tract. The diagnosis and monitoring of IBD are reliant on endoscopy, which is invasive and does not provide information on specific mediators. Symptom flare in IBD is associated with increased activation of innate immune pathways. Immuno-PET approaches have previously demonstrated the ability to detect colitis; however, a direct comparison of antibodies targeted to innate immune mediators and cells has not been done. We aimed to compare immuno-PET of antibodies to IL-1β and CD11b against standard 18 F-FDG and MRI approaches to detect colonic inflammation. Methods: Colonic concentrations of IL-1β and myeloperoxidase were determined by ELISA, and colonic infiltration by CD11b-positive CD3-negative innate immune cells was determined by flow cytometry and compared between healthy and dextran sodium sulphate-treated colitic mice. PET of 89 Zr-lα-IL-1β, 89 Zr-α-CD11b, and 18 F-FDG was compared by volume-of-interest analysis and with MRI by region-of-interest analysis. Imaging results were confirmed by ex vivo biodistribution analysis. Results: Colonic inflammation was associated with impaired colonic epithelial barrier permeability, increased colonic IL-1β and myeloperoxidase concentrations, and increased CD11b-positive CD3-negative innate immune cell infiltration into the colon. 89 Zr-α-IL-1β and 89 Zr-α-CD11b immuno-PET detected colonic inflammation, as did 18 F-FDG, and all PET tracers were more sensitive than MRI. Although 18 F-FDG volumes of interest correlated with colitis severity and a strong trend was observed with 89 Zr-α-IL-1β, no correlation was observed for 89 Zr-α-CD11b or MRI. 89 Zr-α-IL-1β was distributed mainly to the gastrointestinal tract, whereas 89 Zr-α-CD11b was distributed to more tissue types. Conclusion: Immuno-PET using antibodies directed to innate immune markers detected colonic inflammation, with 89 Zr-α-IL-1β providing a more tissue-specific signal than 89 Zr-α-CD11b. Development of these technologies for human subjects will potentially provide a less invasive approach than endoscopy for diagnosing and monitoring IBD. Detects Inflammation inβ Immuno-PET of Innate Immune Markers CD11b and IL-1 http://jnm.snmjournals.org/content/60/6/858 This article and updated information are available at: http://jnm.snmjournals.org/site/subscriptions/online.xhtml Information about subscriptions to JNM can be found at: http://jnm.snmjournals.org/site/misc/permission.xhtml
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Intestinal fibrosis is a common complication of inflammatory bowel disease but remains difficult to detect. Matrix metalloproteases (MMPs) have key roles in fibrosis and are therefore potential targets for fibrosis detection. We determined whether immunoPET of F(ab′)2 antibody fragments targeting MMPs detects colitis induced colonic fibrosis. Mice were administered 2% dextran sulfate sodium treated water for 1 cycle (inflamed) or 3 cycles (fibrotic), or were untreated (control). Colonic and kidney collagen, innate cytokine, MMPs and fecal MPO concentrations were analyzed by multiplex/ELISA. α-pro-MMP-9 F(ab′)2 fragments were engineered and conjugated to 89Zr for PET imaging, ex-vivo Cherenkov analysis and bio-distribution. Colonic innate cytokine concentrations and fecal myeloperoxidase were increased in inflamed mice but not fibrotic mice, while collagen concentrations were increased in fibrotic mice. MMPs were increased in inflamed mice, but only pro-MMP-9 remained increased in fibrotic mice. 89Zr-pro-MMP-9 F(ab′)2 uptake was increased in the intestine but also in the kidney of fibrotic mice, where collagen and pro-MMP-9 concentrations were increased. 89Zr-pro-MMP-9 F(ab′)2 detects colitis induced intestinal fibrosis and associated kidney fibrosis.
Accurate delineation of gross tumor volumes remains a barrier to radiotherapy dose escalation and boost dosing in the treatment of solid tumors, such as prostate cancer. Magnetic resonance imaging (MRI) of tumor targets has the power to enable focal dose boosting, particularly when combined with technological advances such as MRI‐linear accelerator. Fibroblast activation protein (FAP) is overexpressed in stromal components of >90% of epithelial carcinomas. Herein, the authors compare targeted MRI of prostate specific membrane antigen (PSMA) with FAP in the delineation of orthotopic prostate tumors. Control, FAP, and PSMA‐targeting iron oxide nanoparticles were prepared with modification of a lymphotropic MRI agent (FerroTrace, Ferronova). Mice with orthotopic LNCaP tumors underwent MRI 24 h after intravenous injection of nanoparticles. FAP and PSMA nanoparticles produced contrast enhancement on MRI when compared to control nanoparticles. FAP‐targeted MRI increased the proportion of tumor contrast‐enhancing black pixels by 13%, compared to PSMA. Analysis of changes in R2 values between healthy prostates and LNCaP tumors indicated an increase in contrast‐enhancing pixels in the tumor border of 15% when targeting FAP, compared to PSMA. This study demonstrates the preclinical feasibility of PSMA and FAP‐targeted MRI which can enable targeted image‐guided focal therapy of localized prostate cancer.
Inflammatory Bowel Disease (IBD) is characterized by chronic remitting and relapsing inflammation of the lower gastrointestinal tract. The etiology underlying IBD remains unknown but is thought to involve a hypersensitive immune response to environmental antigen, including the microbiota. Diagnosis and monitoring of disease is heavily reliant on endoscopy, which is invasive and does not provide information regarding specific mediators. This review describes recent developments in imaging of IBD with a focus on PET and SPECT imaging of inflammatory mediators, and how this may be applied to the microbiota.
performed spatial transcriptomic profiling to elucidate the molecular differences between TZ and PZ PCa.METHODS: We identified three patients who underwent radical prostatectomy for PCa (one each with PZ only, TZ only, and both PZ and TZ tumors) and used the NanoString's Digital Spatial Profiling (DSP) platform to quantify whole transcriptomic gene expression data (17,128 genes) in multiple regions of interest (ROI) per patient (42 cancer and 8 normal samples). Four morphology markers to facilitate ROI selection in both cancer and normal areas (SYTO13 for nucleus, PanCK for epithelium, SMA for stroma and CD45 for immune cells) were selected. Raw counts for 17,128 genes were imported to R v.4.1.0 for downstream data analyses. Counts were Q3 normalized and scaled (Z-score) to enable plotting of all genes on the same axes. Differential gene expression analysis using a linear model fit by empirical Bayes moderation, gene set enrichment analysis (GSEA) by cancer hallmarks, XCell gene sets for pathway enrichment and immune cell deconvolution using CIBERSORT was performed.RESULTS: There were grade group (GG) 4 (n[10) and 5 (n [10) tumors in PZ and GG 3 (n[10), 4 (n[11) and 5 (n[1) cancers in TZ regions. We observed distinct gene expression profiles between PZ (n [ 20) and TZ (n[22) tumors. Interestingly, androgen receptor (AR) signaling was significantly higher in TZ PCa ROIs compared to PZ ROIs in both GSEA (false discovery rate < 5%) and the androgen subcomponent of the genomic prostate score (p<0.001), regardless of grade, epithelial, stromal or immune component of the region. To standardize the comparison, CIBERSORT's absolute immune signature scores were only computed for GG4 tumors and found to be significantly higher in PZ GG4 tumors compared to TZ GG4 tumors. Notably, CD4þ memory T cells were significantly higher in PZ GG4 regions compared to TZ GG4 tumor regions (p<0.05).CONCLUSIONS: Here, we demonstrate distinct gene expression profiles of PZ and TZ PCa. Specifically, we observed higher AR signaling in TZ cancers and higher levels of immune infiltration on PZ cancers. This is in concordance with prior knowledge that TZ tumors may be associated with higher serum PSA and PZ tumors may be associated with inflammation. Further studies are needed to discern the biological and clinical significance of the different molecular features of PZ and TZ PCa.
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