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Danish Medical Journal Jan 2015Ulcerative colitis (UC) and Crohn's disease (CD), collectively referred to as inflammatory bowel disease (IBD), are chronic immune disorders affecting the... (Review)
Review
Ulcerative colitis (UC) and Crohn's disease (CD), collectively referred to as inflammatory bowel disease (IBD), are chronic immune disorders affecting the gastrointestinal tract. The aetiology of IBD remains an enigma, but increasing evidence suggests that the development of IBD may be triggered by a disturbance in the balance between gut commensal bacteria and host response in the intestinal mucosa. It is now known that epithelial cells have the capacity to secrete and respond to a range of immunological mediators and this suggests that these cells play a prominent role in the pathogenesis of IBD. Current knowledge about the intestinal epithelium has mainly been obtained using models based on animal cells, transformed human intestinal cell lines and isolated cells from resected colonic bowel segments. Species difference, malignant origin and confounders related to surgery, obviously make these cell models however less applicable for patophysiological studies. Consequently, there was a clear need for models of representative intestinal epithelial cells that would allow functional and dynamic studies of the differentiated human colonic epithelium in vitro. The primary purpose of this thesis was to explore and validate the optimal conditions for establishing a model based on short-term cultures of human colonic epithelial cells obtained from endoscopical biopsies. The cell cultures were accordingly used to describe the interplay between proinflammatory cytokines and colonic epithelium, with focus on alterations in viability, butyrate metabolism and secretion of a chemokine and metalloproteinases (MMP). Finally, the model was used to characterize expression and activation of receptors like toll like receptor (TLR)9 and peroxisome activated proliferators (PPAR)- known to be important players in regulation of innate and adaptive immune responses in human colonic epithelium. The results showed that it is possible to establish short-term cultures of representative, viable human colonic epithelial cells from endoscopic mucosal biopsies of patients with IBD. Short-time isolation by EGTA/EDTA from colonic biopsies allowed establishment of small scale cultures of epithelial cells which were viable and metabolic active for up to 48 hours in vitro. The cell model preserved important cellular metabolic and immunological functions of the human colonic epithelium, including the ability to oxidate butyrate, detoxificate phenolic compounds and secrete the chemokine interleukin (IL)-8 in vitro. Tumour necrosis factor (TNF)-α and interferon (IFN)-γ are pro-inflammatory cytokines, which are present in increased amounts in inflamed colonic mucosa. The precise mechanisms of cytokine-mediated mucosal injury are unknown, but one might be that TNF-α and IFN-γ directly impair epithelial cell function similar to effects seen on distinct target cells in other autoimmune diseases. Using the model, both cytokines were found directly to impair the viability of colonic epithelial cells and to induce secretion of IL-8 in vitro. Interestingly, the cells from inflamed IBD mucosa were less sensitive to cytokine-induced damage, which suggests that an intrinsic defense mechanism is triggered in these cells, perhaps as a result of exposure to toxic luminal factors or high local cytokine levels in vivo. TNF-α and IFN-γ may also be involved in regulation of intestinal inflammation through stimulation of MMP expression and proteolytic activity. We found that colonic epithelial cells express a range of MMPs and moreover that expression of distinct MMPs is increased in cells from inflamed IBD mucosa. Using a functional peptide cleavage assay it was shown that epithelial cells secreted proteolytic active enzymes and that the functional MMP activity was increased in inflamed IBD mucosa. This suggests that colonic epithelial cells, like myofibroblasts and immune cells, may contribute to local intestinal mucosal damage, through secretion of active MMPs. Disturbance of recognition and discrimination of potentially harmful pathogens from commensals in the intestinal mucosa have increasingly been implicated in the pathogenesis of IBD. Our results revealed that colonic epithelial cells express TLR9, a key pattern recognition receptor. Interestingly, the differentiated epithelial cells, which have been exposed to the luminal bacterial flora in vivo, were unresponsive to TLR9 ligand stimulation, contrasting findings in the epithelial cell line HT-29 that is cultured continuously in bacteria free environment. These findings suggest, theoretically, that colonic epithelium may regulate immune responses to microbial antigens including commensal bacterial DNA through modulation of the TLR9 pathway. Currently, the results are in line with the emerging view, that the epithelium represents an important frontline cellular component of the innate immune system in the gut. PPARγ is a nuclear receptor involved in the regulation of lipid and carbonhydrate metabolism. Recent studies in rodent colitis models suggest that PPARγ also is involved in modulation of inflammatory processes in the colon. Using the model, we characterise expression and activity of PPARs in human colonic epithelium and, additionally, evaluated the functional significance of a possible imbalanced PPARγ regulation in relation to inflammation. Our experiments showed that colonic epithelial cells express PPARγ and furthermore that PPARγ signalling was impaired in inflamed UC epithelium. It was possible to restore PPARγ signalling in the cell cultures by stimulation with rosiglitazone (a synthetic PPARγ ligand) in vitro. Hence, these experiments prompted us to design a small controlled, clinical study exploring the possible stimulatory effects of rosiglitazone (a PPAR ligand) in vivo. Interestingly, it was found that topical application of rosiglitazone in patients with active distal UC reduced clinical activity and mucosal inflammation similar to the effects measured in patients treated with mesalazine enemas. Moreover, rectal application of rosiglitazone induced PPARγ signalling in the epithelium in vivo, supporting the view that activation of PPARγ may be a new potential therapeutic target in the treatment of UC. Overall, the in vitro model of representative human colonic epithelial cells has shown to be a useful technique for detailed studies of metabolic and immunological functions that are important for homeostasis of the colonic epithelium. Currently, the findings support the view that intestinal epithelial cells actively participate in immunological processes in the colonic mucosa. Additionally, the model seems to be applicable for generating and evaluating new therapeutic approaches from laboratory bench to bed line as illustrated by the PPARγ study. It is therefore probable, that studies in models of representative colonic epithelial cells, as the one described here, could contribute with important knowledge about the pathogenesis of human inflammatory colonic diseases also in the future.
Topics: Adaptive Immunity; Cell Separation; Cells, Cultured; Colon; Cytokines; Epithelial Cells; Humans; Immunity, Innate; In Vitro Techniques; Inflammatory Bowel Diseases; Intestinal Mucosa
PubMed: 25557335
DOI: No ID Found -
Drug Delivery and Translational Research Jun 2018The prophylactic activity of antiretroviral drugs applied as microbicides against sexually transmitted HIV is dependent upon their concentrations in infectable host...
The prophylactic activity of antiretroviral drugs applied as microbicides against sexually transmitted HIV is dependent upon their concentrations in infectable host cells. Within mucosal sites of infection (e.g., vaginal and rectal mucosa), those cells exist primarily in the stromal layer of the tissue. Traditional pharmacokinetic studies of these drugs have been challenged by poor temporal and spatial specificity. Newer techniques to measure drug concentrations, involving Raman spectroscopy, have been limited by laser penetration depth into tissue. Utilizing confocal Raman spectroscopy (RS) in conjunction with optical coherence tomography (OCT), a new lateral imaging assay enabled concentration distributions to be imaged with spatial and temporal specificity throughout the full depth of a tissue specimen. The new methodology was applied in rectal tissue using a clinical rectal gel formulation of 1% tenofovir (TFV). Confocal RS revealed diffusion-like behavior of TFV through the tissue specimen, with significant partitioning of the drug at the interface between the stromal and adipose tissue layers. This has implications for drug delivery to infectable tissue sites. The new assay can be applied to rigorously analyze microbicide transport and delineate fundamental transport parameters of the drugs (released from a variety of delivery vehicles) throughout the mucosa, thus informing microbicide product design.
Topics: Animals; Anti-HIV Agents; Gels; Intestinal Mucosa; Models, Animal; Rectum; Spectrum Analysis, Raman; Swine; Tenofovir; Tomography, Optical Coherence
PubMed: 29468424
DOI: 10.1007/s13346-018-0495-7 -
BMC Gastroenterology Mar 2021The role of IL-12/23 in the pathogenesis of ulcerative colitis (UC) is unclear. We analyzed mucosal IL-12/23 expression and its relationship with endoscopic severity,...
BACKGROUND
The role of IL-12/23 in the pathogenesis of ulcerative colitis (UC) is unclear. We analyzed mucosal IL-12/23 expression and its relationship with endoscopic severity, histological activity, and UC relapse.
METHODS
Rectal biopsies were collected from 70 UC patients with clinical remission. IL-12, IL-23, IFN-γ, IL-17A, and IL-17F mRNA expression was measured by real-time PCR. Endoscopic severity and histological activity were evaluated using the Mayo endoscopic subscore (MES) and the Geboes score, respectively.
RESULTS
The longest follow-up period was 51 months. Thirty-four patients relapsed during the study period. Samples from these subsequently relapsed patients formed the "relapse" group, while those from patients that did not relapse formed the "remission" group. IL-12 (P = 0.0003) and IL-23 (P = 0.014) mRNA expression was significantly higher in the relapse than the remission group. Expression of IL-23 (P = 0.015) but not IL-12 (P = 0.374) was correlated with MES. However, in patients with an MES of 0 and 1, IL-12 expression was statistically higher in the relapse than the remission group (P = 0.0015, P = 0.0342). IL-12 and IL-23 expression did not vary significantly between histologically active and inactive mucosa; both were higher in histologically inactive patients in the remission group (IL-12: P = 0.0002, IL-23: P = 0.046).
CONCLUSIONS
Rectal IL-12 and IL-23 expression was elevated in the relapse group, but IL-12 was more strongly associated with UC relapse, irrespective of endoscopic severity and histological activity. Mucosal IL-12 was elevated in patients with deep mucosal healing. Our results suggest an important role of IL-12 in UC pathogenesis and the molecular mechanism of UC relapse.
Topics: Colitis, Ulcerative; Colonoscopy; Humans; Interleukin-12; Intestinal Mucosa; Recurrence; Severity of Illness Index
PubMed: 33730998
DOI: 10.1186/s12876-021-01709-5 -
AIDS Research and Human Retroviruses Nov 2014CD4(+) T cells in the mucosa of the gastrointestinal (GI) tract are preferentially targeted and depleted by HIV. As such, the induction of an effective anti-HIV immune... (Review)
Review
CD4(+) T cells in the mucosa of the gastrointestinal (GI) tract are preferentially targeted and depleted by HIV. As such, the induction of an effective anti-HIV immune response in the mucosa of the GI tract-through vaccination-could protect this vulnerable population of cells. Mucosal vaccination provides a promising means of inducing robust humoral and cellular responses in the GI tract. Here we review data from the literature about the effectiveness of various mucosal vaccination routes--oral (intraintestinal/tonsilar/sublingual), intranasal, and intrarectal--with regard to the induction of immune responses mediated by cytotoxic T cells and antibodies in the GI mucosa, as well as protective efficacy in challenge models. We present data from the literature indicating that mucosal routes have the potential to effectively elicit GI mucosal immunity and protect against challenge. Given their capacity for the induction of anti-HIV immune responses in the GI mucosa, we propose that mucosal routes, including the nonconventional sublingual, tonsilar, and intrarectal routes, be considered for the delivery of the next generation HIV vaccines. However, further studies are necessary to determine the ideal vectors and vaccination regimens for these routes of immunization and to validate their efficacy in controlling HIV infection.
Topics: AIDS Vaccines; Administration, Intranasal; Administration, Mucosal; Administration, Oral; Administration, Rectal; HIV Infections; Humans; Immunity, Mucosal; Intestinal Mucosa
PubMed: 25354023
DOI: 10.1089/aid.2014.0233 -
HCA Healthcare Journal of Medicine 2021Description Chemical colitis is defined as inflammation of the large intestine or colon as a result of exposure from a harsh chemical through an enema or other...
Description Chemical colitis is defined as inflammation of the large intestine or colon as a result of exposure from a harsh chemical through an enema or other procedure. In this case, the chemical is hydrogen peroxide, which is commonly used as an antiseptic for minor abrasions. Hydrogen peroxide enemas were once popular for difficult to treat constipation. However, resultant colitis and proctitis limited its use. When administered rectally in a high enough concentration, intense abdominal pain and transient bloody diarrhea can occur, with the majority of affected patients making a full recovery with supportive management. Here we discuss a case of an accidental low concentration hydrogen peroxide enema in an otherwise healthy young adult that emphasized the dangers of hydrogen peroxide damage to mucosal membranes.
PubMed: 37425640
DOI: 10.36518/2689-0216.1096 -
Scientific Reports May 2019A better understanding of the distribution and functional capacity of CD4 T helper (Th) and CD8 T cytotoxic (Tc) cell subsets in the rectal mucosa (RM), a major site for...
A better understanding of the distribution and functional capacity of CD4 T helper (Th) and CD8 T cytotoxic (Tc) cell subsets in the rectal mucosa (RM), a major site for HIV acquisition and replication, in adults is needed. In this study, we compared the distribution of Th and Tc cell subsets between blood and RM compartments in 62 HIV negative men, focusing primarily on IL-17-producing CD4 and CD8 T cells due to their importance in establishing and maintaining mucosal defenses, and examined associations between the frequencies of Th17 and Tc17 cell subsets and the availability of highly HIV-susceptible target cells in the RM. The RM exhibited a distinct immune cell composition comprised of higher frequencies of Th2, Th17, and Tc17 cells compared to the peripheral blood. The majority of Tc17 cells in RM were quadruple-cytokine producers (IL-17A, IFN-γ, TNF-α, and IL4), whereas most Th17 cells in blood and RM were single IL-17A producers or dual-cytokine producers (IL-17ATNF-α). In a separate cohort of 21 HIV positive men, we observed similar tissue distributions of Th and Tc cell subsets, although Tc17 cell frequencies in both blood and tissues were very low. Higher frequencies of multi-cytokine-producing Th17 and Tc17 cells in RM of HIV negative men positively correlated with increased mucosal HIV target cells, suggesting a need to further characterize the effector functions of these cells and their role in HIV acquisition and pathogenesis.
Topics: Adolescent; Adult; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Case-Control Studies; Cohort Studies; HIV; HIV Infections; Humans; Interleukin-17; Leukocytes, Mononuclear; Male; Middle Aged; Mucous Membrane; T-Lymphocyte Subsets; T-Lymphocytes, Cytotoxic; Young Adult
PubMed: 31061442
DOI: 10.1038/s41598-019-43311-6 -
International Journal of Molecular... Aug 2022Antagonism of transient receptor potential vanniloid-1 (TRPV1) and desensitization of transient receptor potential ankyrin-1 (TRPA1) nociceptors alleviate inflammatory...
Antagonism of transient receptor potential vanniloid-1 (TRPV1) and desensitization of transient receptor potential ankyrin-1 (TRPA1) nociceptors alleviate inflammatory bowel diseases (IBD)-associated chronic pain. However, there is limited literature available about their role in regulating the mucosal layer, its interaction with host physiology, and luminal microbial community. The present study focuses on the effects' intra rectal administration of capsazepine (modulator of TRPA1/TRPV1 expressing peptidergic sensory neurons) on colonic mucus production and gut health. We performed histological analysis, gut permeability alteration, gene expression changes, metabolite profiling, and gut microbial abundance in the ileum, colon, and cecum content of these animals. Intra rectal administration of capsazepine modulates TRPA1/TRPV1-positive nociceptors (behavioral pain assays) and resulted in damaged mucosal lining, increased gut permeability, and altered transcriptional profile of genes for goblet cell markers, mucus regulation, immune response, and tight junction proteins. The damage to mucosal lining prevented its role in enterosyne (short chain fatty acids) actions. These results suggest that caution must be exercised before employing TRPA1/TRPV1 modulation as a therapeutic option to alleviate pain caused due to IBD.
Topics: Animals; Capsaicin; Colon; Inflammatory Bowel Diseases; Mice; Pain; TRPA1 Cation Channel; TRPV Cation Channels; Transient Receptor Potential Channels
PubMed: 36076974
DOI: 10.3390/ijms23179577 -
Cellular and Molecular Gastroenterology... 2020Despite achieving endoscopic remission, more than 20% of inflammatory bowel disease patients experience chronic abdominal pain. These patients have increased rectal...
BACKGROUND & AIMS
Despite achieving endoscopic remission, more than 20% of inflammatory bowel disease patients experience chronic abdominal pain. These patients have increased rectal transient receptor potential vanilloid-1 receptor (TRPV1) expression, a key transducer of inflammatory pain. Because inflammatory bowel disease patients in remission exhibit dysbiosis and microbial manipulation alters TRPV1 function, our goal was to examine whether microbial perturbation modulated transient receptor potential function in a mouse model.
METHODS
Mice were given dextran sodium sulfate (DSS) to induce colitis and were allowed to recover. The microbiome was perturbed by using antibiotics as well as fecal microbial transplant (FMT). Visceral and somatic sensitivity were assessed by recording visceromotor responses to colorectal distention and using hot plate/automated Von Frey tests, respectively. Calcium imaging of isolated dorsal root ganglia neurons was used as an in vitro correlate of nociception. The microbiome composition was evaluated via 16S rRNA gene variable region V4 amplicon sequencing, whereas fecal short-chain fatty acids (SCFAs) were assessed by using targeted mass spectrometry.
RESULTS
Postinflammatory DSS mice developed visceral and somatic hyperalgesia. Antibiotic administration during DSS recovery induced visceral, but not somatic, hyperalgesia independent of inflammation. FMT of postinflammatory DSS stool into antibiotic-treated mice increased visceral hypersensitivity, whereas FMT of control stool reversed antibiotics' sensitizing effects. Postinflammatory mice exhibited both increased SCFA-producing species and fecal acetate/butyrate content compared with controls. Capsaicin-evoked calcium responses were increased in naive dorsal root ganglion neurons incubated with both sodium butyrate/propionate alone and with colonic supernatants derived from postinflammatory mice.
CONCLUSIONS
The microbiome plays a central role in postinflammatory visceral hypersensitivity. Microbial-derived SCFAs can sensitize nociceptive neurons and may contribute to the pathogenesis of postinflammatory visceral pain.
Topics: Animals; Colitis, Ulcerative; Colon; Dextran Sulfate; Disease Models, Animal; Dysbiosis; Fatty Acids, Volatile; Feces; Gastrointestinal Microbiome; Humans; Intestinal Mucosa; Male; Mice; Nociception; Nociceptors; TRPV Cation Channels; Visceral Pain
PubMed: 32289500
DOI: 10.1016/j.jcmgh.2020.04.003 -
Zhongguo Ying Yong Sheng Li Xue Za Zhi... Dec 2023Mucoadhesive polymers are a new and exciting development in drug delivery systems that have the potential to significantly increase therapeutic efficacy. These polymers... (Review)
Review
Mucoadhesive polymers are a new and exciting development in drug delivery systems that have the potential to significantly increase therapeutic efficacy. These polymers stick to mucosal surfaces, increasing the amount of time that medications stay at the site of absorption and improving their bioavailability. These mechanisms include longer contact times with the mucosal surface, better drug solubility, and defence against enzymatic degradation of pharmaceuticals. Mucoadhesive polymers also provide a number of benefits over traditional drug delivery methods, including less frequent dosage, better patient compliance, and fewer adverse effects. Due to their adaptability, Mucoadhesive polymers may be used in the rectal, vaginal, ophthalmic, nasal, and oral routes of drug delivery. Mucoadhesive polymers have advantages now, but they also have potential for the future of medication delivery. Mucoadhesion offers excellent possibilities for the delivery of a range of substances through the nasal, vaginal, buccal, and ocular routes of administration. Furthermore, mucoadhesion facilitates the achievement of an extended local or systemic pharmacological effect. In this study, we covered the mechanisms behind mucoadhesion, possible uses for Mucoadhesive polymers in drug administration, and techniques for assessing Mucoadhesive drug delivery systems. The goal of current research is to create innovative Mucoadhesive polymers that have better biodegradability, biocompatibility, and adhesive qualities. Moreover, it is anticipated that the effectiveness of Mucoadhesive polymers would be increased when combined with other cutting-edge drug delivery technologies, such as micro particles and nanoparticles.
Topics: Humans; Adhesiveness; Drug Delivery Systems; Mucous Membrane; Polymers
PubMed: 38751344
DOI: 10.62958/j.cjap.2023.005 -
BMC Medicine Aug 2021The risk for several common cancers is influenced by the transcriptomic landscape of the respective tissue-of-origin. Vitamin D influences in vitro gene expression and...
BACKGROUND
The risk for several common cancers is influenced by the transcriptomic landscape of the respective tissue-of-origin. Vitamin D influences in vitro gene expression and cancer cell growth. We sought to determine whether oral vitamin D induces beneficial gene expression effects in human rectal epithelium and identify biomarkers of response.
METHODS
Blood and rectal mucosa was sampled from 191 human subjects and mucosa gene expression (HT12) correlated with plasma vitamin D (25-OHD) to identify differentially expressed genes. Fifty subjects were then administered 3200IU/day oral vitamin D3 and matched blood/mucosa resampled after 12 weeks. Transcriptomic changes (HT12/RNAseq) after supplementation were tested against the prioritised genes for gene-set and GO-process enrichment. To identify blood biomarkers of mucosal response, we derived receiver-operator curves and C-statistic (AUC) and tested biomarker reproducibility in an independent Supplementation Trial (BEST-D).
RESULTS
Six hundred twenty-nine genes were associated with 25-OHD level (P < 0.01), highlighting 453 GO-term processes (FDR<0.05). In the whole intervention cohort, vitamin D supplementation enriched the prioritised mucosal gene-set (upregulated gene-set P < 1.0E-07; downregulated gene-set P < 2.6E-05) and corresponding GO terms (P = 2.90E-02), highlighting gene expression patterns consistent with anti-tumour effects. However, only 9 individual participants (18%) showed a significant response (NM gene-set enrichment P < 0.001) to supplementation. Expression changes in HIPK2 and PPP1CC expression served as blood biomarkers of mucosal transcriptomic response (AUC=0.84 [95%CI 0.66-1.00]) and replicated in BEST-D trial subjects (HIPK2 AUC=0.83 [95%CI 0.77-0.89]; PPP1CC AUC=0.91 [95%CI 0.86-0.95]).
CONCLUSIONS
Higher plasma 25-OHD correlates with rectal mucosa gene expression patterns consistent with anti-tumour effects, and this beneficial signature is induced by short-term vitamin D supplementation. Heterogenous gene expression responses to vitamin D may limit the ability of randomised trials to identify beneficial effects of supplementation on CRC risk. However, in the current study blood expression changes in HIPK2 and PPP1CC identify those participants with significant anti-tumour transcriptomic responses to supplementation in the rectum. These data provide compelling rationale for a trial of vitamin D and CRC prevention using easily assayed blood gene expression signatures as intermediate biomarkers of response.
Topics: Carrier Proteins; Cholecalciferol; Dietary Supplements; Humans; Mucous Membrane; Protein Serine-Threonine Kinases; Rectum; Reproducibility of Results; Transcriptome; Vitamin D
PubMed: 34340708
DOI: 10.1186/s12916-021-02044-y