| 1. |
- Casado Bedmar, Maria Teresa, 1990-
(författare)
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Neuro-immuno-regulation of inflammation in the colonic mucosa : Focus on mast cells and eosinophils in bowel disorders
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Intestinal homeostasis is key to control uptake across the mucosa and protect from harmful substances. Disturbances in the bidirectional communication between the gut and the brain are implicated in irritable bowel syndrome (IBS) and inflammatory bowel diseases (IBD), being Crohn’s disease (CD) and ulcerative colitis (UC) the two most common IBD subtypes. Although these chronic bowel-relapsing inflammatory disorders present different histopathology, they share similar pathological features. Both IBS and IBD are characterized by a disrupted intestinal barrier function, a pro-inflammatory chronic condition, and an altered gut-brain axis. Despite all the scientific effort, the sequence or exact combination of events that drive these diseases are still unknown, and so is the exact role of every single component. Growing evidence suggests altered neuro-immune interactions as a pathogenic factor.The general aim of this thesis was to elucidate the potential involvement of mast cells and eosinophils in IBS and IBD, and the neuro-immune intercellular circuit via vasoactive intestinal polypeptide (VIP) that might exacerbate mucosal inflammation and intestinal barrier disruption.Intestinal tissues from IBS, inactive IBD, healthy controls (HC), and murine colitis were collected. Electrophysiological and permeability studies were performed using the ex vivo Ussing chamber technique. Tissues were processed with immunohistological procedures to study cell numbers, activation, location, and interactions in relation to VIP.We demonstrated for the very first time an increased transcellular passage of live commensal and pathogenic bacteria through the colonic mucosa of IBS, identifying VIP as a key regulatory molecule together with mast cells activation. In vitro experiments revealed the ability of VIP to activate mast cells. Image analysis identified VIP-mast cells in closer proximity in IBD patients and murine colitis compared to controls. Communication between mast cells and VIP was shown upregulated in IBD and mice colitis via VIP receptor (VPAC)1. Similarities and differences between HC, IBS, and IBD were further studied. Results indicated a pronounced increased intestinal permeability in UC, even during remission, followed by IBS, compared to healthy controls. Surprisingly, permeability results did not correlate with mast cells, but with eosinophil number and activation. A further image analysis suggested an inhibitory effect of eosinophils and VIP on mast cells and an altered interaction between them under inflammatory conditions. Lastly, intestinal VIP levels were shown to increase in IBD patients after the treatment with biological agents and were suggested as a possible biomarker for biological treatment outcome.This thesis presents novel insights into the regulation of intestinal permeability, as well as into the pathophysiology of IBD and IBS by demonstrating the importance of neuro-immune interactions between mast cells, VIP, and eosinophils.Altogether, our findings have broadened the knowledge of neuro-immune interactions in IBS and IBD and might have the potential to onsight lead to new therapeutic approaches thereby improving the outcomes for patients suffering from these diseases.
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| 2. |
- Carlsson, Anders, 1980-
(författare)
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Role of mast cells and probiotics in the regulation of intestinal barrier function
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The intestinal mucosa is the largest contact area and one of the most important barriers to the outside environment. It is highly specialized in aiding us digest and absorb nutrients. It is daily exposed to several potentially dangerous substances and microorganisms, which if they were allowed to pass into the body, could give rise to diseases. Throughout the small intestine certain sites specialized in antigen sampling are found. These sites are named Peyer’s patches and are lymphoid follicles. The epithelium covering the Peyer’s patches is called follicle-associated epithelium and is specialized in antigen sampling and uptake. The special epithelium enables presentation of luminal antigen to immune cells in the underlying follicle.Persistent life stress and stressful life events affect the course of irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) through largely unknown mechanisms. Regulation of epithelial permeability to antigens is crucial for the balance between inflammation and immune-surveillance, and increased intestinal permeability has been shown in patients with ulcerative colitis and Crohns disease. Vasoactive intestinal polypeptide (VIP) and corticotropin-releasing factor have been implicated as important mediators of stress-induced abnormalities in intestinal mucosal functions in animal models. Both of these mediators have been reported to regulate bowel ion secretion in humans during stress and uptake of horseradish peroxidase in rodents. Probiotics have been shown to ameliorate the deleterious effects of stress on intestinal function, but mechanisms remain to be elucidated.The aim of this thesis was to elucidate whether mast cells play an important role in intestinal barrier function during stress and inflammation. Moreover, we wanted to determine whether probiotics can ameliorate the mucosal barrier integrity during stress and inflammation.To study the function of mast cells we conducted in vitro experiments on cell lines and ex vivo experiments in Ussing chambers on mouse, rat and human intestinal tissue. The Ussing chamber technique measures electrophysiological properties of the tissue and also gives the possibility to study transcellular and paracellular passage of markers and bacteria. Immunohistology and confocal microscopy have been used to identify mast cells and receptors of interest.Our results show that stress affects the follicle-associated epithelium barrier by mechanisms involving VIP and mast cells. These findings were corroborated by the localization of VIP receptors on mucosal mast cells. Furthermore, pretreatment with probiotics was effective in protecting the gut against stress-induced intestinal barrier dysfunction and mucosal inflammation. This protection appeared to involve a mast cell and peroxisome proliferatoractivated receptor-γ dependent mechanism.
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| 3. |
- Kalman, Thordis Disa, 1959-
(författare)
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Surgery and stomas in Crohn's disease
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study investigates the evolution of abdominal surgery in treatment of Crohn´s disease (CD) in the era of immunomodulatory drugs and biologicals. It concerns risk of abdominal surgery overall and sub-categories of abdominal surgery, risk of repeat surgery and factors that affect this risk, and risk of getting a stoma. Surgical recurrence is a major clinical problem as repeat procedures are more complex and expose the patients to a higher medical risk both in conjunction with surgery and afterwards. Updated information on abdominal surgery for CD will be of use when making decisions about medical vs surgical interventions.In a nationwide cohort of 21 273 patients with CD during the years 1990-2014, the cumulative incidence of abdominal surgery within five years of diagnosis decreased continuously down to 17.3% for patients diagnosed with CD during the last calendar period of study, 2009–2014. Ileocecal resection was the most common primary procedure. The incidence of colectomy was low in all calendar periods and continuously decreased. The incidence of proctectomy was very low even after decades with the disease, 3.0% for patients diagnosed 1990-1995 with a median follow-up of 21 years. Incidence of repeat abdominal surgery within five years of primary procedure decreased in the 90s down 16.0% in the 1996– 2000 period with a risk of ileocolic reresection of 4.4%. After 2000, despite introduction of biologicals in 1998, no further significant decrease in repeat surgery was observed.In a retrospective review of prospectively maintained databases at three university hospitals, the rate of surgical recurrence for 389 patients with CD who had been treated with a primary ileocecal resection between 2000-2012 was investigated. The patients were operated receiving either a temporary stoma (20%) or a primary anastomosis (80%) with a median follow-up time of 105 months. Patients selected to temporary stoma had a higher prevalence of baseline risk factors usually associated with an increased risk of recurrence such as penetrating disease behaviour. Despite this, there was no difference in long-term surgical recurrence between the one- and two-stage groups; 18% vs 16%.In a retrospective review of prospectively maintained databases at two university hospitals, the effect of smoking cessation on rate of surgical recurrence was assessed. 242 patients were included with a median follow-up of 112 months. Surgical recurrence rate for smokers vs quitters was 16/42 (38%) vs 3/31 (10%); p = 0.02; risk ratio = 3.9 despite a median time for smoking exposure after the primary procedure of three years. Among the non-smokers 28/169 (17%) had a surgical recurrence at last follow-up. 8 out of 11 smoking patients who needed a second resection went on to need a third resection. Of the patients who were free of surgical recurrence at follow-up, those who had quit smoking were significantly less likely to have been put on medical therapy compared with smokers with a risk ratio of 3.2.In an observational study of a nationwide cohort of 19 146 patients with incident CD 2002- 2013 and followed through 2017, the incidence and prevalence of stoma was investigated. The cumulative incidence of stoma formation within five years was 2.4% and remained constant from 2002 and onwards although cumulative ever-use of biologicals increased and time to start with treatment with biologicals decreased. 48% of all stomas were reversed. Ileostomies encompassed about two-thirds of all stomas and risk of stoma was higher among patients with elderly-onset CD and among patients with perianal manifestations of the disease. 28% of the patients who underwent surgery with formation of a stoma had perianal disease. 0.6% of all incident patients had a permanent stoma five years after diagnosis.
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| 4. |
- Myrelid, Pär
(författare)
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Surgery and immuno modulation in Crohn’s disease
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Crohn’s disease is a chronic inflammatory bowel disease with unknown origin. This study investigates the combined use of surgery and immuno modulation in Crohn’s disease. The outcome of medication and surgery in 371 operations on 237 patients between 1989 and 2006 were evaluated. Moreover the effects of prednisolone, azathioprine and infliximab on the healing of colo-colonic anastomosis in 84 mice with or without colitis were evaluated.The use of thiopurines after abdominal surgery in selected cases of severe Crohn’s disease was found to prolong the time to clinical relapse of the disease from 24 to 53 months. Patients on postoperative maintenance therapy with azathioprine had a decreased symptomatic load over time and needed fewer steroid courses.The use of thiopurines was found to be a risk factor of anastomotic complications in abdominal surgery for Crohn’s disease together with pre-operative intra-abdominal sepsis and colo-colonic anastomosis. The risk for anastomotic complications increased from 4 % in those without any of these risk factors to 13 % in those with any one and 24 % if two or three risk factors were present.In patients with two or more of these, or previously established, risk factors prior to surgery one should consider refraining from anastomosis or doing a proximal diverting stoma. Another possibility is to use a split stoma in which both ends of a future delayed anastomosis are brought out in the same ostomy hole of the abdominal wall. This method was found to significantly decrease the number of risk factors prior to the actual anastomosis as well as decreasing the risk of anastomotic complications, without increasing the number of operations or the time spent in hospital.In the animal model all three medications had an ameliorating effect on the colitis compared with placebo. Only prednisolone was found to interfere with the healing of the colo-colonic anastomoses with significantly decreased bursting pressure compared with placebo as well as azathioprine and infliximab.The association between azathioprine therapy and anastomotic complications may be due to a subgroup of patients with a more severe form of the disease who have an increased risk of such complications and also are more prone to receive intense pharmacological therapy.
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| 5. |
- Risto, Anton, 1984-
(författare)
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Reconstruction after Colectomy for Inflammatory Bowel Disease
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- After colectomy there are four options available. The least complicated and most common is to leave the end ileostomy and not go for any reconstructive surgery. Then there is the ileal pouch anal anastomosis (IPAA) in which the rectum is removed, but the anal canal and a small rectal “cuff” is preserved. The pouch is created from the distal ileum and anastomosed to the rectal cuff. In the ileorectal anastomosis (IRA) the rectum is spared, and the distal ileum is anastomosed to the top of the rectum. In the continent ileostomy (CI), also referred to as the Kock pouch, the fecal flow is let out through the abdominal wall, but a pouch and a nipple valve mechanism is created making the stoma continent which needs to be manually emptied. This thesis aims to investigate function, quality of life, satisfaction, complications, and aspects associated with the chance of having reconstructive surgery after colectomy for inflammatory bowel disease (IBD), i.e. ulcerative colitis (UC) or Crohn’s disease (CD).The first two papers focus on the continent ileostomy, the most uncommon of the options after colectomy. In Paper 1 all patients who have received a CI at our center were identified and medical charts were reviewed for complications and CI patency. Function and quality of life were evaluated with the 36-item short form survey (SF-36), short health scale (SHS) and a local CI specific questionnaire for function and satisfaction. In Paper II, the Swedish national patient register (NPR) was used to identify all patients with an IBD diagnosis who had received a CI and data on diagnosis, demographics, reoperations, and excisions were obtained from the register. Paper III describes an ongoing prospective non-randomized, multi-center, open-label, controlled trial between IRA and IPAA in UC patients subjected to colectomy. The primary endpoint is satisfaction but Quality of Life (QoL), sexual function, bowel function and complications are also evaluated. In Paper IV, we investigated if the chance of getting reconstructed after colectomy was dependent on the IPAA volumes at the colectomy hospital using data from the national patient register. The hospitals were arranged in to four categories based on the average annual number of IPAA procedures: (0, 1-3, 4-7, >7 procedures per year). In Paper I we found that 59 % of CI patients needed repeat laparotomy after a median follow up of 24 years and nipple detachment was the most common cause of repeat laparotomy. Fifteen patients (18 %) had their CIs converted to end ileostomies and the most common cause for this was fistulas. Eighty-four per cent of CI patients reported satisfaction with their reconstruction. The national study in Paper II identified 727 IBD patients with CI and the median follow-up time was 27 years. During follow-up, 1484 reoperations were performed on 536 patients (74 %). Twenty-six per cent of the patients did not have any reoperations, 24 % had one reoperation, 20 % had two reoperations and the remaining 30 % had between three and 15 reoperations each. The CIs were identified to have been removed in 77 (11 %) patients. In Paper III we have so far included 47 patients in the intervention arms out of which 35 (74 %) have chosen IRA and 12 patients (26 %) have chosen IPAA. Another 44 (40 % of the whole group) patients have so far received an IPAA but were deemed non-eligible for both IRA and IPAA and were hence not eligible for the intervention arms. So far 18 patients (17 % of the whole group) have chosen an ileostomy. In Paper IV we first identified 4112 UC patients subjected to colectomy between 1997 and 2020. Out of these 4112 patients, 1932 (47 %) went through some kind of reconstruction, 964 (50 %) IRA, 927 (48 %) IPAA and 41 (2 %) CI. The proportion having restorative surgery was larger for patients subjected to colectomy at a high IPAA volume center (62 % vs 38 %) and the chance of getting an IPAA increased with each IPAA volume category (Hazard ratios (HR) were: 1; 1.49 95 % CI (1.25-1.78) ; 1.79 95 % CI (1.49-2.15) and 2.11 95 % CI (1.70-2.62) respectively)The IPAA volumes did not affect the chance of receiving an IRA or the risk of failure of reconstruction.
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| 6. |
- Salim, Sa'ad Yislam, 1977-
(författare)
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Mucosal dendritic cells in inflammatory bowel disease
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Crohn's disease, a chronic inflammation of the bowel, is a multi-factorial condition where uncontrolled immune responses to luminal bacteria occur in genetically predisposed individuals. The first observable clinical signs are small ulcers that form at a specialised form of epithelium, follicle-associated epithelium (FAB). The FAB covers immune inductive sites, Peyer's patches, which function primarily as sensory areas that sample the externaI gut environment. Dendritic cells are one of the key cells that are involved in sensing luminal contents and orchestrating the gut immune system.The main aim of this thesis was to determine whether the barrier of the FAB is breached in Crohn's disease and if dysfunctional immune regulators, namely dendritic cells, playaroIe in initiating and/or maintaining the chronic intestinal inflammation.Using biopsies and surgical specimens, we were able to show that in Crohn's disease, there was an increased transmucosaI transport of Escherichia coli compared to specimens from ulcerative colitis and non-inflammatory bowel disease (IBD) controIs. Dendritic cells internalised a higher percentage of bacteria that had translocated across the FAB in the Crohn's samples. Furthermore, significantly higher concentrations of TNF-u was released upon bacterial stimulation by tissues from patients with Crohn's disease than in controIs.We went on to characterise the dendritic cells present in the Peyer's patches of patients with Crohn's disease. We found an accumulation of both immature and mature dendritic cells beneath the FAB, in the sub-epithelial dome (SED). Normally, mature dendritic cells migrate towards T cell-rich areas. However, we observed mature dendritic cells accumulating in the SED because they lacked the CCR7 migratory receptor. Furthermore, they were more prone to take-up bacteria, and produced TNF-α.To study the function of mucosal dendritic cells, we performed isolation experiments and mixed Iymphocyte reactions. Dendritic cells from both the ileum and blood of patients with active Crohn's had reduced capacity for inducing T cell proliferation than non-IBD controIs. Blood dendritic cells of patients in remission had normalised function that was similar to dendritic cells from healthy controls.The SAMPl/YitFc mice, considered an appropriate murine model for Crohn's disease, had an inherent permeability defect that increased with the chronicity of intestinaI inflammation. However unlike in human Crohn's disease, dendritic cells did not seem to playaroIe in murine ileitis.This thesis highlights the accumulation of the actively surveying dendritic cells that are prone to bacterial internalisation, and points to their possible different functional roles in active versus in-active disease; thereby confirming dendritic cells as one ofthe key components in the pathogenesis ofCrohn's disease.
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| 7. |
- Schoultz, Ida, 1979-
(författare)
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Mechanisms of bacterial-epithelial interaction in Crohn’s disease
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Crohn’s disease (CD) is believed to be initiated when an individual, who has agenetic predisposition either leading to a disturbance in the barrier functionand/or the innate immune system is exposed to triggering environmentalfactors, the most important being intraluminal bacteria. Genetic and functionalstudies have confirmed the Pattern-recognition receptors (PRRs), Nod2, TLR4and NALP3, as important mediators of the inflammatory process associatedwith disease progression. However, the mechanisms that link enteric bacteriaand barrier function in a background of genetic predisposition to CD are justbeginning to emerge. The general aim of this thesis was therefore to morethoroughly investigate the mechanisms of bacterial-epithelial interaction in CD.Here we present evidence suggesting that the small bowel is able to inducetranscytosis of antigens after short term exposure to Yersinia pseudotuberculosis. This suggests that small bowel enterocytes are able toattain follicle associated epithelial (FAE) abilities and contribute to the barrierdysfunction observed in CD. Furthermore we report a positive effect of anti-TNFα treatment (infliximab) on the translocation of adherent invasive E.coli (AIEC) across the colonic mucosa of patients suffering from severe CD.We also confirm the importance of the Nod-like receptors (NLRs) in thepathogenesis of CD by showing that combined polymorphisms in the genesencoding NALP3 and CARD8 confer susceptibility to CD among Swedish menand in addition to previous published results add a gender aspect on thegenotype-phenotype relationship in CD. Finally, we show that Nod2 is rapidlysubjected to ubiquitination followed by proteasomal degradation, henceproviding important clues about how NLR regulation might occur in the cell,suggesting that the ubiquitin-proteasome pathway is an important factor toconsider in the development of the disease.In conclusion we report novel insights into the bacterial-epithelial interactionsoccurring in CD and contribute important clues about the origin of this disease.ISBN: 978-
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| 8. |
- Abdalla, Maie
(författare)
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Cancer and reconstructive surgery in Inflammatory bowel disease
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ulcerative colitis (UC) is a chronic inflammatory disease that affects the colon. According to the literature, some thirty percent of UC patients may require a subtotal colectomy and ileostomy due to failure of medical treatment, acute toxic colitis or dysplasia/cancer diagnosis. Some patients choose to get continence restored with either an ileorectal anastomosis (IRA) or an ileal pouch-anal anastomosis (IPAA). Worldwide most surgeons prefer an IPAA to an IRA, despite reports of pouchitis, impaired fertility and fecundity. Fear of recurring proctitis and fear of rectal cancer in the remaining rectum is contributing to the choice of an IPAA. Little is known regarding the outcomes of IRA compared with IPAA in UC patients. We aimed to investigate the anorectal function, quality of life (QoL), risk of failure and rectal cancer in patients with UC restored with IRA and IPAA respectively. Methods: Data about all Inflammatory bowel disease (IBD) patients was obtained from the Swedish National Patient Register (NPR) between 1964-2014 and in one study from the Linköping University Hospital medical records 2006-2012. Patients who developed cancer were identified from the Swedish National Cancer Register. We investigated the risk of cancer and inflammation, functional outcome and failure as well as the quality of life for IRA and IPAA patients. Investigation of risk for cancer in IRA and IPAA compared with the background population was performed using survival analytic techniques: uni-and multivariate regression, Kaplan Meier curves and standardized incidence ratio. Results: Twelve percent (7,889 /63,795) of UC patients required colectomy according to the NPR. The relative risk for rectal cancer among patients with an IRA was increased (SIR 8.7). However, the absolute risk was 1.8% after a mean follow up of 8.6 years and the cumulative risk 10- and 20-years after IRA was 1.6% and 5.6%, respectively. Risk factors for rectal cancer were primary sclerosing cholangitis in patients with an IRA (hazard ratio 6.12), and severe dysplasia or cancer of the colon prior to subtotal colectomy in patients with a diverted rectum in place (hazard ratio 3.67). Regarding IPAA, the relative risk to develop rectal cancer was (SIR 0.4) compared with the background population and the absolute risk was only 0.06% after a mean of 12.2 years of follow up. Among patients operated at the Linköping University Hospital: IRA patients reported better overall continence according to the Öresland score with in median3 (IQR 2–5) for IRA (n=38) and 10 (IQR 5–15) for IPAA (n=39, p<0.001). There were no major differences regarding the QoL. According to the NPR, after a median follow up of 12.4 years failure occurred in 265(32%) out of 1112 patients, of which 76 were secondarily reconstructed with an IPAA. Failure of the IPAA occurred in 103 (6%) patients with primary and in 6 (8%) patients after secondary IPAA (log-rank p=0.38). Conclusion: IRA is a safe restorative procedure for selected UC patients. Patients should be aware of the annual postoperative endoscopic evaluation with biopsies as well as the need to the use of local anti-inflammatory preparations. However, IRA should not be offered for UC patients with an associated primary sclerosing cholangitis diagnosis due to the increased risk to develop rectal cancer in their rectal mucosa. In such case, IPAA is probably the treatment of choice.
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| 9. |
- Ellegård, Rada, 1985-
(författare)
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Effects of Complement Opsonization of HIV on Dendritic Cells : and Implications for the Immune Response
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dendritic cells are key players during HIV pathogenesis, and shape both the immediate immune response at the site of infection as well as directing the adaptive immune response against the virus. HIV has developed a plethora of immune evasion mechanisms that hijack dendritic cell functions, suppressing their ability to mount an accurate immune response and exploiting them for efficient viral transfer to target T cells.To achieve successful replication within dendritic cells without triggering danger signaling, HIV accomplishes a delicate balance where only a low level of transcription can be sustained without triggering antiviral responses that would harm the virus. Here, we describe how the presence of HSV2 coinfection, which is very common in geographic areas with a high HIV prevalence and almost triples the risk of HIV acquisition, alters dendritic cell state to support much higher levels of HIV infection. We found this effect to be mediated by the STING pathway, which is involved in the sensing of DNA in the cell cytosol. STING activation led to an upregulation of factors such as IRF3 and NFkB that can be used for HIV transcription and a degradation of factors that restrict HIV replication.In addition, we describe how HIV exploits the human complement system, a group of proteins that usually help the human body to identify dangerous pathogens while avoiding reaction towards self. HIV can coat itself, i.e. become opsonized, in complement fragments that are typically only present on the body’s own cells, allowing it to activate signaling pathways that are associated with tolerance. Dendritic cells that come into contact with complement opsonized HIV do not mount danger responses, despite the fact that HIV-derived single stranded RNA triggers the pathogen recognition receptor TLR8. The suppression of danger responses is mediated by activation of complement receptor 3, and leads to an increased infection of the dendritic cell and affects its interactions with other immune cells. There is a lack of recruitment of NK cells to the site of infection, and an inhibition of NK cell killing, which plays an important role in the destruction of HIV-infected cells in vivo. T cells primed by dendritic cells exposed to complement opsonized HIV have a lower ability to develop towards effector phenotype, and have an increased expression of the markers PD1, TIM3 and LAG3 which are associated with T cell dysfunction and exhaustion. In addition, T cells primed by these dendritic cells in the presence of NK cells upregulate markers CD38, CXCR3 and CCR4, which have been linked to an increased susceptibility to HIV infection.In summary, we add to the current knowledge on HIV immune evasion mechanisms that allow the virus to establish infection, as well as describing mechanisms that govern whether dendritic cells mount danger signaling and an immune response or not.
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| 10. |
- Jönsson, Maria, 1980-
(författare)
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The neuronal and non-neuronal substance P, VIP and cholinergic systems in the colon in ulcerative colitis
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ulcerative colitis (UC) is a chronic relapsing inflammatory bowel disease. Neuropeptides, especially vasoactive intestinal peptide (VIP) and substance P (SP), have long been considered to play key roles in UC. Among other effects, these neuropeptides have trophic and growth-modulating as well as wound-healing effects. Furthermore, whilst VIP has anti-inflammatory properties, SP has pro-inflammatory effects. It is generally assumed that the main source of SP and VIP in the intestine is the tissue innervation. It is not known whether or not they are produced in the epithelial layer. The details concerning the expressions of their receptors in UC are also, to a great extent, unclear. Apart from the occurrence of peptidergic systems in the intestine, there are also neuronal as well as non-neuronal cholinergic systems. The pattern concerning the latter is unknown with respect to UC. The studies in this thesis aimed to investigate the expression of SP and VIP and their major receptors (NK-1R and VPAC1) in UC colon, compared to non-UC colon. The main emphasis was devoted to the epithelium. A second aim was to examine for levels of these neuropeptides in blood plasma in UC. Another aim was to examine for the non-neuronal cholinergic system in UC, thus, to investigate whether there is acetylcholine production outside nerves in the UC colon. Methods used in the thesis were immunohistochemistry, in situ hybridization, enzyme immunosorbent assay, and in vitro receptor autoradiography. For the first time, mRNA for VIP and SP has here been found in the colonic epithelium. That was especially noted in UC mucosa showing a rather normal morphology, and in non-UC mucosa. Marked derangement of the mucosa was found to lead to a distinct decrease in VIP binding, and also a decrease in the expression level of VIP receptor VPAC1 in the epithelium. In general, there was an upregulation of the SP receptor NK-1R in the epithelium when the mucosa was deranged. The plasma levels of SP and VIP were higher for UC patients compared to healthy controls. There were marked correlations between the levels of the peptides in plasma, their levels in the mucosa and the degree of mucosal derangement/inflammation. A pronounced nonneuronal cholinergic system was found in both UC and non-UC colon. Certain changes occurred in this system in response to inflammation/derangement in UC. The present study shows unexpectedly that expressions for VIP and SP are not only related to the nerve structures and the inflammatory cells. The downregulation of VPAC1 expression, and the tendencies of upregulation of NK-1R expression levels when there is marked tissue derangement, may be a drawback for the intestinal function. The study also shows that there is a marked release of neuropeptides to the bloodstream in parallel with a marked derangement of the mucosa in UC. The cholinergic effects in the UC colon appear not only to be associated with nerverelated effects, but also effects of acetylcholine produced in local non-neuronal cells. The thesis shows that local productions for not only acetylcholine, but also SP and VIP, occur to a larger extent than previously considered.
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