The influence of HIV infection to the periodontium; a clinical, microbiological, and enzymological study

The main targets of human immunodeficiency virus (HIV) are CD4 receptors of CD4+ lymphocytes and many other cells such as monocytes/macrophages, megakaryocytes, peripheral blood dendritic cells, follicular dendritic cells (DC), epidermal Langerhans cells, and astrocytes. Infection and killing of CD4+ lymphocytes or false reaction of the body to HIV infection and the spontaneous apoptosis of CD4+ lymphocytes decrease CD4+ lymphocyte counts leading to immunosuppression, further disease progression, and appearance of opportunistic infections and malignancies. Oral manifestations are considered to be among the first signs of HIV infection. Enhanced degradation of extracellular matrix and basement membrane components in oral diseases including periodontitis is caused by Zn-dependent enzymes called matrix metalloproteinases (MMPs). The levels and degrees of activation of MMP-1, -2, -3, -7, -8, -9, -25, -26, tissue inhibitors of MMPs (TIMP)-1 and -2, and myeloperoxidase (MPO) and collagenolytic/gelatinolytic activities, and also Ig A, -G, and -M, total protein, and albumin levels in a two-year follow-up were studied from salivary samples. The expression of MMP-7, -8, -9, -25, and -26 immunoreactivities in gingival tissue specimens were studied. Healthy HIV-negative subjects served as controls. All studied clinical periodontal parameters and microbiological evaluation of the periodontopathogens showed that periodontal health of the HIV-positive patients was moderately decreased in comparison to the healthy controls. The levels of Candida in the periodontal pockets and salivary MPO increased with the severity of HIV infection. Immunoreactivities and levels of MMPs and TIMPs, and MMP activities (collagenase, gelatinase) were enhanced in the HIV-positive patient salivary samples relative to the healthy controls regardless of the phase of HIV infection. However, these parameters did not reflect periodontal status in a similar way as in the generally healthy periodontitis patients. Salivary total protein, albumin, IgA, -G, and -M levels were significantly higher in all phases of HIV infection compared to the controls, and salivary total protein, IgG and IgM levels remained higher after two years follow-up, partly correlating with the disease progression and which may reflect the leakage of serum components into the mouth and thus a decreased mucosal barrier. Salivary analyses of MMPs and TIMPs with immunohistochemical analyses showed that HIV infection could predispose to periodontal destruction when compared with healthy controls or the body s defence reactions associated with HIV infection may have been reflected or mediated by MMPs.

Toxicity of dioxin to developing teeth and salivary glands : An experimental study

Dioxins are ubiquitous environmental poisons having unequivocal adverse health effects on various species. The majority of their effects are thought to be mediated by the aryl hydrocarbon receptor (AhR). Developing human teeth may be sensitive to dioxins and the most toxic dioxin congener, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), is developmentally toxic to rodent teeth. Mechanisms of TCDD toxicity can be studied only experimentally. The aim of the present thesis work was to delineate morphological end points of developmental toxicity of TCDD in rat and mouse teeth and salivary glands in vivo and in vitro and to characterize their cellular and molecular background. Mouse embryonic teeth and submandibular gland explants were grown in organ culture without/with TCDD at various concentrations, examined stereomicroscopically and processed for histological examination. The effects of TCDD on cellular mechanisms essential for organogenesis were investigated. The expression of various genes eliciting the response to TCDD exposure or involved in tooth and salivary gland development was studied at the mRNA and/or protein levels by in situ hybridization and immunohistochemistry. Association of the dental effects of TCDD with the resistance of a rat strain to TCDD acute lethality was analyzed in two lactationally exposed rat strains. The effect of TCDD on rat molar tooth mineralization was studied in tissue sections. TCDD dose- and developmental stage-dependently interfered with tooth formation. TCDD prevented early mouse molar tooth morphogenesis and altered cuspal morphology by enhancing programmend cell death, or apoptosis, in dental epithelial cells programmed to undergo apotosis. Cell proliferation was not affected. TCDD impaired mineralization of rat molar dental matrices, possibly by specifically reducing the expression of the mineralization-related dentin sialophosphoprotein gene shown in cultured mouse teeth. The impaired mineralization of rat teeth was accompanied by decreased expression of AhR and the TCDD-inducible xenobiotic-metabolozing enzyme P4501 A1 (CYP1A1), suggesting mediation of the TCDD effect by the AhR pathway. The severe interference by TCDD with rat incisor formation was independent of the genotypic variation of AhR determining the resistance of a rat strain to TCDD acute lethality. The impairment by TCDD of mouse submandibular gland branching morphogenesis was associated with CYP1A1 induction and involved blockage of EGF receptor signalling. In conclusion, TCDD exposure is likely to have activated the AhR pathway in target organs with the consequent activation of other signalling pathways involving developmentally regulated genes. The resultant phenotype is organ specific and modified by epithelial-mesenchymal interactions and dependent on dose as well as the stage of organogenesis at the time of TCDD exposure. Teeth appear to be responsive to TCDD exposure throughout their development.

Pathological changes at the target tissue level in Sjögren's syndrome and their effect on the exocrine function of the salivary glands

Sjögren s syndrome (SS) is a common autoimmune disease affecting the lacrimal and salivary glands. SS is characterized by a considerable female predominance and a late age of onset, commonly at the time of adreno- and menopause. The levels of the androgen prohormone dehydroepiandrosterone-sulphate (DHEA-S) in the serum are lower in patients with SS than in age- and sex-matched healthy control subjects. The eventual systemic effects of low androgen levels in SS are not currently well understood. Basement membranes (BM) are specialized layers of extracellular matrix and are composed of laminin (LM) and type IV collagen matrix networks. BMs deliver messages to epithelial cells via cellular LM-receptors including integrins (Int) and Lutheran blood group antigen (Lu). The composition of BMs and distribution of LM-receptors in labial salivary glands (LSGs) of normal healthy controls and patients with SS was assessed. LMs have complex and highly regulated distribution in LSGs. LMs seem to have specific tasks in the dynamic regulation of acinar cell function. LM-111 is important for the normal acinar cell differentiation and its expression is diminished in SS. Also LM-211 and -411 seem to have some acinar specific functional tasks in LSGs. LM-311, -332 and -511 seem to have more general structure maintaining and supporting roles in LSGs and are relatively intact also in SS. Ints α3β1, α6β1, α6β4 and Lu seem to supply structural basis for the firm attachment of epithelial cells to the BM in LSGs. The expression of Ints α1β1 and α2β1 differed clearly from other LM-receptors in that they were found almost exclusively around the acini and intercalated duct cells in salivons suggesting some type of acinar cell compartment-specific or dominant function. Expression of these integrins was lower in SS compared to healthy controls suggesting that the LM-111 and -211-to-Int α1β1 and α2β1 interactions are defective in SS and are crucial to the maintenance of the acini in LSGs. DHEA/DHEA-S concentration in serum and locally in saliva of patients with SS seems to have effects on the salivary glands. These effects were first detected using the androgen-dependent CRISP-3 protein, the production and secretion of which were clearly diminished in SS. This might be due to the impaired function of the intracrine DHEA prohormone metabolizing machinery, which fails to successfully convert DHEA into its active metabolites in LSGs. The progenitor epithelial cells from the intercalated ductal area of LSGs migrate to the acinar compartment and then undergo a phenotype change into secretory acinar cells. This migration and phenotype change seem to be regulated by the LM-111-to-Int α1β1/Int α2β1 interactions. Lack of these interactions could be one factor limiting the normal remodelling process. Androgens are effective stimulators of Int α1β1 and α2β1 expression in physiologic concentrations. Addition of DHEA to the culture medium had effective stimulating effect on the Int α1β1 and α2β1 expression and its effect may be deficient in the LSGs of patients with SS.

IgA nephropathy and Henoch-Schönlein nephritis in adults : with special reference to factors affecting outcome

IgA nephropathy (IgAN) is the most common primary glomerulonephritis. In one third of the patients the disease progresses, and they eventually need renal replacement therapy. IgAN is in most cases a slowly progressing disease, and the prediction of progression has been difficult, and the results of studies have been conflicting. Henoch-Schönlein nephritis (HSN) is rare in adults, and prediction of the outcome is even more difficult than in IgAN. This study was conducted to evaluate the clinical and histopathological features and predictors of the outcome of IgAN and HSN diagnosed in one centre (313 IgAN patients and 38 HSN patients), and especially in patients with normal renal function at the time of renal biopsy. The study also aimed to evaluate whether there is a difference in the progression rates in four countries (259 patients from Finland, 112 from UK, 121 from Australia and 274 from Canada), and if so, can this be explained by differences in renal biopsy policy. The third aim was to measure urinary excretions of cytokines interleukin 1ß (IL-1ß) and interleukin 1 receptor antagonist (IL-1ra) in patients with IgAN and HSN and the correlations of excretion of these substances with histopathological damage and clinical factors. A large proportion of the patients diagnosed in Helsinki as having IgAN had normal renal function (161/313 patients). Four factors, (hypertension, higher amounts of urinary erythrocytes, severe arteriolosclerosis and a higher glomerular score) which independently predicted progression (logistic regression analysis), were identified in mild disease. There was geographic variability in renal survival in patients with IgAN. When age, levels of renal function, proteinuria and blood pressure were taken into account, it showed that the variability related mostly to lead-time bias and renal biopsy indications. Amount of proteinuria more than 0.4g/24h was the only factor that was significantly related to the progression of HSN. the Hypertension and the level of renal function were found to be factors predicting outcome in patients with normal renal function at the time of diagnosis. In IgAN patients, IL-1ra excretion into urine was found to be decreased as compared with HSN patients and healthy controls. Patients with a high IL-1ra/IL-1ß ratio had milder histopathological changes in renal biopsy than patients with a low/normal IL-1ra/IL-1ß ratio. It was also found that the excretion of IL-1ß and especially IL-1ra were significantly higher in women. In conclusion, it was shown that factors associated with outcome can reliably be identified even in mild cases of IgAN. Predicting outcome in adult HSN, however, remains difficult.

Oral health and kidney disease with emphasis on diabetic nephropathy

Chronic kidney disease (CKD) is a worldwide health problem, with adverse outcomes of cardiovascular disease and premature death. The ageing of populations along with the growing prevalence of chronic diseases such as diabetes and hypertension is leading to worldwide increase in the number of CKD patients. It has become evident that inflammation plays an important role in the pathogenesis of atherosclerosis complications. CKD patients also have an increased risk of atherosclerosis complications (including myocardial infarction, sudden death to cardiac arrhythmia, cerebrovascular accidents, and peripheral vascular disease). In line with this, oral and dental problems can be an important source of systemic inflammation. A decline in oral health may potentially act as an early marker of systemic disease progression. This series of studies examined oral health of CKD patients from predialysis, to dialysis and kidney transplantation in a 10-year follow-up study and in a cross-sectional study of predialysis CKD patients. Patients had clinical and radiographic oral and dental examination, resting and stimulated saliva flow rates were measured, whilst the biochemical and microbiological composition of saliva was analyzed. Lifestyle and oral symptoms were recorded using a questionnaire, and blood parameters were collected from the hospital records. The hypothesis was that the oral health status, symptoms, sensations, salivary flow rates and salivary composition vary in different renal failure stages and depend on the etiology of the kidney disease. No statistically significant difference were seen in the longitudinal study in the clinical parameters. However, some saliva parameters after renal transplantation were significantly improved compared to levels at the predialysis stage. The urea concentration of saliva was high in all stages. The salivary and plasma urea concentrations followed a similar trend, showing the lowest values in kidney transplant patients. Levels of immunoglobulin (Ig) A, G and M all decreased significantly after kidney transplantation. Increased concentrations of IgA, IgG and IgM may reflect disintegration of the oral epithelium and are usually markers of poor general oral condition. In the cross-sectional investigation of predialysis CKD patients we compared oral health findings of diabetic nephropathy patients to those with other kidney disease than diabetes. The results showed eg. more dental caries and lower stimulated salivary flow rates in the diabetic patients. HbA1C values of the diabetic patients were significantly higher than those in the other kidney disease group. A statistically significant difference was observed in the number of drugs used daily in the diabetic nephropathy group than in the other kidney disease group. In the logistic regression analyses, age was the principal explanatory factor for high salivary total protein concentration, and for low unstimulated salivary flow. Poor dental health, severity of periodontal disease seemed to be an explanatory factor for high salivary albumin concentrations. Salivary urea levels were significantly linked with diabetic nephropathy and with serum urea concentrations. Contrary to our expectation, however, diabetic nephropathy did not seem to affect periodontal health more severely than the other kidney diseases. Although diabetes is known to associate with xerostomia and other oral symptoms, it did not seem to increase the prevalence of oral discomfort. In summary, this series of studies has provided new information regarding the oral health of CKD patients. As expected, the commencement of renal disease reflects in oral symptoms and signs. Diabetic nephropathy, in particular, appears to impart a requirement for special attention in the oral health care of patients suffering from this disease.

ADAMs, Osteoclastogenesis and Bone Destruction in the Loosening of the Totally Replaced Hip

Total hip replacement is the golden standard treatment for severe osteoarthritis refractory for conservative treatment. Aseptic loosening and osteolysis are the major long-term complications after total hip replacement. Foreign body giant cells and osteoclasts are locally formed around aseptically loosening implants from precursor cells by cell fusion. When the foreign body response is fully developed, it mediates inflammatory and destructive host responses, such as collagen degradation. In the present study, it was hypothesized that the wear debris and foreign body inflammation are the forces driving local osteoclast formation, peri-implant bone resorption and enhanced tissue remodeling. Therefore the object was to characterize the eventual expression and the role of fusion molecules, ADAMs (an abbreviation for A Disintegrin And Metalloproteinase, ADAM9 and ADAM12) in the fusion of progenitor cells into multinuclear giant cells. For generation of such cells, activated macrophages trying to respond to foreign debris play an important role. Matured osteoclasts together with activated macrophages mediate bone destruction by secreting protons and proteinases, including matrix metalloproteinases (MMPs) and cathepsin K. Thus this study also assessed collagen degradation and its relationship to some of the key collagenolytic proteinases in the aggressive synovial membrane-like interface tissue around aseptically loosened hip replacement implants. ADAMs were found in the interface tissues of revision total hip replacement patients. Increased expression of ADAMs at both transcriptional and translational levels was found in synovial membrane-like interface tissue of revision total hip replacement (THR) samples compared with that in primary THR samples. These studies also demonstrate that multinucleate cell formation from monocytes by stimulation with macrophage-colony stimiulating factor (M-CSF) and receptor activator of nuclear factor kappa B ligand (RANKL) is characterized by time dependent changes of the proportion of ADAMs positive cells. This was observed both in the interface membrane in patients and in two different in vitro models. In addition to an already established MCS-F and RANKL driven model, a new virally (parainfluenza 2) driven model (of human salivary adenocarcinoma (HSY) cells or green monkey kidney (GMK) cells) was developed to study various fusion molecules and their role in cell fusion in general. In interface membranes, collagen was highly degraded and collagen degradation significantly correlated with the number of local cells containing collagenolytic enzymes, particularly cathepsin K. As a conclusion, fusion molecules ADAM9 and ADAM12 seem to be dynamically involved in cell-cell fusion processes and multinucleate cell formation. The highly significant correlation between collagen degradation and collagenolytic enzymes, particularly cathepsin K, indicates that the local acidity of the interface membrane in the pathologic bone and soft tissue destruction. This study provides profound knowledge about cell fusion and mechanism responsible for aseptic loosening as well as increases knowledge helpful for prevention and treatment.

Distribution and adhesion-promoting activity of alpha4 and alpha5 chain laminins in human endothelia and carcinomas

Basement membranes are specialized sheets of extracellular matrix found in contact with epithelia, endothelia, and certain isolated cells. They support tissue architecture and regulate cell behaviour. Laminins are among the main constituents of basement membranes. Due to differences between laminin isoforms, laminins confer structural and functional diversity to basement membranes. The first aim of this study was to gain insights into the potential functions of the then least characterized laminins, alpha4 chain laminins, by evaluating their distribution in human tissues. We thus created a monoclonal antibody specific for laminin alpha4 chain. By immunohistochemistry, alpha4 chain laminins were primarily localized to basement membranes of blood vessel endothelia, skeletal, heart, and smooth muscle cells, nerves, and adipocytes. In addition, alpha4 chain laminins were found in the region of certain epithelial basement membranes in the epidermis, salivary gland, pancreas, esophagus, stomach, intestine, and kidney. Because of the consistent presence of alpha4 chain laminins in endothelial basement membranes of blood vessels, we evaluated the potential roles of endothelial laminins in blood vessels, lymphatic vessels, and carcinomas. Human endothelial cells produced alpha4 and alpha5 chain laminins. In quantitative and morphological adhesion assays, human endothelial cells barely adhered to alpha4 chain-containing laminin-411. The weak interaction of endothelial cells with laminin-411 appeared to be mediated by alpha6beta1 integrin. The alpha5 chain-containing laminin-511 promoted endothelial cell adhesion better than laminin-411, but it did not promote the formation of cell-extracellular matrix adhesion complexes. The adhesion of endothelial cells to laminin-511 appeared to be mediated by Lutheran glycoprotein together with beta1 and alphavbeta3 integrins. The results suggest that these laminins may induce a migratory phenotype in endothelial cells. In lymphatic capillaries, endothelial basement membranes showed immunoreactivity for laminin alpha4, beta1, beta2, and gamma1 chains, type IV and XVIII collagens, and nidogen-1. Considering the assumed inability of alpha4 chain laminins to polymerize and to promote basement membrane assembly, the findings may in part explain the incomplete basement membrane formation in these vessels. Lymphatic capillaries of ovarian carcinomas showed immunoreactivity also for laminin alpha5 chain and its receptor Lutheran glycoprotein, emphasizing a difference between normal and ovarian carcinoma lymphatic capillaries. In renal cell carcinomas, immunoreactivity for laminin alpha4 chain was found in stroma and basement membranes of blood vessels. In most tumours, immunoreactivity for laminin alpha4 chain was also observed in the basement membrane region of tumour cell islets. Renal carcinoma cells produced alpha4 chain laminins. Laminin-411 did not promote adhesion of renal carcinoma cells, but inhibited their adhesion to fibronectin. Renal carcinoma cells migrated more on laminin-411 than on fibronectin. The results suggest that alpha4 chain laminins have a counteradhesive function, and may thus have a role in detachment and invasion of renal carcinoma cells.

Oral Actinomyces Species in Health and Disease: Identification, Occurence and Importance of Early Colonization

The genus Actinomyces consists of a heterogeneous group of gram-positive, mainly facultatively anaerobic or microaerobic rods showing various degrees of branching. In the oral cavity, streptococci and Actinomyces form a fundamental component of the indigenous microbiota, being among initial colonizers in polymicrobial biofilms. The significance of the genus Actinomyces is based on the capability of species to adhere to surfaces such as on teeth and to co-aggregate with other bacteria. Identification of Actinomyces species has mainly been based on only a few biochemical characteristics, such as pigmentation and catalase production, or on the use of a single commercial kit. The limited identification of oral Actinomyces isolates to species level has hampered knowledge of their role both in health and disease. In recent years, Actinomyces and related organisms have attracted the attention of clinical microbiologists because of a growing awareness of their presence in clinical specimens and their association with disease. This series of studies aimed to amplify the identification methods for Actinomyces species. With the newly developed identification scheme, the age-related occurrence of Actinomyces in healthy mouths of infants and their distribution in failed dental implants was investigated. Adhesion of Actinomyces species to titanium surfaces processed in various ways was studied in vitro. The results of phenotypic identification methods indicated a relatively low applicability of commercially available test kits for reliable identification within the genus Actinomyces. However, in the study of conventional phenotypic methods, it was possible to develop an identification scheme that resulted in accurate differentiation of Actinomyces and closely related species, using various different test methods. Genotypic methods based on 16S rRNA sequence analysis of Actinomyces proved to be a useful method for genus level identification and further clarified the species level identification with phenotypic methods. The results of the study of infants showed that the isolation frequency of salivary Actinomyces species increased according to age: thirty-one percent of the infants at 2 months but 97% at 2 years of age were positive for Actinomyces. A. odontolyticus was the most prominent Actinomyces colonizer during the study period followed in frequency by A. naeslundii and A. viscosus. In the study of explanted dental implants, Actinomyces was the most prevalent bacterial genus, colonizing 94% of the fixtures. Also in the implants A. odontolyticus was revealed as the most common Actinomyces species. It was present in 84% of Actinomyces -positive fixtures followed in frequency by A. naeslundii, A. viscosus and A. israelii. In an in vitro study of titanium surfaces, different Actinomyces species showed variation regarding their adhesion to titanium. Surface roughness as well as albumin coating of titanium had significant effects on adhesion. The use of improved phenotypic and molecular diagnostic methods increased the accuracy of the identification of the Actinomyces to species level. This facilitated an investigation of their occurrence and distribution in oral specimens in both health and disease.

Oral Cancer in Tehran, Iran: An approach for understanding disease burden

Suusyöpä Teheranissa, Iranissa 1993-2003 Tämän väitöskirjan tavoitteena oli kuvata suusyövän yleisyyttä ja siihen vaikuttavia tekijöitä Teheranissa, Iranissa tutkimalla suusyöpäpotilaita, suusyöpäkasvainten ominaisuuksia, potilaille tehtyjä diagnooseja ja niiden viivästymistä sekä heidän selviytymistä sairaudestaan. Suusyöpäkasvainten tietoja kerättiin 1042 suusyöpäpotilaalta. Nämä tiedot kerättiin 30 suurimman Teheranilaissairaalan potilaskortistoista vuosien 1993-2003 ajalta. Eloonjäämisanalyysiä varten tiedot kerättiin vuosien 1996-2003 arkistoista 470 suusyöpä- ja 82 huulisyöpäpotilaan osalta ja heitä seurattiin vuoden 2005 loppuun. Potilaan kokemien ensioireiden ja lopullisen syöpädiagnoosin välistä viivettä varten kerättiin tiedot Teheranilaisista sairaaloista 100 peräkkäisen suusyöpäpotilaan tiedoista vuosien 2004-2006 välillä. Ns diagnostinen viive jaettiin kahteen osaan: 1) ensioireiden ja ensimmäisen sitä seuranneen lääkärikäynnin väli ja 2) ensimmäisen lääkärikäynnin ja lopullisen diagnoosin välinen ero. Useimmat suusyövät olivat pitkälle edenneitä diagnoosin tekemisen hetkellä, kasvain oli siis yli 4 senttimetriä halkaisijaltaan ja/tai kaulan alueen imusolmukkeissa oli jo etäpesäkkeitä. Eloonjäämistodennäköisyys viiden vuoden aikavälillä oli suusyöpäpotilaille 30% ja huulisyöpäpotilaille 62%, mitkä olivat merkittävästi alempia kuin yleisesti länsimaissa vastaavat luvut. Tämä tutkimus osoitti, että keskimääräinen diagnostinen viive oli korkea (7,2 kk, SD 7,5), erityisesti kun niitä verrataan kehittyneimpien terveydenhuoltojärjestelmien vastaaviin tietoihin. Yleensä potilaasta aiheutuva viive oli huomattavan suuri ensioireiden ja lopullisen diagnoosin välisestä ajasta. Tässä tutkimuksessa tehtyjen havaintojen pohjalta on perusteltua esittää kehitettäväksi ennaltaehkäisevä tiedotusohjelma, jossa kansalaiset voisivat saada enemmän tietoa suusyövästä, sen ensioireista jotta he hakeutuisivat aikaisemmin hoitoon. Lisäksi terveydenhoitohenkilöstöä, erityisesti hammaslääkärejä ja suuhygienistejä tulisi kouluttaa varhaisen diagnoosin tekemiseksi, jotta Iranissa tehtävien suusyöpähoitojen lopputulokset paranisivat.

Helicobacter pylori in Vammala, Finland: seroepidemiological studies and a population-based ‘screen-and-treat’ programme

Helicobacter pylorin (helikobakteeri) tartunta saadaan yleensä lapsena ja tauti jää tavallisesti pysyväksi ilman täsmähoitoa. Onnistunut hoito parantaa pysyvästi helikobakteerista aiheutuvan mahan haavataudin ja näyttää ehkäisevän mahalaukun pahanlaatuisten muutosten kehittymistä. Aloitimme Vammalassa terveyskeskuksessa toteutetun kansainvälisesti ainutlaatuisen väestöpohjaisen helikobakteeritulehduksen seulonta- ja hoito-ohjelman pilottitutkimuksella 1994. 1996 kaikki 15-40-vuotiaat ja 1997-2000 15- ja 45-vuotiaat vammalalaiset kutsuttiin verinäyteseulontaan. Yhteensä 4626 henkilöä (75% kutsutuista) osallistui seulontaan. Vasta-ainepositiivisille tarjottiin helikobakteeritulehduksen lopettava lääkekuuri. Toiminnan seurauksena helikobakteeritulehduksen esiintyvyyden laskettiin vähentyneen 12%:sta 4%:iin 15-40-vuotiaiden ikäryhmässä. Tutkimme myös helikobakteerivasta-ainepositiivisten ja -negatiivisten eroja sekä helikobakteeritulehduksen riskitekijöitä kyselytutkimuksella. Lapsuudenkodin asumisahtauden, äidin matalan koulutusasteen, tupakoinnin, alkoholinkäytön, huonojen asunto-olojen ja ylävatsavaivoista johtuvien sairauslomien todettiin liittyvän helikobakteeritulehdukseen monimuuttuja-analyysissa. Tutkimme seulontaohjelmassa käyttämiemme IgG- ja IgA-luokan helikobakteeri-vasta-ainetestien luotettavuutta eri ikäryhmissä ottaen huomioon atrofisen gastriitin esiintyvyyden. 561 kliinisin perustein gastroskopoidun potilaan aineistossa IgG-testi osoittautui erittäin herkäksi kaikissa ikäryhmissä (99%). Tarkkuus oli myös vanhemmissa ikäryhmissä hyvä (97-93%), kun atrofista gastriittia sairastavat suljettiin pois. IgA- ja CagA-helikobakteerivasta-aineiden on todettu liittyvän lisääntyneeseen mahahaava- ja mahasyöpäriskiin. Analysoimme 560 henkilön pariseeruminäytteet, jotka oli otettu kahden vuosikymmenen välein, ja totesimme, että IgA-vasta-aineiden esiintyvyyden lisääntyyminen iän myötä johtuu paitsi syntymäajankohdasta ja uusista infektioista myös IgA-vasta-ainetasojen kohoamisesta helikobakteeritulehduksen aikana. Selvitimme myös CagA-vasta-ainetasojen muuttumista analysoimalla seeruminäytteet, jotka oli otettu kahden vuosikymmenen välein. Totesimme, että samanaikaisesti kun helikobakteerin esiintyvyys väestössä on alentunut, erityisesti CagA-positiiviset infektiot ovat vähentyneet. Tutkimuksemme osoittaa, että Suomessa terveyskeskuksen yhteydessä voidaan toteuttaa näin laajamittainen seulonta- ja hoito-ohjelma, johon suomalaiset osallistuvat aktiivisesti. Nähtäväksi jää, kuinka paljon ohjelma kykeni vähentämään helikobakteeritulehdukseen liittyviä myöhäisseuraamuksia.

Genetics of T cell co-stimulatory receptors -CD28, CTLA4, ICOS and PDCD1 in immunity and transplantation

Co-stimulatory signals are essential for the activation of naïve T cells and productive immune response. Naïve T cells receive first, antigen-specific signal through T cell receptor. Co-stimulatory receptors provide the second signal which can be either activating or inhibitory. The balance between signals determines the outcome of an immune response. CD28 is crucial for T cell activation; whereas cytotoxic T lymphocyte associated antigen 4 (CTLA4) mediates critical inhibitory signal. Inducible co-stimulator (ICOS) augments cytokine expression and plays role in immunoglobulin class switching. Programmed cell death 1 (PDCD1) acts as negative regulator of T cell proliferation and cytokine responses. The co-stimulatory receptor pathways are potentially involved in self-tolerance and thus, they provide a promising therapeutic strategy for autoimmune diseases and transplantation. The genes encoding CD28, CTLA4 and ICOS are located adjacently in the chromosome region 2q33. The PDCD1 gene maps further, to the region 2q37. CTLA4 and PDCD1 are associated with the risk of a few autoimmune diseases. There is strong linkage disequilibrium (LD) on the 2q33 region; the whole gene of CD28 exists in its own LD block but CTLA4 and the 5' part of ICOS are within a same LD block. The 3' part of ICOS and PDCD1 are in their own separate LD blocks. Extended haplotypes covering the 2q33 region can be identified. This study focuses on immune related conditions like coeliac disease (CD) which is a chronic inflammatory disease with autoimmune features. Immunoglobulin A deficiency (IgAD) belongs to the group of primary antibody deficiencies characterised by reduced levels of immunoglobulins. IgAD co-occurs often with coeliac disease. Renal transplantation is needed in the end stage kidney diseases. Transplantation causes strong immune response which is tried to suppress with drugs. All these conditions are multifactorial with complex genetic background and multiple environmental factors affecting the outcome. We have screened ICOS for polymorphisms by sequencing the exon regions. We detected 11 new variants and determined their frequencies in Finnish population. We have measured linkage disequilibrium on the 2q33 region in Finnish as well as other European populations and observed conserved haplotypes. We analysed genetic association and linkage of the co-stimulatory receptor gene region aiming to study if it is a common risk locus for immune diseases. The 2q33 region was replicated to be linked to coeliac disease in Finnish population and CTLA4-ICOS haplotypes were found to be associated with CD and IgAD being the first non-HLA risk locus common for CD and immunodeficiencies. We also showed association between ICOS and the outcome of kidney transplantation. Our results suggest new evidence for CTLA4-ICOS gene region to be involved in susceptibility of coeliac disease. The earlier published contradictory association results can be explained by involvement of both CTLA4 and ICOS in disease susceptibility. The pattern of variants acting together rather than a single polymorphism may confer the disease risk. These genes may predispose also to immunodeficiencies as well as decreased graft survival and delayed graft function. Consequently, the present study indicates that like the well established HLA locus, the co-stimulatory receptor genes predispose to variety of immune disorders.

GDNF family receptors in peripheral target innervation and hormone production

Glial cell line-derived neurotrophic factor (GDNF) family ligands: GDNF, neurturin, persephin and artemin, signal through a receptor tyrosine kinase Ret by binding first to a co-receptor (GFRα1-4) that is attached to the plasma membrane. The GDNF family factors can support the survival of various peripheral and central neuronal populations and have important functions also outside the nervous system, especially in kidney development. Activating mutations in the RET gene cause tumours in neuroendocrine cells, whereas inactivating mutations in RET are found in patients with Hirschsprung s disease (HSCR) characterized by loss of ganglionic cells along the intestine. The aim of this study was to examine the in vivo functions of neurturin receptor GFRα2 and persephin receptor GFRα4 using knockout (KO) mice. Mice lacking GFRα2 grow poorly after weaning and have deficits in parasympathetic and enteric innervation. This study shows that impaired secretion of the salivary glands and exocrine pancreas contribute to growth retardation in GFRα2-KO mice. These mice have a reduced number of intrapancreatic neurons and decreased cholinergic innervation of the exocrine pancreas as well as reduced excitatory fibres in the myenteric plexus of the small intestine. This study also demonstrates that GFRα2-mediated Ret signalling is required for target innervation and maintenance of soma size of sympathetic cholinergic neurons and sensory nociceptive IB4-binding neurons. Furthermore, lack of GFRα2 in mice results in deficient perception of temperatures above and below thermoneutrality and in attenuated inflammatory pain response. GFRα4 is co-expressed with Ret predominantly in calcitonin-producing thyroid C-cells in the mouse. In this study GFRα4-deficient mice were generated. The mice show no gross developmental deficits and have a normal number of C-cells. However, young but not adult mice lacking GFRα4 have a lower production of calcitonin in thyroid tissue and consequently, an increased bone formation rate. Thus, GFRα4/Ret signalling may regulate calcitonin production. In conclusion, this study reveals that GFRα2/Ret signalling is crucial for the development and function of specific components of the peripheral nervous system and that GFRα4-mediated Ret signalling is required for controlling transmitter synthesis in thyroid C-cells.