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.

The scientific basis and development of a matrix metalloproteinase (MMP) -8 specific chair-side test for monitoring of periodontal health and disease from gingival crevicular fluid

Matrix metalloproteinase (MMP) -8, collagenase-2, is a key mediator of irreversible tissue destruction in chronic periodontitis and detectable in gingival crevicular fluid (GCF). MMP-8 mostly originates from neutrophil leukocytes, the first line of defence cells which exist abundantly in GCF, especially in inflammation. MMP-8 is capable of degrading almost all extra-cellular matrix and basement membrane components and is especially efficient against type I collagen. Thus the expression of MMP-8 in GCF could be valuable in monitoring the activity of periodontitis and possibly offers a diagnostic means to predict progression of periodontitis. In this study the value of MMP-8 detection from GCF in monitoring of periodontal health and disease was evaluated with special reference to its ability to differentiate periodontal health and different disease states of the periodontium and to recognise the progression of periodontitis, i.e. active sites. For chair-side detection of MMP-8 from the GCF or peri-implant sulcus fluid (PISF) samples, a dip-stick test based on immunochromatography involving two monoclonal antibodies was developed. The immunoassay for the detection of MMP-8 from GCF was found to be more suitable for monitoring of periodontitis than detection of GCF elastase concentration or activity. Periodontally healthy subjects and individuals suffering of gingivitis or of periodontitis could be differentiated by means of GCF MMP-8 levels and dipstick testing when the positive threshold value of the MMP-8 chair-side test was set at 1000 µg/l. MMP-8 dipstick test results from periodontally healthy and from subjects with gingivitis were mainly negative while periodontitis patients sites with deep pockets ( 5 mm) and which were bleeding on probing were most often test positive. Periodontitis patients GCF MMP-8 levels decreased with hygiene phase periodontal treatment (scaling and root planing, SRP) and even reduced during the three month maintenance phase. A decrease in GCF MMP-8 levels could be monitored with the MMP-8 test. Agreement between the test stick and the quantitative assay was very good (κ = 0.81) and the test provided a baseline sensitivity of 0.83 and specificity of 0.96. During the 12-month longitudinal maintenance phase, periodontitis patients progressing sites (sites with an increase in attachment loss ≥ 2 mm during the maintenance phase) had elevated GCF MMP-8 levels compared with stable sites. General mean MMP-8 concentrations in smokers (S) sites were lower than in non-smokers (NS) sites but in progressing S and NS sites concentrations were at an equal level. Sites with exceptionally and repeatedly elevated MMP-8 concentrations during the maintenance phase were clustered in smoking patients with poor response to SRP (refractory patients). These sites especially were identified by the MMP-8 test. Subgingival plaque samples from periodontitis patients deep periodontal pockets were examined by polymerase chain reaction (PCR) to find out if periodontal lesions may serve as a niche for Chlamydia pneumoniae. Findings were compared with the clinical periodontal parameters and GCF MMP-8 levels to determine the correlation with periodontal status. Traces of C. pneumoniae were identified from one periodontitis patient s pooled subgingival plaque sample by means of PCR. After periodontal treatment (SRP) the sample was negative for C. pneumoniae. Clinical parameters or biomarkers (MMP-8) of the patient with the positive C. pneumoniae finding did not differ from other study patients. In this study it was concluded that MMP-8 concentrations in GCF of sites from periodontally healthy individuals, subjects with gingivitis or with periodontitis are at different levels. The cut-off value of the developed MMP-8 test is at an optimal level to differentiate between these conditions and can possibly be utilised in identification of individuals at the risk of the transition of gingivitis to periodontitis. In periodontitis patients, repeatedly elevated GCF MMP-8 concentrations may indicate sites at risk of progression of periodontitis as well as patients with poor response to conventional periodontal treatment (SRP). This can be monitored by MMP-8 testing. Despite the lower mean GCF MMP-8 concentrations in smokers, a fraction of smokers sites expressed very high MMP-8 concentrations together with enhanced periodontal activity and could be identified with MMP-8 specific chair-side test. Deep periodontal lesions may be niches for non-periodontopathogenic micro-organisms with systemic effects like C. pneumoniae and possibly play a role in the transmission from one subject to another.

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.

Dyslipidaemia, glucose intolerance and cardiovascular disease mortality and morbidity in Europeans and Asians

Dyslipidaemia, a major risk factor of cardiovascular disease (CVD), is prevalent not only in diabetic patients but also in individuals with impaired glucose tolerance (IGT) or impaired fasting glucose (IFG). The aims of this study were: 1) to investigate lipid levels in relation to glucose in European (Study I) and Asian (Study II) populations without a prior history of diabetes; 2) to study the ethnic difference in lipid profiles controlling for glucose levels (Study III); 3) to estimate the relative risk for cardiovascular mortality (Study IV) and morbidity (Study V) associated with dyslipidaemia in individuals with different glucose tolerance status. Data of 15 European cohorts with 19 476 subjects (I and III) and 13 Asian cohorts with 19 763 individuals (II and III) from 21 countries aged 25-89 years, without a prior history of diabetes at enrollment, representing Asian Indian, Chinese, European, Japanese and Mauritian Indian, were compared. The lipid-CVD relationship was studied in 14 European cohorts of 17 763 men and women which provided with follow-up data on vital status, with 871 CVD deaths occurred during the average 10-year follow-up (IV). The impact of dyslipidaemia on incidence of coronary heart disease (CHD) in persons with different glucose categories (V) was further evaluated in 6 European studies, with 9087 individuals free of CHD at baseline and 457 developed CHD during follow-up. Z-scores of each lipid component were used in the data analysis (I, II, IV and V) to reduce the differences in methodology between studies. Analyses of cardiovascular mortality and morbidity were performed using Cox proportional hazards regression analysis adjusting for potential confounding factors. Within each glucose category, fasting plasma glucose (FPG) levels were correlated with increasing levels of triglycerides (TG), total cholesterol (TC), TC to high-density lipoprotein (HDL) ratio and non-HDL cholesterol (non-HDL-C) (p<0.05 in most of the ethnic groups) and inversely associated with HDL-C (p<0.05 in some, but not all, of the populations). The association of lipids with 2-h plasma glucose (2hPG) followed a similar pattern as that for the FPG, except the stronger association of HDL-C with 2hPG. Compared with Central & Northern (C & N) Europeans, multivariable adjusted odd ratios (95% CIs) for having low HDL-C were 4.74 (4.19-5.37), 5.05 (3.88-6.56), 3.07 (2.15-4.40) and 2.37 (1.67-3.35) in Asian Indian men but 0.12 (0.09-0.16), 0.07 (0.04-0.13), 0.11 (0.07-0.20) and 0.16 (0.08-0.32) in Chinese men who had normoglycaemia, prediabetes, undiagnosed and diagnosed diabetes, respectively. Similar results were obtained for women. The prevalence of low HDL-C remained higher in Asian Indians than in others even in individuals with LDL-C < 3 mmol/l. Dyslipidaemia was associated with increased CVD mortality or CHD incidence in individuals with isolated fasting hyperglycaemia or IFG, but not in those with isolated post-load hyperglycaemia or IGT. In conclusion, hyperglycaemia is associated with adverse lipid profiles in Europeans and Asians without a prior history of diabetes. There are distinct patterns of lipid profiles associated with ethnicity regardless of the glucose levels, suggesting that ethnic-specific strategies and guidelines on risk assessment and prevention of CVD are required. Dyslipidaemia predicts CVD in either diabetic or non-diabetic individuals defined based on the fasting glucose criteria, but not on the 2-hour criteria. The findings may imply considering different management strategies in people with fasting or post-load hyperglycaemia.

Mast cells and endothelial erosion: Implications for human atherothrombotic disease

More than 40% of all deaths in Finland are caused by atherosclerosis. The complications of atherosclerosis are due to either detachment of the luminal endothelium (erosion) or rupture of the fibrous cap of an atherosclerotic plaque (rupture). As a result, a thrombus is formed at the site of the intimal lesion. Indeed, erosions cause roughly 40% of sudden atherothrombotic deaths and 25% of all atherothrombotic deaths. Erosions are overrepresented in young subjects, diabetics, smokers and women. This dissertation focuses on endothelial erosion. Endothelial erosions were studied in the context of arterial grafting and vascular inflammation. Special attention was given to the role of intimal mast cells and the methodological viewpoints of reliable identification of endothelial erosions. Mast cells are inflammatory cells mostly known for their ability to cause allergic symptoms. In addition to occurring in skin and mucosal surfaces, mast cells are abundant in arterial intima and adventitia. In this study, mast cells were found to associate with endothelial erosions in non-lesional and atherosclerotic human coronary arteries. Thus, mast cells may participate in atherogenesis at the initial phases of the disease process already. We also showed that the mast cell proteases tryptase, chymase, and cathepsin G are all capable of cleaving molecules essential for endothelial cell-to-cell and cell-to-extracellular matrix interactions, such as VE-cadherin and fibronectin. Symptom-causing carotid plaques were found to contain more inflammatory cells, especially mast cells, than non-symptom-causing plaques. Furthermore, the atherogenic serum lipid profile and the degree of carotid stenosis turned out to correlate with the density of carotid plaque mast cells. Apoptotic and proliferating cells were more abundant in non-symptom causing plaques (active renewal of endothelial cells), but erosions were larger in symptom-causing plaques (capacity of endothelial regeneration exceeded). The process of identifying endothelial erosions with immunostainings has been ambiguous, since both endothelial cells and platelets express largely the same antigens. This may have caused inaccurate interpretations of the presence of endothelial erosion. In the last substudy of this thesis we developed a double immunostaining method for simultaneous identification of endothelial cells and platelets. This method enables more reliable identification of endothelial erosions.

Stroke and coronary heart disease in relation to hyperglycemia gender and age

This study was carried out to compare the fasting plasma glucose (FPG) and 2-h plasma glucose (2-h PG) criteria for diabetes with regard to their relation to stroke mortality and the incidence of ischemic and hemorrhagic stroke. In addition, the age-and gender difference in the incidence of coronary heart disease (CHD) and stroke and their relation with known cardiovascular disease risk factors and diabetes mellitus was examined. The study was a sub-data analysis of the Diabetes Epidemiology: Collaborative analysis Of Diagnostic criteria in Europe (DECODE) study including 25 181 individuals, 11 844 (47%) men and 13 345 (53%) women aged 25 to 90 years, from 14 European cohorts. In individuals without a history of diabetes elevated 2-h post-challenge glucose was a better predictor of stroke mortality than elevated fasting glucose in men, whereas the latter was better than the former in women. Elevated FPG and 2-h PG levels were associated with an increased risk of ischemic stroke incidence. 2-h PG contributed to the risk more strongly than FPG. No relationship between hyperglycemia and the risk of hemorrhagic stroke was found. The risk of CHD and ischemic stroke incidence increased with age in both genders, but was higher in all age groups in men than in women. The gender difference was, however, more marked for CHD than for ischemic stroke. Age, smoking and diabetes contributed to the development of both CHD and ischemic stroke. Elevated cholesterol levels predicted CHD only, whereas elevated blood pressure was a risk predictor for the incidence of ischemic stroke. The CHD and ischemic stroke risk was higher in men than in women with and without diabetes, however, the gender difference diminished for CHD but enlarged for ischemic stroke in diabetic individuals. The known risk factors including diabetes contributed differently to the risk of CHD and ischemic stroke in women and in men. Hyperglycemia defined by FPG or 2-h PG increases the risk of ischemic stroke in individuals without diabetes. FPG better predicts stroke mortality in women and 2-h PG in men. The risk of acute CHD and ischemic stroke is higher in men than in women in all ages, but such gender difference is more marked for CHD than for ischemic stroke. CHD risk is higher in men than in women, but the difference is reduced in diabetic population. Diabetes, however, increases stroke risk more in men than in women in all ages.

Complement system and alcoholic liver disease

Alcoholic liver disease (ALD) is a well recognized and growing health problem worldwide. ALD advances from fatty liver to inflammation, necrosis, fibrosis and cirrhosis. There is accumulating evidence that the innate immune system is involved in alcoholic liver injury. Within the innate and acquired immune systems, the complement system participates in inflammatory reactions and in the elimination of invading foreign, as well as endogenous apoptotic or injured cells. The present study aimed at evaluating the role of the complement system in the development of alcoholic liver injury. First, in order to study the effects of chronic ethanol intake on the complement system, the deposition of complement components in liver and the expression of liver genes associated with complement in animals with alcohol-induced liver injury were examined. It was demonstrated that chronic alcohol exposure leads to hepatic deposition of the complement components C1, C3, C8 and C9 in the livers of rats. Liver gene expression analysis showed that ethanol up-regulated the expression of transcripts for complement factors B, C1qA, C2, C3 and clusterin. In contrast, ethanol down-regulated the expression of the complement regulators factor H, C4bp and factor D and the terminal complement components C6, C8α and C9. Secondly, the role of the terminal complement pathway in the development of ALD was evaluated by using rats genetically deficient in the complement component C6 (C6-/-). It was found that chronic ethanol feeding induced more liver pathology (steatosis and inflammatory changes) in C6-/- rats than in wild type rats. The hepatic triacylglyceride content and plasma alanine aminotransferase activity increased in C6-/- rats, supporting the histopathological findings and elevation of the plasma pro-/anti-inflammatory TNF-/IL-10 ratio was also more marked in C6-/- rats. Third, the role of the alternative pathway in the development of alcoholic liver steatosis was characterized by using C3-/- mice. In C3-/- mice ethanol feeding tended to reduce steatosis and had no further effect on liver triacylglyceride, liver/body weight ratio nor on liver malondialdehyde level and serum alanine aminotransferase activity. In C3-/- mice alcohol-induced liver steatosis was reduced also after an acute alcohol challenge. In both wild type and C3-/- mice ethanol markedly reduced serum cholesterol and ApoA-I levels, phospholipid transfer protein activity and hepatic mRNA levels of fatty acid binding proteins and fatty acid -oxidation enzymes. In contrast, exclusively in C3-/- mice, ethanol treatment increased serum and liver adiponectin levels but down-regulated the expression of transcripts of lipogenic enzymes, adiponectin receptor 2 and adipose differentiation-related protein and up-regulated phospholipase D1. In conclusion, this study has demonstrated that the complement system is involved in the development of alcohol-induced liver injury. Chronic alcohol exposure causes local complement activation and induction of mRNA expression of classical and alternative pathway components in the liver. In contrast expression of the terminal pathway components and soluble regulators were decreased. A deficient terminal complement pathway predisposes to alcoholic liver damage and promotes a pro-inflammatory cytokine response. Complement component C3 contributes to the development of alcohol-induced fatty liver and its consequences by affecting regulatory and specific transcription factors of lipid homeostasis.