Humoral immune response to heat shock protein 60 of Aggregatibacter actinomycetemcomitans and cross-reactivity with malondialdehyde acetaldehyde-modified LDL

Publisher Copyright: Copyright: © 2020 Kyrklund et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Atherosclerosis is a chronic inflammatory disease and major cause of mortality worldwide. One of the crucial steps for atherosclerotic plaque development is oxidation of low-density lipoprotein (LDL). Through the oxidation, highly immunogenic epitopes are created and the immune system is activated. Association between atherosclerosis and periodontal diseases is well documented, and one of the main oral pathogens common in periodontitis is Aggregatibacter actinomycetemcomitans (Aa). Heat shock protein 60 (HSP60) is an important virulence factor for Aa bacteria and a strong activator of the immune system. Cross-reactivity of HSP60 and oxidized LDL (OxLDL) antibodies could be a potential mechanism in the progression of atherosclerosis and one possible link between atherosclerosis and periodontitis. Human plasma samples from neonates and mothers were analyzed to determine if antibody titer to Aa-HSP60 protein is already present in newborns. Further objectives were to characterize antibody response in Aa-HSP60 immunized mice and to determine possible antibody cross-reaction with oxidized LDL. We demonstrated that newborns already have IgM antibody levels to Aa-HSP60. We also showed that in mice, Aa-HSP60 immunization provoked IgG and IgM antibody response not only to Aa-HSP60 but also to malondialdehyde acetaldehyde-modified LDL (MAA-LDL). Competition assay revealed that the antibodies were specific to Aa-HSP60 and cross-reacted with MAA-LDL. Our results suggest a possibility of molecular mimicry between Aa-HSP60 and MAA-LDL, making it intriguing to speculate on the role of HSP60 protein in atherosclerosis that manifests at young age.Peer reviewe

Immunization with gingipain A hemagglutinin domain of Porphyromonas gingivalis induces IgM antibodies binding to malondialdehyde-acetaldehyde modified low-density lipoprotein

Publisher Copyright: © 2018 Kyrklund et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Treatment of periodontitis has beneficial effects on systemic inflammation markers that relate to progression of atherosclerosis. We aimed to investigate whether immunization with A hemagglutinin domain (Rgp44) of Porphyromonas gingivalis (Pg), a major etiologic agent of periodontitis, would lead to an antibody response cross-reacting with oxidized low-density lipoprotein (OxLDL) and how it would affect the progression of atherosclerosis in low-density lipoprotein receptor-deficient (LDLR-/-) mice. The data revealed a prominent IgM but not IgG response to malondialdehyde-acetaldehyde modified LDL (MAA-LDL) after Rgp44 and Pg immunizations, implying that Rgp44/Pgand MAA adducts may share cross-reactive epitopes that prompt IgM antibody production and consequently confer atheroprotection. A significant negative association was observed between atherosclerotic lesion and plasma IgA to Rgp44 in Rgp44 immunized mice, supporting further the anti-atherogenic effect of Rgp44 immunization. Plasma IgA levels to Rgp44 and to Pg in both Rgp44-and Pg-immunized mice were significantly higher than those in saline control, suggesting that IgA to Rgp44 could be a surrogate marker of immunization in Pg-immunized mice. Distinct antibody responses in plasma IgA levels to MAA-LDL, to Pg lipopolysaccharides (Pg-LPS), and to phosphocholine (PCho) were observed after Rgp44 and Pg immunizations, indicating that different immunogenic components between Rpg44 and Pg may behave differently in regard of their roles in the development of atherosclerosis. Immunization with Rgp44 also displayed atheroprotective features in modulation of plaque size through association with plasma levels of IL-1 alpha whereas whole Pg bacteria achieved through regulation of antiinflammatory cytokine levels of IL-5 and IL-10. The present study may contribute to refining therapeutic approaches aiming to modulate immune responses and inflammatory/antiinflammatory processes in atherosclerosis.Peer reviewe

Compensatory IgM to the Rescue: Patients with Selective IgA Deficiency Have Increased Natural IgM Antibodies to MAA-LDL and No Changes in Oral Microbiota

IgA is the most abundant Ab in the human body. However, most patients with selective IgA deficiency (SIgAD) are asymptomatic. IgM, and to lesser extent IgG Abs, are generally presumed to compensate for the lack of IgA in SIgAD by multiplying and adopting functions of IgA. We used data from the Northern Finland Birth Cohort 1966 to investigate whether SIgAD patients have differences in levels of natural Abs to oxidized epitopes compared with 20 randomly selected healthy controls. First, we screened the saliva and serum samples from the Northern Finland Birth Cohort 1966 cohort (n 5 1610) for IgA concentration. We detected five IgA-deficient subjects, yielding a prevalence of 0.3%, which is consistent with the general prevalence of 0.25% in the Finnish population. To detect natural Abs, we used malondialdehyde acetaldehyde–low-density lipoprotein (MAA–LDL), an Ag known to bind natural Abs. In this study, we show that natural secretory IgM and IgG Abs to MAA–DL were significantly increased in subjects with SIgAD. Given that secretory IgA is an important part of mucosal immune defense and that, in the gut microbiota, dysbiosis with SIgAD patients has been observed, we characterized the oral bacterial microbiota of the subjects with and without SIgAD using high-throughput 16S rRNA gene sequencing. We found no significant alterations in diversity and composition of the oral microbiota in subjects with SIgAD. Our data suggest that increased levels of secretory natural Abs in patients with SIgAD could be a compensatory mechanism, providing alternative first-line defense against infections and adjusting mucosal milieu to maintain a healthy oral microbiota. ImmunoHorizons, 2021, 5: 170–181.Peer reviewe

Total fecal IgA levels increase and natural IgM antibodies decrease after gastric bypass surgery

Obesity is associated with low-grade inflammation and increased systemic oxidative stress. Roux-en-Y gastric bypass (RYGB) surgery is known to ameliorate the obesity-induced metabolic dysfunctions. We aimed to study the levels of natural antibodies in feces, before and 6 months after RYGB surgery in obese individuals with and without type 2 diabetes (T2D). Sixteen individuals with T2D and 14 non-diabetic (ND) individuals were operated. Total IgA, IgG and IgM antibody levels and specific antibodies to oxidized low-density lipoprotein (oxLDL), malondialdehyde-acetaldehyde adducts (MAA adducts), Porphyromonas gingivalis gingipain A hemagglutinin domain (Rgp44) and phosphocholine (PCho) were measured using chemiluminescence immunoassay. Total fecal IgA was elevated, while total IgM and IgG were not affected by the surgery. Fecal natural IgM specific to oxLDL decreased significantly in both T2D and ND individuals, while fecal IgM to Rgp44 and PCho decreased significantly in T2D individuals. A decrease in IgG to MAA-LDL, Rgp44 and PCho was detected. RYGB surgery increases the levels of total fecal IgA and decreases fecal natural IgG and IgM antibodies specific to oxLDL. Natural antibodies and IgA are important in maintaining the normal gut homeostasis and first-line defense against microbes, and their production is markedly altered with RYGB surgery.Peer reviewe

Saliva and Serum Immune Responses in Apical Periodontitis

Apical periodontitis is an inflammatory reaction at the apex of an infected tooth. Its microbiota resembles that of marginal periodontitis and may induce local and systemic antibodies binding to bacteria- and host-derived epitopes. Our aim was to investigate the features of the adaptive immune response in apical periodontitis. The present Parogene cohort (n = 453) comprises patients with cardiac symptoms. Clinical and radiographic oral examination was performed to diagnose apical and marginal periodontitis. A three-category endodontic lesion score was designed. Antibodies binding to the bacteria- and host-derived epitopes were determined from saliva and serum, and bacterial compositions were examined from saliva and subgingival samples. The significant ORs (95% CI) for the highest endodontic scores were observed for saliva IgA and IgG to bacterial antigens (2.90 (1.01–8.33) and 4.91 (2.48–9.71)/log10 unit), saliva cross-reacting IgG (2.10 (1.48–2.97)), serum IgG to bacterial antigens (4.66 (1.22–10.1)), and Gram-negative subgingival species (1.98 (1.16–3.37)). In a subgroup without marginal periodontitis, only saliva IgG against bacterial antigens associated with untreated apical periodontitis (4.77 (1.05–21.7)). Apical periodontitis associates with versatile adaptive immune responses against both bacterial- and host-derived epitopes independently of marginal periodontitis. Saliva immunoglobulins could be useful biomarkers of oral infections including apical periodontitis—a putative risk factor for systemic diseases

Immunological and Microbiological Profiling of Cumulative Risk Score for Periodontitis

The cumulative risk score (CRS) is a mathematical salivary diagnostic model to define an individual’s risk of having periodontitis. In order to further validate this salivary biomarker, we investigated how periodontal bacteria, lipopolysaccharide (LPS), and systemic and local host immune responses relate to CRS. Subgingival plaque, saliva, and serum samples collected from 445 individuals were used in the analyses. Plaque levels of 28 microbial species, especially those of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Porphyromonas endodontalis, Prevotella intermedia, and Tannerella forsythia, and serum and salivary levels of IgA and IgG against these five species were determined. Additionally, LPS activity was measured. High CRS associated strongly with all IgA/IgG antibody and LPS levels in saliva, whereas in serum the associations were not that obvious. In the final logistic regression model, the best predictors of high CRS were saliva IgA burden against the five species (OR 7.04, 95% CI 2.25–22.0), IgG burden (3.79, 1.78–8.08), LPS (2.19, 1.38–3.47), and the sum of 17 subgingival Gram-negative species (6.19, 2.10–18.3). CRS is strongly associated with microbial biomarker species of periodontitis and salivary humoral immune responses against them

Immunological and Microbiological Profiling of Cumulative Risk Score for Periodontitis

The cumulative risk score (CRS) is a mathematical salivary diagnostic model to define an individual’s risk of having periodontitis. In order to further validate this salivary biomarker, we investigated how periodontal bacteria, lipopolysaccharide (LPS), and systemic and local host immune responses relate to CRS. Subgingival plaque, saliva, and serum samples collected from 445 individuals were used in the analyses. Plaque levels of 28 microbial species, especially those of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Porphyromonas endodontalis, Prevotella intermedia, and Tannerella forsythia, and serum and salivary levels of IgA and IgG against these five species were determined. Additionally, LPS activity was measured. High CRS associated strongly with all IgA/IgG antibody and LPS levels in saliva, whereas in serum the associations were not that obvious. In the final logistic regression model, the best predictors of high CRS were saliva IgA burden against the five species (OR 7.04, 95% CI 2.25–22.0), IgG burden (3.79, 1.78–8.08), LPS (2.19, 1.38–3.47), and the sum of 17 subgingival Gram-negative species (6.19, 2.10–18.3). CRS is strongly associated with microbial biomarker species of periodontitis and salivary humoral immune responses against them

Immunological and Microbiological Profiling of Cumulative Risk Score for Periodontitis

The cumulative risk score (CRS) is a mathematical salivary diagnostic model to define an individual's risk of having periodontitis. In order to further validate this salivary biomarker, we investigated how periodontal bacteria, lipopolysaccharide (LPS), and systemic and local host immune responses relate to CRS. Subgingival plaque, saliva, and serum samples collected from 445 individuals were used in the analyses. Plaque levels of 28 microbial species, especially those ofAggregatibacter actinomycetemcomitans,Porphyromonas gingivalis,Porphyromonas endodontalis,Prevotella intermedia, andTannerella forsythia, and serum and salivary levels of IgA and IgG against these five species were determined. Additionally, LPS activity was measured. High CRS associated strongly with all IgA/IgG antibody and LPS levels in saliva, whereas in serum the associations were not that obvious. In the final logistic regression model, the best predictors of high CRS were saliva IgA burden against the five species (OR 7.04, 95% CI 2.25-22.0), IgG burden (3.79, 1.78-8.08), LPS (2.19, 1.38-3.47), and the sum of 17 subgingival Gram-negative species (6.19, 2.10-18.3). CRS is strongly associated with microbial biomarker species of periodontitis and salivary humoral immune responses against them

Oral humoral immune response to oxidized LDL epitopes and periodontal pathogens in coronary artery disease and periodontitis

Abstract Atherosclerosis is a chronic inflammatory disease, characterized by retention of low-density lipoproteins (LDL) in the arterial wall, leading to atherosclerotic plaque formation. Subsequently, the retained LDL go through oxidative reactions forming immunogenic Oxidized-LDL (Ox-LDL). The humoral immune response to model oxidized epitopes, such as Malondialdehyde-acetaldehyde adducts (MAA-LDL), and copper-oxidized LDL play a key role in atherogenesis. Accumulating evidence has shown the link of atherosclerosis with oral health. Periodontitis is an inflammatory disease where the tooth-surrounding tissue is compromised. Periodontitis contributes to systemic inflammation and if left untreated, leads to tooth loss. The association of atherosclerosis with periodontitis has been extensively studied and several mechanisms have been suggested. Molecular mimicry of malondialdehyde epitopes with key periodontal pathogen virulence factor Porphyromonas gingivalis A hemagglutinin domain (Rgp44) epitope has been reported. On the other hand, an atherosclerotic mouse model immunized with Rgp44 showed increased levels of IgM to MAA-LDL. The above-mentioned findings raise the question whether atherosclerosis and periodontitis are associated through the cross-activation of mucosal humoral immune response by molecular mimicry. The aim of the current thesis work was to characterize salivary antibodies to oxidized epitopes and examine their cross-reactivity with antibodies to periodontal pathogens. Finally, the aim was to explore whether salivary immunoglobulins are associated with coronary artery disease (CAD) or periodontal diseases. In the first study, the salivary immunoglobulins to oxidized epitopes were characterized. In study I and II, the cross-reactivities of salivary IgA to MAA epitopes with periodontal pathogens virulence factors Rgp44 and Aggregatibacter actinomycetemcomitans Heat Shock Protein 60 (Aa-HSP60) were shown. In the second study, an independent association of salivary IgA to MAA-LDL with CAD and acute coronary artery syndrome (ACS) was also reported. Finally, in the third study, salivary IgA to MAA-LDL was shown to associate independently with periodontal pocket depth (PPD) 4- 5 mm, which is a major symptom of periodontitis. The findings of this thesis highlight the potential role of humoral mucosal immune response to oxidized epitopes in atherosclerosis and periodontal disease.Tiivistelmä Ateroskleroosiin eli valtimonkovettumatautiin liittyy krooninen matala-asteinen tulehdustila, jossa LDL (low-density lipoprotein) kolesteroli kertyy verisuonien seinämiin muodostaen ateroskleroottista plakkia. Myöhemmässä vaiheessa LDL-lipidiperoksidaatio tuottaa reaktiivisia aldehydejä, kuten malondialdehydi-asetaldehydi (MAA) -epitooppia. Hapettuneiden epitooppien synnyttämällä humoraalisella immuniteetilla on merkittävä rooli ateroskleroosin kehityksessä. Infektiot edesauttavat valtimokovettumataudin kehittymistä. Tutkimukset ovat osoittaneet, että hampaita ympäröivän kudoksen tulehdustila eli parodontiitti on valtimokovettumataudin merkittävä riskitekijä. Ateroskleroosin ja parodontiitin yhteyttä on tutkittu laajasti, mutta tarkkaa mekanismia ei vielä tunneta. On raportoitu, että MAA-epitoopilla on rakenteellista samankaltaisuutta parodontaalisen patogeenin virulenssitekijän Porphyromonas gingivalis hemagglutiniini-domeenin (Rgp44) molekyylien kanssa. Toisaalta Rgp44:llä immunisoiduilla ateroskleroottisilla hiirillä on korkeampi MAA-LDL-IgM taso kuin kontrollihiirillä. Edellä mainitut havainnot herättivät kysymyksen siitä, millainen rooli suun humoraalisella immuunivasteella on ateroskleroosin ja parodontiitin välisessä assosiaatiossa. Tämän väitöstyön tarkoituksena oli karakterisoida hapettuneita epitooppeja tunnistavia syljen vasta-aineita sekä niiden spesifisyyttä ja ristireagointia parodontaalisten patogeenien kanssa. Myös syljen hapettuneiden epitooppien vasta-aineiden assosiaatiota sepelvaltimotautiin (CAD) tai parodontaalisiin sairauksiin tutkittiin. Ensimmäisessä työssä karakterisoitiin syljen vasta-aineita, jotka tunnistavat hapettuneita epitooppeja. Tutkimustyön I ja II osassa osoitettiin, että syljen IgA MAA vasta-aineet ristireagoivat Rgp44:n ja Aggregatibacter actinomycetemcomitans heat shock protein 60:n (Aa-HSP60) kanssa. Toisessa tutkimustyössä havaittiin myös, että syljen MAA-LDL IgA-vasta-aineiden pitoisuus liittyy itsenäisenä riskitekijänä sepelvaltimotautiin. Lopuksi kolmannessa osatyössä osoitettiin, että syljen MAA-LDL IgA-vasta-aineet assosioituvat itsenäisesti 4–5 mm:n ientaskusyvyyteen (PPD). Tämän väitöskirjan tutkimustulokset osoittavat suun humoraalisen immuniteetin mahdollisen roolin ateroskleroosin ja parodontaalisairauksien välisessä yhteydessä