Clin Oral Invest DOI 10.1007/s00784-015-1570-9
ORIGINAL ARTICLE
Prevalence of periodontitis in individuals with human leukocyte antigens (HLA) A9, B15, A2, and B5 Jamal M. Stein 1 & Helmut KG Machulla 2 & James Deschner 3 & Stefan Fickl 4 & Yvonne Jockel-Schneider 4 & Miriam Tamm 5 & Susanne Schulz 6 & Stefan Reichert 6
Received: 20 January 2015 / Accepted: 16 August 2015 # Springer-Verlag Berlin Heidelberg 2015
Abstract Objective Human leukocyte antigens (HLA) have been associated with periodontitis. Previous studies revealed HLA-A9 and HLA-B15 as potential susceptibility factors, while HLAA2 and HLA-B5 might have protective effects. The aim of the study was to verify these associations in a group of HLAtyped blood donors with previously unknown periodontal status. Materials and methods In four German centers, 140 blood donors with known HLA class I status were enrolled and allocated to the following five groups: HLA-A9 (N = 24), HLA-B15 (N = 20), HLA-A2 (N = 30), HLA-B5 (N = 26), and controls (N = 40). Periodontal examination included the measurement of probing depths (PDs), clinical attachment level (CAL), bleeding on probing (BOP), and community periodontal index of treatment needs (CPITN). * Jamal M. Stein [email protected] 1
Department of Operative Dentistry, Periodontology and Preventive Dentistry, University Hospital (RWTH) Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany
2
Institute of Physiology, University of the Saarland, Kirrberger Straße 100, 66424 Homburg/Saar, Germany
3
Section of Experimental Dento-Maxillo-Facial Medicine, University of Bonn, Welschnonnenstraße 17, 53111 Bonn, Germany
4
Department of Periodontology, University Hospital Würzburg, Pleicherwall 2, 97070 Würzburg, Germany
5
Department of Medical Statistics, University Hospital (RWTH) Aachen, Pauwelsstraße 30, 52074 Aachen, Germany
6
Department of Operative Dentistry and Periodontology, Martin Luther University Halle-Wittenberg, Große Steinstraße 19, 06108 Halle (Saale), Germany
Results Carriers with HLA-A9 and HLA-B15 had higher values of mean PD (P < 0.0001), CAL (P < 0.0001), and BOP (P < 0.002) as well as sites with PD and CAL with ≥4 and ≥6 mm (P < 0.0003), respectively, than controls. Multiple regression analyses revealed HLA-A9, HLA-B15, and smoking as risk indicators for moderate to severe (CPITN 3–4; odds ratio (OR): 66.7, 15.3, and 5.1) and severe (CPITN 4; OR: 6.6, 7.4, and 3.8) periodontitis. HLA-A2 and HLA-B5 did not show any relevant associations. Conclusion The present data support a role of HLA-A9 and HLA-B15 as susceptibility factors for periodontitis, whereas HLA-A2 and HLA-B5 could not be confirmed as resistance factors. Clinical relevance Both HLA antigens A9 and B15 are potential candidates for periodontal risk assessment. Keywords Major histocompatibility complex . HLA . Periodontitis . Risk factors
Introduction It is generally accepted that gingivitis and periodontitis are the result of an infection with periodontopathic bacteria and the host response towards the bacterial challenge [1, 2]. The manifestation, severity, and course of these diseases are dependent on the virulence of the microorganisms and the effectiveness of unspecific and specific paths of the immune response [3, 4]. Thereby, genetic factors have been reported to contribute up to 50 % to the risk factors [5, 6]. Studies on polymorphisms of genes involved in processes of the innate immune response such as those encoding for interleukin-1 [7], TNF alpha [8, 9], matrix metalloproteinases [10], or Fc gamma receptors [11] have confirmed the meaning of these factors in the
Clin Oral Invest
pathogenesis of periodontitis. Besides, multiple alleles of genes affecting the components of the specific B and T cell immune responses also contribute as background factors for periodontal infection. In the last decades, the major histocompatibility complex (MHC) has come into the focus of research on the etiology of severe chronic and aggressive periodontitis [12–14]. Since the MHC is able to present antigen peptides to T cells, the effectiveness of antigen-specific response towards periodontal pathogens is depending on the binding capability of the MHC molecules (MHC restriction of antigen recognition) [15]. The polymorphism of the human MHC molecules (human leukocyte antigens (HLA)) can directly affect the efficacy of antigen binding and is, therefore, suggested to explain inter-individual differences in immune response to periodontal pathogens [14, 16, 17]. Thus, particular HLA antigens might act as genetic susceptibility or resistance factors. In several studies, a number of HLA class I and II antigens have been associated with chronic and aggressive periodontitis [12–14, 18–20]. However, due to different selection criteria for patients and controls as well as inclusion of different ethnic groups in previous studies, consistent results could not be concluded. In a recent meta-analysis of 12 case-control studies in Caucasian populations, we reported a positive association of HLA-A9 and HLA-B15 with aggressive periodontitis and a negative association of HLA-A2 and HLA-B5 with (both aggressive and chronic) periodontitis, whereas for HLA class II antigens, no association could be found. Although the results of the aforementioned meta-analysis represented the highest degree of evidence compared to all previous reports so far, it retrospectively summarized studies with a high heterogeneity among each other, in particular for HLA-A9 and HLA-B15 [21]. Other cofactors such as age or smoking and methodological aspects (e.g., different diagnostic thresholds for disease definition, missing reproducibility of periodontal examinations) might be potential explanations for this observation. Moreover, synergistic or antagonistic effects of (positive or negative) HLA associations could not be excluded. In order to verify the meaning of HLA-A9 and HLAB15 as potential susceptibility factors and HLA-A2 and HLAB5 as potential protective factors, it was the aim of the present study to examine the prevalence and severity of periodontitis in a group of Caucasian blood donors who were carriers of HLA-A9, HLA-B15, HLA-A2, and HLA-B5 in comparison to those who were not carriers of any of these HLA antigens (controls).
Materials and methods Study population The study was designed as a multicenter cross-sectional study. In four German centers (University Hospitals of Aachen,
Halle, Bonn, and Würzburg), blood donors with known HLA class I (A, B, Cw) type have been recruited from January 2008 to November 2013. This was done in cooperation with the HLA laboratories of the institutes for transfusion medicine at each center. Therefore, the databanks of all HLAtyped blood donors were screened. In total, 392 blood donors that were positive for HLA-A9, HLA-B15, HLA-A2, or HLA-B5 have been found. Out of these, volunteers were selected for the recruitment when they (i) were free from diabetes mellitus, obesity, osteoporosis, or other systemic diseases and (ii) were aged between 30 and 60 years. Moreover (iii), in order to exclude bias due to potential synergistic or antagonistic effects, individuals were only included when they had only one of the four HLA antigens A9, B15, A2, or B5. In case of the presence of two or more of these HLA markers, they were excluded from the recruitment procedure. All potentially appropriate blood donors meeting the inclusion and exclusion criteria received an information letter about the present study and were requested to participate on the study. In total, 140 subjects agreed and were included into the study. According to their HLA status, they were allocated to the following five groups: HLA-A9 (N = 24), HLA-B15 (N = 20), HLA-A2 (N = 30), HLA-B5 (N = 26), and controls who were not carriers of HLA-A9, HLA-B15, HLA-A2, and HLA-B5 (N = 40). Figure 1 shows a flow diagram on the selection of all participants according to the described criteria. None of the finally included blood donors had taken any medicaments known to increase gingival overgrowth. Further, none of them had received antibiotics or glucocorticoid therapy in the last 6 months. All participants gave their written informed consent to participate in this study. All investigations were carried out in accordance with the Declaration of Helsinki, including all revisions and amendments (last revision: Seoul in 2008); the study protocol was reviewed and approved by the Ethics Committee of the University of Aachen. Clinical examination The clinical periodontal examination included the assessment of the plaque index (PI) [22], gingival index (GI) [23], periodontal probing depths (PD), and clinical attachment level (CAL). PD and CAL values were recorded at six sites per tooth. The CAL (distance between the cemento-enamel junction and bottom of the pocket) was obtained by adding the PD values to gingival recession values (the distance between the gingival margin and cemento-enamel junction). Further, the community periodontal index of treatment needs (CPITN) was recorded [24]. Therefore, the oral cavity was divided into sextants; for each sextant, the highest index found was recorded by applying the following scores: 0 = periodontal health, 1 = gingival bleeding, 2 = calculus and/or overhanging restorations, 3 = PD of ≥4 but
ORIGINAL ARTICLE
Prevalence of periodontitis in individuals with human leukocyte antigens (HLA) A9, B15, A2, and B5 Jamal M. Stein 1 & Helmut KG Machulla 2 & James Deschner 3 & Stefan Fickl 4 & Yvonne Jockel-Schneider 4 & Miriam Tamm 5 & Susanne Schulz 6 & Stefan Reichert 6
Received: 20 January 2015 / Accepted: 16 August 2015 # Springer-Verlag Berlin Heidelberg 2015
Abstract Objective Human leukocyte antigens (HLA) have been associated with periodontitis. Previous studies revealed HLA-A9 and HLA-B15 as potential susceptibility factors, while HLAA2 and HLA-B5 might have protective effects. The aim of the study was to verify these associations in a group of HLAtyped blood donors with previously unknown periodontal status. Materials and methods In four German centers, 140 blood donors with known HLA class I status were enrolled and allocated to the following five groups: HLA-A9 (N = 24), HLA-B15 (N = 20), HLA-A2 (N = 30), HLA-B5 (N = 26), and controls (N = 40). Periodontal examination included the measurement of probing depths (PDs), clinical attachment level (CAL), bleeding on probing (BOP), and community periodontal index of treatment needs (CPITN). * Jamal M. Stein [email protected] 1
Department of Operative Dentistry, Periodontology and Preventive Dentistry, University Hospital (RWTH) Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany
2
Institute of Physiology, University of the Saarland, Kirrberger Straße 100, 66424 Homburg/Saar, Germany
3
Section of Experimental Dento-Maxillo-Facial Medicine, University of Bonn, Welschnonnenstraße 17, 53111 Bonn, Germany
4
Department of Periodontology, University Hospital Würzburg, Pleicherwall 2, 97070 Würzburg, Germany
5
Department of Medical Statistics, University Hospital (RWTH) Aachen, Pauwelsstraße 30, 52074 Aachen, Germany
6
Department of Operative Dentistry and Periodontology, Martin Luther University Halle-Wittenberg, Große Steinstraße 19, 06108 Halle (Saale), Germany
Results Carriers with HLA-A9 and HLA-B15 had higher values of mean PD (P < 0.0001), CAL (P < 0.0001), and BOP (P < 0.002) as well as sites with PD and CAL with ≥4 and ≥6 mm (P < 0.0003), respectively, than controls. Multiple regression analyses revealed HLA-A9, HLA-B15, and smoking as risk indicators for moderate to severe (CPITN 3–4; odds ratio (OR): 66.7, 15.3, and 5.1) and severe (CPITN 4; OR: 6.6, 7.4, and 3.8) periodontitis. HLA-A2 and HLA-B5 did not show any relevant associations. Conclusion The present data support a role of HLA-A9 and HLA-B15 as susceptibility factors for periodontitis, whereas HLA-A2 and HLA-B5 could not be confirmed as resistance factors. Clinical relevance Both HLA antigens A9 and B15 are potential candidates for periodontal risk assessment. Keywords Major histocompatibility complex . HLA . Periodontitis . Risk factors
Introduction It is generally accepted that gingivitis and periodontitis are the result of an infection with periodontopathic bacteria and the host response towards the bacterial challenge [1, 2]. The manifestation, severity, and course of these diseases are dependent on the virulence of the microorganisms and the effectiveness of unspecific and specific paths of the immune response [3, 4]. Thereby, genetic factors have been reported to contribute up to 50 % to the risk factors [5, 6]. Studies on polymorphisms of genes involved in processes of the innate immune response such as those encoding for interleukin-1 [7], TNF alpha [8, 9], matrix metalloproteinases [10], or Fc gamma receptors [11] have confirmed the meaning of these factors in the
Clin Oral Invest
pathogenesis of periodontitis. Besides, multiple alleles of genes affecting the components of the specific B and T cell immune responses also contribute as background factors for periodontal infection. In the last decades, the major histocompatibility complex (MHC) has come into the focus of research on the etiology of severe chronic and aggressive periodontitis [12–14]. Since the MHC is able to present antigen peptides to T cells, the effectiveness of antigen-specific response towards periodontal pathogens is depending on the binding capability of the MHC molecules (MHC restriction of antigen recognition) [15]. The polymorphism of the human MHC molecules (human leukocyte antigens (HLA)) can directly affect the efficacy of antigen binding and is, therefore, suggested to explain inter-individual differences in immune response to periodontal pathogens [14, 16, 17]. Thus, particular HLA antigens might act as genetic susceptibility or resistance factors. In several studies, a number of HLA class I and II antigens have been associated with chronic and aggressive periodontitis [12–14, 18–20]. However, due to different selection criteria for patients and controls as well as inclusion of different ethnic groups in previous studies, consistent results could not be concluded. In a recent meta-analysis of 12 case-control studies in Caucasian populations, we reported a positive association of HLA-A9 and HLA-B15 with aggressive periodontitis and a negative association of HLA-A2 and HLA-B5 with (both aggressive and chronic) periodontitis, whereas for HLA class II antigens, no association could be found. Although the results of the aforementioned meta-analysis represented the highest degree of evidence compared to all previous reports so far, it retrospectively summarized studies with a high heterogeneity among each other, in particular for HLA-A9 and HLA-B15 [21]. Other cofactors such as age or smoking and methodological aspects (e.g., different diagnostic thresholds for disease definition, missing reproducibility of periodontal examinations) might be potential explanations for this observation. Moreover, synergistic or antagonistic effects of (positive or negative) HLA associations could not be excluded. In order to verify the meaning of HLA-A9 and HLAB15 as potential susceptibility factors and HLA-A2 and HLAB5 as potential protective factors, it was the aim of the present study to examine the prevalence and severity of periodontitis in a group of Caucasian blood donors who were carriers of HLA-A9, HLA-B15, HLA-A2, and HLA-B5 in comparison to those who were not carriers of any of these HLA antigens (controls).
Materials and methods Study population The study was designed as a multicenter cross-sectional study. In four German centers (University Hospitals of Aachen,
Halle, Bonn, and Würzburg), blood donors with known HLA class I (A, B, Cw) type have been recruited from January 2008 to November 2013. This was done in cooperation with the HLA laboratories of the institutes for transfusion medicine at each center. Therefore, the databanks of all HLAtyped blood donors were screened. In total, 392 blood donors that were positive for HLA-A9, HLA-B15, HLA-A2, or HLA-B5 have been found. Out of these, volunteers were selected for the recruitment when they (i) were free from diabetes mellitus, obesity, osteoporosis, or other systemic diseases and (ii) were aged between 30 and 60 years. Moreover (iii), in order to exclude bias due to potential synergistic or antagonistic effects, individuals were only included when they had only one of the four HLA antigens A9, B15, A2, or B5. In case of the presence of two or more of these HLA markers, they were excluded from the recruitment procedure. All potentially appropriate blood donors meeting the inclusion and exclusion criteria received an information letter about the present study and were requested to participate on the study. In total, 140 subjects agreed and were included into the study. According to their HLA status, they were allocated to the following five groups: HLA-A9 (N = 24), HLA-B15 (N = 20), HLA-A2 (N = 30), HLA-B5 (N = 26), and controls who were not carriers of HLA-A9, HLA-B15, HLA-A2, and HLA-B5 (N = 40). Figure 1 shows a flow diagram on the selection of all participants according to the described criteria. None of the finally included blood donors had taken any medicaments known to increase gingival overgrowth. Further, none of them had received antibiotics or glucocorticoid therapy in the last 6 months. All participants gave their written informed consent to participate in this study. All investigations were carried out in accordance with the Declaration of Helsinki, including all revisions and amendments (last revision: Seoul in 2008); the study protocol was reviewed and approved by the Ethics Committee of the University of Aachen. Clinical examination The clinical periodontal examination included the assessment of the plaque index (PI) [22], gingival index (GI) [23], periodontal probing depths (PD), and clinical attachment level (CAL). PD and CAL values were recorded at six sites per tooth. The CAL (distance between the cemento-enamel junction and bottom of the pocket) was obtained by adding the PD values to gingival recession values (the distance between the gingival margin and cemento-enamel junction). Further, the community periodontal index of treatment needs (CPITN) was recorded [24]. Therefore, the oral cavity was divided into sextants; for each sextant, the highest index found was recorded by applying the following scores: 0 = periodontal health, 1 = gingival bleeding, 2 = calculus and/or overhanging restorations, 3 = PD of ≥4 but
