Molecular basis of leukocyte adhesion molecules in early-onset periodontitis patients with decreased CD11/CD18 expression on leukocytes

Feline leukocyte adhesion (CD18) deficiency caused by a deletion in the integrin β2 (ITGB2) gene

BACKGROUND

Leukocyte adhesion deficiency (LAD) or CD18 deficiency is an autosomal recessive immunodeficiency which has been described in people, cattle, dogs, and knockout mice.

OBJECTIVES

The study goals were to characterize the clinicopathologic, immunologic, and molecular genetic features of feline LAD (FLAD) in a neutered male adult Domestic Longhair cat with severe leukocytosis and recurrent infections.

METHODS

Flow cytometry evaluated surface expression of CD18 on neutrophils. In vitro functional assays assessed CD18-dependent neutrophil adhesion and T-cell proliferation. Genomic DNA and cDNA were used to identify a causative mutation in the coding sequence of the integrin β₂ subunit (ITGB2) gene.

RESULTS

The affected cat developed periodontitis during the first months of life followed by recurrent infections poorly responsive to antibiotic therapy, accompanied by extreme neutrophilia. Neutrophils from the proband, compared to feline controls, did not express any CD18 on the cell surface. Adhesion of affected neutrophils was severely impaired with and without phorbol-myristate-acetate activation. The proband's T-cells proliferated weakly to 1 pg but normally to 100 pg staphylococcal enterotoxin A, suggesting a CD18-independent T-cell response at higher doses. Molecular genetic analysis of the ITGB2 gene revealed a 24 bp deletion at the exon 2 to intron 2 boundary (c.46_58 + 11del), predicting premature translational termination due to abnormal splicing of exon 1 to exon 3 or 4.

CONCLUSIONS

Feline LAD exhibits features similar to LAD in other species. However, clinical episodes in FLAD appeared milder allowing for an extended life expectancy under long-term antimicrobial therapy, possibly due to an alternative, CD18-independent T-cell proliferation pathway.

Leukocyte adhesion deficiency type 1: an important consideration in the clinical differential diagnosis of prepubertal periodontitis. A case report and review of the literature

Leukocyte adhesion deficiency type 1 (LAD-1) is a rare, inherited immunodeficiency that affects 1 in 1 million people yearly and usually presents with recurrent, indolent bacterial infections of the skin, mouth, and respiratory tract and impaired pus formation and wound healing. Features of this disease result from mutations in the region of the CD18 gene, which is encoded on chromosome 21q22.3. This gene codes for the common subunit of the leukocyte integrins LFA-1, Mac 1, and p150,95. Failure to produce a functional subunit results in the defective expression of all 3 leukocyte integrins, and the leukocytes of LAD have subnormal adhesion properties. We present a case of the moderate-to-severe form of LAD in a 3-year-old girl who initially presented with generalized swelling and erythema of the gingiva, with slight tooth mobility and a nonhealing labial ulceration. Her medical history was significant for recurrent urinary tract infections. Periodontal pathogens, including Capnocytophaga, Eikenella corrodens, and Candida albicans, were cultured. The patient had a significantly elevated white blood cell count and absolute neutrophil count. The diagnosis of LAD was confirmed with flow cytometry, which revealed significantly decreased subunits. Twenty-four months after the diagnosis was made and after a series of granulocyte transfusions and bone marrow transplantations, she expired as the result of respiratory failure.

Otolaryngologic manifestations of immunodeficiency

Otolaryngologists are frequently consulted to manage infectious and noninfectious complications of immune deficiency. Although defects of host defense and recurrent or severe infections are the most obvious manifestations of immune deficiency, patients are often at increased risk for autoimmune and malignant disease as well. Knowledge of primary and acquired immune deficiencies will facilitate appropriate identification, treatment, and referral of patients with these defects. When immunodeficiency is known or suspected, it is particularly important to have a high index of suspicion for unusual or severe manifestations of infection, to have a low threshold for obtaining imaging to aid in diagnosis, and to treat infections for longer periods of time with higher doses of antibiotic. Surgery may be required for definitive treatment of infections that do not respond to medical therapy and for management of complications of infectious disease

Heterogeneity of host immunological risk factors in patients with aggressive periodontitis

BACKGROUND

The pathogenesis of early-onset periodontitis (EOP) can be explained by various host risk factors. Previous studies have focused on a single (among many possible) immunological risk factor and the association among the factors has not been assessed. We comprehensively investigated the associations among multiple host immunological risk factors in EOP patients to further elucidate their role in the pathogenesis of EOP.

METHODS

Sixty-eight EOP patients (50 generalized EOP, 18 localized EOP), 51 EOP-suspected patients (S-EOP), 43 adult periodontitis (AP) patients, and 36 periodontally healthy subjects (HS) participated in this cross-sectional study. We examined peripheral neutrophil functions, phenotypic and functional characterization of peripheral lymphocytes (lymphocyte subsets, T-cell proliferative activity), cytokine productivity (interleukin [IL]-1, IL-2, tumor necrosis factor [TNF]-alpha, interferon [IFN]-gamma, IL-4 and IL-6), serum immunoglobulin G (IgG) antibody titers against 12 periodontal bacteria, and HLA class II genotypes.

RESULTS

G-EOP, S-EOP, and AP patient groups showed significantly lower percentages of pan T cells and CD8-positive cells (P < 0.02) compared with the HS group. L-EOP patients showed depressed IL-4 and TNF-alpha productivity compared with the HS group (P < 0.02). The EOP group showed significantly elevated antibody levels against Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Treponema denticola, and Fusobacterium nucleatum compared with the HS group (P < 0.05). The frequency with DQB1*0503 was significantly higher in the EOP patient group than the HS group (P = 0.045) due to the higher frequency in L-EOP patients than the HS group (P = 0.035). There were wide interindividual variations in each of the tests among patient and HS groups; however, EOP patients showed wider intradiagnostic group variations in certain host defensive cell functions than the other groups. There were some EOP patients who showed extremely low or high values in some tests; the EOP patients could be further divided into subgroups according to their host defensive and immunological profiles. However, there was heterogeneity in some of the other host immunological tests even in the subgroups.

CONCLUSIONS

The association of host immunological risk factors in EOP patients is widely varied and more complex than previously thought. These results indicate the difficulty of explaining the pathogenesis of EOP based on a single host risk factor and also emphasize the importance of critical assessment of not only EOP patient groups, but also individual patients.

Regulation of immunoglobulin G2 production by prostaglandin E(2) and platelet-activating factor

Patients with localized juvenile periodontitis (LJP) have elevated levels of immunoglobulin G2 (IgG2) in their sera. This is also observed in vitro when peripheral blood leukocytes from LJP patients are stimulated with pokeweed mitogen. In previous studies, we showed that lymphocytes from subjects with no periodontitis (NP subjects) produced substantial amounts of IgG2 when they were cultured with monocytes from LJP patients (LJP monocytes). These observations indicate that monocytes or monocyte-derived mediators are positive regulators of the production of IgG2. The present study was initiated to determine if secreted factors from LJP monocytes were capable of enhancing IgG2 production and to determine if prostaglandin E2 (PGE(2)), which LJP monocytes produce at elevated levels, enhances IgG2 production. Experiments in a transwell system and with monocyte-conditioned media indicated that cell-cell contact was not necessary for LJP monocytes to augment the production of IgG2 by T and B cells from NP subjects. Moreover, the production of IgG2 was selectively induced by the addition of PGE(2) or platelet-activating factor (PAF), another lipid cytokine, which can elevate PGE(2) synthesis. Furthermore, IgG2 production was abrogated when cells were treated with indomethacin, a cyclooxygenase inhibitor that blocks the synthesis of PGE(2), or the PAF antagonists CV3988 and TEPC-15. The effects of indomethacin were completely reversed by PGE(2), indicating that this is the only prostanoid that is essential for the production of IgG2. Similarly, PGE(2) reversed the effects of a PAF antagonist, suggesting that the effects of PAF are mediated through the induction of PGE(2) synthesis. Together, these data indicate that PGE(2) and PAF are essential for the production of IgG2.

Neutrophil Dysfunctions, IL-8, and Soluble L-Selectin Plasma Levels in Rapidly Progressive Versus Adult and Localized Juvenile Periodontitis: Variations According to Disease Severity and Microbial Flora

We used flow cytometry to analyze the expression of adhesion molecules and the oxidative burst of whole-blood polymorphonuclear neutrophils (PMN) from 26 patients with periodontitis. Three different clinical entities were studied: adult periodontitis (AP), localized juvenile periodontitis (LJP), and rapidly progressive periodontitis (RPP). Unstimulated PMN from the patients showed reduced Lewis x, sialyl-Lewis x, and L-selectin expression relative to those from healthy control subjects. These alterations were present whatever the severity of periodontal disease. However, PMN from RPP patients showed increased basal H2O2 production and decreased L-selectin shedding. These latter impairments, which correlated with increased IL-8 plasma levels, could contribute to initial vascular damage. In addition, decreased IL-8 priming of H2O2 production by PMN from RPP patients could account for a lower bactericidal capacity of PMN, leading to the large number of bacteria in the subgingival region of RPP patients. Soluble L-selectin plasma levels were also decreased in the RPP group, indicating more severe or diffuse endothelial damage. These abnormalities were not found in the patients with less destructive forms of periodontitis (AP and LJP). Porphyromonas gingivalis, a bacterial pathogen known to increase IL-8 production by PMN, was found in the periodontal pockets of RPP patients only. These results show links among PMN abnormalities, the clinical form of periodontitis, and the gingival bacterial flora.

Leukocyte adhesion deficiency in a child with severe oral involvement

Leukocyte adhesion deficiency is a rare inherited defect of phagocytic function resulting from a lack of leukocyte cell surface expression of beta2 integrin molecules (CD11 and CD18) that are essential for leukocyte adhesion to endothelial cells and chemotaxis. A small number of patients with leukocyte adhesion deficiency-1 have a milder defect, with residual expression of CD18. These patients tend to survive beyond infancy; they manifest progressive severe periodontitis, alveolar bone loss, periodontal pocket formation, and partial or total premature loss of the primary and permanent dentitions. We report on a 13-year-old boy with moderate leukocyte adhesion deficiency-1 and severe prepubertal periodontitis. This case illustrates the need for the dentist to work closely with the pediatrician in the prevention of premature tooth loss and control of oral infection in these patients.

A potential role of an intracellular signaling defect in neutrophil functional abnormalities and promotion of tissue damage in patients with localized juvenile periodontitis

Localized juvenile periodontitis is a destructive form of periodontal inflammatory disease which has its onset at puberty. The etiopathology of the disease is still unclear but neutrophils have been suggested to play a major role both in the production and development of the disorder. About 70% of the patients with localized juvenile periodontitis exhibit neutrophil functional abnormalities, such as decreased chemotaxis and phagocytosis. Interestingly, it has been frequently reported that the same hypoactive cells show an enhanced respiratory burst response and increased adhesion. Several possible mechanisms explaining neutrophil anomalies in localized juvenile periodontitis have been proposed. These include the presence of soluble serum factors capable of modulating neutrophil function, altered cell-surface receptor expression and/or function, and a change in the post-receptor signaling events. Recently, a growing evidence has accumulated showing that the diacylglycerol metabolism could be altered in neutrophils from patients with localized juvenile periodontitis. This change, which may be due to a defect in a major diacylglycerol metabolizing enzyme, diacylglycerol kinase, results in enhanced accumulation of diacylglycerol in activated cells. Because diacylglycerol is an endogenous activator of protein kinase C, the increased and prolonged generation of diacylglycerol could lead to abnormal pattern of protein kinase C-regulated neutrophil functions, explaining the parallel hypo- and hyperactivities.

Alterations of neutrophil L-selectin and CD18 expression by tobacco smoke: implications for periodontal diseases

Alterations in neutrophil functions by both chronic low levels of tobacco and by acute short-term higher levels of tobacco smoke, as encountered during the act of smoking, may play a role in the pathogenesis of periodontal diseases in smokers. Among the early migration events of neutrophil function is the alteration in surface expression of L-selectin and the CD11/18 integrins. In the present study we examined the effect of in vitro smoke exposure and nicotine alone on the expression of these 2 adhesion molecules in neutrophils from smokers and non-smokers. We also determined the physiological relevance of this in vitro system by assessing the levels of nicotine exposure in this in vitro system and comparing these levels to acute and chronic levels of nicotine in saliva and gingival crevicular fluid. Peripheral neutrophils were isolated from the blood of smokers (> 1 pack/d) and non-smokers and incubated in vitro with either cigarette smoke (0-5 min), 10(-7) M F-met-leu-phe, or nicotine alone at 1.62 mg/ml to 162 ng/ml (10(-2) M-10(-6) M). The neutrophils were then incubated with fluoresceine conjugated anti-Leu8 (L-selectin), anti-CD18 (CD18 integrin), or gamma-4 (non-specific control), fixed and analyzed by flow cytometry. With cigarette smoke exposure, there was an approximate 75% shedding of L-selectin in both smokers and non-smokers with no marked difference between groups at 1-5 min of smoke exposure. Cigarette smoke exposure resulted in a 15-20% increase in CD18 expression in both smokers and non-smokers. At all time points, there was slightly greater but statistically insignificant expression of CD18 integrin in non-smokers when compared to smokers. These patterns of CD18 increases and L-selectin shedding were similar in magnitude to incubations with 10(-7) M F-met-leu-phe. Acute smoke exposure resulted in elevation of nicotine in the smoke box to 529 ng/ml at 5 min, in saliva from 109.2 ng/ml before smoking to 1821.4 ng/ml after smoking, and in gingival crevicular fluid to 5961 ng/ml after smoking. No significant alterations in L-selectin or CD18 expression were noted with in vitro nicotine from 1.62 mg/ml to 162 ng/ml.

Host defensive, immunological, and microbiological observations of an early-onset periodontitis patient with virus-associated hemophagocytic syndrome

Virus-associated hemophagocytic syndrome (VAHS) is a disorder characterized by benign generalized histiocytic proliferation and marked hemophagocytosis associated with systemic viral infection. An immunodeficiency which includes an extremely decreased leukocyte and platelet count together with abnormalities in the CD4/CD8 ratio are the most common features of VAHS. Here we report an early-onset periodontitis (EOP) patient with VAHS from the standpoint of host-parasite interaction to understand the effect of this systemic disorder which might possibly influence susceptibility to periodontal disease. The patient is a 16-year-old Japanese male clinically diagnosed as having generalized EOP with slight gingival inflammation and moderate bone loss. This patient manifested VAHS at 3 years of age, and then had an unusual 4 recurrences (at 5, 7, 11, and 14 years old). Laboratory tests conducted include: 1) complete blood analyses: 2) peripheral neutrophil functions (chemotaxis, phagocytosis, superoxide production, and adherence); 3) peripheral lymphocyte subpopulations and functions, T-cell proliferative activity and productivity of cytokines (interleukin-2 [IL-2], interferon gamma [IFN-gamma], and tumor necrosis factor alpha [TNF-alpha]); 4) serum cytokine levels (IL-1 beta, IL-2, soluble IL-2 receptor [sIL-2R], IL-4, IL-6, IFN-gamma, and TNF-alpha; 5) serum immunoglobulin G (IgG) antibody titers against periodontopathic bacteria; 6) serological human leukocyte antigen (HLA) typing; and 7) determination of bacterial flora of the periodontal pockets. The results indicated that the patient's neutrophil chemotaxis and random migration were below the normal range. In lymphocyte examinations, T-cell proliferative activity, IL-2, and IFN-gamma productivity were elevated. Serum IFN-gamma level was also significantly higher than normal range. No specific periodontopathic bacteria were predominant in the periodontal pockets, however, the serum IgG titer against Porphyromonas gingivalis was elevated throughout the examination period. It is suggested that VAHS might be a possible risk factor for periodontal disease, and hence may serve as a model in understanding the role of host defense mechanisms in the establishment of inflammatory periodontal disease.

Immunological, genetic, and microbiological study of family members manifesting early-onset periodontitis

From the standpoint of host-parasite interactions, family studies help us understand the host defensive factors and the molecular mechanisms involved in the periodontal immune response. In this study, we report the immunological profile of host-defensive functions, human leukocyte antigen (HLA) phenotypes, and the microflora of a mother (rapidly progressive periodontitis), an older son (periodontally healthy), a younger son (localized juvenile periodontitis), and a daughter (localized juvenile periodontitis). We examined the peripheral neutrophil functions, phenotypic and functional analysis of peripheral lymphocytes, serum immunoglobulin G (IgG) antibody titers against periodontopathic bacteria, serological type of HLA class II antigens, and bacterial flora in all periodontal pockets. The results showed that Actinobacillus actinomycetemcomitans was dominant in the pockets of all subjects. The mother and two sons showed a depressed neutrophil chemotaxis to N-formyl-methionyl-leucyl-phenylalanine. All subjects except the older son exhibited low T4/T8 ratios. The mother and daughter had raised levels of IgG titers to Porphyromonas gingivalis. All subjects had HLA phenotypes of DRw52 and DQ1 in common. We found that the family members had similar disorders in certain defensive functions. This family has been a model for our understanding of the host defensive factors in the development of early-onset periodontitis.