|Molecular Vision 2007;
Received 17 January 2007 | Accepted 14 May 2007 | Published 14 May 2007
Investigation of the association between interleukin-1β polymorphism and normal tension glaucoma
Chun Yuan Wang,1,3
Ying-Cheng Shen,1,4 Chien-Hui Su,2 Fai-Yun Lo,2
Shi-Huang Lee,1 Hin-Yeung Tsai,1 Seng-Sheen Fan2
1Department of Ophthalmology, Taichung Veterans General Hospital, National Yang-Ming University; 2Department of Life Science and Life Science Research Center, Tunghai University; 3Hung Kuang University; 4Overseas Chinese Institute of Technology, Taichung, Taiwan, Republic of China
Correspondence to: Hin-Yeung Tsai, Department of Ophthalmology, Taichung Veterans General Hospital, No.160, sec. 3, Taichung Harbor Road, Taichung, 407, Taiwan, Republic of China; Phone: 886-4-23592525, ext. 4207; FAX: 886-4-23591607; email:firstname.lastname@example.org
Purpose: In normal tension glaucoma (NTG), factors other than elevated intraocular pressure are likely to have a role in the pathogenesis of optic neuropathy. The potential similarities in cellular apoptosis leading to neurodegeneration between Alzheimer's disease and NTG were shown in recent studies. The interleukin-1β (IL-1β; -511) and IL-1β (+3953) polymorphisms were found to increase risk with Alzheimer's disease. The purpose of this study was to test the hypothesis that the IL-1β polymorphism is associated with NTG in the Chinese population.
Methods: This is a cohort study in a Chinese population that involved 231 people with NTG and 245 healthy controls. Genomic DNA was amplified by a polymerase chain reaction, followed by the enzymatic restriction fragment length polymorphism technique. Patients and controls were genotyped for the C/T polymorphism at position -511 and +3953 of the IL-1β gene. Genotypes for NTG and control groups were compared for statistically significant differences.
Results: There was no significant difference in genotype frequency or allele frequency distribution of the IL-1β gene polymorphisms (position -511 and +3953) between NTG patients and the control group (p >0.3).
Conclusions: Our study showed no evidence for an association between the IL-1β (-511) and IL-1β (+3953) polymorphisms and NTG. The IL-1β gene polymorphisms (position -511 and +3953) may not play a key role in NTG pathogenesis in Chinese population.
Glaucoma is a degenerative optic neuropathy characterized by loss of retinal ganglion cells, cupping of the optic nerve head, and visual field defects often related to elevated intraocular pressure. The disease affects approximately 70 million people worldwide and is the second most common cause of blindness . Factors other than IOP are likely to have a role in the pathogenesis of glaucomatous optic neuropathy, particularly in individuals with normal tension glaucoma (NTG). NTG is a subtype of primary open angle glaucoma (POAG) and accounts for one-third of all cases of POAG . Patients with NTG show IOP measurements within the statistically normal range, and these patients usually present late in life after a visual field defect has occurred. A genetic approach is needed to identify those at risk of developing NTG.
Recent laboratory evidence shows a connection between abnormal autoimmunity and NTG, suggesting NTG may be a glaucomatous condition affected by antibodies damaging retinal tissue and inducing apoptosis. Wax et al.  found deposition of IgG, IgA, and retinal antibodies in the retinal ganglion cell of NTG patients. Fellman et al.  noted that patients with NTG and rheumatoid disease have a high level of serum antibodies to rhodopsin and heat shock protein 60.
Shinji et al.  found interleukin-1β (IL-1β) plays an important role in mediating ischemic and excitotoxic damage in the retina in glaucoma. Proinflammatory cytokines, such as IL-1, as well as other indicators of microglial activation, have been suggested as drivers of neuropathological changes in several neurodegenerative conditions.
Vickers et al.  presented evidence that the neuronal pathology of Alzheimer's disease contributes to an aberrant regenerative response of nerve cells triggered by the gradual compression and physical damage to axons within beta-amyloid plaques that form in the brain. Glaucoma may be a chronic neurodegeneration like Alzheimer's disease, because similar evidence also indicates there is beta-amyloid build-up in retinal ganglion cells in rats with experimental glaucoma [7,8]. In this regard, glaucoma may be viewed as a chronic neurodegenerative disease similar to Alzheimer's disease, and a slow build up of beta-amyloid in the ganglion cell may eventually trigger cell death and optic nerve axon loss. There is evidence that the IL-1 protein may act to promote the development of beta-amyloid deposits [9-12].
Researchers have noted several polymorphic regions in the IL-1β gene. A C/T polymorphism at position -511 of the IL-1β gene in the promoter region has been reported to be associated with Alzheimer's disease, with the IL-1β(-511) T allele polymorphism found to increase the risk for late-onset Alzheimer's disease [13-15]. The other polymorphism in IL-1β (at position +3953 in exon 5) has shown an association with the risk for Alzheimer's disease .
NTG may be a chronic neurodegeneration like Alzheimer's disease. Given the potential similarities in cellular events leading to neurodegeneration between Alzheimer's disease and glaucoma, we hypothesized that the IL-1β (-511) and IL-1β (+3953) polymorphisms, because of the effect on IL-1 protein expression, may predispose affected individuals to glaucoma. We therefore sought to investigate the distribution of IL-1β (-511) and IL-1β (+3953) polymorphisms in NTG patients and compare them with a healthy control population.
Subjects were recruited at the outpatient clinic in the Department of Ophthalmology at the Veterans General Hospital, Taichung, Taiwan from January 2004 to February 2007. NTG patients were approached as they visited the clinic for previously scheduled visits and were enrolled after consenting to participate in the study. Normal control subjects were recruited during their visits to the outpatient clinic for various other reasons. Written informed consent was obtained from all study subjects prior to enrollment. The study was carried out with the approval of the Human Study Committee of the Veterans General Hospital.
All participants received comprehensive ophthalmologic examinations including visual acuity testing with refraction, IOP measurement, Humphrey 30-2, slit lamp examination, and dilated slit lamp stereobiomicroscopy. Comprehensive ophthalmologic history and longitudinal follow data were also obtained for each individual. The definition for NTG included the presence of typical glaucomatous optic neuropathy with compatible visual field defects (arcuate, Bjerrum, Seidel and/or paracentral scotoma and/or nasal step on Humphrey 30-2), open anterior chamber angle, and absence of any contributing ocular or systemic disorders. Patients with NTG had untreated IOP measurements that were consistently 21 mmHg or lower on diurnal test and at follow-up.
Unrelated control subjects were recruited from clinic patients who were seeking treatment for senile cataract, floater, refractive errors, or itchy eye. All normal control subjects had no systemic disease and no family history of glaucoma. They were excluded from glaucoma using the same criteria of diagnosis as the NTG patients after the same ophthalmic examination procedure.
DNA preparation and genotype identification
Blood samples were collected from each subject (5 ml) and genomic DNA was isolated using the Qiagen QiaAmp Blood mini kit (Qiagen, Valencia, CA). IL-1β C(-511)T and C(+3953)T genotyping of genomic DNA were determined with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. A 304 bp PCR fragment of the IL-1β (-511) in the promoter region was amplified using the following primers: F5'-TGG CAT TGA TCT GGT TCA TC-3' and R5'-GTT TAG GAA TCT TCC CAC TT-3'. PCR conditions were as follows: a denaturing step of 95 °C for 10 min, then 35 cycles of 95 °C for 45 s, 60 °C for 45 s, 72 °C for 1 min, and a final incubation at 72 °C for 5 min. The products were digested with Bsu36I (New England Biolabs, Inc., Beverly, MA) at 37 °C for 3 h and were run on ethidium bromide-stained 2% agarose gel. This gave products that either remained intact (C allele) or were cut into two fragments of 190 and 114 bp (T allele).
The polymorphic region containing the TaqI (New England Biolabs, Inc.) restriction site at position +3953 within exon 5 of the IL-1β gene was amplified using the following primers: F5'-GTT GTC ATC AGA CTT TGA CC-3' and 5'-TTC AGT TCA TAT GGA CCA GA-3'. The PCR conditions were the same as described in the previous. The products were digested with TaqI at 65 °C for 3 h. TaqI digestions of the 249 bp fragments were cut into two fragment of 135 and 114 bp (allele C) or remained intact (allele T).
Genotype and allele frequencies between the control and NTG groups were compared using the chi-square test and Fisher's exact test, respectively. Age and gender were compared between the control and NTG groups using the Student's t-test and Fisher's exact test, respectively. Odds ratios were computed to assess the strength of association between the presence of each genotype and the clinical diagnosis of NTG. A p value of less than 0.05 was defined to be of statistical significance. All statistical analyses were performed using SPSS 10.0 (SPSS Inc., Chicago, IL).The power calculation was carried out according to the method by Schlesselman .
The study consisted of 231 NTG patients (127 men, 104 women) and 245 normal controls (135 men, 110 women). The mean age was 70 years for the NTG patients (range 31-85) and 71 years for the controls (range 30-85). There was no difference between the control and NTG groups in age (p>0.05, t-test) and gender (p>0.05, Fisher's exact test). The mean and standard deviation of the maximum IOP was 17.5±2.1 mmHg for the NTG patients and 16.9 ±2.3 mmHg for the control subjects. No deviations from Hardy-Weinberg equilibrium could be seen in NTG patients and control studies.
The genotype and allele frequencies of the IL-1β (-511) and IL-1β (+3953) polymorphism in NTG and control subjects are presented in Table 1. There was no statistically significant difference in genotype frequency (GF) or allele frequency (AF) distribution of the two polymorphisms between NTG and control subjects. (IL-1β -511 AF: p=0.3, GF: p=0.4; IL-1β +3953 AF: p=0.88, GF: p=0.98)
The statistical power over 80% suggested that the probability of detecting a difference could be believable in this sample size.
Mutations in three genes (myocilin, optineurin, and WDR36) have been implicated in NTG [18-22]. Mutation in the optineurin gene was initially reported in 16.7% of families with hereditary primary open angle glaucoma (POAG), with most of them having NTG . Aung et al.  and Powell et al.  reported that NTG demonstrates an association with polymorphisms of the OPA1 gene on chromosome 3, which is responsible for dominant optic atrophy in the Caucasian population . Many more important gene variants have recently been associated with glaucoma risk, such as apolipoprotein E (APOE) [26,27], endothelin receptor type A gene (EDNRA) [28,29], IL-1α , methylenetetrahydrofolate reductase (MTHFR) [31,32], and beta-adrenergic receptors . However, these genes cannot interpret the overall inheritance susceptibility of NTG pathogenesis. The other associations involved in the development of NTG should be further investigated.
Recent evidence indicates a close link between chronic neurodegenerative disease and IL-1β expression. Polymorphism in the IL-1 gene clusters have been shown in myasthenia gravis, multiple sclerosis, Parkinson's disease, temporal lobe epilepsy with hippocampal sclerosis and Alzheimer's disease [34-38]. NTG may be a chronic neurodegeneration like Alzheimer's disease, considering the potential similarities in cellular events leading to neurodegeneration between Alzheimer's disease and glaucoma. There is evidence that IL-1β upregulates the production and processing of β-amyloid protein in neurons  as well as the expression and activity of acetylcholine esterase . Furthermore, it has been shown that IL-1β activated microglia selectively killed cholinergic neurons in Alzheimer's patients . The death of retinal ganglion cells in glaucoma involving chronic β-amyloid neurotoxicity mimics Alzheimer's disease at the molecular level . Our study was designed to see whether patients with NTG had a higher risk of developing the disease as a result of their IL-1β genotype.
NTG has been considered a subtype of POAG, sharing many similar characteristics. However, some studies show a connection between abnormal autoimmunity and NTG, suggesting the disease is affected more by antibodies damaging retinal ganglion cells and inducing apoptosis . Lin et al.  found that IL-1β (+3953) T allele was significantly more common in POAG patients than in control subjects in a Chinese population. However, there was no association between the IL-1β (position -511 and +3953) polymorphisms and NTG in our study. The dissimilar findings revealed that the pathogenesis and effect of IL-1β may be different between NTG and POAG. IL-1β may not have a significant role in the pathogenesis of the optic neuropathy.
Genes coding for the two isoforms of IL-1 (IL-1α and IL-1β) and for the IL-1 receptor antagonist (IL-1RA) are located within the IL1 gene cluster at chromosomal locus 2q13 . Polymorphisms within this gene cluster have been associated with a large variety of human diseases . Some of these polymorphisms have been shown to alter the amount of IL-1 produced [46-49]. These allelic variants are known to alter function. The C/T polymorphism at position -511 in the promoter region of IL-1β regulates the production of IL-1β protein and in vitro synthetic capacity of C/C genotype carriers are lower than that of C/T of T/T carriers . The homozygosity for the IL-1β (+3953T) allele has been associated with a fourfold increase in the production of IL-1β when compared to homozygosity for IL-1β (+3953C) allele .
Lack of association between IL-1β genetic polymorphism and NTG was observed in our study of a Chinese population. In our control group, the allele frequencies of the IL-1β (-511) were similar to those previous reported in other controls [43,51,52]. The frequency of IL-1β (-511) C allele and IL-1β (+3953) T allele were significantly lower among Chinese populations compared to Caucasians . The observed negative association could be due to the low frequency of the IL-1β (-511) C allele and IL-1β (+3953) T allele in a Chinese population. Further studies with NTG cohort of different ethnic background are required to further define this association. We cannot exclude the possibility of IL-1β (-511) and IL-1β (+3953) polymorphism being associated with NTG in different ethnic population or the likelihood of an association between NTG and another IL-1β polymorphism. The lack of an association of the common polymorphisms of the IL-1β with NTG in Chinese population suggests this factor may not have a significant role in the pathogenesis of the optic neuropathy.
In conclusion, we found no significant associations between polymorphisms in the IL-1β (-511 and +3953) and NTG in a Chinese population. However, the possibility of other mutations or sequence change in the IL-1β gene cannot be excluded. Further genetic studies of NTG are necessary to investigate the development of the neurodegenerative process.
This work was supported by grants from the Taichung Veterans General Hospital and Tunghai University (TCVGH-T-947802) Taichung, Taiwan, Republic of China. We express our sincere thanks to Dr. M. Elizabeth Fini at Bascom Palmer Eye Institute, University of Miami Miller School of Medicine for helpful comments during the preparation of this manuscript.
1. Quigley HA, Broman AT. The number of people with glaucoma worldwide in 2010 and 2020. Br J Ophthalmol 2006; 90:262-7.
2. Kamal D, Hitchings R. Normal tension glaucoma--a practical approach. Br J Ophthalmol 1998; 82:835-40.
3. Wax MB, Tezel G, Edward PD. Clinical and ocular histopathological findings in a patient with normal-pressure glaucoma. Arch Ophthalmol 1998; 116:993-1001.
4. Fellman RL, Tezel G, Wax MB. Effects of methotrexate treatment on serum immunoreactivity of a patient with normal-pressure glaucoma. Am J Ophthalmol 1999; 127:724-5.
5. Yoneda S, Tanihara H, Kido N, Honda Y, Goto W, Hara H, Miyawaki N. Interleukin-1beta mediates ischemic injury in the rat retina. Exp Eye Res 2001; 73:661-7.
6. Vickers JC, Dickson TC, Adlard PA, Saunders HL, King CE, McCormack G. The cause of neuronal degeneration in Alzheimer's disease. Prog Neurobiol 2000; 60:139-65.
7. McKinnon SJ. Glaucoma: ocular Alzheimer's disease? Front Biosci 2003; 8:s1140-56.
8. McDowell TL, Symons JA, Ploski R, Forre O, Duff GW. A genetic association between juvenile rheumatoid arthritis and a novel interleukin-1 alpha polymorphism. Arthritis Rheum 1995; 38:221-8.
9. Wisniewski T, Frangione B. Apolipoprotein E: a pathological chaperone protein in patients with cerebral and systemic amyloid. Neurosci Lett 1992; 135:235-8.
10. Rebeck GW, Reiter JS, Strickland DK, Hyman BT. Apolipoprotein E in sporadic Alzheimer's disease: allelic variation and receptor interactions. Neuron 1993; 11:575-80.
11. Schmechel DE, Saunders AM, Strittmatter WJ, Crain BJ, Hulette CM, Joo SH, Pericak-Vance MA, Goldgaber D, Roses AD. Increased amyloid beta-peptide deposition in cerebral cortex as a consequence of apolipoprotein E genotype in late-onset Alzheimer disease. Proc Natl Acad Sci U S A 1993; 90:9649-53.
12. Ma J, Yee A, Brewer HB Jr, Das S, Potter H. Amyloid-associated proteins alpha 1-antichymotrypsin and apolipoprotein E promote assembly of Alzheimer beta-protein into filaments. Nature 1994; 372:92-4.
13. Du Y, Dodel RC, Eastwood BJ, Bales KR, Gao F, Lohmuller F, Muller U, Kurz A, Zimmer R, Evans RM, Hake A, Gasser T, Oertel WH, Griffin WS, Paul SM, Farlow MR. Association of an interleukin 1 alpha polymorphism with Alzheimer's disease. Neurology 2000; 55:480-3.
14. Grimaldi LM, Casadei VM, Ferri C, Veglia F, Licastro F, Annoni G, Biunno I, De Bellis G, Sorbi S, Mariani C, Canal N, Griffin WS, Franceschi M. Association of early-onset Alzheimer's disease with an interleukin-1alpha gene polymorphism. Ann Neurol 2000; 47:361-5.
15. Nicoll JA, Mrak RE, Graham DI, Stewart J, Wilcock G, MacGowan S, Esiri MM, Murray LS, Dewar D, Love S, Moss T, Griffin WS. Association of interleukin-1 gene polymorphisms with Alzheimer's disease. Ann Neurol 2000; 47:365-8.
16. Hedley R, Hallmayer J, Groth DM, Brooks WS, Gandy SE, Martins RN. Association of interleukin-1 polymorphisms with Alzheimer's disease in Australia. Ann Neurol 2002; 51:795-7.
17. Schlesselman, JJ Case-control studies. New York: Oxford University Press; 1982.
18. Stone EM, Fingert JH, Alward WL, Nguyen TD, Polansky JR, Sunden SL, Nishimura D, Clark AF, Nystuen A, Nichols BE, Mackey DA, Ritch R, Kalenak JW, Craven ER, Sheffield VC. Identification of a gene that causes primary open angle glaucoma. Science 1997; 275:668-70.
19. Rezaie T, Child A, Hitchings R, Brice G, Miller L, Coca-Prados M, Heon E, Krupin T, Ritch R, Kreutzer D, Crick RP, Sarfarazi M. Adult-onset primary open-angle glaucoma caused by mutations in optineurin. Science 2002; 295:1077-9.
20. Monemi S, Spaeth G, DaSilva A, Popinchalk S, Ilitchev E, Liebmann J, Ritch R, Heon E, Crick RP, Child A, Sarfarazi M. Identification of a novel adult-onset primary open-angle glaucoma (POAG) gene on 5q22.1. Hum Mol Genet 2005; 14:725-33.
21. Weisschuh N, Neumann D, Wolf C, Wissinger B, Gramer E. Prevalence of myocilin and optineurin sequence variants in German normal tension glaucoma patients. Mol Vis 2005; 11:284-7 <http://www.molvis.org/molvis/v11/a33/>.
22. Sripriya S, Nirmaladevi J, George R, Hemamalini A, Baskaran M, Prema R, Ve Ramesh S, Karthiyayini T, Amali J, Job S, Vijaya L, Kumaramanickavel G. OPTN gene: profile of patients with glaucoma from India. Mol Vis 2006; 12:816-20 <http://www.molvis.org/molvis/v12/a92/>.
23. Aung T, Ocaka L, Ebenezer ND, Morris AG, Brice G, Child AH, Hitchings RA, Lehmann OJ, Bhattacharya SS. Investigating the association between OPA1 polymorphisms and glaucoma: comparison between normal tension and high tension primary open angle glaucoma. Hum Genet 2002; 110:513-4.
24. Powell BL, Toomes C, Scott S, Yeung A, Marchbank NJ, Spry PG, Lumb R, Inglehearn CF, Churchill AJ. Polymorphisms in OPA1 are associated with normal tension glaucoma. Mol Vis 2003; 9:460-4 <http://www.molvis.org/molvis/v9/a58/>.
25. Yao W, Jiao X, Hejtmancik JF, Leske MC, Hennis A, Nemesure B, Barbados Family Study Group. Evaluation of the association between OPA1 polymorphisms and primary open-angle glaucoma in Barbados families. Mol Vis 2006; 12:649-54 <http://www.molvis.org/molvis/v12/a73/>.
26. Vickers JC, Craig JE, Stankovich J, McCormack GH, West AK, Dickinson JL, McCartney PJ, Coote MA, Healey DL, Mackey DA. The apolipoprotein epsilon4 gene is associated with elevated risk of normal tension glaucoma. Mol Vis 2002; 8:389-93 <http://www.molvis.org/molvis/v8/a46/>.
27. Mabuchi F, Tang S, Ando D, Yamakita M, Wang J, Kashiwagi K, Yamagata Z, Iijima H, Tsukahara S. The apolipoprotein E gene polymorphism is associated with open angle glaucoma in the Japanese population. Mol Vis 2005; 11:609-12 <http://www.molvis.org/molvis/v11/a72/>.
28. Ishikawa K, Funayama T, Ohtake Y, Kimura I, Ideta H, Nakamoto K, Yasuda N, Fukuchi T, Fujimaki T, Murakami A, Asaoka R, Hotta Y, Kanamoto T, Tanihara H, Miyaki K, Mashima Y. Association between glaucoma and gene polymorphism of endothelin type A receptor. Mol Vis 2005; 11:431-7 <http://www.molvis.org/molvis/v11/a50/>.
29. Kim SH, Kim JY, Kim DM, Ko HS, Kim SY, Yoo T, Hwang SS, Park SS. Investigations on the association between normal tension glaucoma and single nucleotide polymorphisms of the endothelin-1 and endothelin receptor genes. Mol Vis 2006; 12:1016-21 <http://www.molvis.org/molvis/v12/a114/>.
30. Wang CY, Shen YC, Lo FY, Su CH, Lee SH, Lin KH, Tsai HY, Kuo NW, Fan SS. Polymorphism in the IL-1alpha (-889) locus associated with elevated risk of primary open angle glaucoma. Mol Vis 2006; 12:1380-5 <http://www.molvis.org/molvis/v12/a155/>.
31. Junemann AG, von Ahsen N, Reulbach U, Roedl J, Bonsch D, Kornhuber J, Kruse FE, Bleich S. C677T variant in the methylentetrahydrofolate reductase gene is a genetic risk factor for primary open-angle glaucoma. Am J Ophthalmol 2005; 139:721-3.
32. Mabuchi F, Tang S, Kashiwagi K, Yamagata Z, Iijima H, Tsukahara S. Methylenetetrahydrofolate reductase gene polymorphisms c.677C/T and c.1298A/C are not associated with open angle glaucoma. Mol Vis 2006; 12:735-9 <http://www.molvis.org/molvis/v12/a82/>.
33. Inagaki Y, Mashima Y, Fuse N, Funayama T, Ohtake Y, Yasuda N, Murakami A, Hotta Y, Fukuchi T, Tsubota K. Polymorphism of beta-adrenergic receptors and susceptibility to open-angle glaucoma. Mol Vis 2006; 12:673-80 <http://www.molvis.org/molvis/v12/a75/>.
34. Griffin WS, Mrak RE. Interleukin-1 in the genesis and progression of and risk for development of neuronal degeneration in Alzheimer's disease. J Leukoc Biol 2002; 72:233-8.
35. Huang D, Pirskanen R, Hjelmstrom P, Lefvert AK. Polymorphisms in IL-1beta and IL-1 receptor antagonist genes are associated with myasthenia gravis. J Neuroimmunol 1998; 81:76-81.
36. Kanemoto K, Kawasaki J, Miyamoto T, Obayashi H, Nishimura M. Interleukin (IL)1beta, IL-1alpha, and IL-1 receptor antagonist gene polymorphisms in patients with temporal lobe epilepsy. Ann Neurol 2000; 47:571-4.
37. Muller N, Ackenheil M. Psychoneuroimmunology and the cytokine action in the CNS: implications for psychiatric disorders. Prog Neuropsychopharmacol Biol Psychiatry 1998; 22:1-33.
38. Sciacca FL, Ferri C, Vandenbroeck K, Veglia F, Gobbi C, Martinelli F, Franciotta D, Zaffaroni M, Marrosu M, Martino G, Martinelli V, Comi G, Canal N, Grimaldi LM. Relevance of interleukin 1 receptor antagonist intron 2 polymorphism in Italian MS patients. Neurology 1999; 52:1896-8.
39. Sheng JG, Ito K, Skinner RD, Mrak RE, Rovnaghi CR, Van Eldik LJ, Griffin WS. In vivo and in vitro evidence supporting a role for the inflammatory cytokine interleukin-1 as a driving force in Alzheimer pathogenesis. Neurobiol Aging 1996; 17:761-6.
40. Li Y, Liu L, Kang J, Sheng JG, Barger SW, Mrak RE, Griffin WS. Neuronal-glial interactions mediated by interleukin-1 enhance neuronal acetylcholinesterase activity and mRNA expression. J Neurosci 2000; 20:149-55.
41. McMillian M, Kong LY, Sawin SM, Wilson B, Das K, Hudson P, Hong JS, Bing G. Selective killing of cholinergic neurons by microglial activation in basal forebrain mixed neuronal/glial cultures. Biochem Biophys Res Commun 1995; 215:572-7.
42. Gutteridge IF. Normal tension glaucoma: diagnostic features and comparisons with primary open angle glaucoma. Clin Exp Optom 2000; 83:161-172.
43. Lin HJ, Tsai SC, Tsai FJ, Chen WC, Tsai JJ, Hsu CD. Association of interleukin 1beta and receptor antagonist gene polymorphisms with primary open-angle glaucoma. Ophthalmologica 2003; 217:358-64.
44. Nicklin MJ, Barton JL, Nguyen M, FitzGerald MG, Duff GW, Kornman K. A sequence-based map of the nine genes of the human interleukin-1 cluster. Genomics 2002; 79:718-25.
45. Haukim N, Bidwell JL, Smith AJ, Keen LJ, Gallagher G, Kimberly R, Huizinga T, McDermott MF, Oksenberg J, McNicholl J, Pociot F, Hardt C, D'Alfonso S. Cytokine gene polymorphism in human disease: on-line databases, supplement 2. Genes Immun 2002; 3:313-30.
46. Pociot F, Molvig J, Wogensen L, Worsaae H, Nerup J. A TaqI polymorphism in the human interleukin-1 beta (IL-1 beta) gene correlates with IL-1 beta secretion in vitro. Eur J Clin Invest 1992; 22:396-402.
47. Hall SK, Perregaux DG, Gabel CA, Woodworth T, Durham LK, Huizinga TW, Breedveld FC, Seymour AB. Correlation of polymorphic variation in the promoter region of the interleukin-1 beta gene with secretion of interleukin-1 beta protein. Arthritis Rheum 2004; 50:1976-83.
48. Maury CP, Liljestrom M, Laiho K, Tiitinen S, Kaarela K, Hurme M. Anaemia of chronic disease in AA amyloidosis is associated with allele 2 of the interleukin-1beta-511 promoter gene and raised levels of interleukin-1beta and interleukin-18. J Intern Med 2004; 256:145-52.
49. Dominici R, Cattaneo M, Malferrari G, Archi D, Mariani C, Grimaldi LM, Biunno I. Cloning and functional analysis of the allelic polymorphism in the transcription regulatory region of interleukin-1 alpha. Immunogenetics 2002; 54:82-6.
50. Santtila S, Savinainen K, Hurme M. Presence of the IL-1RA allele 2 (IL1RN*2) is associated with enhanced IL-1beta production in vitro. Scand J Immunol 1998; 47:195-8.
51. Hurme M, Santtila S. IL-1 receptor antagonist (IL-1Ra) plasma levels are co-ordinately regulated by both IL-1Ra and IL-1beta genes. Eur J Immunol 1998; 28:2598-602.
52. Tarlow JK, Blakemore AI, Lennard A, Solari R, Hughes HN, Steinkasserer A, Duff GW. Polymorphism in human IL-1 receptor antagonist gene intron 2 is caused by variable numbers of an 86-bp tandem repeat. Hum Genet 1993; 91:403-4.
53. Tseng LH, Chen PJ, Lin MT, Shau WY, Chaung SM, Martin PJ, Hansen JA. Single nucleotide polymorphisms in intron 2 of the human interleukin-1 receptor antagonist (IL-1Ra) gene: further definition of the IL-1 beta and IL-1Ra polymorphisms in North American Caucasians and Taiwanese Chinese. Tissue Antigens 2001; 57:318-24.