4. Conclusions

In this study, there were several main findings. First we noted that there was a trend for a reduced frequency of the GG polymorphism of IL-6 in the octo/nonagen- arians from the BELFAST study group compared with younger subjects in the local population, aged 20(cid:4)45 / years of age. This trend appeared more marked in elderly males compared with females (Ross et al., 2003) but both groups showed an almost 10% decrease in

The effect of IL-6-174C/G genotype on IL-6 and IL- 10 secretion into supernatants from in vitro monocyte monocultures is shown in Fig. 2. Although the sponta- neous secretion of IL-6 into the supernatants increased

asneasdCn Se SS 1L10-TO IL6-T20hrs 1L10-T20

Fig. 2. Monocyte supernatant levels of IL-6 and IL-10 categorised by CC, CG and GG genotypes of -174 C/G polymorphism of IL-6 at zero time (TO) or at 20 h (T20).

finding which deserves further focused attention and priority study. In this context, there are well described differences in ApoE genotype frequency across Europe and world populations which undoubtedly link into pathological and environmental disease mechanisms and differential morbidity and mortality rates from atherosclerotic-related disease, and there may be similar effects for C/G IL-6 genotypes.

noted a marked reduction in GG homozygotes in male though not female Italian centenarians compared with elderly (60(cid:4)80 years) and long-lived (80(cid:4)99 years) / / subjects. The finding of a decrease in the GG poly- morphism in Irish male octo/nonagenarian subjects is intriguing since it appears to confirm in a different study population and with a different study design, the earlier findings obtained in the Italian population (Bonafe et al., 2001). In contrast, Wang et al. (2001), in a study of community living and hospitalised nonagenarians in Finland detected no significant change in IL-6 frequen- cies between nonagenarians and 400 healthy blood donors, aged 18(cid:4)60 years, though a reduction of 2% / was noted in GG frequency in comparison with their widely age-selected younger control group. Interest- ingly, the frequency of the C allele of the IL-6-174 polymorphism, appears to vary across Europe(cid:4)Ireland / 0.45 (present study), UK 0.37(cid:4)0.45 (Fishman et al., / 1998; Brull et al., 2001), Finland 0.54 (Wang et al., 2001) and Italy 0.50 (Bonafe et al., 2001), with a report in USA of 0.39 (Ferrari et al., 2001). Intriguingly, in Asian and African-American populations the CC homozy- gotes and heterozygotes are relatively rare (Oisiri et al., 1999; Zhai et al., 2001). It is unclear whether these differences represent true pathological and disease- related pressures on population genotypes or whether they represent methodological differences. However, the trend for a reduction in GG homozygosity in elderly males would seem to be an important and consistent

Also of interest is the finding of the dichotomy of effect of the C/G 174 polymorphism on IL-6 serum levels. In this study, we have found an increase in serum IL-6 levels in CC homozygotes and subjects carrying the C allele in our octo/nonagenarian subjects in the BELFAST study. In his original study, Fishman noted an increase in serum IL-6 levels in GG homozygotes in healthy subjects compared with those with juvenile rheumatoid arthritis. Additionally, he demonstrated in HeLa cells that an -174C construct showed lower basal and stimulated expression of the reporter gene, com- pared with the -174G construct (Fishman et al., 1998). Conversely Jones et al. (2001) showed that subjects with small aortic aneurysms who carried the CC genotype had both the highest serum IL-6 and mortality risk, but argued that the association might not be direct but could track with co-existing atherosclerotic disease. Recently Basso et al. (2002) also showed increased IL-6, CRP and fibrinogen associated with CC genotype and improved fall in LDL with statin treatment. In other data Franceschi et al. (2001) has shown higher IL-6 levels in CC dementia subjects. In a Finnish study in neonates

A third aspect of our study was to describe the effect of the IL-6-174 C/G polymorphism on IL-6 and IL-10 secreted into supernatants collected from separated mononuclear monolayers. IL-6 has been widely de- scribed to be increased in the serum in older subjects, considered to mainly originate from mononuclear cells and its production to be influenced by a variety of physiological and other stimuli (Roubenoff et al., 1998; Bornefalk et al., 1997; Fagiola et al., 1993; Rachon et al., 2002; Ershler et al., 1993b). Like other groups, we found that IL-6 was spontaneously released from monocytes prepared from elderly subjects with increases of 100 and 10 fold for IL-6 and IL-10, respectively, after unstimulated incubation for 20 h. As in serum, we found similar effects for the monocyte supernatants with C allele subjects releasing higher levels of IL-6, with reciprocal effects for IL-10. Presumably in most infec- tious or chronic inflammatory situations, there is a balancing between the pro inflammatory and anti inflammatory cytokine network and if up regulation of the IL-6-174 C/G polymorphism can influence both IL-6 and IL-10 directly, then the fine tuning of the immune response mechanism is improved.