Optimizing human fertility and survival

Interleukin 10-2849AA genotype protects against pre-eclampsia

Recently, it has been described that human fertility is associated with the interleukin 10 (IL10) -2849 AA genotype. Pre-eclampsia is the most common pregnancy-specific complication. In the pathogenesis of pre-eclampsia, IL10 may affect maternal intravascular inflammation as well as endothelial dysfunction. Therefore, we tested the hypothesis that pre-eclampsia is associated with genetic variation in the IL10 promoter region in a case-control study for pre-eclampsia. Women homozygous for the IL10 -2849A allele have a threefold reduced risk for pre-eclampsia compared to controls (odds ratio 0.29; 95% CI 0.10-0.83). No differences in genotype frequency were found for polymorphisms in the IL10 promoter region at positions -1082, -819 and -592. This suggests that there is a genetically determined mechanism which protects the mother against pre-eclampsia, as reflected in the lower frequency of the IL10 -2849AA genotype in pre-eclamptic women.

Miscarriage but not fecundity is associated with progression of joint destruction in rheumatoid arthritis

OBJECTIVE

To determine whether reproductive history before disease onset is associated with severity of joint destruction in rheumatoid arthritis.

METHODS

A special early arthritis clinic (EAC) was established at the department of rheumatology of Leiden University Medical Centre. General practitioners were encouraged to refer patients with joint complaints to this clinic, where the diagnosis of rheumatoid arthritis was made by a rheumatologist. In all, 113 female patients with definite rheumatoid arthritis were included in this study. A structured questionnaire was administered and joint damage was assessed by sequential x rays of the hands and feet, using the modified Sharp score.

RESULTS

The length of time of unprotected intercourse until first pregnancy (fecundity) was comparable with data from earlier studies, with 16% of the patients reporting a time to first pregnancy of more than 12 months. Fecundity did not reflect the extent of joint damage over time. The miscarriage rate was 15% per pregnancy, comparable to population figures (12-15%). A significant increase in joint damage over a two year follow up was found in patients with rheumatoid arthritis who had experienced at least one miscarriage compared with those who had never had a miscarriage (mean modified Sharp scores at 2 years, 24 (95% confidence interval, 15 to 32) and 16 (10 to 23), respectively; p<0.05). At baseline, the Sharp scores were similar in the two subgroups.

CONCLUSIONS

Miscarriage before disease onset but not fecundity is associated with the progression of joint damage in rheumatoid arthritis.

Host factors impacting the innate response in humans to the candidate adjuvants RC529 and monophosphoryl lipid A

The aim of this study was to determine if certain genotypes might be associated with variable responses to the candidate vaccine adjuvants RC529 and monophosphoryl lipid A (MPL), as well as to bacterial LPS, a structurally similar control stimulus. In this study, the +896 TLR4 polymorphism and selected cytokine polymorphisms were genotyped, and together with the donor sex, these factors were used to model the in vitro cytokine responses to RC529, MPL, and LPS. We show evidence that each of the three stimuli engage human TLR4, that each gave higher responses in men than women, and that TLR4 expression levels in blood monocytes were higher in men than women. From 74 to 92% of the response variation in the whole blood assay was between subjects, yet the multifactorial analyses accounted for only 3-18% of the variation within the study. Potentially there was a sex-dependent TLR4 effect since there was a significant sex-TLR4 interaction term in the multifactorial model for some responses. Since the genotypes we analyzed had such a modest impact in the study, we anticipate that +896 TLR4 genotype and the other factors analyzed in this study have only incremental effects in determining the overall response to TLR4-engaging stimuli.

Transcription of the IL10 gene reveals allele-specific regulation at the mRNA level

Interleukin-10 (IL10) is a cytokine with key regulatory and anti-inflammatory function involved in the pathogenesis of various diseases. Although the large interindividual differences in the production of IL10 have been extensively associated with polymorphisms and haplotypes of the IL10 gene, surprisingly little evidence exists that this variation is actually dictated by IL10 haplotypes. Using the technique of allele-specific transcript quantification, the ratio between two alleles (A and G) of the IL10 gene was characterized in 15 healthy heterozygous individuals. Two groups were identified whereby donors in group 1 exhibited a 1 : 1 ratio, whereas those in group 2 exhibited a ratio>1 (P<0.0017). We found that donors heterozygous for haplotype IL10.2 (one of the four ancient IL10 haplotypes) were only prevalent in the group that showed higher allelic expression ratios. In this study we show that IL10 alleles are indeed differentially transcribed in cells from heterozygous individuals and that IL10 haplotypes dictate production of IL10. These findings show that interindividual differences in IL10 protein levels can be explained at the transcriptional level.

Inflammation underlying cardiovascular mortality is a late consequence of evolutionary programming

With the increase in life expectancy, death from cardiovascular disease has risen greatly. There is increasing evidence that inflammation plays an important role in cardiovascular disease. We postulate that the development of cardiovascular disease in old age is a late consequence of evolutionary programming for a pro-inflammatory response to resist infections in early age. In 311 women, aged 85 yr old, the production of the pro- and anti-inflammatory cytokines tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 was determined in lipopolysaccharide-stimulated whole blood samples and studied prospectively in association with cardiovascular mortality. High TNF-alpha was a risk factor for death from cardiovascular disease (relative risk [RR] = 1.56; 95% confidence interval [CI]: 1-2.40), whereas high IL-10 was protective (RR = 0.58; 95% CI: 0.40-0.85). A genetic variant of the IL-10 gene promoter, which is associated with lower IL-10 production, was found to predispose to a 2.8-fold higher cardiovascular mortality risk (95% CI: 1.17-6.60). Reproductive success, which was studied as a measure of evolutionary programming because it trades off with early survival by pro-inflammatory resistance genes, was negatively associated with an increasing production of TNF-alpha (RR = 0.77; 95% CI: 0.68-0.88), while a positive association with IL-10 was found (RR = 1.22; 95% CI: 1.05-1.41). We suggest that cardiovascular mortality is a late consequence of evolutionary programming for a pro-inflammatory response.

Tying It Together

Rudi Westendorp, a Dutch physician-scientist known for his love of bow ties, seeks elegant solutions in his work as a clinical epidemiologist, geriatrician, and gerontologist at Leiden University Medical Center in the Netherlands. After completing his residency training and earning a Ph.D., in 1993 he made a detour into clinical epidemiology, studying patient populations to identify underlying risk factors for disease. He now supervises the long-running Leiden 85-plus study, which tracks cognitive decline, heart disease, and other illnesses in very old people. To round out his knowledge, Westendorp spent 1998 studying the biology of aging at the University of Manchester, U.K. His quest to test the evolutionary theory of the tradeoff between fertility and longevity has led him into the genealogical archives of British aristocrats and, more recently, to Ghana.

Comparative Studies of Senescence in Natural Populations of Guppies

Investigators have rarely sought evidence for senescence in natural populations because it is assumed that relatively few individuals will survive long enough in the wild to exhibit the intrinsic increase in mortality with age expected from senescent individuals. Nevertheless, senescence has been documented in some natural populations, mostly in birds and mammals. Here we report on a comparative study of senescence in two natural populations of guppies (Poecilia reticulata). We document senescence as an age-specific increase in mortality rate, with use of mark-recapture studies and implementation of program MARK for analysis of such observations. Extrinsic mortality was controlled for by choosing populations that experience low rates of predation because they coexist with only a single piscine predator (Rivulus hartii). These populations differ in their evolutionary history because one was native to such a site whereas the other was introduced to a site that previously contained no guppies. The source of the introduced guppies was a high-predation population downstream below a barrier waterfall. Theory predicts that the guppies derived from a high-predation locality should experience senescence at an earlier age than the native low-predation population; however, the historical differences among these populations are also confounded with everything else that differs among the two localities. We found that females from a natural low-predation population have delayed senescence compared with the recently established population and hence that the differences among localities in senescence conform to theoretical predictions. The males from natural low-predation environments also had lower overall mortality rates, but contrary to predictions, the pattern of senescence for males did not differ between populations. The difference between the sexes is potentially attributable to two factors that lower the statistical power for distinguishing differences in the age-specific acceleration of mortality in males. One factor is that males have higher mortality rates, so fewer survive to advanced ages. A second is that we had a greater ability to discriminate among older age classes in females. We also found that the introduced population sustained a higher rate of disease than the native low-predation population. Such disease may represent a confounding factor in our comparison, but it may also reflect one of the trade-offs inherent in the life-history differences of these populations.

Are we becoming less disposable?

Evolution has programmed us for early survival and reproduction but has left us vulnerable to disease in old age. In our present affluent environment, we are better adapting to these improved conditions.

Evidence for extensive transmission distortion in the human genome

It is a basic principle of genetics that each chromosome is transmitted from parent to offspring with a probability that is given by Mendel's laws. However, several known biological processes lead to skewed transmission probabilities among surviving offspring and, therefore, to excess genetic sharing among relatives. Examples include in utero selection against deleterious mutations, meiotic drive, and maternal-fetal incompatibility. Although these processes affect our basic understanding of inheritance, little is known about their overall impact in humans or other mammals. In this study, we examined genome screen data from 148 nuclear families, collected without reference to phenotype, to look for departures from Mendelian transmission proportions. Using single-point and multipoint linkage analysis, we detected a modest but significant genomewide shift towards excess genetic sharing among siblings (average sharing of 50.43% for the autosomes; P=.009). Our calculations indicate that many loci with skewed transmission are required to produce a genomewide shift of this magnitude. Since transmission distortion loci are subject to strong selection, this raises interesting questions about the evolutionary forces that keep them polymorphic. Finally, our results also have implications for mapping disease genes and for the genetics of fertility.

Will Human Life Expectancy Quadruple in the Next Hundred Years? Sixty Gerontologists Say Public Debate on Life Extension Is Necessary

Sixty gerontologists were asked for estimates regarding the development of future life expectancy. For a person born in the year 2100, life expectancy estimates had a median of 100 years and a mean of 292 years. Changes in biogerontology suggest that the search for the "fountain of youth" is gaining respectability, becoming competitive with compression of morbidity as the predominant scientific goal. Appropriate debate should address questions raised by such a goal and prepare for sudden advances that may have a large impact on society.

Reproduction and longevity among the British peerage: the effect of frailty and health selection

Whether a cost of reproduction exists among humans is still questionable. A major study of aristocratic British families finds a significant positive correlation between parity and late-life mortality, which indicates a trade-off between reproduction and longevity. This result is supported by four other studies, while earlier studies have not found a relationship or came to the opposite conclusion. We show that in natural fertility populations the relationship between fertility and late-life mortality cannot be studied correctly without considering the effects of differences in health and of mortality selection during childbearing ages because these two effects lead to a dampening of the true relationship. If these effects are controlled in Hollingsworth's genealogy of the British peerage a significant trade-off between reproduction and longevity exists for females but not for males.

Association of the -2849 interleukin-10 promoter polymorphism with autoantibody production and joint destruction in rheumatoid arthritis

OBJECTIVE

To analyze the -2849 A/G interleukin-10 (IL-10) promoter polymorphism, which is associated with high (AG/GG) and low (AA) IL-10 production, in a cohort of rheumatoid arthritis (RA) patients and controls in order to gain a better understanding of its role in the incidence and progression of RA.

METHODS

Allele frequencies of the promoter polymorphism -2849 A/G and carriage rates were compared in 283 RA patients, 413 patients with other rheumatic diseases, and 1,220 healthy controls. The rate of joint damage and baseline levels of IgG and IgM rheumatoid factors and anti-citrullinated peptide antibodies were measured and were correlated with the IL-10 gene polymorphism. Furthermore, the correlation between the invasiveness of fibroblast-like synoviocytes (FLS) and the -2849 IL-10 genotype was tested.

RESULTS

The IL-10 genotype was not associated with the incidence of RA, but instead, correlated with disease progression, as determined by the extent of joint destruction. A higher rate of joint destruction was observed in patients with the genotype associated with high IL-10 production. Since FLS are thought to be involved in joint destruction, we analyzed IL-10 genotypes in conjunction with FLS invasiveness. Although adenoviral gene transfer of IL-10 to FLS inhibited their invasiveness, no differences were observed in vitro in the FLS from RA patients who were -2849 non-G carriers compared with those who were G carriers. Instead, patients with the -2849 AG/GG genotype, which is associated with high IL-10 production, had higher autoantibody titers at baseline.

CONCLUSION

The -2849 IL-10 promoter polymorphism is associated with autoantibody production and subsequent joint damage in RA.

Gonadotropin-releasing hormone alters the T helper cytokine balance in the pregnant rat

The interactions between immune-endocrine and reproductive systems are heightened during pregnancy as an adaptive mechanism, and are regulated by a complex array of hormones and cytokines that control the survival of a semiallogeneic conceptus. GnRH can exert direct effects on the immune system via its receptor (GnRH-R) on lymphoid cells. In the present study, we employed in vitro, ex vivo, and in vivo approaches to investigate the role of GnRH in the modulation of T helper cytokines in pregnant rats undergoing termination of pregnancy. Day 8 pregnant rats were infused with a GnRH agonist (GnRH-Ag) for 24 h using an osmotic minipump. Sham control rats were infused with the vehicle, saline. Lymphocytes were isolated from sham and treated rats and polyclonally stimulated with immobilized anti-CD3 antibody. The levels of the signature T helper 1 (Th-1) cytokines (interferon-gamma [IFN-gamma] and interleukin-2 [IL-2]) and Th-2 cytokines (IL-4 and IL-10) were measured in culture supernatants. Using immunoflourescence confocal microscopy, we demonstrated for the first time the spatial localization of GnRH-R protein on the surface of lymphocytes. We observed a marked increase in IFN-gamma and inhibition of IL-4 production from lymphocytes of pregnant rats treated in vitro with different doses of GnRH-Ag. Further, the responsiveness of lymphocytes to produce IFN-gamma was markedly increased in cells cultured ex vivo from GnRH-Ag infused rats, whereas the capacity of lymphocytes to produce IL-4 was significantly inhibited. In addition, GnRH-Ag infusion in pregnant rats induced a shift toward Th-1 cytokines in the serum. We did not observe any significant difference in IL-2 and IL-10 production in response to GnRH-Ag. Our results suggest an additional function for GnRH as a Th-1 inducer and Th-2 inhibitor. GnRH can thus skew the cytokine balance to predominantly Th-1 type in pregnancy, leading to the termination of pregnancy in rats.

Interleukin-10 promoter polymorphism in sporadic Alzheimer's disease

Proinflammatory cytokines and acute-phase proteins play an important role in Alzheimer's disease (AD) neurodegeneration, and common polymorphisms of genes controlling their high production have been shown to be associated with AD. Thus, AD patients display a proinflammatory genotype and the control of inflammation might play a protective role in AD development. By sequence-specific probes, we have evaluated the role of anti-inflammatory cytokine interleukin(IL)-10 in AD, by analysing in 132 AD patients and 213 healthy controls the prevalence of three different haplotypes, involving three single-nucleotide polymorphisms (SNPs) at -1082 (G-->A), -819 (C-->T) and -592 (C-->A) nucleotides of IL-10 promoter, associated with different IL-10 production. The percentage of -1082A carrier subjects was significantly increased among AD patients, and this increase was mainly due to the increase of ATA haplotype. Analysing these results according to the well-known genetic risk factor APOE-e4 allele, no significant differences were observed in SNP IL-10 allele distribution between AD patients carrying the genotype or not. So we may conclude that the presence of -1082A allele and in particular of -1082A/-819T/-592A haplotype, associated with a low production of anti-inflammatory cytokine IL-10, may be considered as an additive and independent genetic risk factor for AD.

Correlation between transcranial interleukin-6 gradient and outcome in patients with acute brain injury

OBJECTIVE

This study was performed to examine both brain and systemic interleukin-6 (IL-6) release in patients with an acute brain injury (ABI), to study whether a correlation exists between the transcranial IL-6 gradient during the first days after injury and prognosis, and finally, to investigate the relationship between a nucleotide polymorphism at position -174 in the promoter of the gene encoding IL-6, IL-6 responsiveness, and clinical evolution.

DESIGN

Prospective clinical investigation.

SETTING

A 19-bed intensive care unit in a university hospital.

PATIENTS AND METHODS

A total of 62 patients were followed up for 3 days after acute brain injury, and both their arterial and jugular IL-6 levels were measured serially and at the moment of brain death diagnosis. Genetic polymorphism of IL-6 was also determined in all patients. Data were correlated with those from score procedures for clinical severity. Neurologic outcome was graded according to the Glasgow Outcome Scale 6 months after injury. IL-6 levels and IL-6 genotyping was performed in control healthy individuals.

MAIN RESULTS

There is a significant transcranial IL-6 gradient at admission and at the moment of brain death. The gradient is higher in those patients who evolved toward a fatal outcome during the first 6 months after injury (p <.001). There is significant correlation between the transcranial IL-6 gradient and the acute brain injury severity.

CONCLUSIONS

IL-6 is elevated in patients with acute brain injury, and a significant relationship exits between the severity of acute brain injury and the transcranial IL-6 gradient at admission. It can be considered to be a prognosis marker at admission. When data at the moment of brain death are considered, venous IL-6 (p <.01) and the transcranial IL-6 gradient (p <.005) are significantly higher than at the time of admission. Although the IL-6 C allele is associated with significantly lower concentrations of IL-6, there was no correlation between low or high IL-6 responders and patient outcome.

Interleukin-10 promoter haplotypes are differently distributed in the Brazilian versus the Dutch population

The frequency of five different single nucleotide polymorphisms of the promoter interleukin-10 (IL-10) gene (-3575, -2849, 2763, -1082, -819) was compared between two healthy populations, one originating from the Netherlands and one from Rio de Janeiro, Brazil. A total of 321 Caucasian Dutch individuals and 293 Brazilians, grouped as Afro-Brazilians and Euro-Brazilians, were genotyped using PCR-RFLP. The frequencies of the genotypes in the Brazilian population were different (P<0.05) from the frequencies in the Dutch population in all but one (-2763) genotype. The comparison of genotype frequencies between Afro- and Euro-Brazilians did not demonstrate any differences. The haplotype combination of the most-distant three polymorphisms showed strong linkage disequilibrium. All eight possible combinations were observed in Brazilians, but only seven in Dutch Caucasians. The haplotype frequencies were also significantly different between Brazilians when compared with Dutch and also between Euro-Brazilians and Dutch. No differences were observed in haplotype frequencies between Afro-Brazilians and Euro-Brazilians. The -3575T/-2849G/-2763C is more frequent, while the AAA haplotype was much less represented in the Brazilian than in the Dutch population. The haplotype TAC, which was described in African-Americans, was observed only in Brazilians, almost exclusively among those of European origin. The results corroborate the data indicating that the Brazilian population exhibits a genetic admixture of Africans, Europeans, and Amerindians, and the data may serve as a background for clinical and immunological studies involving the IL-10 locus.

Association tests with systemic lupus erythematosus (SLE) of IL10 markers indicate a direct involvement of a CA repeat in the 5' regulatory region

Many lines of evidence suggest that IL10 is a strong candidate gene for systemic lupus erythematosus (SLE) susceptibility. In our previously reported study an allele (IL10.G-140bp) of the microsatellite IL10.G located at position -1100 was significantly increased in Italian SLE patients in comparison with controls. Starting from this observation, we tested if sequence variations in the vicinity of IL10.G were more strongly associated with SLE. We performed a comprehensive association study including 26 SNPs (of which four were newly identified in the present study by DHPLC analysis) spanning 8.5 Kb of the 5' flanking and the transcribed region of the IL10 gene. The association study was performed by the DNA pool method on an extended panel of Italian patients (205) and controls (631). Haplotypic associations were studied by individual typing of seven selected markers surrounding IL10.G. Gene, genotype and haplotype frequencies were not significantly different in patients and controls. Thus the IL10.G microsatellite remains to date the only IL10 marker associated with SLE in our population. A meta-analysis of all published results indicates a possible direct role of the IL10.G repeat number in SLE susceptibility.

Leiden research program on ageing

Research into ageing is among the priorities of the Leiden University Medical Center. Several tight collaborations between basic and clinical departments are the basis of this program. Our focus is to identify determinants of human longevity and disease at old age with an emphasis on inflammation, atherosclerosis, and cognitive decline. To this end we enroll a large series of long-lived families for genetic screening, prospectively follow large cohorts of old people dependent on various genetic and environmental risk factors, and perform randomized controlled trials in the general population testing plausible hypotheses how interventions can maximize rewarding lifespans.

Evolution of ageing

Explaining why ageing occurs is a solution to the longstanding enigma of the role of senescence in nature. Even after half a century of progress, this solution continues to unfold. Evolution theory argues strongly against programmed ageing, suggesting instead that organisms are programmed for survival, not death. In the current view, ageing results from the twin principles that (i) the force of natural selection declines with age, and (ii) longevity requires investments in somatic maintenance and repair that must compete against investments in growth, reproduction and activities that might enhance fitness. In addition to explaining why ageing occurs, the evolutionary theory also provides insight into the mechanisms underlying the complex cellular and molecular changes that contribute to senescence, as well as an array of testable predictions. Some of the most interesting current problems are to understand how the genetic factors influencing ageing and longevity are predicted to respond to fluctuating environments, such as temporary periods of famine, as well as to other kinds of spatial and/or temporal heterogeneity. Rapid progress in human genomics raises the prospect of greatly increasing our knowledge of the determinants of human longevity. To make progress in understanding the role and evolution of genetic and non-genetic factors in human longevity, we need more detailed theoretical studies of how intra-population variables, such as socio-economic status, influence the selection forces that shape the life history.

Frequency of functional interleukin-10 promoter polymorphism is different between relapse-onset and primary progressive multiple sclerosis

Interleukin-10 (IL-10) secretion affects the inducibility of experimental autoimmune encephalomyelitis and the outcome of multiple sclerosis (MS). Here, we report that a G to A polymorphism in the IL-10 promoter at position -2849 is significantly associated with low IL-10 production. The frequency of this polymorphism is lower among patients with primary progressive compared with patients with relapse-onset MS and control persons.

Gender-specific association between -1082 IL-10 promoter polymorphism and longevity

Ageing is characterized by a pro-inflammatory status, which could contribute to the onset of major age-related diseases. Thus, genetic variations in pro- or anti-inflammatory cytokines might influence successful ageing and longevity. IL-10 is an appropriate candidate because it exerts powerful inhibitory effects on pro-inflammatory function. IL-10 production is controlled by several polymorphic elements in the 5' flanking region of IL-10 gene on 1q32 locus, involving alleles at two microsatellite regions and several polymorphisms in promoter region. We analysed in 190 Italian centenarians (>99 years old, 159 women and 31 men) and in 260 <60 years old control subjects (99 women and 161 men), matched for geographical distribution, genotype frequencies for -1082G-->A, -819C-->T and -592C-->A IL-10 proximal promoter gene biallelic polymorphisms by sequence specific probes. -1082G homozygous genotype was increased in centenarian men (P < 0.025) but not in centenarian women. No difference was found between centenarians and control subjects regarding the other two polymorphisms. The presence of -1082GG genotype, suggested to be associated with high IL-10 production, significantly increases the possibility to reach the extreme limit of human lifespan in men. Together with previous data on other polymorphic loci (Tyrosine Hydroxylase, mitochondrial DNA, IL-6, haemochromatosis, IFN-gamma), this finding points out that that gender is a major variable in the genetics of longevity, suggesting that men and women follow different strategies to reach longevity. Concerning the biological significance of this association, we have not searched for functional proves that IL-10 is involved. Thus, we should conclude that our data only suggest that a marker on 1q32 genomic region may be involved in successful ageing in man. However, recent data on IL-6 and IFN-gamma genes suggest that longevity is negatively associated with genotypes coding for a pro-inflammatory profile. Thus, it is intriguing that the possession of -1082G genotype, suggested to be associated with IL-10 high production, is significantly increased in centenarians.