Interleukin 1-beta responses to bacterial toxins and sudden infant death syndrome

We tested the hypothesis that significantly higher IL-1beta responses to toxic shock syndrome toxin (TSST) noted for parents of sudden infant death syndrome (SIDS) infants might be due in part to genetic factors such as the IL-1beta (C-511T) and IL-1RN (T+2018C) single nucleotide polymorphisms (SNP). The first objective was to assess the distribution of these polymorphisms among SIDS infants, parents of SIDS infants and controls, and two ethnic groups: Aboriginal Australians who have a high incidence of SIDS; and Bangladeshis who in Britain have a low incidence of SIDS compared with Europeans. The second objective was to assess IL-1beta responses to endotoxin and toxic shock syndrome toxin (TSST) from leukocytes of smokers and non-smokers in relation to these polymorphisms. There were major differences in the distributions of the IL-1beta (C-511T) SNP between Europeans and Bangladeshis (p=0.00) and between Europeans and Aboriginal Australians (p=0.00); however, they were similar for the Bangladeshi and Aboriginal Australian subjects. The allele frequency distribution of the IL-1RN (T+2018C) SNP for the Aboriginal Australians was statistically different from the European group (p=0.00), but it was not different from the Bangladeshi group (p=0.09). Compared with controls of European origin, there were no significant differences in the distribution of these polymorphisms among SIDS infants or parents of SIDS infants. For the IL-1beta (C-511T) SNP, the highest IL-1beta responses to endotoxin were obtained with leukocytes of non-smokers with the heterozygous CT genotype. Smokers had significantly lower levels of IL-1beta in response to endotoxin (p=0.01) and these differences were significant for donors with the wild type CC (p=0.00) and CT (p=0.03) genotypes. Similar patterns were observed for IL-1beta responses to TSST, but the differences were not significant. For the IL-1RN (T+2018C) SNP, the highest IL-1beta responses to endotoxin were obtained with leukocytes from non-smoker donors with the wildtype TT genotype and significantly lower responses were found with leukocytes from donors with the TC genotype (p=0.02). The responses of smokers were lower but the differences were significant only for donors with the TT genotype (p=0.00). Similar patterns were observed for IL-1beta responses to TSST, but the differences were not significant. IL-1beta responses to both endotoxin and TSST were increased for the small number of smokers with the TT genotype of the IL-1beta (C-511T) SNP. The TT genotype of the IL-1beta (C-511T) was found predominantly among Aboriginal Australian and Bangladeshi individuals but only a small proportion of Europeans. Smokers with the AA genotype of the IL-10 (G-1082A) SNP which is found predominantly among these two groups had significantly lower levels of IL-10 responses. If cigarette smoke enhances pro-inflammatory responses and reduces anti-inflammatory responses in individuals with these genotypes, this might partly explain the increased susceptibility of Aboriginal Australian infants to infections and SIDS.     

Ethnicity, infection and sudden infant death syndrome

Epidemiological studies found the incidence of SIDS among Indigenous groups such as Aboriginal Australians, New Zealand Maoris and Native Americans were significantly higher than those for non-Indigenous groups within the same countries. Among other groups such as Asian families in Britain, the incidence of SIDS has been lower than among groups of European origin. Cultural and childrearing practices as well as socio-economic factors have been proposed to explain the greater risk of SIDS among Indigenous peoples; however, there are no definitive data to account for the differences observed. We addressed the differences among ethnic groups in relation to susceptibility to infection because there is evidence from studies of populations of European origin that infectious agents, particularly toxigenic bacteria might trigger the events leading to SIDS. The risk factors for SIDS parallel those for susceptibility to infections in infants, particularly respiratory tract infections which are also major health problems among Indigenous groups. Many of the risk factors identified in epidemiological studies of SIDS could affect three stages in the infectious process: (1) frequency or density of colonisation by the toxigenic species implicated in SIDS; (2) induction of temperature-sensitive toxins; (3) modulation of the inflammatory responses to infection or toxins. In this review we compare genetic, developmental and environmental risk factors for SIDS in ethnic groups with different incidences of SIDS: low (Asians in Britain); moderate (European/Caucasian); high (Aboriginal Australian). Our findings indicate: (1) the major difference was high levels of exposure to cigarette smoke among infants in the high risk groups; (2) cigarette smoke significantly reduced the anti-inflammatory cytokine interleukin-10 responses which control pro-inflammatory responses implicated in SIDS; (3) the most significant effect of cigarette smoke on reduction of IL-10 responses was observed for donors with a single nucleotide polymorphism for the IL-10 gene that is predominant among both Asian and Aboriginal populations. If genetic makeup were a major factor for susceptibility to SIDS, the incidence of these deaths should be similar for both populations. They are, however, significantly different and most likely reflect differences in maternal smoking which could affect frequency and density of colonisation of infants by potentially pathogenic bacteria and induction and control of inflammatory responses.     

Pyrogenic toxins of Staphylococcus aureus in sudden unexpected nocturnal deaths in adults and older children: factors influencing the control of inflammatory responses to toxic shock syndrome toxins

Sudden unexpected nocturnal deaths (SUND) occur in young immigrant workers, mainly from south-east Asia, who are employed in countries such as Singapore and Saudi Arabia. Pyrogenic toxins of Staphylococcus aureus have been identified in two cases of sudden unexpected death in adults in the UK and it has been suggested that these or other toxins with superantigen properties might induce strong inflammatory responses leading to sudden unexpected nocturnal deaths. The objectives of the present study were (1) to assess the levels of antibodies to pyrogenic staphylococcal toxins in the general population, (2) to assess the levels of IgG to the toxins needed to reduce the production of inflammatory mediators by 50% in a model system, (3) to assess in a model system the effects on inflammatory responses to toxic shock syndrome toxin-1 (TSST) of cortisol levels present at night, during the day and under conditions of physiological stress. Enzyme linked immunosorbent assays were used to assess levels of IgG to TSST, staphylococcal enterotoxin A (SEA) and staphylococcal enterotoxin C (SEC). Human buffy coats were used to examine the effect of IgG to the toxins for neutralising activity and the effect of cortisol on induction of inflammatory mediators. Tumour necrosis factor alpha (TNF-alpha) was detected by a bioassay with L929 cells, interleukin-6 (IL-6) and interleukin-10 (IL-10) were measured by an enzyme linked immunosorbent assay. IL-6 and TNF-alpha levels elicited by the toxins were not reduced by night time levels of cortisol (5-10 microg dl(-1)) levels. Day time levels of cortisol (10-20 microg dl(-1)) significantly inhibited IL-6 production but not TNF-alpha in responses. Stress levels of cortisol (40 80 microg dl(-1)) significantly reduced all three cytokines earlier than the normal day time levels. The majority of the population tested had sufficient antibodies to reduce TNF-alpha and IL-6 responses elicited by TSST and SEC in the model system. In the age range in which most sudden unexpected nocturnal death cases occur (20-39 years), males had significantly lower levels of IgG to TSST compared with females. If these toxins play a role in precipitating the series of events leading to sudden unexpected nocturnal death, the higher levels of IgG to the toxins observed in females might explain partly the much higher prevalence of these deaths among men in this age range. If inflammatory responses play a role in sudden unexpected nocturnal death, the inability of the night time levels of cortisol to control IL-6 and TNF-alpha in the model system might reflect these interactions in vivo. The methods developed for detection of the toxins in tissue samples and the quantitative IgG assays for anti-toxins can be applied to investigation of SUND victims to test the hypothesis that some of these deaths are precipitated by pyrogenic staphylococcal toxins.     

Sudden infant death syndrome and Canadian Aboriginals: bacteria and infections

Aboriginal populations in Canada, America and Australia have higher incidences of sudden infant death syndrome (SIDS) than non-Aboriginal groups. Canadian Aboriginal populations (known also as first nation, native or Indian) experience infant morbidity/mortality rates 3-7 times that of non-Aboriginals, with upper track respiratory infection and SIDS recorded as the leading causes. The aim of this investigation was to examine the home environment of Aboriginal infants, particularly during winter months when respiratory tract infections and SIDS are more common. Environmental bacteria, fungi and air particulates were examined in the residences of Aboriginal infants during visits to individual homes on an Aboriginal reserve. The physical histories of SIDS victims were gathered from medical files. Air and surfaces were sampled by agar strips which were processed by a commercial laboratory. The levels of fungi, bacteria and air particulate rates recorded in the reserve homes of Aboriginal infants registered levels considered to be detrimental to the health of the inhabitants. Such extreme levels could contribute to the high incidence of respiratory disease and SIDS experienced by Canadian Aboriginal infants.     

Interleukin 10 genotype as a risk factor for sudden infant death syndrome: determination of IL-10 genotype from wax-embedded postmortem samples

In a previous study an association was shown between SIDS and an interleukin-10 (IL-10) genotype. That study was carried out on frozen, unfixed tissue samples, but these are difficult to obtain. Fixed samples used for pathological examination are available. The purpose of this study was to extend the previous work by establishing methods to extract and genotype DNA from fixed, wax-embedded tissues specimens and to use the results to seek confirmation of the association between IL-10 genotype and SIDS in a larger collection of SIDS babies. Using an amplification refractory mutation system-polymerase chain reaction method, a total of 38 infants were genotyped for IL-10 alleles and compared with controls. There was a significant association between the IL-10 -592*A allele and SIDS, consistent with the earlier findings. This study lends support to the hypothesis that IL-10 genotype is related to the susceptibility of babies to SIDS.     

Cortisol levels and control of inflammatory responses to toxic shock syndrome toxin-1 (TSST-1): the prevalence of night-time deaths in sudden infant death syndrome (SIDS)

There is evidence that inflammatory responses have been induced in the tissues and body fluids of many SIDS infants. We suggested that some of these deaths are due to uncontrolled inflammatory responses to infectious agents and possibly cigarette smoke. The majority of SIDS deaths occur during the 2-4 month age range when infants have decreasing levels of maternal antibodies to infectious agents. Most deaths occur during the early hours of the morning. Adults are more susceptible to inflammatory responses at night due to lower levels of cortisol associated with circadian rhythm patterns. Infants develop these patterns between the ages of 7 weeks and 4 months, at which time their night-time cortisol levels drop dramatically. The objective of this study was to use an in vitro model system to assess the effects of different cortisol levels on proinflammatory cytokine production in response to the staphylococcal toxic shock syndrome toxin-1 (TSST-1) which has been identified in a significant number of SIDS infants. Levels of cortisol present in infants at night and during the day before and after the development of the circadian rhythm pattern were examined. Human buffy coats (n = 9) were stimulated with TSST-1 and responses assessed over 72 hours by a bioassay for tumour necrosis factor-alpha (TNF-alpha) and an enzyme linked immunosorbent assay (ELISA) for interleukin-6 (IL-6). Cortisol levels present in an infant at night after development of circadian rhythm (< or = 5 microg dl(-1)), did not significantly increase or decrease production of either TNF-alpha or IL-6. Concentrations of cortisol greater than 5 microg dl(-1) usually found in infants during the day or at night prior to the physiological change significantly decreased production of TNF-alpha at 12 hours and of IL-6 at 12 and 16 hours. Only cortisol levels greater than 5 microg dl(-1) significantly decreased production of the pro-inflammatory cytokines by human buffy coats stimulated with TSST-1. If the switch to the circadian rhythm pattern occurs in an infant when maternal antibodies are still present or after they have developed their own active immunity, the infant could neutralise common viruses, toxins or bacteria: however, if this switch occurs in an infant when antibody levels are low, this could be a window of vulnerability during which infants are at an increased risk of death if uncontrolled inflammatory responses are induced by infectious agents or their products.     

Serotonin transporter gene variation, infant abuse, and responsiveness to stress in rhesus macaque mothers and infants

A functional polymorphism in the promoter region of the serotonin transporter (5-HTTLPR) gene has been associated with variation in anxiety and hypothalamus-pituitary-adrenal (HPA) axis function in humans and rhesus macaques. Individuals carrying the short allele are at a higher risk for developmental psychopathology, and this risk is magnified in short allele carriers who have experienced early life stress. This study investigated the relationship between 5-HTTLPR allelic variation, infant abuse, and behavioral and hormonal responses to stress in rhesus macaques. Subjects were 10 abusive mothers and their infants, and 10 nonabusive mother-infant pairs. Mothers and infants were genotyped for the rh5-HTTLPR, and studied in the first 6 months of infant life. For mothers and infants, we measured social group behavior, behavioral responses to handling procedures, and plasma concentrations of ACTH and cortisol under basal conditions and in response to stress tests. The proportion of individuals carrying the short rh5-HTTLPR allele was significantly higher among abusive mothers than controls. Among mothers and infants, the short allele was associated with higher basal cortisol levels and greater hormonal stress responses in the infants. In addition, infants who carried the short rh5-HTTLPR allele had higher anxiety scores than infants homozygous for the long allele. The rh5-HTTLPR genotype also interacted with early adverse experience to impact HPA axis function in the infants. These results are consistent with those of previous studies which demonstrate associations between serotonergic activity and anxiety and stress reactivity, and add additional evidence suggesting that genetic variation in serotonergic function may contribute to the occurrence of abusive parenting in rhesus macaques and modulate emotional behavior and HPA axis function.     

Detection of pyrogenic toxins of Staphylococcus aureus in sudden infant death syndrome

It has been suggested that pyrogenic toxins of Staphylococcus aureus are involved in the series of events leading to some cases of sudden infant death syndrome (SIDS). The objectives of the study were to screen tissues from SIDS infants for pyrogenic toxins and to compare incidence of identification of these toxins among these infants from different countries. An enzyme-linked immunosorbent assay (ELISA) and a flow cytometry method were used to screen body fluids and frozen or formalin-fixed tissues for pyrogenic toxins of S. aureus, toxic shock syndrome toxin 1 (TSST), staphylococcal enterotoxins A (SEA), B (SEB), and C1 (SEC). Toxins were identified in tissues of 33/62 (53%) SIDS infants from three different countries: Scotland (10/ 19, 56%); France (7/13, 55%); Australia (16/30, 53%). In the Australian series, toxins were identified in only 3/19 (16%) non-SIDS deaths (chi2 = 5.42, P < 0.02). The flow cytometry method was useful for toxin detection in both frozen and fixed tissues, but ELISA was suitable only for frozen tissues or those fixed for less than 12 months. Identification of pyrogenic toxins in > 50% of SIDS infants from three different countries indicated further investigation into the role the toxins play in cot deaths might result in development of additional measures to reduce further the incidence of these infant deaths.     

Interleukin-10 (IL-10) gene polymorphism as a potential host susceptibility factor in tuberculosis

Several genes encoding for different cytokines may play crucial roles in host susceptibility to tuberculosis (TB), since the cytokine production capacity varies among individuals and depends on the cytokine gene polymorphism. The association of the cytokine gene polymorphisms with the development of TB was investigated in this study. DNA samples were obtained from a Turkish population of 81 patients with the different clinical forms of TB, and 50 healthy control subjects. All genotyping (IL-6, IL-10, IFN-gamma, TGF-beta and TNF-alpha) experiments were performed using sequence-specific primers PCR (PCR-SSP). Analysis of allele frequencies showed that IL-10 -1082 G allele frequency was significantly more common in TB patients than healthy controls (37.7% vs 23.0%, p: 0.014). No statistically significant differences were observed between the different clinical forms of the disease. These results suggest that the polymorphisms in IL-10 gene may affect susceptibility to TB and increase risk of developing the disease. To confirm the biological significance of our results, further studies should be performed on other population groups.     

Staphylococcal enterotoxin genes are common in Staphylococcus aureus intestinal flora in Sudden Infant Death Syndrome (SIDS) and live comparison infants

Pathological and epidemiological findings in sudden infant death syndrome (SIDS) suggest an infectious aetiology with indications of involvement of staphylococcal enterotoxins (SEs). While SEA, SEB and SEC have been found in the sera and tissues of SIDS cases, little is known about the role of intestinal Staphylococcus aureus or the roles of later-described toxins SEE, SEG, SEH, SEI and SEJ in SIDS. We used a molecular-based approach to define whether the intestinal tract could be a source of SEs to support the staphylococcal toxic shock hypothesis for SIDS. Intestinal contents from 57 SIDS infants and faeces from 79 age- and gender-matched live comparison infants were cultured and tested for S. aureus and sea-b-c-e-g-h-j and TSST using PCR. High proportions of infants in both groups carried toxigenic and nontoxigenic S. aureus . Significantly greater proportions of SIDS compared with comparison babies were positive for S. aureus (68.4% vs. 40.5%) and for SE genes (43.8% vs. 21.5%), suggesting a possible role in SIDS. The results indicate that colonization by S. aureus with SE genes is common in infants; however, their detection is unlikely to be a strong predictive tool for SIDS. Other factors (including immune response) may reveal a specific susceptibility to SEs in SIDS infants.     

The −1082A/G polymorphism in the Interleukin-10 gene and the risk of rheumatoid arthritis: A meta-analysis

A large number of studies have shown that the −1082A/G polymorphism (rs1800896) in the Interleukin-10 gene (IL-10) is implicated in the susceptibility to rheumatoid arthritis (RA). However, the results are inconsistent and inconclusive. The aim of this study is to analyze the association between the −1082A/G polymorphism in the IL-10 gene and the RA risk by meta-analysis. A total of 1480 cases and 1413 controls in 10 case–control studies were included in this meta-analysis. The results indicated that the G allele carriers (GG + GA) had a 25% decreased risk of RA, when compared with the homozygote AA (odds ratio (OR) = 0.75, 95% confidence interval (CI): 0.59–0.93). In the analysis in Europeans, significant decreased risks were associated with the G allele carriers (OR = 0.73 and 95% CI: 0.57–0.93 for GG + GA vs. AA). The results from this meta-analysis provide evidence for the association between the IL-10 −1082A/G polymorphism and the risk of RA. To further evaluate gene × gene and gene × environment interactions between the polymorphisms in the IL-10 gene and RA risk, more studies with large groups of patients are required.     

The association of the carrier state of the tumor necrosis factor-alpha (TNFalpha) -308A allele with the duration of oxygen supplementation in preterm neonates

BACKGROUND: High levels of inflammatory cytokines lead to lung damage in premature newborns. We investigated whether single nucleotide polymorphisms (SNP) of innate immunity cytokine genes influence the length of oxygen supplementation. METHODS: We genotyped 123 very low birth weight (VLBW) infants for the tumour necrosis factor (TNF)- alpha G(-308)A, interleukin (IL)-1beta C(3954)T, IL-6 G(-174)C and IL-10 G(-1082)A SNPs. Genomic DNA was isolated from remnant dried blood samples from the neonates. We tested the association between SNPs and ventilation characteristics using a stepwise multiple regression analysis model. RESULTS: The carrier state of the TNF-alpha G(-308)A allele was associated with a 40-hour longer period of mechanical ventilation (p=0.004) and, on average, an additional 36 hours of oxygen supplementation (p=0.0008). The association was significant after its adjustment for perinatal risk factors for lung damage. CONCLUSIONS:The TNF-alpha G(308)A genotype - which is associated with increased TNF-alpha levels - might influence the supplemental oxygen requirement of VLBW infants.     

Cytokine gene promoter polymorphisms and mortality in acute renal failure

BACKGROUND: Although cytokines play a pivotal role in the inflammatory responses that mediate the severity of acute renal failure (ARF), the importance of pro- and anti-inflammatory cytokine gene promoter polymorphisms has been unexplored. METHODS: We prospectively evaluated the relationship of single nucleotide polymorphism in the promoter region of tumor necrosis factor alpha (TNF-alpha) and interleukin-10 (IL-10) to mortality in 61 patients with ARF requiring intermittent hemodialysis. Cytokine genotyping was performed on leukocytes using PCR techniques. Cox proportional-hazards regression analysis was used to explore these relationships. RESULTS: The mean (+/-SD) APACHE II score was 24 +/- 7, MOF score 2 +/- 1, and 64% had sepsis. The TNF-alpha high producer genotype (-308 A-allele carrier) was associated with a higher risk of death after adjustment for the APACHE II score (HR=2.5; P=0.04), and the IL-10 intermediate/high producer genotype (-1082 G-allele carrier) was associated with a lower risk of death after adjustment for the MOF score (HR=0.36; P=0.03). Considering combinations of genotypes, the TNF-alpha high and IL-10 low producer genotype combination was associated with a approximately 6-fold increased risk of death compared to the TNF-alpha-low and IL-10 intermediate/high producer genotype combination, after adjustment for either APACHE II (P=0.004), MOF score (P=0.004) or sepsis (P=0.006). CONCLUSIONS: TNF-alpha and IL-10 gene polymorphisms are related to the risk of death among patients with ARF who require dialysis. Larger studies are needed to confirm these relationships.     

Heterogeneity of coronary heart disease risk factors in Indian,Pakistani, Bangladeshi,and European origin populations: cross sectional study

ObjectiveTo compare coronary risk factors and disease prevalence among Indians, Pakistanis, and Bangladeshis, and in all South Asians (these three groups together) with Europeans.DesignCross sectional survey.SettingNewcastle upon Tyne.Participants259 Indian, 305 Pakistani, 120 Bangladeshi, and 825 European men and women aged 25-74 years.ResultsThere were differences in social and economic circumstances, lifestyles, anthropometric measures and disease both between Indians, Pakistanis, and Bangladeshis and between all South Asians and Europeans. Bangladeshis and Pakistanis were the poorest groups. For most risk factors, the Bangladeshis (particularly men) fared the worst: smoking was most common (57%) in that group, and Bangladeshis had the highest concentrations of triglycerides (2.04 mmol/l) and fasting blood glucose (6.6 mmol/l) and the lowest concentration of high density lipoprotein cholesterol (0.97 mmol/l). Blood pressure, however, was lowest in Bangladeshis. Bangladeshis were the shortest (men 164 cm tall v 170 cm for Indians and 174 cm for Europeans). A higher proportion of Pakistani and Bangladeshi men had diabetes (22.4% and 26.6% respectively) than Indians (15.2%). Comparisons of all South Asians with Europeans hid some important differences, but South Asians were still disadvantaged in a wide range of risk factors. Findings in women were similar.ConclusionRisk of coronary heart disease is not uniform among South Asians, and there are important differences between Indians, Pakistanis, and Bangladeshis for many coronary risk factors. The belief that, except for insulin resistance, South Asians have lower levels of coronary risk factors than Europeans is incorrect, and may have arisen from combining ethnic subgroups and examining a narrow range of factors.

Key messages

• South Asians have more coronary heart disease than Europeans despite apparently lower levels of risk factors
• This study shows that Indians, Pakistanis and Bangladeshis differ in a wide range of coronary risk factors and combining their data is misleading
• Among South Asians, Indians were least and Bangladeshis most disadvantaged in a range of coronary risk factors. South Asians were disadvantaged in comparison with Europeans
• Future research and prevention strategies for coronary heart disease in South Asians should acknowledge a broad range of risk factors, the heterogeneity of these populations, linguistic and cultural needs, and environmental factors

     

吸烟对下呼吸道诱导痰中IFN-γ、IL-4、IL-5表达的影响

目的 探究吸烟对下呼吸道诱导痰中干扰素-γ（IFN-γ）、白细胞介素-4（IL-4）和白细胞介素-5（IL-5）表达的影响。方法 采用酶联免疫吸附法检测2016年3月‒2017年3月沈阳医学院附属第二医院收治的下呼吸道感染患者88例（其中吸烟者44例作为观察组,非吸烟者44例作为对照组）、健康体检者76例（其中吸烟者34例作为观察组,非吸烟者42例作为对照组）诱导痰中IFN-γ、IL-4和IL-5的表达,并对结果进行数据分析。结果 （1）健康体检者中吸烟者与非吸烟者相比,吸烟者IL-4、IL-5水平显著上升,IFN-γ水平显著下降（P<0.05）;（2）下呼吸道感染患者中吸烟者与非吸烟者相比,吸烟者IL-4、IL-5水平显著上升,INF-γ水平显著下降（P<0.05）。结论 吸烟与下呼吸道诱导痰中IL-4、IL-5和IFN-γ的水平有关,吸烟可使下呼吸道诱导痰中IL-4、IL-5水平升高而IFN-γ的水平下降。     

IL10 Haplotype Associated with Tuberculin Skin Test Response but Not with Pulmonary TB

Evidence from genetic association and twin studies indicates that susceptibility to tuberculosis (TB) is under genetic control. One gene implicated in susceptibility to TB is that encoding interleukin-10 (IL10). In a group of 2010 Ghanaian patients with pulmonary TB and 2346 healthy controls exposed to Mycobacterium tuberculosis, among them 129 individuals lacking a tuberculin skin test (PPD) response, we genotyped four IL10 promoter variants at positions −2849 , −1082 , −819 , and −592 and reconstructed the haplotypes. The IL10 low-producer haplotype −2849A/−1082A/−819C/−592C, compared to the high-producer haplotype −2849G/−1082G/−819C/−592C, occurred less frequent among PPD-negative controls than among cases (OR 2.15, CI 1.3–3.6) and PPD-positive controls (OR 2.09, CI 1.2–3.5). Lower IL-10 plasma levels in homozygous −2849A/−1082A/−819C/−592C carriers, compared to homozygous −2849G/−1082G/−819C/−592C carriers, were confirmed by a IL-10 ELISA (p = 0.016). Although we did not observe differences between the TB patients and all controls, our results provide evidence that a group of individuals exposed to M. tuberculosis transmission is genetically distinct from healthy PPD positives and TB cases. In these PPD-negative individuals, higher IL-10 production appears to reflect IL-10-dependent suppression of adaptive immune responses and sustained long-term specific anergy.     

Does breathing other people's tobacco smoke cause lung cancer?

The available epidemiological studies of lung cancer and exposure to other people''s tobacco smoke, in which exposure was assessed by whether or not a person classified as a non-smoker lived with a smoker, were identified and the results combined. There were 10 case-control studies and three prospective studies. Overall, there was a highly significant 35% increase in the risk of lung cancer among non-smokers living with smokers compared with non-smokers living with non-smokers (relative risk 1.35, 95% confidence interval 1.19 to 1.54). Part of this increase was almost certainly caused by the misclassification of some smokers as non-smokers. As smokers, who are more likely to get lung cancer than non-smokers, tend to live with smokers this misclassification probably exaggerated the estimated increase in risk. Adjustment for this error reduced the estimate to 30% (relative risk 1.30), but as people who live with non-smokers may still be exposed to other people''s smoke this estimate was revised again to allow for the fact that a truly unexposed reference group was not used. The increase in risk among non-smokers living with smokers compared with a completely unexposed group was thus estimated as 53% (relative risk of 1.53). This analysis, and the fact that non-smokers breathe environmental tobacco smoke, which contains carcinogens, into their lungs and that the generally accepted view is that there is no safe threshold for the effect of carcinogens, leads to the conclusion that breathing other people''s tobacco smoke is a cause of lung cancer. About a third of the cases of lung cancer in non-smokers who live with smokers, and about a quarter of the cases in non-smokers in general, may be attributed to such exposure.     

Interleukin-10-1082 gene polymorphism is associated with papillary thyroid cancer

The etiopathogenesis of thyroid cancer has not been clearly elucidated although the role of chronical inflammation and the imbalance between pro- and anti-inflammatory cytokines may play a role in the etiology. The aim of the present study was to investigate whether cytokine gene polymorphisms are associated with papillary thyroid cancer (PTC), and to evaluate the relationship between genotypes and clinical/laboratory manifestation of PTC. Tumor necrosis factorα (TNFα) G-308A (rs 1800629), interleukin-6 (IL-6) G-174C (rs 1800795) and IL-10 A-1082G (rs 1800896) single nucleotide polymorphisms in DNA from peripheral blood leukocytes of 190 patients with thyroid cancer and 216 healthy controls were investigated by real-time PCR combined with melting curve analysis. There was no notable risk for PTC afflicted by TNFα-308 and IL-6-174 alone. However, IL-10-1082 G allele frequency were higher among PTC patients than healthy controls (p = 0.009). The patients with IL-10-1082 GG geotype have twofold increased risk of developing thyroid cancer according to AA genotype (OR 2.07, 95 % CI 1.21–3.55). In addition, the concomitant presence of IL-10-1082 G allele (GG + AG genotypes) together with IL-6 -174 GG genotype has a nearly twofold increased risk for thyroid cancer (OR 1.75 with 95 % CI 1.00–3.05, p = 0.049). We suggest that IL-10-1082 G allele is associated with an increased risk of PTC. The polymorphism of IL-10 gene can improve our knowledge about the pathogenesis of PTC, and could provide to estimate people at the increased risk for PTC.     

Mucosal immune responses to infections in infants with acute life threatening events classified as 'near-miss' sudden infant death syndrome

This study examined the hypothesis that dysregulation of mucosal immune responses to respiratory infections is a critical event, which could be causal in respiratory arrest of some previously healthy infants. To examine this hypothesis, a prospective study was undertaken of infants presenting to the emergency department of a major teaching hospital with acute life threatening events (ALTE) of unknown cause and classified as "near-miss" SIDS. Salivary immunoglobulin concentrations were measured on admission and again after 14 days. The salivary immunoglobulins were compared with three control groups: infants with a mild upper respiratory tract infection (URTI); bronchiolitis; and healthy age-matched infants. The salivary IgA and IgM concentrations in the ALTE infants at presentation to hospital indicated a significant mucosal immune response had already occurred, with nearly 60% of the IgA concentrations significantly above the population-based reference ranges. The hyper-immune response was most evident in the ALTE infants with pathology evidence of an infection; 87% of these infants had salivary IgA concentrations on average 10 times higher that the age-related median concentration. The most prevalent pathogen identified in the ALTE infants was respiratory syncytial virus (RSV) (64%). RSV was also identified in all subjects with bronchiolitis. Risk factors for SIDS were assessed in each group. The data indicated that the ALTE infants diagnosed as 'near-miss' SIDS were a relatively homogeneous group, and most likely these ALTE infants and SIDS represent associated clinical outcomes. The study identified exposure to cigarette smoke and elevated salivary IgA concentrations as predictors of an ALTE. The study findings support the hypothesis of mucosal immune dysregulation in response to a respiratory infection in some infants with an ALTE. They provide a plausible explanation for certain SIDS risk factors. The underlying patho-physiological mechanism of proinflammatory responses to infections during a critical developmental period might be a critical factor in infants who have life-threatening apnoea or succumb to SIDS. The study raises the possibility of using salivary IgA to test infants who present with mild respiratory infections to identify a substantial number of infants at risk of developing an ALTE or SIDS, thus enabling intervention management to prevent such outcomes.