Lennart Kjellberg

Smoking, diet, pregnancy and oral contraceptive use as risk factors for cervical intra-epithelial neoplasia in relation to human papillomavirus infection

Smoking, nutrition, parity and oral contraceptive use have been reported as major environmental risk factors for cervical cancer. After the discovery of the very strong link between human papillomavirus (HPV) infection and cervical cancer, it is unclear whether the association of these environmental factors with cervical cancer reflect secondary associations attributable to confounding by HPV, if they are independent risk factors or whether they may act as cofactors to HPV infection in cervical carcinogenesis. To investigate this issue, we performed a population-based case–control study in the Västerbotten county of Northern Sweden of 137 women with high-grade cervical intra-epithelial neoplasia (CIN 2–3) and 253 healthy age-matched women. The women answered a 94-item questionnaire on diet, smoking, oral contraceptive use and sexual history and donated specimens for diagnosis of present HPV infection (nested polymerase chain reaction on cervical brush samples) and for past or present HPV infections (HPV seropositivity). The previously described protective effects of dietary micronutrients were not detected. Pregnancy appeared to be a risk factor in the multivariate analysis (P< 0.0001). Prolonged oral contraceptive use and sexual history were associated with CIN 2–3 in univariate analysis, but these associations lost significance after taking HPV into account. Smoking was associated with CIN 2–3 (odds ratio (OR) 2.6, 95% confidence interval (CI) 1.7–4.0), the effect was dose-dependent (P = 0.002) and the smoking-associated risk was not affected by adjusting for HPV, neither when adjusting for HPV DNA (OR 2.5, CI 1.3–4.9) nor when adjusting for HPV seropositivity (OR 3.0, CI 1.9–4.7). In conclusion, after taking HPV into account, smoking appeared to be the most significant environmental risk factor for cervical neoplasia.

Human Placenta Expresses and Secretes NKG2D Ligands via Exosomes that Down-Modulate the Cognate Receptor Expression: Evidence for Immunosuppressive Function

During mammalian pregnancy maternal-fetal tolerance involves a number of immunosuppressive factors produced by placenta. Recently, placenta-derived exosomes have emerged as new immune regulators in the maternal immune tolerance. Exosomes are membrane nanovesicles with defined morphology, which are secreted from endosomal multivesicular bodies (MVB) upon fusion with the plasma membrane. Previously, we reported that the MHC class I chain-related (MIC) proteins A and B, human ligands of the activating NK cell receptor NKG2D, are expressed by placenta, sorted to MVB of syncytiotrophoblast and probably released via MIC-bearing exosomes. In this report, we show that the second family of human NKG2D ligands, the UL-16 binding proteins (ULBP), is also expressed by placenta. Importantly, this expression was not due to placental CMV infection. Immunoelectron microscopy disclosed that ULBP1–5 are produced and retained in MVB of the syncytiotrophoblast on microvesicles/exosomes. Using human placenta explant cultures and different assays, we demonstrate that exosomes bearing NKG2D ligands are released by human placenta. Isolated placental exosomes carried ULBP1–5 and MIC on their surface and induced down-regulation of the NKG2D receptor on NK, CD8+, and γδ T cells, leading to reduction of their in vitro cytotoxicity without affecting the perforin-mediated lytic pathway. Release of placental NKG2D ligands via exosomes is an alternative mechanism for generation of bioactive soluble form of these ligands. These findings highlight a role for NKG2D ligand-bearing placental exosomes in the fetal immune escape and support the view of placenta as a unique immunosuppressive organ.

Sexual behaviour and papillomavirus exposure in cervical intraepithelial neoplasia: a population-based case-control study.

Sexual history is an established risk determinant for cervical neoplasia. It is not clear if human papillomavirus (HPV) exposure entirely explains the sexual behaviour-related risk or if other sexually transmitted agents may act as cofactors for HPV in carcinogenesis. The aim of this study was to elucidate whether HPV exposure or HPV persistence explains the sexual history-related risk of high-grade cervical intraepithelial neoplasia (CIN) using a population-based case-control study of most of the 254 women referred to colposcopy in the Vasterbotten county in Sweden because of an abnormal cervical smear during October 1993 to December 1995 and 320 age-matched women from the general population. The women were interviewed for sexual history and tested for presence of serum antibodies to HPV-16, -18 and -33 as well as for presence of HPV DNA in cervical brush samples. HPV-16, -18 and -33 seropositivity was specific for the corresponding type of HPV DNA, dependent on the lifetime sexual history and associated with a two- to threefold increased risk of CIN 3. There was no sexual history-related risk of CIN among HPV-seropositive women and adjustment for HPV DNA presence explained the sexual history-related risk of CIN. In conclusion, HPV exposure appeared to explain the sexual history-related risk of high-grade CIN.

Association of HLA-DRB1, interleukin-6 and cyclin D1 polymorphisms with cervical cancer in the Swedish population―A candidate gene approach

High‐risk human papillomavirus (hrHPV) infection is the major risk factor for cervical cancer (CxCa). The role of genetic susceptibility in the disease has been suggested, but the existing data lack consistency. We conducted a nested case‐control study on 973 CxCa cases and 1,763 matched controls, from two Swedish population‐based cohorts to examine the association of common genetic variants with CxCa risk. Human leukocyte antigen (HLA) alleles and 24 other polymorphisms in 14 genes were selected on the basis of reported association or mechanistic plausibility with an HPV infection or cervical cancer development. Genotyping was conducted using multiplex PCR and Luminex technology. A significant association of CxCa with various polymorphisms was observed: rs1800797 in the IL‐6 gene (odds ratio [OR] = 0.88, 95% confidence intervals [CI]: 0.79–0.99); rs1041981 in the LTA gene (OR = 0.87, 95% CI: 0.78–0.98), and rs9344 in the CCND1 gene (OR = 1.14, 95% CI: 1.02–1.27), for those individuals carrying the rare allele. Additionally, the alleles 0401 and 1501 of the HLA class II DRB1 locus were associated with an increased risk (OR = 1.23, 95% CI: 1.04–1.45 and OR = 1.29, 95% CI: 1.11–1.50, respectively), and allele 1301 was associated with decreased risk (OR = 0.59, 95% CI: 0.47–0.73). The effects of CCND1 and the HLA*DRB1 alleles were independent of the effect of smoking. We did not find any association of risk with polymorphisms in genes related to the innate immune system. In conclusion, our study provides evidence for genetic susceptibility to CxCa due to variations in genes involved in the immune system and in cell cycle.

Type Specificity and Significance of Different Isotypes of Serum Antibodies to Human Papillomavirus Capsids

Isotype-specific serum antibody responses against human papillomavirus (HPV) type 16 were evaluated by use of cross-sectional, prospective, and population-based seroepidemiologic studies. IgG1 and IgA were the most abundant isotypes. No sample contained IgG2, and <25 samples contained IgG3 or IgM. Total IgG, IgA, and IgG1 were HPV type specific and were associated with HPV-16 DNA (odds ratios [ORs], 5.4, 5.0, and 5.9, respectively; P<.001) but not with other HPV DNA (ORs, 1.2, 1.2, and 0.8, respectively; P value was not significant). Total IgG and IgG1 were strongly associated with number of lifetime sex partners (P<.001); IgA was only associated with number of recent sex partners and lifetime sex partners among younger women. Total IgG, IgG1, and IgA were associated with cervical intraepithelial neoplasia type III and also predicted risk of future cervical neoplasia. IgG and IgG1 appeared to mark lifetime cumulative exposure, whereas IgA may mark recent or ongoing infection.

Galectin-1 influences trophoblast immune evasion and emerges as a predictive factor for the outcome of pregnancy

Galectin-1 (gal-1) is expressed at the feto-maternal interface and plays a role in regulating the maternal immune response against placental alloantigens, contributing to pregnancy maintenance. Both decidua and placenta contribute to gal-1 expression and may be important for the maternal immune regulation. The expression of gal-1 within the placenta is considered relevant to cell-adhesion and invasion of trophoblasts, but the role of gal-1 in the immune evasion machinery exhibited by trophoblast cells remains to be elucidated. In this study, we analyzed gal-1 expression in preimplantation human embryos and first-trimester decidua-placenta specimens and serum gal-1 levels to investigate the physiological role played by this lectin during pregnancy. The effect on human leukocyte antigen G (HLA-G) expression in response to stimulation or silencing of gal-1 was also determined in the human invasive, proliferative extravillous cytotrophoblast 65 (HIPEC65) cell line. Compared with normal pregnant women, circulating gal-1 levels were significantly decreased in patients who subsequently suffered a miscarriage. Human embryos undergoing preimplantation development expressed gal-1 on the trophectoderm and inner cell mass. Furthermore, our in vitro experiments showed that exogenous gal-1 positively regulated the membrane-bound HLA-G isoforms (HLA-G1 and G2) in HIPEC65 cells, whereas endogenous gal-1 also induced expression of the soluble isoforms (HLA-G5 and -G6). Our results suggest that gal-1 plays a key role in pregnancy maternal immune regulation by modulating HLA-G expression on trophoblast cells. Circulating gal-1 levels could serve as a predictive factor for pregnancy success in early human gestation.

Maternal Foxp3 Expressing CD4+ CD25+ and CD4+ CD25− Regulatory T-Cell Populations are Enriched in Human Early Normal Pregnancy Decidua: A Phenotypic Study of Paired Decidual and Peripheral Blood Samples

Citation Dimova T, Nagaeva O, Stenqvist A‐Christin, Hedlund M, Kjellberg L, Strand M, Dehlin E, Mincheva‐Nilsson L. Maternal Foxp3 Expressing CD4+ CD25+ and CD4+ CD25− Regulatory T‐Cell Populations are Enriched in Human Early Normal Pregnancy Decidua: A Phenotypic Study of Paired Decidual and Peripheral Blood Samples. Am J Reprod Immunol 2011; 66 (Suppl. 1): 44–56

Dietary factors and in situ and invasive cervical cancer risk in the European prospective investigation into cancer and nutrition study.

Some dietary factors could be involved as cofactors in cervical carcinogenesis, but evidence is inconclusive. There are no data about the effect of fruits and vegetables intake (F&V) on cervical cancer from cohort studies. We examined the association between the intake of F&V and selected nutrients and the incidence of carcinoma in situ (CIS) and invasive squamous cervical cancer (ISC) in a prospective study of 299,649 women, participating in the European Prospective Investigation into Cancer and Nutrition study. Cox proportional hazard models were used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (95% CI). A calibration study was used to control measurement errors in the dietary questionnaire. After a mean of 9 years of follow‐up, 253 ISC and 817 CIS cases were diagnosed. In the calibrated model, we observed a statistically significant inverse association of ISC with a daily increase in intake of 100 g of total fruits (HR 0.83; 95% CI 0.72–0.98) and a statistically nonsignificant inverse association with a daily increase in intake of 100 g of total vegetables (HR 0.85: 95% CI 0.65–1.10). Statistically nonsignificant inverse associations were also observed for leafy vegetables, root vegetables, garlic and onions, citrus fruits, vitamin C, vitamin E and retinol for ISC. No association was found regarding beta‐carotene, vitamin D and folic acid for ISC. None of the dietary factors examined was associated with CIS. Our study suggests a possible protective role of fruit intake and other dietary factors on ISC that need to be confirmed on a larger number of ISC cases.

Clinical and pregnancy outcome following ectopic pregnancy; a prospective study comparing expectancy, surgery and systemic methotrexate treatment

Background. The improved possibility of an early diagnosis of ectopic pregnancy by use of serial quantitative beta‐subunit human chorionic gonadotropin hormone levels together with transvaginal ultrasound has opened up options for conservative treatment. Systemic methotrexate treatment of unruptured ectopic pregnancy has emerged as a safe and effective alternative to surgical procedures. The aim of the present study was to investigate the effectiveness of methotrexate treatment in routine clinical practice, but also to assess pregnancy outcome during a 2.5‐year follow‐up period.

Endogenous sex steroids and risk of cervical carcinoma : results from the EPIC study

Background: Epidemiologic data and animal models suggest that, despite the predominant role of human papillomavirus infection, sex steroid hormones are also involved in the etiology of invasive cervical carcinoma (ICC). Methods: Ninety-nine ICC cases, 121 cervical intraepithelial neoplasia grade 3 (CIN3) cases and 2 control women matched with each case for center, age, menopausal status and blood collection–related variables, were identified in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Circulating levels of testosterone (T) and estradiol (E2); dehydroepiandrosterone sulfate (DHEAS); progesterone (premenopausal women); and sex hormone–binding globulin (SHBG) were measured using immunoassays. Levels of free (f) T and E2 were calculated from absolute concentrations of T, E2, and SHBG. Odds ratios (ORs) and 95% confidence intervals (CI) were computed using regularized conditional logistic regression. Results: Among premenopausal women, associations with ICC were observed for fT (OR for highest vs. lowest tertile = 5.16, 95% CI, 1.50–20.1). SHBG level was associated with a significant downward trend in ICC risk. T, E2, fE2, and DHEAS showed nonsignificant positive association with ICC. Progesterone was uninfluential. Among postmenopausal women, associations with ICC were found for T (OR = 3.14; 95% CI, 1.21–9.37), whereas E2 and fT showed nonsignificant positive association. SHBG level was unrelated to ICC risk in postmenopausal women. No associations between any hormone and CIN3 were detected in either pre- or postmenopausal women. Conclusions: Our findings suggest for the first time that T and possibly E2 may be involved in the etiology of ICC. Impact: The responsiveness of cervical tumors to hormone modulators is worth exploring. Cancer Epidemiol Biomarkers Prev; 20(12); 2532–40. ©2011 AACR.