Marjaana Mäkinen

Selective ovary resistance to insulin signaling in women with polycystic ovary syndrome

OBJECTIVE Insulin resistance is a common feature of both polycystic ovary syndrome (PCOS) and non-insulin-dependent diabetes mellitus (NIDDM); however, the persistent reproductive disturbances appear to be limited to the former, suggesting that insulin resistance in the ovary itself may confer this susceptibility. DESIGN Prospective study. SETTING University-affiliated department. PATIENT(S) Forty-four women undergoing IVF treatment, of whom 11 had polycystic ovaries and 33 had normal ovulation (NO). INTERVENTION(S) The various effects and signaling of insulin and insulin-like growth factor-1 (IGF-1) were examined in cultured ovarian granulosa cells treated with troglitazone (1 microg/mL) or with vehicle by reverse transcription-polymerase chain reaction, western blot, and in vitro functional analyses. MAIN OUTCOME MEASURE(S) Glycogen and DNA syntheses, mRNA and protein expression, and cellular localization of insulin/IGF-1 receptors and insulin receptor substrates (IRSs). RESULT(S) There were significant decreases in insulin-stimulated glucose incorporation into glycogen in PCOS cells, which is a metabolic action of insulin. However, IGF-1 stimulation was found to be greater in PCOS cells at all experimental concentrations with respect to thymidine incorporation compared with NO cells, which is a mitogenic action. Troglitazone increased the insulin-induced glycogen synthesis but reduced the IGF-1-augmented responses of DNA synthesis in PCOS cells to the range within those of NO granulosa cells. We then found that troglitazone treatment reversed the expression imbalance between IRS-1 and IRS-2 in PCOS cells. CONCLUSION(S) There is a selective defect in insulin actions in PCOS granulosa cells, which suggests ovarian insulin resistance, and this metabolic phenotype is associated with an enhanced IGF-1 mitogenic potential. Troglitazone could divergently alter expression of various IRS molecules and insulin actions and could be used as an ovarian insulin sensitizer and mitogen/steroidogenic inhibitor in PCOS.

Association of Human Bocavirus 1 Infection with Respiratory Disease in Childhood Follow-up Study, Finland

Since its discovery in 2005, human bocavirus type 1 has often been found in the upper airways of young children with respiratory disease. But is this virus the cause of the respiratory disease or just an innocent bystander? A unique study in Finland, which examined follow-up blood samples of 109 healthy children with no underlying illness starting at birth and until they were 13 years of age, found that acute bocavirus infection resulted in respiratory disease. All children had been infected by age 6. Most retained their antibodies to this virus; some lost them. Children who were later re-exposed to bocavirus did not get sick from this virus. Thus, human bocavirus type 1 is a major cause of respiratory disease in childhood.

Expression of insulin-receptor substrate-1 and -2 in ovaries from women with insulin resistance and from controls

OBJECTIVE To evaluate the role of insulin-receptor substrate (IRS)-1 and -2 in ovary dysfunction in women with insulin resistance. DESIGN Immunoblotting and immunohistochemical analyses of the localization and staining intensity of IRS-1 and IRS-2 in the ovaries of women with the polycystic ovary syndrome (PCOS) and gestational diabetes mellitus. SETTING Department of Obstetrics and Gynecology, Turku University Central Hospital. PATIENT(S) Sections of ovary were obtained at the time of cesarean section from five volunteers without medical complications and three patients with gestational diabetes mellitus. Paraffin-embedded ovary sections were selected from those on file from the department of pathology; four were from women with a histologic diagnosis of PCOS and seven were from women with endometriosis (controls). INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Protein expression of IRS in human ovary samples. RESULT(S) Immunoblotting with specific monoclonal and polyclonal antibodies showed the presence of 165-kDa and 183-kDa proteins that corresponded to the size of IRS-1 and IRS-2, respectively, in normal pregnant ovaries and human cultured follicles. Immunohistochemical staining showed that positive IRS-2 expression in antral follicles was restricted to theca internal cells in ovulatory ovaries but was distributed widely in all compartments of follicles in different stages in polycystic ovaries. Compared with follicles at a similar stage of development in ovulatory ovaries, follicles in polycystic ovaries showed decreased staining for IRS-1 in granulosa cells but increased staining for IRS-2 in theca internal cells. These features of IRS-1 and -2 expression were also noted in preantral and atretic follicles from patients with gestational diabetes mellitus compared with those who had uncomplicated pregnancy. CONCLUSION(S) This study highlights a shift of the follicular insulin signal protein from IRS-1 to IRS-2 in insulin-resistant states and suggests an association between this change and ovarian abnormality in PCOS and gestational diabetes mellitus.

Cord Serum Lipidome in Prediction of Islet Autoimmunity and Type 1 Diabetes

Previous studies show that children who later progress to type 1 diabetes (T1D) have decreased preautoimmune concentrations of multiple phospholipids as compared with nonprogressors. It is still unclear whether these changes associate with development of β-cell autoimmunity or specifically with clinical T1D. Here, we studied umbilical cord serum lipidome in infants who later developed T1D (N = 33); infants who developed three or four (N = 31) islet autoantibodies, two (N = 31) islet autoantibodies, or one (N = 48) islet autoantibody during the follow-up; and controls (N = 143) matched for sex, HLA-DQB1 genotype, city of birth, and period of birth. The analyses of serum molecular lipids were performed using the established lipidomics platform based on ultra-performance liquid chromatography coupled to mass spectrometry. We found that T1D progressors are characterized by a distinct cord blood lipidomic profile that includes reduced major choline-containing phospholipids, including sphingomyelins and phosphatidylcholines. A molecular signature was developed comprising seven lipids that predicted high risk for progression to T1D with an odds ratio of 5.94 (95% CI, 1.07–17.50). Reduction in choline-containing phospholipids in cord blood therefore is specifically associated with progression to T1D but not with development of β-cell autoimmunity in general.

An Increase in Serum 25-Hydroxyvitamin D Concentrations Preceded a Plateau in Type 1 Diabetes Incidence in Finnish Children

Abstract Context In Finland the world-record for the highest incidence of type 1 diabetes has risen steeply over the past decades. However, after 2006 the incidence rate has plateaued. We showed earlier, that despite the strong genetic disease component, environmental factors are driving the increasing disease incidence. Objective Since vitamin D intake has increased considerably in the country since 2003, we analyzed how serum 25-hydroxyvitamin D (25[OH]D) concentration changed over time in healthy children, and the timely relation of these changes to disease incidence. Design, Setting and Participants The birth cohort of the Finnish Type 1 Diabetes Prediction and Prevention project was used to explore longitudinal changes in serum 25-hydroxyvitamin concentrations. The sampling period was limited to children born from 1994 to 2004, with serum samples collected during 1998–2006 in the Turku area, Southwest Finland (60 °N). Main Outcome Measure 25(OH)D concentrations were measured every 3–6 months from birth, ages ranging from 0.3 to 12.2 years (387 subjects, 5334 measurements). Results Serum 25(OH)D concentrations were markedly lower before 2003 than after (69.3 ± 1.0 nmol/L vs 84.9 ± 1.3 nmol/L, respectively, P < .001) in both genders. The mean difference between the periods was 15.7 ± 1.3 nmol/L (P < .001). Importantly, the frequency of children with low serum 25(OH)D levels (< 50 nmol/L) was reduced to almost half from 2003 (37.3% vs 69.9 %; P < .001). Similarly, severe vitamin D deficiency (<25 nmol/L) also decreased (2.7% vs 7.7%; P = .005). In addition, we detected higher 25(OH)D concentrations in young children (< 2 years) as compared to older children, which is explained by higher vitamin D intake in this group. Conclusions We provide evidence that an increase in circulating concentrations of 25(OH)D shows a delayed temporal association with leveling off of type 1 diabetes incidence in Finland after 2006.

Reduced β-cell function in early preclinical type 1 diabetes

Objective We aimed to characterize insulin responses to i.v. glucose during the preclinical period of type 1 diabetes starting from the emergence of islet autoimmunity. Design and methods A large population-based cohort of children with HLA-conferred susceptibility to type 1 diabetes was observed from birth. During regular follow-up visits islet autoantibodies were analysed. We compared markers of glucose metabolism in sequential intravenous glucose tolerance tests between 210 children who were positive for multiple (≥2) islet autoantibodies and progressed to type 1 diabetes (progressors) and 192 children testing positive for classical islet-cell antibodies only and remained healthy (non-progressors). Results In the progressors, the first phase insulin response (FPIR) was decreased as early as 4–6 years before the diagnosis when compared to the non-progressors (P=0.001). The difference in FPIR between the progressors and non-progressors was significant (P<0.001) in all age groups, increasing with age (at 2 years: difference 50% (95% CI 28–75%) and at 10 years: difference 172% (95% CI 128–224%)). The area under the 10-min insulin curve showed a similar difference between the groups (P<0.001; at 2 years: difference 36% (95% CI 17–58%) and at 10 years: difference 186% (95% CI 143–237%)). Insulin sensitivity did not differ between the groups. Conclusions FPIR is decreased several years before the diagnosis of type 1 diabetes, implying an intrinsic defect in β-cell mass and/or function.

Serum 25-Hydroxyvitamin D Concentrations in Children Progressing to Autoimmunity and Clinical Type 1 Diabetes

CONTEXT The role of vitamin D in the development of type 1 diabetes (T1D) remains controversial. OBJECTIVE The objective of the investigation was to study whether there are detectable differences in serum 25-hydroxyvitamin D (25[OH]D) concentrations between children who later progressed to T1D (cases) and matched children who remained nondiabetic and negative for islet autoantibodies (controls) when followed up from birth until disease onset. DESIGN A total of 3702 prospective serum samples from 252 children were measured for 25(OH)D from the age of 3 months onward using an enzyme immunoassay. Differences between the groups were compared by the mixed-model analysis of variance. SETTING T1D prediction and prevention study clinics in Turku, Oulu, and Tampere University Hospitals, Finland, participated in the study. PARTICIPANTS By the end of 2012, all 126 case children were diagnosed with T1D. The control children (n = 126) were matched for age, sex, study site, and human leukocyte antigen-HLA-DQ-conferred risk for T1D. MAIN OUTCOME MEASURE Median circulating 25(OH)D concentration (nanomoles per liter) was measured. RESULTS The patterns of variation in circulating 25(OH)D concentrations were similar between cases and controls and did not correlate with the age at seroconversion to autoantibody positivity (P = .79) or disease onset (P = .13). The median concentration of all collected samples did not differ between case and control children (66.6 nmol/L [range 14.0-262.8] vs 67.4 nmol/L [range 19.9-213.0]) P = .56). CONCLUSIONS This study shows that serum 25(OH)D concentrations are not associated with the development of T1D in Finland.

B-Cell Responses to Human Bocaviruses 1-4: New Insights from a Childhood Follow-Up Study.

Human bocaviruses (HBoVs) 1–4 are recently discovered, antigenically similar parvoviruses. We examined the hypothesis that the antigenic similarity of these viruses could give rise to clinically and diagnostically important immunological interactions. IgG and IgM EIAs as well as qPCR were used to study ~2000 sera collected from infancy to early adolescence at 3–6-month intervals from 109 children whose symptoms were recorded. We found that HBoV1-4-specific seroprevalences at age 6 years were 80%, 48%, 10%, and 0%, respectively. HBoV1 infections resulted in significantly weaker IgG responses among children who had pre-existing HBoV2 IgG, and vice versa. Furthermore, we documented a complete absence of virus type-specific immune responses in six viremic children who had pre-existing IgG for another bocavirus, indicating that not all HBoV infections can be diagnosed serologically. Our results strongly indicate that interactions between consecutive HBoV infections affect HBoV immunity via a phenomenon called “original antigenic sin”, cross-protection, or both; however, without evident clinical consequences but with important ramifications for the serodiagnosis of HBoV infections. Serological data is likely to underestimate human exposure to these viruses.

Diagnostic Methods for and Clinical Pictures of Polyomavirus Primary Infections in Children, Finland

We used comprehensive serodiagnostic methods (IgM, IgG, and IgG avidity) and PCR to study Merkel cell polyomavirus and trichodysplasia spinulosa-associated polyomavirus infections in children observed from infancy to adolescence. Comparing seroconversion intervals with previous and subsequent intervals, we found that primary infections with these 2 viruses were asymptomatic in childhood.

Correction: B-Cell Responses to Human Bocaviruses 1–4: New Insights from a Childhood Follow-Up Study

[This corrects the article DOI: 10.1371/journal.pone.0139096.].