This study was approved by the Ethics Review Board of Lund University and performed in accordance with the declaration of Helsinki. All subjects gave their written, informed consent before inclusion in the study. Naïve blood samples from the patients taken during the very first pre-IVF screening was used in accordance with the Swedish Act ’Biobanks in Medical Care Act‘ (SFS 2002:297).
Patients
Patients were recruited to the study at a fertility clinic in Malmö where they sought care for infertility. The clinic receives patients from the southernmost districts of Sweden. The reasons for the infertility were not further investigated. After appropriate consultation, an IVF regime was planned. One selected nurse was responsible for recruiting consecutive patients passing her with a planned regime involving the GnRH analog buserelin, from 2007 through 2008.
Controls
Two age- and gender-matched controls for each included patient were randomly acquired from the Swedish Population Registry at the 5-year follow-up. Thus, 248 women were contacted via mail. After one reminder, 29 questionnaires were returned. As the response rate was low, further controls were recruited amongst hospital staff. In total, 65 healthy women, median age 37 (IQR 34–42) years, were recruited and completed the questionnaires.
Blood samples from 169 consecutive healthy female blood donors, median age 45 (IQR 31–54) years, collected at Skåne University Hospital, Malmö, served as a control group for antibody analyses within the study.
Study design
Figure 1 illustrates the study design. Patients underwent IVF according to clinical routines. The Visual Analogue Scale for Irritable Bowel Syndrome (VAS-IBS) was completed and the IVF treatment started with two nasal inhalations of the GnRH analog buserelin (Suprecur®, Sanofi-Aventis, Bromma, Sweden) four times a day for three weeks; dose was varying according to clinical response. The VAS-IBS was again completed after these three weeks and blood samples collected. Blood samples consisted of 7.0 ml whole blood drawn into heparinized or untreated tubes. Plasma and serum were separated and immediately frozen at −20°C. This was followed by one inhalation four times a day for another two weeks, along with FSH and human chorionic gonadotropin (hCG) administered according to clinical routines. The total dose of buserelin was 28.8 (IQR 27.0–31.6) mg. Treatment naïve blood samples were obtained from the Department of Medical Microbiology, Skåne University Hospital, Malmö. Sera were analyzed for the presence of antibodies against buserelin, GnRH, LH, and their receptors.
Five years after the initial treatment, the VAS-IBS questionnaire and the 36-item Short-Form questionnaire (SF-36) were sent to patients and matched controls. One reminder was sent within one month, if no reply was returned.
Questionnaires
Visual Analogue Scale for Irritable Bowel Syndrome
The VAS-IBS was used to estimate gastrointestinal complaints. This is a validated questionnaire for estimation of the most common gastrointestinal complaints in patients with functional, non-organic bowel disease [13]. This instrument has also been validated for evaluation of symptoms over time [14]. The seven VAS items used assess each of the following symptoms: abdominal pain, diarrhea, constipation, bloating, nausea and vomiting, psychological well-being, and intestinal symptoms’ influence on daily life. The scale measures from 0–100 mm, where 0 represents very severe problems and 100 represent absence of problems. Two questions at the end of the form are to be answered with yes or no; feeling of incomplete evacuation and presence of tenesms.
36-item Short-Form questionnaire
The SF-36 was used to assess health-related quality of life (HRQOL). It is a generic questionnaire divided into eight subscales of general health and ordered according to which degree they measure physical or mental health. Four subscales correspond mainly to the Physical Composite Score (PCS), namely, physical functioning (PF), role physical (RP), bodily pain (BP), and general health (GH). Four subscales correspond mainly to the Mental Composite Score (MCS), namely, vitality (VT), social functioning (SF), role emotional (RE), and mental health (MH). The subscales GH, VT, and SF also correspond with the PCS [15]. SF-36 is an extensively used HRQOL instrument, which provides reproducible, reliable data in large populations and is used as a global health monitor [16]. The maximum score is 100, the higher score the better the HRQOL. Norm-based scores for the SF-36 questionnaire were calculated for patients as well as for controls, using the QualityMetric Health Outcomes™ Scoring Software 4.5 [17].
Measurement of antibodies against buserelin, GnRH and GnRH receptor
Analyses of antibodies against GnRH and GnRH-R were carried out by an ELISA as described previously [18]. The wells of microtiter plates (456537 Nunc, Roskilde, Denmark) were either coated with buserelin (Suprefact® lot 2 F0174, Sanofi-Aventis, Bromma, Stockholm), or human GnRH or N-terminal GnRH-R peptide ((NH2)-ANSASPEQNQNHCSAINNSIPLMQGNLPY) conjugated with ovalbumin (OVA) (Innovagen, Lund, Sweden), in an overnight incubation at 4°C. Thereafter the plastic wells were blocked with 0.5% bovine serum albumin (BSA) (A-7030, Sigma, St Louis, USA) in phosphate-buffered saline (PBS) containing 0.05% Tween-20 (PBS-T). The dilutions of patient serum (1:400 in 1.0 μg OVA (A-5503, Sigma)/ml 0.5% BSA in PBS-T) or mouse anti-human GnRH antibody (ab62432, Abcam, Cambridge, MA, USA) in serial dilution (to construct a standard curve) were then added to the plates and incubated for 2 h at room temperature (RT). After rinsing with PBS-T, deposition of antibodies directed to buserelin, GnRH or GnRH-R was detected using biotinylated rabbit anti-human IgM- (673211, MP Biomedicals, Solon, OH, USA), IgG- (ab7159, Abcam), or IgA antibodies (ab97218, Abcam), or goat anti-mouse IgG antibodies (E0433, DAKO, Glostrup, Denmark) appropriately diluted in PBS-T. After another incubation for 2 h at RT, the plates were washed and the bound, biotinylated antibodies detected by alkaline phosphatase-conjugated streptavidin (405211, Biolegend, San Diego, CA, USA), incubated for 1 h at RT. To develop a color reaction, a phosphatase substrate kit (37620, Pierce, Rockford, Ill, USA) was used. The absorbance at 405 nm was measured after 30 min of incubation at RT. Antibody levels are expressed as relative units (RU) (absorbance values after subtracted background levels and multiplied with 1000). The cut-off value to determine presence of antibodies in the control group of 169 healthy female blood donors was defined as RU >97.5th percentile. The intra-assay correlation coefficient of variation (CV) of GnRH- and GnRH-R IgM antibodies was 10% and 8%, respectively (n = 6), and inter-assay CV was 11% and 6%, respectively (n = 12). No intra-assay or inter-assay CV of IgG antibodies, IgA antibodies or buserelin antibodies was calculated due to lack of positive serum.
For competitive ELISA, diluted sera from patients with antibodies above the cut-off level were incubated in 0.05% BSA in PBS-T with various amounts of GnRH or GnRH-R peptide, both unconjugated and conjugated with OVA (Innovagen), prior to application to the microtiter plate.
Measurement of antibodies against LH and LH receptor
An in-house ELISA was set up for analysis of anti-IgG- and anti-IgM antibodies against LH and its receptor (LH-R).
LH
The microtiter plates (456537, Nunc) were coated with intact, purified, native human LH (MBS537383, MyBiosource, San Diego, CA, USA) in PBS-T or only PBS-T (to provide an internal blank). After overnight incubation at 4°C, the plates were washed three times with PBS-T and blocked with 0.5% BSA in PBS-T. Dilutions of serum (1:200) from patients and blood donors, or rabbit anti-human LH antibody (MBS535386, MyBiosource) in serial dilution (to construct a standard curve), with BSA in PBS-T were then added to the plates in triplicate (two wells coated with LH and one well coated with PBS-T) and incubated for 2 h at RT. The washing procedure was repeated and deposition of autoantibodies directed to LH was detected using biotinylated rabbit anti-human IgM- (673211, MP Biomedicals) or IgG antibodies (ab7159, ABcam), or goat anti-rabbit IgG antibodies (B7389, Sigma) appropriately diluted in PBS-T.
LH receptor
Microtiter plates were coated with the N-terminal LH-R peptide ((NH2)-MKQRFSSALQLLKLLLLQPPLPRALC), conjugated with OVA (Innovagen), in 100 mM Carbonate buffer pH 9.2 or only Carbonate buffer (to provide an internal blank). After overnight incubation at 4°C, the plates were washed three times with PBS-T and blocked with 0.5% BSA in PBS-T. Dilutions of serum (1:200) from patients and blood donors with BSA in PBS-T were then added to the plates in triplicate, two to LH-R and one to Carbonate buffer-coated wells, and incubated for 2 h at RT. The washing procedure was repeated and deposition of autoantibodies directed to LH-R was detected using biotinylated rabbit anti-human IgM- (673211, MP Biomedicals) or IgG antibodies (ab7159, Abcam) appropriately diluted in PBS-T.
To develop a color reaction, a phosphatase substrate kit (37620, Pierce) was used. The absorbance at 405 nm was measured after 30 min (LH IgM and LH-R) or 60 min (LH IgG) of incubation at RT. Antibody levels are presented as RU (absorbance values after subtracted background levels and multiplied with 1000) and the cut-off value to determine presence of antibodies in the control group of 169 healthy female blood donors was defined as RU >97.5th percentile. The intra-assay CV of LH IgG and LH IgM was 5.6% and 9.2%, respectively (n = 8), and inter-assay CV of LH IgG and LH IgM was 7.7% and 6.1%, respectively (n = 17). No intra-assay or inter-assay CV of LH-R was calculated due to lack of appropriate commercial antibody.
For competitive ELISA, diluted sera from patients with antibodies above the cut-off level were incubated in 0.5% BSA in PBS-T with various amounts of LH (MBS537383, MyBiosource) or LH-R, unconjugated and conjugated with OVA (Innovagen), i.e. 50, 100, or 200 ng/100 μl, 30 min prior to application to the microtiter plates.
Statistical methods
The data were analyzed using the statistical software package SPSS for Windows© (Release 20.0; IBM). All variables were analyzed for normal distribution by Kolmogorov-Smirnov test. As normality was rejected, the Wilcoxon’s signed rank test was used to calculate differences within the group and the Mann-Whitney U-test to compare different groups. When appropriate, Fisher’s exact test was used. Spearman’s rank correlation test was applied for correlations. Values are expressed as median, interquartile range (IQR). P < 0.05 was considered statistically significant.