The Untapped Potential of Comparative Biology in Aging Research: Insights From the Extraordinary-Long-Lived Naked Mole-Rat.

The search for solutions to the vagaries of aging has, historically, been akin to searching at night in the bright light under street lamps by utilizing the few preexisting and well-established animal model systems. Throughout my career as a comparative biologist, I have ventured into the darkness across 4 continents and studied over 150 different animal species, many of which have evolved remarkable adaptations to survive on the harsh and rugged fitness landscape that exists outside of the laboratory setting. In this Fellows Forum, I will discuss the main focus of my research for the last 25 years and dig deeply into the biology of the preternaturally long-lived naked mole-rat that makes it an ideal model system for the characterization of successful strategies to combat aging.

Naked Mole-Rats Demonstrate Profound Tolerance to Low Oxygen, High Carbon Dioxide, and Chemical Pain.

Naked mole-rats (Heterocephalus glaber) are very unusual among subterranean mammals in that they live in large colonies and are extremely social, spending large amounts of time gathered together in underground nests more than a meter below the surface. Many respiring individuals resting in deep, poorly ventilated nests deplete the oxygen supply and increase the concentration of carbon dioxide. Consistent with living in that atmosphere, naked mole-rats tolerate levels of low oxygen and high carbon dioxide that are deadly to most surface-dwelling mammals. Naked mole-rats appear to have evolved a number of remarkable adaptations to be able to thrive in this harsh atmosphere. In order to successfully survive low oxygen atmospheres, they conserve energy utilization by reducing the physiological activity of all organs, manifest by reduced heart rate and brain activity. Amazingly, they resort to the anaerobic metabolism of fructose rather than glucose as a fuel to generate energy when challenged by anoxia. Similarly, high carbon dioxide atmospheres normally cause tissue acidosis, while naked mole-rats have a genetic mutation preventing both acid-induced pain and pulmonary edema. Together, these putative adaptations and the tolerances they provide make the naked mole-rat an important model for studying a host of biomedical challenges.

Epigenetic aging of the demographically non-aging naked mole-rat.

The naked mole-rat (NMR) is an exceptionally long-lived rodent that shows no increase of mortality with age, defining it as a demographically non-aging mammal. Here, we perform bisulfite sequencing of the blood of > 100 NMRs, assessing > 3 million common CpG sites. Unsupervised clustering based on sites whose methylation correlates with age reveals an age-related methylome remodeling, and we also observe a methylome information loss, suggesting that NMRs age. We develop an epigenetic aging clock that accurately predicts the NMR age. We show that these animals age much slower than mice and much faster than humans, consistent with their known maximum lifespans. Interestingly, patterns of age-related changes of clock sites in Tert and Prpf19 differ between NMRs and mice, but there are also sites conserved between the two species. Together, the data indicate that NMRs, like other mammals, epigenetically age even in the absence of demographic aging of this species.

PPARα and PPARγ Signaling Is Enhanced in the Brain of the Naked Mole-Rat, a Mammal that Shows Intrinsic Neuroprotection from Oxygen Deprivation.

Naked mole-rats (NMRs) are a long-lived animal that do not develop age-related diseases including neurodegeneration and cancer. Additionally, NMRs have a profound ability to consume reactive oxygen species (ROS) and survive long periods of oxygen deprivation. Here, we evaluated the unique proteome across selected brain regions of NMRs at different ages. Compared to mice, we observed numerous differentially expressed proteins related to altered mitochondrial function in all brain regions, suggesting that the mitochondria in NMRs may have adapted to compensate for energy demands associated with living in a harsh, underground environment. Keeping in mind that ROS can induce polyunsaturated fatty acid peroxidation under periods of neuronal stress, we investigated docosahexaenoic acid (DHA) and arachidonic acid (AA) peroxidation under oxygen-deprived conditions and observed that NMRs undergo DHA and AA peroxidation to a far less extent compared to mice. Further, our proteomic analysis also suggested enhanced peroxisome proliferator-activated receptor (PPAR)-retinoid X receptor (RXR) activation in NMRs via the PPARα-RXR and PPARγ-RXR complexes. Correspondingly, we present several lines of evidence supporting PPAR activation, including increased eicosapetenoic and omega-3 docosapentaenoic acid, as well as an upregulation of fatty acid-binding protein 3 and 4, known transporters of omega-3 fatty acids and PPAR activators. These results suggest enhanced PPARα and PPARγ signaling as a potential, innate neuroprotective mechanism in NMRs.

Comparison between autologous bone grafts and acrylic (PMMA) implants - A retrospective analysis of 286 cranioplasty procedures.

Decompressive craniectomy (DC) is an accepted surgical technique for reducing life-threatening levels of intracranial pressure. Remodelling the cranial vault following DC can constitute a reconstructive challenge and is known to carry significant morbidity. The aim of our study was to evaluate acrylic versus autologous cranioplasty with regard to specific complication rates. A retrospective analysis was conducted of 286 consecutive adult patients who underwent cranioplasty following supratentorial decompressive craniectomy at our institution between January 2003 and June 2013. The patients were followed based on medical records, operative reports, imaging and outpatient contacts in the postoperative course. A total of 221/286 patients in our series received an autologous bone flap. 65/286 cranioplasty procedures were carried out using acrylic (PMMA) implants to cover uni- or bilateral defects. Within the follow-up period a total of 100 operative revisions were performed. 33.3% patients in the autologous bone group and 40.6% of patients in the acrylic group developed complications requiring surgical attention. The main reason for revision was infection with a total of 37 revisions necessary to treat disturbed wound healing. Postoperative sub- and epidural hematomas requiring revision were more frequent in the acrylic group. Resorption of the autologous bone flap requiring operative revision was seen in 8/222 (3.6%) cases. Other complications included loosening of the implant or dislocation. From our data it can be concluded that cranioplasty procedures using autologous bone-flaps and acrylic implants carry signifikant morbidity, but that both are justifiable techniques for cranioplasty in adult patients.

Fructose-driven glycolysis supports anoxia resistance in the naked mole-rat.

The African naked mole-rat's (Heterocephalus glaber) social and subterranean lifestyle generates a hypoxic niche. Under experimental conditions, naked mole-rats tolerate hours of extreme hypoxia and survive 18 minutes of total oxygen deprivation (anoxia) without apparent injury. During anoxia, the naked mole-rat switches to anaerobic metabolism fueled by fructose, which is actively accumulated and metabolized to lactate in the brain. Global expression of the GLUT5 fructose transporter and high levels of ketohexokinase were identified as molecular signatures of fructose metabolism. Fructose-driven glycolytic respiration in naked mole-rat tissues avoids feedback inhibition of glycolysis via phosphofructokinase, supporting viability. The metabolic rewiring of glycolysis can circumvent the normally lethal effects of oxygen deprivation, a mechanism that could be harnessed to minimize hypoxic damage in human disease.

Risk of Bacterial Infection in Patients With Cirrhosis and Acute Variceal Hemorrhage, Based on Child-Pugh Class, and Effects of Antibiotics.

BACKGROUND & AIMS: Antibiotics frequently are overused and are associated with serious adverse events in patients with cirrhosis. However, these drugs are recommended for all patients presenting with acute variceal hemorrhage (AVH). We investigated whether patients should be stratified for antibiotic prophylaxis based on Child-Pugh scores, to estimate risks of bacterial infection, rebleeding, and mortality, and whether antibiotics have equal effects on patients of all Child-Pugh classes. We performed a sensitivity analysis using model for end-stage liver disease (MELD) scores. METHODS: In a retrospective study, we analyzed data from 381 adult patients with cirrhosis and AVH (70% men; mean age, 56 y), admitted from 2000 through 2009 to 2 tertiary care hospitals in Edmonton, Alberta, Canada. We excluded patients with bacterial infection on the day of AVH. The association between antibiotic prophylaxis and outcomes was adjusted by liver disease severity and by a propensity score. RESULTS: The patients included in the study had mean MELD scores of 16, and 54% received antibiotic prophylaxis. Overall, antibiotic therapy was associated with lower risks of infection (adjusted odds ratio, 0.37; 95% confidence interval, 0.91-0.74) and mortality (adjusted odds ratio, 0.63; 95% confidence interval, 0.31-1.29). Among patients categorized as Child-Pugh class A given antibiotics, only 2% developed infections and the mortality rate was 0.4%. Among patients categorized as Child-Pugh class B given antibiotics, 6% developed infections, compared with 14% of patients who did not receive antibiotics; antibiotics did not affect mortality. Administration of antibiotics to patients categorized as Child-Pugh class C reduced infections and mortality by approximately 50%, compared with patients who did not receive antibiotics. MELD scores were not as useful as Child-Pugh class in identifying patients at risk for infection. CONCLUSIONS: Based on a retrospective analysis of patients with cirrhosis and AVH, those categorized as Child-Pugh class A had lower rates of bacterial infection and lower mortality rates in the absence of antibiotic prophylaxis than patients categorized as classes B or C. The recommendation for routine antibiotic prophylaxis for this subgroup requires further evaluation.

Relative survival of patients with non-malignant central nervous system tumours: a descriptive study by the Austrian Brain Tumour Registry.

BACKGROUND: Unlike malignant primary central nervous system (CNS) tumours outcome data on non-malignant CNS tumours are scarce. For patients diagnosed from 1996 to 2002 5-year relative survival of only 85.0% has been reported. We investigated this rate in a contemporary patient cohort to update information on survival. METHODS: We followed a cohort of 3983 cases within the Austrian Brain Tumour Registry. All patients were newly diagnosed from 2005 to 2010 with a histologically confirmed non-malignant CNS tumour. Vital status, cause of death, and population life tables were obtained by 31 December 2011 to calculate relative survival. RESULTS: Overall 5-year relative survival was 96.1% (95% CI 95.1-97.1%), being significantly lower in tumours of borderline (90.2%, 87.2-92.7%) than benign behaviour (97.4%, 96.3-98.3%). Benign tumour survival ranged from 86.8 for neurofibroma to 99.7% for Schwannoma; for borderline tumours survival rates varied from 83.2 for haemangiopericytoma to 98.4% for myxopapillary ependymoma. Cause of death was directly attributed to the CNS tumour in 39.6%, followed by other cancer (20.4%) and cardiovascular disease (15.8%). CONCLUSION: The overall excess mortality in patients with non-malignant CNS tumours is 5.5%, indicating a significant improvement in survival over the last decade. Still, the remaining adverse impact on survival underpins the importance of systematic registration of these tumours.

Managing the post-liver transplantation anastomotic biliary stricture: multiple plastic versus metal stents: a systematic review.

BACKGROUND: Anastomotic biliary strictures (ABSs) are common after liver transplantation, especially with living donors. The strategy of balloon dilation and multiple plastic stents (MPSs) is effective in treating ABSs, but requires multiple ERCPs with the associated risks, cost, and patient burden. Covered self-expandable metal stents (SEMSs) have been increasingly used in this setting. However, it is not clear whether there are definite advantages of using SEMSs over MPSs. OBJECTIVE: To compare the efficacy and safety of MPSs and SEMSs in ABS after orthotopic liver transplantation (OLT) and living donor liver transplantation (LDLT). DESIGN: Systematic review by searching MEDLINE and EMBASE databases. PATIENTS: OLT and LDLT patients. INTERVENTIONS: MPSs versus SEMSs. MAIN OUTCOME MEASUREMENTS: Stricture resolution and adverse event rates. RESULTS: Eight studies (446 patients) using MPSs in OLT, 3 studies (120 patients) using MPSs in LDLT, and 10 studies (200 patients) using SEMSs fulfilled the inclusion and exclusion criteria. The stricture resolution rates were highest (94%-100%) when MPS duration was 12 months or longer. The stricture resolution rates with SEMSs in OLT patients were also high when stent duration was 3 months or longer (80%-95%) compared with a duration less than 3 months (53%-88%). Although the overall adverse event rates were low, the overall SEMS migration rate was significant at 16%. LIMITATIONS: No randomized, controlled trials were identified; only small case series using either MPSs or SEMSs were included. CONCLUSIONS: Although SEMSs appeared to be a promising option in the endoscopic management of ABSs after liver transplantation, current evidence does not suggest a clear advantage of SEMS use over MPSs for this indication.

Patients with recurrent glioblastoma multiforme. Initial experience with p-[(131)I]iodo-L-phenylalanine and external beam radiation therapy.

AIM: The objective of this study was to assess the feasibility, dosimetry, tolerability and efficacy of systemically administrated p-[(131)I]iodo-L-phenylalanine ((131)IPA) combined with hypo-fractionated external beam radiation therapy (EBRT) in patients with recurrent glioblastoma multiforme (GBM). PATIENTS, METHODS: Five patients (2 women, 3 men, aged 27-69) with recurrent GBM and exhaustion of regular therapy options were included. All had a positive O-(2-[(18)F]Fluoroethyl)-L-tyrosine positron emission tomography (FET-PET) and pretherapeutic dosimetry was performed. Tumour targeting was verified by (131)IPA-SPECT up to six days after radiotracer administration. After (131)IPA therapy, patients were treated with hypo-fractionated EBRT in six fractions of 5 Gy (n = 4) or in eleven fractions of 2 Gy in one case. RESULTS: Based on the individual dosimetry, the patients received a single intravenous administration of 2 to 7 GBq of (131)IPA, resulting in radiation absorbed doses to the blood of 0.80-1.47 Gy. The treatment was well tolerated; only minor complaints of nausea and vomiting that responded to ondansetron and pantoprazol were noticed in the first two patients. After preventive medication, the last three patients had no complaints during therapy. In none of the patients a decrease of leukocyte or thrombocyte counts below the baseline level or the lower normal limit was observed. Tumour doses from (131)IPA were low (≤ 1 Gy) and all patients died three to eight (median 5.5) months after therapy. CONCLUSION: In this initial experience, treatment of GBM with (131)IPA in combination with EBRT was demonstrated to be safe and well tolerated, but less effective than suggested by the animal studies.

Leucocyte subpopulations in the seminal plasma and their effects on fertilisation rates in an IVF cycle.

Controversy exists on the role of leucocytospermia on fertilisation rates and IVF outcomes. The aim of our study was to identify the effect of leucocytes and leucocyte subpopulations on fertilisation rates in an IVF cycle. A prospective comparative study of the leucocyte subpopulations of seminal fluid of partners of women attending an IVF cycle was conducted. The samples underwent immunocytochemical staining. The monoclonal antibodies used in this study include CD3, CD4, CD8 (T Cells), CD14 (monocytes/macrophages), CD16 (granulocytes), CD20 (B Cells), CD45 (Pan Leucocytes), CD56 (natural killer cells) and CD69 (activated T and B Cells). Of 21 patients who were recruited into the study, seven were identified as poor fertilisers (<35%) and 14 were identified as good fertilisers (>60%). Data were analysed with SPSS version 14. The total leucocyte counts (CD45) between the poor and good fertilisers were not statistically significant. The macrophages and the monocytes (CD14) were significantly elevated in the good fertilisers group in comparison with the poor fertilisers (P < 0.05). We also found that T cells (CD2, CD4, CD8) and CD14 (macrophages) correlated significantly (r = 0.47, P value < 0.01) with the fertilisation rate. Our study confirms that the presence of leucocytes does not adversely affect the fertilisation rates and the outcome of an IVF cycle. However, macrophages and the monocytes (CD14) were significantly elevated in the good fertilisers group. The increased phagocytic activity in these individuals might increase their fertilising potential by removing spermatozoa with abnormal morphology.

Detection of subpopulations of leucocytes in different subgroups of semen sample qualities.

The role of leucocytospermia in male subfertility is a much debated topic despite being a frequent finding. This study aimed to identify the role of leucocytes, leucocyte subpopulations and natural killer cells in male subfertility. Seventy-sex subfertile men attending a regional andrology unit were recruited into this prospective study and subdivided into groups based on their semen analysis. The different leucocyte subpopulations were identified using immunocytochemical staining. Significant levels of CD3 helper T lymphocytes (P < 0.001) were present in the oligospermic, asthenospermic, oligoasthenospermic and obstructive azoospermic group compared to the normospermic group. Significant levels of B cells (P < 0.05) were present in the asthenospermic, oligoasthenospermic and obstructive azoospermic group. The natural killer cells (CD56) were significantly raised in the oligoasthenospermic and obstructive azoospermic group (P < 0.05). Our study suggests that leucocytospermia impairs sperm function through enhanced T helper cell modulation, increased B cell population which leads to increased levels of antisperm antibody and natural killer cells mediated sperm damage. The site of seminal leucocyte production is not necessarily confined to the vas or the epididymis.

Cytokine expression in the seminal plasma and its effects on fertilisation rates in an IVF cycle.

Cytokines are released by various immunocompetent cell subsets in the male urogenital tract and are thought to affect sperm cell function and reproductive process. The aim of the study was to evaluate the levels and a possible role of seven seminal plasma cytokines with fertilisation rates in men attending an in vitro fertilisation (IVF) programme. A total of 36 men of couples who were undergoing traditional IVF in a regional reproductive medicine unit were recruited into this prospective study. Cytokines such as interleukin (IL)-6, IL-8, IL-10, IL-11, IL-12, tumour necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) in the seminal plasma were determined using enzyme linked immunosorbent assay. IL-6, IL-8, IL-10, IL-11 and IFN-γ were detected in all samples. IL-12, and TNF-α were detected in most samples. Levels of IL-11 were significantly higher in the good fertiliser group (P ≤ 0.05). Positive correlation between cytokines such as IL-6 and IL-8 (P < 0.03), IL-10 and IL-11 (P < 0.001) and IFN-γ and IL-10 and IL-11 (P < 0.04 and P < 0.0001 respectively) were found. Our study confirms that the six cytokines other than IL-11 do not affect spermatozoon-oocyte interaction and fertilisation rates in IVF. IL-11 could have a role in the fertilising capacity of the spermatozoa. Significant correlation exists among these cytokines which shows that cytokines rarely act in isolation but rather in a network.

The available pool of sex partners and risk for a current bacterial sexually transmitted infection.

PURPOSE: Sexually transmitted infection (STI) transmission models propose that incident STIs are related to exposure to infected sex partners. The objective of this study was to determine whether the prevalence of STIs among the available pool of sex partners in a neighborhood, measured indirectly, is an independent determinant of a current incident STI. METHODS: The target population comprised 58,299 English-speaking, sexually active 15- to 24-year-olds in 486 census block groups (CBGs) in Baltimore, MD. A sample of 65 CBGs was selected using a stratified, systematic, probability-proportional-to-size strategy and 13,873 households were randomly selected. From 2004 through 2007, research assistants administered an audio computer-assisted interview survey and collected biologic samples for gonorrhea and chlamydia testing. RESULTS: The final sample size included 575 participants from 63 CBGs. Additional data provided gonorrhea prevalence from 2004 through 2005 per 15- to 49-year-old persons per 100,000 per CBG. After adjustment for individual-level STI risk factors in a multilevel probability model, adolescents and young adults living in high (vs. low) prevalence STI areas were 4.73 times (95% confidence interval [CI]: 3.65-6.15) more likely to have a current incident STI. CONCLUSIONS: To inform prevention programs, future research should focus on identifying mechanisms through which context causes changes in local sexual networks and their STI prevalence.

The natural history of inflammatory bowel disease and primary sclerosing cholangitis after liver transplantation--a single-centre experience.

OBJECTIVE: To describe the natural history of primary sclerosing cholangitis (PSC) and inflammatory bowel disease (IBD) after liver transplant, the predictors of PSC and IBD recurrence, and the interaction of these disease processes. METHODS: Data regarding patients who received liver transplants for PSC at the University of Alberta Hospital (Edmonton, Alberta) from 1989 to 2006 were retrospectively reviewed. Recurrent PSC (rPSC) was defined by the Mayo Clinic criteria. Cox proportional hazards modelling and Kaplan-Meier statistics were used. RESULTS: Fifty-nine patients were studied, with a median follow-up of 68 months. A total of 71.2% of patients were diagnosed with IBD pretransplant. Clinical IBD severity post-transplant compared with severity pretransplant was unchanged in 67%, worse in 26.5% and improved in 6.1% of patients. Twenty-five per cent of patients developed rPSC posttransplant. The occurrence of at least one episode of acute cellular rejection (hazard ratio 5.7; 95% CI 1.3 to 25.8) and cytomegalovirus mismatch (hazard ratio 4.2; 95% CI 1.1 to 15.4) were found to be significant predictors of rPSC. Although not statistically significant, there was no rPSC in patients without pre- or post-transplant IBD, and in only one patient with a colectomy. Actuarial patient survival rates at one, five and 10 years posttransplant were 97%, 86% and 79%, respectively. Although a significant proportion of patients experienced worsening IBD post-transplantation, the presence or severity of IBD did not influence rPSC or patient survival. CONCLUSION: Acute cellular rejection and cytomegalovirus mismatch were both identified as independent predictors of rPSC. The impact of steroids and the ideal immunosuppressive regimen for the control of both IBD and PSC post-transplant requires further examination in prospective studies.

Effects of probiotic therapy on portal pressure in patients with cirrhosis: a pilot study.

BACKGROUND: Recent literature has supported the role of bacterial translocation as a mediator of splanchnic vasodilatation and portal hypertension. The objective of this study was to determine whether the probiotic VSL#3 would reduce portal pressure in patients with cirrhosis. METHODS: Eight patients with compensated or very early decompensated cirrhosis and hepatic venous pressure gradient (HVPG) >10 mmHg, received 2 months of VSL#3 (3600 billion bacteria daily). The HVPG, intestinal permeability, endotoxin, tumour necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-8, renin and aldosterone were measured at baseline and study end. RESULTS: There was no change in the HVPG or intestinal permeability from baseline to study end but there was a trend to reduction in plasma endotoxin (P=0.09), a mild but significant increase in serum TNF-alpha (P=0.02) and a significant reduction in plasma aldosterone (P=0.03). CONCLUSIONS: Within the limitations of small sample size, there does not appear to be a benefit of probiotic therapy for portal pressure reduction in patients with compensated or early decompensated cirrhosis. The reductions in endotoxin and aldosterone suggest possible beneficial effects of probiotics for this patient population. The clinical significance of the small but unexpected increase in TNF-alpha is unclear. Future studies are planned in patients with decompensated cirrhosis.

Outcomes of peginterferon alpha-2a and ribavirin hepatitis C therapy in Aboriginal Canadians.

BACKGROUND: There is little published information on baseline characteristics and therapeutic outcomes in hepatitis C virus (HCV)-infected Aboriginal Canadians. It is unclear what proportion of HCV-infected Aboriginal people receive therapy relative to other populations. METHODS: Adults with chronic HCV infection, quantifiable serum HCV-RNA levels and compensated liver disease were assigned, at the physician's discretion, to either 24 or 48 weeks of treatment with peginterferon alpha-2a 180 mug/week plus ribavirin at a dose of 800 mg/day, or 1000 mg/day or 1200 mg/day in an open-label, expanded access program. The primary outcome was sustained virological response, defined as undetectable HCV-RNA by qualitative polymerase chain reaction (less than 50 IU/mL) at the end of 24 weeks of untreated follow-up. Baseline characteristics and outcomes in Aboriginal and non-Aboriginal patients were compared. RESULTS: A total of 2614 patients were eligible for the analysis; 44 individuals (1.7%) self-identified as being of Aboriginal heritage. The baseline characteristics of these two groups were similar. An overall sustained virological response was achieved in 47.7% and 46.5% of Aboriginal and non-Aboriginal patients, respectively. The overall frequencies of adverse events and laboratory abnormalities were similar between the two groups, although cytopenias occurred less frequently in Aboriginal patients. INTERPRETATION: Aboriginal patients were greatly under-represented in the present 'community'-based treatment program, yet viral responses were similar to those of a non-Aboriginal cohort. To increase the uptake of HCV therapy in the Aboriginal population, clarification of the obstacles to treatment is warranted.

Follicular fluid expression of alpha-defensins and their role in ovulation.

INTRODUCTION: Defensins are cytotoxic peptides and have a well-defined role in host defense. Human alpha defensins 1-3 (HNP1-3) are primarily produced by peripheral neutrophils and constitute about 50% of the azurphil granule protein. Studies have suggested that peripheral neutrophils and the resident neutrophils in the ovary enhance the release of IL-8 and TNF-alpha that play a role in ovulation and influence fertilisation rate and IVF outcome. The production of HNP1-3 by follicular fluid and its role in ovulation has never studied. The aim of this study was to demonstrate the presence of HNP1-3 in follicular fluid and to ascertain its correlation with fertilisation rate and IVF outcome. METHOD: Women attending the Reproductive Medicine Unit at Liverpool Women's Hospital UK, for IVF treatment were invited to participate in the study. Sixty-three patients were recruited for the study and underwent controlled ovarian stimulation and oocyte retrieval according to the unit's protocol. Fluid from the first follicle only was collected to minimise blood contamination of the sample and HNP1-3 was estimated using ELISA technique. RESULTS: HNP1-3 was detected in follicular fluid samples. The concentration did not correlate with the fertilisation rate (r=0.01). The concentrations were also not significantly different in the women who did or did not become pregnant following treatment. Subgroup analysis showed that women with endometriosis were not more likely to have higher levels of the HNP1-3 when compared with controls (male factor infertility group). CONCLUSION: This is the first study to show the expression of HNP1-3 in follicular fluid. HNP1-3 concentrations did not correlate with fertilisation rate or IVF outcome. It did not show an increased expression of HNP1-3 in fluid collected from women with endometriosis suggesting that inflammatory processes associated with endometriosis do not influence HNP1-3 concentration in the follicular fluid. Further studies to evaluate the correlation between HNP1-3 and IL-8 and TNF-alpha may clarify the role of defensins in ovulation.

The expression of human alpha and beta defensin in the endometrium and their effect on implantation.

BACKGROUND: Alpha and beta defensins have been isolated from various human tissues and form an important part of the innate immune system. Their role in implantation of the embryo has not yet been studied. This study was designed to detect both alpha and beta defensins in the mid luteal phase endometrium and investigate the correlation between the defensin expression and implantation of the embryo. METHOD AND RESULTS: An experimental study was designed to detect alpha defensin (HNP1-3) and beta defensin (HBD1) in midluteal phase endometrial samples obtained from women attending the IVF unit at the Liverpool Women's Hospital, UK. Samples were obtained at least two menstrual cycles before IVF treatment was commenced. Immunohistochemical staining was conducted to estimate defensin expression. Some endometrial stromal cells stained positive for HNP1-3 during the midluteal phase. HNP1-3 expression is significantly higher in cases presenting with female factor infertility as compared with purely male factor infertility. A significant increase was not observed in tubal factor or endometriosis when considered separately. Endometrial stromal neutrophils were shown to be the main source of endometrial HNP1-3. HBD1 was the only beta defensin detected by immunochemical staining in the midluteal phase endometrium. The intensity of staining was significantly different in the endometrial stroma, luminal and glandular epithelia. HBD1 expression is not significantly higher in female factor infertility. CONCLUSION: The study confirmed secretion of HNP1-3 by endometrial stromal neutrophils. Glandular epithelium is the main source of HBD1 expression in the human endometrium. HNP1-3 shows increased expression in female factor infertility. HBD1 expression is not higher in female factor infertility. These defensins do not appear to influence implantation.