Infertility in females with cystic fibrosis is multifactorial: evidence from mouse models

Endocytosis at the maternal-fetal interface: balancing nutrient transport and pathogen defense

Endocytosis represents a category of regulated active transport mechanisms. These encompass clathrin-dependent and -independent mechanisms, as well as fluid phase micropinocytosis and macropinocytosis, each demonstrating varying degrees of specificity and capacity. Collectively, these mechanisms facilitate the internalization of cargo into cellular vesicles. Pregnancy is one such physiological state during which endocytosis may play critical roles. A successful pregnancy necessitates ongoing communication between maternal and fetal cells at the maternal-fetal interface to ensure immunologic tolerance for the semi-allogenic fetus whilst providing adequate protection against infection from pathogens, such as viruses and bacteria. It also requires transport of nutrients across the maternal-fetal interface, but restriction of potentially harmful chemicals and drugs to allow fetal development. In this context, trogocytosis, a specific form of endocytosis, plays a crucial role in immunological tolerance and infection prevention. Endocytosis is also thought to play a significant role in nutrient and toxin handling at the maternal-fetal interface, though its mechanisms remain less understood. A comprehensive understanding of endocytosis and its mechanisms not only enhances our knowledge of maternal-fetal interactions but is also essential for identifying the pathogenesis of pregnancy pathologies and providing new avenues for therapeutic intervention.

The role of CFTR channel in female infertility

The cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-activated trans-membrane ATP gated anion channel present in most epithelia, which transports chloride and bicarbonate ions across the apical membrane. Mutations in the CFTR protein are known to result in defective expression or function, notably the inhibition of chloride and bicarbonate transport. This can result in cystic fibrosis (CF), a disorder characterised by thickness of the mucus lining of the epithelial cells of the alimentary and respiratory tracts, sweat ducts and reproductive organs. As a consequence, there is a reduction in fluid transport at the apical surface. While the most devastating effect of CF is mortality, about 98% of men with CF are infertile, consequent of early blockage of or failure to develop the mesonephrotic ducts as well as the vas deferens. The effect of CF of female fertility is less well-understood. This review highlights the genetics and pathophysiology as well as the mechanism of action of CF on female infertility.

The modern landscape of fertility, pregnancy, and parenthood in people with cystic fibrosis

PURPOSE OF REVIEW

With improved long-term survival and the expanding availability of cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapies that treat the underlying genetic defect in cystic fibrosis, more people are interested in parenthood. Cystic fibrosis care centers and people with cystic fibrosis need more information to guide decisions related to parenting.

RECENT FINDINGS

Here we present currently available data on fertility, pregnancy, and parenthood in the modern era of cystic fibrosis care. Fertility may be improving in female individuals with cystic fibrosis with the use of CFTR modulator therapies, and there is an associated increase in annual pregnancies. Infertility in male individuals with cystic fibrosis remains approximately 97-98% and is unchanged with CFTR modulators in those already born with cystic fibrosis. As more female individuals with cystic fibrosis experience pregnancy, questions remain about the impact of pregnancy on their health and that of their child. Fortunately, there are multiple routes to becoming a parent; however, more work is needed to understand the impact of pregnancy and parenthood in the context of CF as some previous data suggests potential challenges to the health of parents with cystic fibrosis.

SUMMARY

We encourage cystic fibrosis care teams to have knowledge and resources available to support the reproductive goals of all individuals with cystic fibrosis.

Ovarian reserve in women with cystic fibrosis: is this a cause of sub-fertility?

BACKGROUND

Over the past two decades, increasing number of people with cystic fibrosis (CF) survive into adulthood. Compared to the general population, sub-fertility is an obstacle for many women with CF (wwCF). Decreased ovarian reserve has been proposed as a possible cause, but limited data is available to support this. The aim of this study was to evaluate the ovarian reserve in wwCF and to correlate this with patients' demographic and clinical data.

METHODS

Reproductive-aged wwCF were enrolled during their routine medical appointments. Assessment included Anti-Mullerian hormone (AMH) levels, routine blood tests and antral follicular count (AFC) evaluation. Additionally, demographic, and clinical information were collected.

RESULTS

A total of wenty-three wwCF were enrolled, with ages ranging from 19 to 40 years (median 27 years). Among the fourteen wwCF who were considering pregnancy, five (35.7%) disclosed undergoing an infertility assessment and receiving fertility treatments. All but one patient had an Anti-Mullerian hormone (AMH) level between the 5th and 95th % for age. Measurement of the antral follicular count (AFC) was possible in 12 of the 23 patients and was ranging 8-40 with a median of 17. The proportion of wwCF presenting below median AMH values was not different in sub-fertile as compared to fertile wwCF (P value 0.54). There were no correlations between AMH levels and disease severity parameters. AMH seemed to be relatively higher in wwCF with mild class mutations, but this was not shown to have statistical significance.

CONCLUSIONS

Our results, in contrast with the limited available published data, do not support the hypothesis that decreased ovarian reserve plays a major role in infertility in wwCF.

Role of innate immunity and systemic inflammation in cystic fibrosis disease progression

Pathophysiological manifestations of cystic fibrosis (CF) result from a functional defect in the cystic fibrosis transmembrane conductance regulator (CFTR) paving way for mucus obstruction and pathogen colonization. The role of CFTR in modulating immune cell function and vascular integrity, irrespective of mucus thickening, in determining the host cell response to pathogens/allergens and causing systemic inflammation is least appreciated. Since CFTR plays a key role in the conductance of anions like Cl^-, loss of CFTR function could affect various basic cellular processes, such as cellular homeostasis, lysosome acidification, and redox balance. CFTR aids in endotoxin tolerance by regulating Toll-like receptor-mediated signaling resulting in uncontrolled activation of innate immune cells. Although leukocytes of CF patients are hyperactivated, they exhibit compromised phagosome activity thus favouring the orchestration of sepsis from defective pathogen clearance. This review will emphasize the importance of innate immunity and systemic inflammatory response in the development of CF and other CFTR-associated pathologies.

Cystic fibrosis and primary ciliary dyskinesia: Similarities and differences

Cystic fibrosis (CF) and Primary ciliary dyskinesia (PCD) are both rare chronic diseases, inherited disorders associated with multiple complications, namely respiratory complications, due to impaired mucociliary clearance that affect severely patients' lives. Although both are classified as rare diseases, PCD has a much lower prevalence than CF, particularly among Caucasians. As a result, CF is well studied, better recognized by clinicians, and with some therapeutic approaches already available. Whereas PCD is still largely unknown, and thus the approach is based on consensus guidelines, expert opinion, and extrapolation from the larger evidence base available for patients with CF. Both diseases have some clinical similarities but are very different, necessitating different treatment by specialists who are familiar with the complexities of each disease.This review aims to provide an overview of the knowledge about the two diseases with a focus on the similarities and differences between both in terms of disease mechanisms, common clinical manifestations, genetics and the most relevant therapeutic options. We hoped to raise clinical awareness about PCD, what it is, how it differs from CF, and how much information is still lacking. Furthermore, this review emphasises the fact that both diseases require ongoing research to find better treatments and, in particular for PCD, to fill the medical and scientific gaps.

The Impact of Highly Effective Cystic Fibrosis Transmembrane Conductance Regulator Modulators on the Health of Female Subjects With CF

Cystic fibrosis (CF) is a genetic disorder that occurs in people of all genetic ancestries. CF is caused by variants in the CF transmembrane conductance regulator (CFTR) gene that result in decreased, absent, or nonfunctional CFTR protein at the cell surface of the mucous membranes. Clinical manifestations include chronic respiratory disease, malabsorption, and decreased fertility. Historically, therapies for CF were focused on the signs and symptoms of the disease. However, more recently, CFTR modulators, therapies directed at the basic defect, are improving the quality and duration of the lives of people with CF. The predicted survival of people with CF in the United States is now 53 years of age. With the hope of longer, healthier lives, female individuals with CF (fwCF) are expressing the desire to discuss fertility, pregnancy, and parenthood. Furthermore, pregnancy rates are increasing substantially. Understanding the impact of use or discontinuation of highly effective modulator therapy on the reproductive health of fwCF is critical. Finally, fwCF and their providers must consider preventative cancer screening. (Clin Ther. 2023;45:XXX-XXX) © 2023 Elsevier HS Journals, Inc.

Functional evaluation of the cystic fibrosis transmembrane conductance regulator in the endocervix†

The cystic fibrosis transmembrane conductance regulator (CFTR) is an apical membrane chloride/bicarbonate ion channel in epithelial cells. Mutations in CFTR cause cystic fibrosis, a disease characterized by thickened mucus secretions and is associated with subfertility and infertility. CFTR function has been well characterized in vitro and in vivo in airway and other epithelia studies. However, little is known about CFTR function in the cervix in health and its contribution to cyclic regulation of fertility from endocervical mucus changes. Contributing to this research gap is the lack of information on the effect of sex steroid hormones on CFTR expression in cervical epithelial cells across the menstrual cycle. Herein, we demonstrate the hormonal regulation of CFTR expression in endocervical cells both in vitro and in vivo, and that conditionally reprogrammed endocervical epithelial cells can be used to interrogate CFTR ion channel function. CFTR activity was demonstrated in vitro using electrophysiological methods and functionally inhibited by the CFTR-specific inhibitors inh-172 and GlyH-101. We also report that CFTR expression is increased by estradiol in the macaque cervix both in vitro and in vivo in Rhesus macaques treated with artificial menstrual cycles. Estrogen upregulation of CFTR is blocked in vivo by cotreatment with progesterone. Our findings provide the most comprehensive evidence to date that steroid hormones drive changes in CFTR expression. These data are integral to understanding the role of CFTR as a fertility regulator in the endocervix.

Family-building and parenting considerations for people with cystic fibrosis

As people with cystic fibrosis (CF) live longer and healthier lives, increasing numbers are considering the full range of reproductive options for their futures, including parenthood, pregnancy, or pregnancy prevention. As the face of CF changes, the CF care model must adapt to meet the reproductive health needs of both parents and nonparents with CF. This article summarizes the reproductive goals and family-building concerns faced by people with CF, including fertility, pregnancy, and alternative paths to parenthood, the impact of parenthood on mental and physical health, and important future research.

The Prognosis of ART Is Not Altered in Cystic Fibrosis Women: A Case-Report Study

RESEARCH QUESTION

Unlike in men, a very limited number of studies were focused on the specificity of ART management of cystic fibrosis (CF) in women. The purpose of this study was to determine the causes of infertility in patients, the appropriate ART treatment, and their prognosis in terms of pregnancy.

DESIGN

We conducted a multicentre analytical case-control study including CF women who were age-matched to non-CF women. We reported the causes of infertility, the ART management type and pregnancy outcomes.

RESULTS

17 cases were compared to 34 controls. There was no significant difference between the groups concerning cause infertility. There was a non-statistically significant trend with a lower antral follicle count in CF compared to controls (19.5 versus 26.8, p=0.08). IUI seemed to be as successful as IVF/ICSI in CF as opposed to controls where the IVF/ICSI was the most effective (in CF group for HCG >100 UI/L: 38.8% vs. 36.8%, p=0.4175). There were more embryos obtained in CF than in controls (3.1 versus 1.6, p=0.02). The number of oocytes and embryos obtained and pregnancy outcomes remained similar between DF508 homozygous group and others CFTR mutations group. The results of ART procedures and pregnancy evolution were not influenced by FEV1.

CONCLUSION

In absence of any other pathology, IUI may be first option for CF women. If insemination fails, IVF with a low dose of gonadotropins may be more appropriate to prevent the risk of hyperstimulation syndrome. FEV1 and genetic do not seem to be contributing factors in the prognosis of ART.

Gynecologic health care for females with cystic fibrosis

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Females with CF may have cyclic lung symptoms, yeast infections, and urinary incontinence.

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Contraception is safe, but comorbidities should be considered in method selection.

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Females with CF have reduced fertility, though the etiology is unknown.

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Females with CF underutilize basic preventive gynecologic services.

As females with cystic fibrosis (CF) increasingly reach their reproductive years, gynecologic issues have become an important area of clinical care and research. First, females with CF may have disease-specific gynecologic problems, including cyclic pulmonary symptoms, vaginal yeast infections, and urinary incontinence. Next, contraceptive methods are thought to be overall safe and effective, however further research is needed to confirm this and to understand the lower rates of uptake among females with CF compared to the general population. Further, females with CF have reduced fertility, although the etiology of this is unknown and under investigation. While assisted reproductive technologies may help achieve pregnancy, decision-making around parenthood remains complex. Finally, while patients and providers agree on the importance of sexual and reproductive health care, females with CF underutilize basic preventive services such as cervical cancer screening, and better approaches are needed to bridge the gap with gynecology. In this review, we discuss the current state of gynecologic care for females with CF, as well as clinical and research opportunities for improvement.

Challenges Faced by Women with Cystic Fibrosis

Women with cystic fibrosis (CF) face several unaddressed concerns related to their health. These areas of concern include explanations and guidance on a sex disparity in outcomes, timing of puberty, effects of contraception, prevalence of infertility and impact of pregnancy, and prevention of urinary incontinence and osteoporosis. These understudied topics leave women with numerous unanswered questions about how to manage sexual and reproductive health in the setting of CF. Because people with CF are living longer and healthier lives, there is an increasing awareness of these important aspects of care and multiple ongoing studies to address these understudied topics.

Comparative analyses of long non-coding RNA profiles in vivo in cystic fibrosis lung airway and parenchyma tissues

BACKGROUND

Recent advances in the functional analyses of endogenous non-coding RNA (ncRNA) molecules, including long non-coding RNAs (LncRNAs), have provided a new perspective on the crucial roles of RNA in gene regulation. Consequently, LncRNA deregulation is a key factor in various diseases, including pulmonary disorders like Cystic Fibrosis (CF). CF is the most common life limiting recessive disease in the U.S., and is due to mutations in the CFTR gene. CF mutations, of which the most common is F508del-CFTR, prevents correct folding, trafficking and function of the mutant CFTR protein and is further manifested by the hyper-expression of pro-inflammatory cytokines and chemokines into the airway lumen leading to bronchiectasis and culminating in lung destruction.

METHODS

Here we report a distinct LncRNA signature and corresponding mRNAs that distinguishes CF lung (airway and parenchyma) tissues from matched non-CF controls (n = 4 each group), generated by microarray specific for LncRNAs which includes corresponding mRNA expressions. In silico analyses of the cellular processes that are impacted by these LncRNAs was performed using Gene Ontology (GO). A selected subset of LncRNAs were validated by quantitative real-time PCR.

RESULTS

We have identified 636 LncRNAs differentially expressed in CF airway epithelium and 1974 in CF lung parenchyma compared to matched non-CF controls (fold change ≥2, p < 0.05), majority of which (> 50%) are intergenic. Interestingly, 15 of these differentially expressed LncRNAs and 9 coding mRNAs are common to airway and parenchyma tissues. GO analyses indicates that signaling pathways and cell membrane functions are significantly affected by the alteration in LncRNA expressions in CF lung tissues. Seven of the differentially expressed LncRNAs, exhibit similar expression trends in CFBE41o- compared to control cells.

CONCLUSION

Understanding the mechanisms by which these LncRNAs regulate CF disease phenotype will help develop novel therapeutic targets for CF and related pulmonary diseases, such as COPD and Asthma.

CFTR and FOXO1 gene expression are reduced and high mobility group box 1 (HMGB1) is increased in the ovaries and serum of women with polycystic ovarian syndrome

We previously described increased HMGB1 and reduced FOXO1 dependent on CFTR loss of function in cystic fibrosis (CF) and we showed in vitro that HMGB1 was lowered by insulin. Reduced CFTR gene expression has been described in granulosa cells (GC) from PCOS-induced rats. We aimed at studying CFTR and FOXO1 gene expression in GC, HMGB1 concentrations in serum and follicular fluids (FF), and insulin and IL-6 in FF in PCOS women. Thirty PCOS and 36 non-PCOS women (CTRL) undergoing in vitro fertilization were enrolled. CFTR and FOXO1 gene expression were downregulated in PCOS (p ≤ .05). HMGB1 was higher in PCOS both in FF (p ≤ .05) and in serum (p < .005) whereas insulin was lower, and IL-6 was unchanged with respect to controls. 17-β estradiol was higher in PCOS than in CTRL (p ≤ .005). HMGB1 correlated negatively with insulin in FF (p ≤ .005). The increase in HMGB1 both in FF and in serum, likely reflects both low grade inflammation and insulin sensitivity. IL-6 was unchanged possibly reflecting functions other than inflammation.

HDAC6 depletion improves cystic fibrosis mouse airway responses to bacterial challenge

The hypothesis of this study was that Hdac6 depletion would restore cystic fibrosis (CF) responses to bacterial challenge to more wild type profiles using a CF mouse model. CF mice harboring the F508del Cftr mutation respond to bacterial challenge with 25,000 CFU Pseudomonas aeruginosa embedded into agarose beads to slow clearance. CF mice respond significantly more aggressively to this challenge compared to WT mice with respect to bacterial clearance, weight loss, neutrophil recruitment, and MIP-2 production. Depletion of Hdac6 expression in the CF mice (CF/Hdac6) significantly improves these responses to more WT levels. Weight loss in response to infection is most severe in CF mice and significantly attenuated in CF/Hdac6 mice. Bacterial levels are reduced at a faster rate in CF/Hdac6 mice compared to CF mice where infection persists. Percent neutrophils in lung lavage fluid post-infection are significantly higher in CF mice, but returned to WT levels with CF/Hdac6 mice. Similarly, CF Mip-2 levels are restored to WT levels in the absence of Hdac6 expression. These data demonstrate that Hdac6 depletion restores CF responses to bacterial challenge to WT-like profiles and offer a potential therapeutic avenue for addressing inflammation and infection in CF airways independently of Cftr correction.

CFTR regulates B cell activation and lymphoid follicle development

Background

Cystic fibrosis (CF) is an inherited disorder caused by mutations in the CF transmembrane conductance regulator (CFTR) gene that promotes persistent lung infection and inflammation and progressive loss of lung function. Patients with CF have increased lung lymphoid follicles (LFs) and B cell-activating factor of tumor necrosis factor family (BAFF) that regulates B cell survival and maturation. A direct role for CFTR in B cell activation and disease pathogenesis in CF remains unclear.

Methods

The number of LFs, BAFF⁺, TLR4⁺ and proliferation marker Ki67⁺ B cells in lung explants or resections from subjects with CF and normal controls was quantified by immunostaining. The role of CFTR in B cell activation and LF development was then examined in two independent cohorts of uninfected CFTR-deficient mice (Cftr^−/−) and wild type controls. The number of lung LFs, B cells and BAFF⁺, CXCR4⁺, immunoglobulin G⁺ B cells was examined by immunostaining. Lung and splenocyte B cell activation marker and major histocompatibility complex class II (MHC class II) expression was quantified by flow cytometry. Inflammatory cytokine levels were measured in supernatants from isolated B cells from Cftr^−/− and wild type mice stimulated in vitro with Pseudomonas aeruginosa lipopolysaccharide (LPS).

Results

There was a significant increase in well-formed LFs in subjects with CF compared to normal controls. Increased B cell activation and proliferation was observed in lung LFs from CF subjects as was quantified by a significant increase in B cell BAFF, TLR4 and Ki67 expression. Uninfected Cftr^−/− mice had increased lung LFs and BAFF⁺ and CXCR4⁺ B cells compared to wild type controls. Lung B cells isolated from uninfected Cftr^−/− mice demonstrated increased MHC class II expression. In vitro, isolated B cells from Cftr^−/− mice produced increased IL-6 when stimulated with LPS compared to wild type controls.

Conclusions

These data support a direct role for CFTR in B cell activation, proliferation and inflammatory cytokine production that promotes lung LF follicle development in cystic fibrosis.

Creatine enhances the duration of sperm capacitation: a novel factor for improving in vitro fertilization with small numbers of sperm

STUDY QUESTION

Why are many sperm required for successful fertilization of oocytes in vitro, even though fertilization occurs in vivo when only a few sperm reach the oocyte?

SUMMARY ANSWER

Creatine produced in the ovary promotes efficient fertilization in vivo; however, in vitro, creatine is not contained in the in vitro fertilization (IVF) medium.

WHAT IS KNOWN ALREADY

The IVF medium enables capacitation of sperm. However, the IVF medium does not fully mimic the in vivo environment during fertilization. Consequently, fertilization in vitro is more inefficient than in the oviduct.

STUDY DESIGN, SIZE, DURATION

Follicular and oviductal fluids were collected and then analyzed for creatine and glucose levels. To determine the physiological functions of creatine, the creatine antagonist 3-guanidinopropionic acid (GPA) was injected into hormonally primed mice. Using conventional IVF protocols, sperm were pre-incubated in IVF medium with creatine and then co-cultured with 10 ovulated cumulus-oocyte complexes (1-1000 per oocyte) in 50 μl medium droplets.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Glucose and creatine levels were measured using commercial enzymatic assay kits. The effect of creatine in vivo was assessed by mating experiments using mice treated with or without GPA just before ovulation. To assess the functions of sperm incubated in IVF medium containing creatine, we analyzed (1) the motility of sperm using computer-assisted sperm assay, (2) the capacitation level of sperm by western blot analyses, and (3) the condition of sperm acrosomes by peanut agglutinin lectin-FITC staining.

MAIN RESULTS AND THE ROLE OF CHANCE

Oviductal creatine levels were significantly increased following ovulation. Injecting mice with GPA just before ovulation significantly reduced the number of fertilized oocytes. The addition of creatine to IVF medium enhanced sperm capacitation by increasing ATP levels. Successful fertilization was achieved with as few as five sperm/oocyte in the creatine group, and the number of fertilized oocytes was significantly higher than in the control without creatine (P < 0.01).

LIMITATIONS, REASONS FOR CAUTION

In the present study, a pharmacological approach, creatine antagonist (GPA) treatment, but not a knockout mouse model, was used to understand the role of creatine in vivo. The role of creatine in fertilization processes can only be shown in a mouse model.

WIDER IMPLICATIONS OF THE FINDINGS

A modified IVF technique using creatine-containing medium was developed and shown to markedly improve fertilization with small numbers of sperm. This approach has the potential to be highly beneficial for human assisted reproductive technologies, especially for patients with a limited number of good quality sperm.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported in part by JSPS KAKENHI Grant numbers JP24688028, JP16H05017 (to M.S.), and JP15J05331 (to T.U.), the Japan Agency for Medical Research and Development (AMED) (16gk0110015h0001 to M.S.), and National Institutes of Health (NIH-HD-076980 to J.S.R). The authors have nothing to disclose.

Personalized medicine in CF: from modulator development to therapy for cystic fibrosis patients with rare CFTR mutations

Cystic fibrosis (CF) is the most common life-shortening genetic disease affecting ~1 in 3,500 of the Caucasian population. CF is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. To date, more than 2,000 CFTR mutations have been identified, which produce a wide range of phenotypes. The CFTR protein, a chloride channel, is normally expressed on epithelial cells lining the lung, gut, and exocrine glands. Mutations in CFTR have led to pleiotropic effects in CF patients and have resulted in early morbidity and mortality. Research has focused on identifying small molecules, or modulators, that can restore CFTR function. In recent years, two modulators, ivacaftor (Kalydeco) and lumacaftor/ivacaftor (Orkambi), have been approved by the U.S. Food and Drug Administration to treat CF patients with certain CFTR mutations. The development of these modulators has served as proof-of-concept that targeting CFTR by modulators is a viable therapeutic option. Efforts to discover new modulators that could deliver a wider and greater clinical benefit are still ongoing. However, traditional randomized controlled trials (RCTs) require large numbers of patients and become impracticable to test the modulators' efficacy in CF patients with CFTR mutations at frequencies much lower than 1%, suggesting the need for personalized medicine in these CF patients.

Reduced bone length, growth plate thickness, bone content, and IGF-I as a model for poor growth in the CFTR-deficient rat

Background

Reduced growth and osteopenia are common in individuals with cystic fibrosis (CF). Additionally, improved weight and height are associated with better lung function and overall health in the disease. Mechanisms for this reduction in growth are not understood. We utilized a new CFTR knockout rat to evaluate growth in young CF animals, via femur length, microarchitecture of bone and growth plate, as well as serum IGF-I concentrations.

Methods

Femur length was measured in wild-type (WT) and SD-CFTR^tm1sage (Cftr-/-) rats, as a surrogate marker for growth. Quantitative bone parameters in Cftr-/- and WT rats were measured by micro computed tomography (micro-CT). Bone histomorphometry and cartilaginous growth plates were analyzed. Serum IGF-I concentrations were also compared.

Results

Femur length was reduced in both Cftr-/- male and female rats compared to WT. Multiple parameters of bone microarchitecture (of both trabecular and cortical bone) were adversely affected in Cftr-/- rats. There was a reduction in overall growth plate thichkness in both male and female Cftr-/- rats, as well as hypertrophic zone thickness and mean hypertrophic cell volume in male rats, indicating abnormal growth characteristics at the plate. Serum IGF-I concentrations were severely reduced in Cftr-/- rats compared to WT littermates.

Conclusions

Despite absence of overt lung or pancreatic disease, reduced growth and bone content were readily detected in young Cftr-/- rats. Reduced size of the growth plate and decreased IGF-I concentrations suggest the mechanistic basis for this phenotype. These findings appear to be intrinsic to the CFTR deficient state and independent of significant clinical confounders, providing substantive evidence for the importance of CFTR on maintinaing normal bone growth.

Improved Growth Patterns in Cystic Fibrosis Mice after Loss of Histone Deacetylase 6

Growth failure in cystic fibrosis (CF) patients has been well-documented and shown to correlate with poorer disease outcomes. This observation is also true in CF animal models, including mouse, pig, rat, and ferret. The etiology underlying growth deficits is unknown, and our previous work demonstrated reduced tubulin acetylation in CF cell models and tissue that is correctable by inhibition of histone deacetylase-6 (HDAC6). Here, we hypothesize that loss of HDAC6 will improve growth phenotype in a CF mouse model. Hdac6 knockout mice were crossed with F508del (CF) mice to generate F508del/Hdac6 (CF/HDA) mice. Growth, fat deposits, survival, and bioelectric measurements were analyzed. CF/HDA mice displayed improvements in length and weight with no correction of CFTR function. Mechanistically, Igf1 levels likely account for increased length and improvements in fertility. Weight gain is attributed to increased fat deposits potentially mediated by increased adipocyte differentiation. CF-related growth deficits can be improved via inhibition of HDAC6, further implicating it as a potential therapeutic target for CF.

A Case Report of Pregnancy During Use of Targeted Therapeutics for Cystic Fibrosis

New therapeutics, such as ivacaftor, and the combination drug lumacaftor/ivacaftor that target the underlying genetic cause of cystic fibrosis are being hailed as game-changers in this era of personalized medicine. Although these drugs improve lung function, their effects on female fertility have not been studied. In this case report we describe one woman's experience with ivacaftor and her unanticipated pregnancy. Implications related to comprehensive sexual and reproductive health care for women with cystic fibrosis are presented.

Animal Models of Cystic Fibrosis Pathology: Phenotypic Parallels and Divergences

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The resultant characteristic ion transport defect results in decreased mucociliary clearance, bacterial colonisation, and chronic neutrophil-dominated inflammation. Much knowledge surrounding the pathophysiology of the disease has been gained through the generation of animal models, despite inherent limitations in each. The failure of certain mouse models to recapitulate the phenotypic manifestations of human disease has initiated the generation of larger animals in which to study CF, including the pig and the ferret. This review will summarise the basic phenotypes of three animal models and describe the contributions of such animal studies to our current understanding of CF.

A Genotypic-Oriented View of CFTR Genetics Highlights Specific Mutational Patterns Underlying Clinical Macrocategories of Cystic Fibrosis

Cystic fibrosis (CF) is a monogenic disease caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The genotype-phenotype relationship in this disease is still unclear, and diagnostic, prognostic and therapeutic challenges persist. We enrolled 610 patients with different forms of CF and studied them from a clinical, biochemical, microbiological and genetic point of view. Overall, there were 125 different mutated alleles (11 with novel mutations and 10 with complex mutations) and 225 genotypes. A strong correlation between mutational patterns at the genotypic level and phenotypic macrocategories emerged. This specificity appears to largely depend on rare and individual mutations, as well as on the varying prevalence of common alleles in different clinical macrocategories. However, 19 genotypes appeared to underlie different clinical forms of the disease. The dissection of the pathway from the CFTR mutated genotype to the clinical phenotype allowed to identify at least two components of the variability usually found in the genotype-phenotype relationship. One component seems to depend on the genetic variation of CFTR, the other component on the cumulative effect of variations in other genes and cellular pathways independent from CFTR. The experimental dissection of the overall biological CFTR pathway appears to be a powerful approach for a better comprehension of the genotype-phenotype relationship. However, a change from an allele-oriented to a genotypic-oriented view of CFTR genetics is mandatory, as well as a better assessment of sources of variability within the CFTR pathway.

Cystic fibrosis (cf) and ovarian reserve: A cross-sectional study examining serum anti-mullerian hormone (amh) in young women

BACKGROUND

Reduced female fertility in CF is believed to be due to thick cervical mucous, poor nutritional status, functional hypogonadotropic hypogonadism and possibly increased inflammation. Literature suggests that reduced ovarian reserve may also play a role.

METHODS

20 women with CF and 20 controls age 18-35 years were recruited. Serum anti-mullerian hormone (AMH), estradiol and follicle stimulating hormone (FSH) were assessed as well as antral follicle count (AFC) using transvaginal ultrasound.

RESULTS

Women with CF had significantly lower AMH levels than controls (17.8+/-4.7 vs. 33.2+/-21.0 pmol/L respectively; p=0.004). There were no differences in estradiol, FSH or AFC.

CONCLUSIONS

Women with CF have reduced ovarian reserve which may contribute to sub-fertility. CF care providers should consider referring women with CF to fertility specialists early to optimize chances of pregnancy.

Multidrug-resistant transport activity protects oocytes from chemotherapeutic agents and changes during oocyte maturation

OBJECTIVE

To determine the multidrug-resistant transporter (MDR) activity in oocytes and their potential role in oocyte susceptibility to chemotherapy.

DESIGN

Experimental laboratory study.

SETTING

University and academic center for reproductive medicine.

SUBJECT(S)

Women with eggs retrieved for intracytoplasmic sperm injection cycles and adult female FVBN and B6C3F1 mouse strains.

INTERVENTION(S)

Inhibition of MDR activity in oocytes.

MAIN OUTCOME MEASURE(S)

Efflux activity of MDRs with the use of quantitative fluorescent dye efflux, and oocyte cell death when exposed to chemotherapy.

RESULT(S)

Oocytes effluxed fluorescent reporters, and this activity was significantly reduced in the presence of the MDR inhibitor PSC 833. Geminal vesicle oocytes were more efficient at efflux than metaphase 2 oocytes. Human oocytes exposed to cyclophosphamide and PSC 833 showed cell death with the use of two different viability assays compared with control samples and those exposed to cyclophosphamide alone. Immunoblots detected MDR-1 in all oocytes, with the greatest accumulation in the geminal vesicle stage.

CONCLUSION(S)

Oocytes have a vast repertoire of active MDRs. The implications of this study are that these protective mechanisms are important during oogenesis and that these activities change with maturation, increasing susceptibility to toxicants. Future directions may exploit the up-regulation of these transporters during gonadotoxic therapy.

Atypical cystic fibrosis: identification in the primary care setting

OBJECTIVE

To review the diagnosis of patients with atypical cystic fibrosis (CF).

SOURCES OF INFORMATION

A comprehensive search of MEDLINE (1950 to the third week of May 2009), MEDLINE In-Process and Other Non-Indexed Citations and Cases (1950 to the third week of May 2009), and EMBASE (1980 to the fourth week of March 2009). The Cystic Fibrosis Canada website was also reviewed and the most recent patient data registry report was consulted.

MAIN MESSAGE

Atypical CF is a milder form of the CF disorder, which is associated with mutations of the cystic fibrosis transmembrane receptor gene. Instead of having classic symptoms, individuals with atypical CF might only have mild dysfunction in 1 organ system and might or might not have elevated sweat chloride levels. Atypical CF is a very diverse disorder affecting different organ systems to varying degrees. The symptoms patients experience can also fluctuate over time; however, certain clinical signs and symptoms affecting the respiratory, gastrointestinal, endocrine and metabolic, and genitourinary systems should alert physicians to the possibility of CF. Patients with atypical CF often have fewer hospitalizations during childhood than those with classic CF do, and the disorder can remain undiagnosed for many years, at times into adulthood.

CONCLUSION

Although patients diagnosed with atypical CF have longer life expectancies than individuals with classic CF, the long-term expected outcome for many individuals with atypical CF is unknown. It is important to counsel patients about the possibility of future illness. Education about CF can help patients understand their symptoms, modify their lifestyles to optimize health, reduce the incidence of complications, and receive family planning counseling when appropriate.

Infertility: evaluation and initial management

Treating the infertile client with competence and compassion is within the scope of practice for advanced practice clinicians. However, due to both a lack of emphasis on infertility treatment in many advanced practice education programs and confusion regarding diagnosis and treatment by many practitioners, infertility is often undertreated by these providers. A basic infertility evaluation, patient counseling, and prescriptive therapy with oral ovulation-inducing agents by a knowledgeable practitioner is cost-effective and may result in successful pregnancy in women who otherwise may not be adequately and quickly treated prior to referral to a reproductive endocrinologist. A diagnosis of infertility is often stressful and frustrating for a couple. Midwives and advanced practice nurses are uniquely qualified to provide both compassionate care and competent treatment during this time. This article provides the clinician with an overview of infertility diagnosis, evaluation, and initial management with lifestyle modifications and oral ovulation-inducing agents.

Anatomy of female puberty: The clinical relevance of developmental changes in the reproductive system

Puberty is the period of biologic transition from childhood to adulthood. The changes that occur at this time are related to the increasing concentrations of sex steroid hormones. In females, most pubertal changes are caused by estrogen stimulation that results from the onset of central puberty. Significant development occurs in the organs of the female reproductive system and results in anatomic changes that characterize reproductive maturity. Adrenal and ovarian androgens also increase during puberty, affecting change that includes the promotion of certain secondary sex characteristics. The ability to recognize normal pubertal anatomy and distinguish between estrogen and androgen effects is important in the ability to diagnose and treat disorders of sex development, precocious puberty, pubertal delay, and menstrual irregularities in children and adolescents. An understanding of this developmental process can also help clinicians identify and treat reproductive pathology in adults and across all female life stages.

CFTR, mucins, and mucus obstruction in cystic fibrosis

Mucus pathology in cystic fibrosis (CF) has been known for as long as the disease has been recognized and is sometimes called mucoviscidosis. The disease is marked by mucus hyperproduction and plugging in many organs, which are usually most fatal in the airways of CF patients, once the problem of meconium ileus at birth is resolved. After the CF gene, CFTR, was cloned and its protein product identified as a cAMP-regulated Cl(-) channel, causal mechanisms underlying the strong mucus phenotype of the disease became obscure. Here we focus on mucin genes and polymeric mucin glycoproteins, examining their regulation and potential relationships to a dysfunctional cystic fibrosis transmembrane conductance regulator (CFTR). Detailed examination of CFTR expression in organs and different cell types indicates that changes in CFTR expression do not always correlate with the severity of CF disease or mucus accumulation. Thus, the mucus hyperproduction that typifies CF does not appear to be a direct cause of a defective CFTR but, rather, to be a downstream consequence. In organs like the lung, up-regulation of mucin gene expression by inflammation results from chronic infection; however, in other instances and organs, the inflammation may have a non-infectious origin. The mucus plugging phenotype of the β-subunit of the epithelial Na(+) channel (βENaC)-overexpressing mouse is proving to be an archetypal example of this kind of inflammation, with a dehydrated airway surface/concentrated mucus gel apparently providing the inflammatory stimulus. Data indicate that the luminal HCO(3)(-) deficiency recently described for CF epithelia may also provide such a stimulus, perhaps by causing a mal-maturation of mucins as they are released onto luminal surfaces. In any event, the path between CFTR dysfunction and mucus hyperproduction has proven tortuous, and its unraveling continues to offer its own twists and turns, along with fascinating glimpses into biology.

Impaired CFTR-dependent amplification of FSH-stimulated estrogen production in cystic fibrosis and PCOS

CONTEXT

Estrogens play important roles in a wide range of physiological and pathological processes, and their biosynthesis is profoundly influenced by FSH that regulates the rate-limiting enzyme aromatase-converting estrogens from androgens. Abnormal estrogen levels are often seen in diseases such as ovarian disorders in polycystic ovarian syndrome (PCOS), an endocrine disorder affecting 5-10% of women of reproductive age, and cystic fibrosis (CF), a common genetic disease caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR).

OBJECTIVES

We undertook the present study to investigate the mechanism underlying these ovarian disorders, which is not well understood.

RESULTS

FSH-stimulated cAMP-responsive element binding protein phosphorylation, aromatase expression, and estradiol production are found to be enhanced by HCO3- and a HCO3- sensor, the soluble adenylyl cyclase, which could be significantly reduced by CFTR inhibition or in ovaries or granulosa cells of cftr knockout/ΔF508 mutant mice. CFTR expression is found positively correlated with aromatase expression in human granulosa cells, supporting its role in regulating estrogen production in humans. Reduced CFTR and aromatase expression is also found in PCOS rodent models and human patients.

CONCLUSIONS

CFTR regulates ovarian estrogen biosynthesis by amplifying the FSH-stimulated signal via the nuclear soluble adenylyl cyclase. The present findings suggest that defective CFTR-dependent regulation of estrogen production may underlie the ovarian disorders seen in CF and PCOS.

New animal models of cystic fibrosis: what are they teaching us?

PURPOSE OF REVIEW

Cystic fibrosis is the first human genetic disease to benefit from the directed engineering of three different species of animal models (mice, pigs, and ferrets). Recent studies on the cystic fibrosis pig and ferret models are providing new information about the pathophysiology of cystic fibrosis in various organ systems. Additionally, new conditional cystic fibrosis transmembrane conductance regulator (CFTR) knockout mice are teaching unexpected lessons about CFTR function in surprising cellular locations. Comparisons between these animal models and the human condition are key to dissecting the complexities of disease pathophysiology in cystic fibrosis.

RECENT FINDINGS

Cystic fibrosis pigs and ferrets have provided new models to study the spontaneous development of disease in the lung and pancreas, two organs that are largely spared overt spontaneous disease in cystic fibrosis mice. New cystic fibrosis mouse models are now interrogating CFTR functions involved in growth and inflammation at an organ-based level using conditional knockout technology. Together, these models are providing new insights on the human condition.

SUMMARY

Basic and clinical cystic fibrosis research will benefit greatly from the comparative pathophysiology of cystic fibrosis mice, pigs, and ferrets. Both similarities and differences between these three cystic fibrosis models will inform pathophysiologically important mechanisms of CFTR function in humans and aid in the development of both organ-specific and general therapies for cystic fibrosis.

Using computational modeling to investigate sperm navigation and behavior in the female reproductive tract

The processes by which individual sperm cells navigate the length and complexity of the female reproductive tract and then reach and fertilize the oocyte is fascinating. Numerous complex processes potentially influence the transport of spermatozoa within the tract, resulting in a regulated supply of spermatozoa to the oocytes at the site of fertilization. Despite significant differences between species, breeds, and individuals, these processes converge to ensure that a sufficient number of high quality spermatozoa reach the oocytes, resulting in successful fertilization without a significant risk of polyspermy. Different factors, such as the physical complexity of the oviductal environment, changing swimming patterns, capacitation, chemotactic and thermotactic attraction, attachment and detachment from the oviductal epithelium, interactions with local oviductal secretions, individual variations in spermatozoa and subpopulations, peristaltic contractions, and the movement of fluid have all been theorized to influence the transport of spermatozoa to the site of fertilization. However, the predominance of each factor is not fully understood. Computational modeling provides a useful method for combining knowledge about the individual processes in complex systems to help understand the relative significance of each factor. The process of constructing and validating an agent-based computational model of sperm movement and transport within the oviductal environment is described in this report. Spermatozoa are modeled as individual cells with a set of behavioral rules defining how they interact with their local environment and regulate their internal state. The inclusion or potential exclusion of each factor is discussed, along with problems identifying parameters and defining behavioral rules from available literature. Finally, the benefits and limitations of the model are described.

The testis anion transporter TAT1 (SLC26A8) physically and functionally interacts with the cystic fibrosis transmembrane conductance regulator channel: a potential role during sperm capacitation

The Slc26 gene family encodes several conserved anion transporters implicated in human genetic disorders, including Pendred syndrome, diastrophic dysplasia and congenital chloride diarrhea. We previously characterized the TAT1 (testis anion transporter 1; SLC26A8) protein specifically expressed in male germ cells and mature sperm and showed that in the mouse, deletion of Tat1 caused male sterility due to a lack of sperm motility, impaired sperm capacitation and structural defects of the flagella. Ca(2+), Cl(-) and HCO(3)(-) influxes trigger sperm capacitation events required for oocyte fertilization; these events include the intracellular rise of cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA)-dependent protein phosphorylation. The cystic fibrosis transmembrane conductance regulator (CFTR) is expressed in mature sperm and has been shown to contribute to Cl(-) and HCO(3)(-) movements during capacitation. Furthermore, several members of the SLC26 family have been described to form complexes with CFTR, resulting in the reciprocal regulation of their activities. We show here that TAT1 and CFTR physically interact and that in Xenopus laevis oocytes and in CHO-K1 cells, TAT1 expression strongly stimulates CFTR activity. Consistent with this, we show that Tat1 inactivation in mouse sperm results in deregulation of the intracellular cAMP content, preventing the activation of PKA-dependent downstream phosphorylation cascades essential for sperm activation. These various results suggest that TAT1 and CFTR may form a molecular complex involved in the regulation of Cl(-) and HCO(3)(-) fluxes during sperm capacitation. In humans, mutations in CFTR and/or TAT1 may therefore be causes of asthenozoospermia and low fertilizing capacity of sperm.

Comparative biology of cystic fibrosis animal models

Animal models of human diseases are critical for dissecting mechanisms of pathophysiology and developing therapies. In the context of cystic fibrosis (CF), mouse models have been the dominant species by which to study CF disease processes in vivo for the past two decades. Although much has been learned through these CF mouse models, limitations in the ability of this species to recapitulate spontaneous lung disease and several other organ abnormalities seen in CF humans have created a need for additional species on which to study CF. To this end, pig and ferret CF models have been generated by somatic cell nuclear transfer and are currently being characterized. These new larger animal models have phenotypes that appear to closely resemble human CF disease seen in newborns, and efforts to characterize their adult phenotypes are ongoing. This chapter will review current knowledge about comparative lung cell biology and cystic fibrosis transmembrane conductance regulator (CFTR) biology among mice, pigs, and ferrets that has implications for CF disease modeling in these species. We will focus on methods used to compare the biology and function of CFTR between these species and their relevance to phenotypes seen in the animal models. These cross-species comparisons and the development of both the pig and the ferret CF models may help elucidate pathophysiologic mechanisms of CF lung disease and lead to new therapeutic approaches.

Cloning and identification of two novel NBCe1 splice variants from mouse reproductive tract tissues: a comparative study of NCBT genes

Na(+)-coupled HCO(3)(-) transporters (NCBTs) of the SLC4 family play critical roles in pH regulation as well as transepithelial HCO(3)(-) transport. We systematically examined, in the mouse reproductive tract tissues, the mRNA expression of five NCBTs as well as the five NBCe1 (Slc4a4) variants NBCe1-A through -E, of which NBCe1-D and NBCe1-E are novel. Cloning of NBCe1-D and NBCe1-E, both lacking a 27-nucleotide cassette I, reveals a novel alternative splicing unit in the mouse Slc4a4 gene. Transcripts of Slc4a4 lacking cassette I are expressed in diverse murine tissues as shown by RT-PCR analysis and in diverse tissues of other vertebrate species as shown by blast against GenBank database. Genomic sequence analysis indicates that cassette I of SLC4A4 is conserved in all NCBT genes except for SLC4A5, which presumably lost cassette I during its evolution. Our present study represents an important step towards understanding the molecular physiology of NBCe1, and presumably other NCBTs.

Contraception, communication and counseling for sexuality and reproductive health in adolescents and young adults with CF

With survival now into the fourth decade and rapid growth of the adolescent and adult population of people with cystic fibrosis CF sexual and reproductive health issues are integral to the management of adolescents and adults with CF. Education and counseling for sexual health related issues must be included in the daily routine of CF care. With advances in genetic counseling, contraception, assisted reproductive technology and collaborative management adolescents and young adults with CF realizing their sexual and reproductive potentials safely and realistically can be possible .

A new role for bicarbonate secretion in cervico-uterine mucus release

Cervical mucus thinning and release during the female reproductive cycle is thought to rely mainly on fluid secretion. However, we now find that mucus released from the murine reproductive tract critically depends upon concurrent bicarbonate (HCO(3)(-)) secretion. Prostaglandin E(2) (PGE(2))- and carbachol-stimulated mucus release was severely inhibited in the absence of serosal HCO(3)(-), HCO(3)(-) transport, or functional cystic fibrosis transmembrane conductance regulator (CFTR). In contrast to mucus release, PGE(2)- and carbachol-stimulated fluid secretion was not dependent on bicarbonate or on CFTR, but was completely blocked by niflumic acid. We found stimulated mucus release was severely impaired in the cystic fibrosis F508 reproductive tract, even though stimulated fluid secretion was preserved. Thus, CFTR mutations and/or poor bicarbonate secretion may be associated with reduced female fertility associated with abnormal mucus and specifically, may account for the increased viscosity and lack of cyclical changes in cervical mucus long noted in women with cystic fibrosis.

Generation of a conditional null allele for Cftr in mice

The cystic fibrosis transmembrane conductance regulator (CFTR) gene encodes a cAMP-regulated chloride channel that is important in controlling the exchange of fluid and electrolytes across epithelial cells. Mutation of CFTR can lead to cystic fibrosis (CF), the most common lethal genetic disease in Caucasians. CF is a systemic illness with multiple organ systems affected including pulmonary, gastrointestinal, pancreatic, immune, endocrine, and reproductive systems. To understand the role of CFTR in the various tissues in which it is expressed, we generated a murine conditional null allele of Cftr (Cftr(fl10)) in which loxP sites were inserted around exon 10 of the Cftr gene. The Cftr(fl10) allele was validated by generating constitutive Cftr null (Cftr(Delta10)) mice using the protamine-cre system. The Cftr(Delta10/Delta10) mice displayed almost identical phenotypes to previously published CF mouse models, including poor growth, decreased survival, intestinal obstruction, and loss of Cftr function as assessed by electrophysiology measurements on gut and nasal epithelium. Mice containing the conditional null Cftr allele will be useful in future studies to understand the role of Cftr in specific tissues and developmental time points and lead to a better understanding of CF disease.

Murine model for cystic fibrosis bone disease demonstrates osteopenia and sex-related differences in bone formation

As the incidence of cystic fibrosis (CF) bone disease is increasing, we analyzed CF transmembrane conductance regulator (CFTR) deficient mice (CF mice) to gain pathogenic insights. In these studies comparing adult (14 wk) CF and C57BL/6J mice, both bone length and total area were decreased in CF mice. Metaphyseal trabecular and cortical density were also decreased, as well as diaphyseal cortical and total density. Trabecular bone volume was diminished in CF mice. Female CF mice revealed decreased trabecular width and number compared with C57BL/6J, whereas males demonstrated no difference in trabecular number. Female CF mice had reduced mineralizing surface and bone formation rates. Conversely, male CF mice had increased mineralizing surface, mineral apposition, and bone formation rates compared with C57BL/6J males. Bone formation rate was greater in males compared with female CF mice. Smaller bones with decreased density in CF, despite absent differences in osteoblast and osteoclast surfaces, suggest CF transmembrane conductance regulator influences bone cell activity rather than number. Differences in bone formation rate in CF mice are suggestive of inadequate bone formation in females but increased bone formation in males. This proanabolic observation in male CF mice is consistent with other clinical sex differences in CF.

The cystic fibrosis transmembrane conductance regulator in reproductive health and disease

The cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel regulated by cAMP-dependent phosphorylation, which is expressed in epithelial cells of a wide variety of tissues including the reproductive tracts. Mutations in the gene encoding CFTR cause cystic fibrosis, a common genetic disease in Caucasian populations with a multitude of clinical manifestations including infertility/subfertility in both sexes. However, the physiological role of CFTR in reproduction and its involvement in the pathogenesis of reproductive diseases remain largely unknown. This review discusses the role of CFTR in regulating fluid volume and bicarbonate secretion in the reproductive tracts and their importance in various reproductive events. We also discuss the contribution of CFTR dysfunction to a number of pathological conditions. The evidence presented is consistent with an important role of CFTR in reproductive health and disease, suggesting that CFTR might be a potential target for the diagnosis and treatment of reproductive diseases including infertility.