SEP | SGM
| UGD | UGE | SEGEN
| UGO | Main Page
the menstrual cycle and humanreproduction
|
Zhi-Bin Tong, MD, Staff
Scientist James Anasti, MD, Guest
Researcher Noriyuki Otsuka, MD, Postdoctoral Fellow Konstantina Vanevski, MD, Postdoctoral Fellow Vien Vanderhoof, RN, CRNP, Physician’s Assistant Emily Hui, BA, Postbaccalaureate
Fellow Amanda Spitalnik, BS, Postbaccalaureate Fellow |
|
|
To develop diagnostic tools and therapeutic
approaches for menstrual cycle and human reproduction disorders, we
investigate genetic, immunological, and molecular aspects of such disorders,
using autoimmune premature ovarian failure (POF) as a model condition. POF
causes young women to develop amenorrhea and infertility before age 40 and
was once considered an irreversible condition similar to normal menopause. We
now know that, even though they fail to function normally, follicles remain
in the ovaries of 50 percent of patients with 46,XX spontaneous POF. In 90
percent of such cases, the mechanism of the ovarian insufficiency remains a
mystery. Work in neonatally thymectomized B6A mice, a model of autoimmune
POF, led us to discover Mater, a novel oocyte protein that serves as a major
antigen in ovarian autoimmunity. Using transgenic technology, we demonstrated
that Mater is a maternal effect gene essential for normal female
fertility. In addition, we have been investigating clinical POF by recruiting
patients to research protocols that are designed to gain insight into the
mechanisms of ovarian follicle dysfunction and to develop appropriate
treatments for patients with 46,XX spontaneous POF. MATER and autoimmune premature ovarian failure Vanevski,
Tong, Nelson; in collaboration with Bondy, de Pol Although autoantibodies develop in most
autoimmune diseases, specific ovarian antigens involved in human autoimmune
POF have yet to be confirmed. Autoimmune POF causes young women to develop
amenorrhea, menopausal symptoms, and infertility. A similar syndrome appears
in mice with post-thymectomy autoimmune oophoritis. We have been searching
for a serum marker that will identify women with POF attributable to
autoimmunity. We have demonstrated that mice with autoimmune oophoritis
develop antibodies against MATER and have defined the human homolog of the
mouse Mater. The human MATER gene spans 63 kbp at chromosome 19
and, as in the mouse, comprises 15 exons and 14 introns with expression
restricted to the oocytes. The human and mouse cDNA share 67 percent homology
while their deduced polypeptide chains exhibit 53 percent identity of amino
acids. Further, the human and mouse protein structures have a number of
similar features. We have concluded that the human MATER and mouse Mater
genes and proteins are conserved. Characterization of the human MATER protein
provides us with a basis for investigating the protein’s clinical
implications in autoimmune POF and infertility in women. Over the last year, we analyzed the
expressional profile of Mater and its protein during mouse oogenesis
and embryogenesis as well as its subcellular localization in oocytes. Mater
mRNA was detectable earliest in oocytes of type 2 follicles, whereas
MATER protein appeared earliest in oocytes of type 3a primary follicles. Both
mRNA and protein accumulated during oocyte growth. In situ hybridization
showed that Mater mRNA appeared progressively less abundant in oocytes
beyond type 5a primary follicles. As assessed by ribonuclease protection
assay, Mater mRNA was abundant in germinal vesicle oocytes but was undetectable
in all stages of pre-implantation embryos. In contrast, the protein persisted
throughout pre-implantation development. Immunogold electron microscopic
analysis revealed that MATER was located in oocyte mitochondria and nucleoli
and close to nuclear pores. Taken together, our data indicate that Mater
gene transcription and protein translation are active during oogenesis but
appear inactive during early embryogenesis. Thus, Mater and its
protein are expressed in a manner typical of maternal effect genes. The
presence of MATER protein in mitochondria and nucleoli suggests that it may
participate in both cytoplasmic and nuclear events during early development. We also demonstrated
the unreliability of a commercially available ovarian antibody test that uses
cynomologous monkey ovary as substrate in an indirect immunofluorescence
procedure. Some clinicians use this test to make treatment decisions, but, to
our knowledge, the test had never been validated. We performed the test in a
blinded manner in young women with 46,XX spontaneous POF, in control women
with regular menstrual cycles (matched for age, race, and parity), and in
control men (matched for age and race). We also compared the frequency of
other autoantibodies associated with ovarian autoimmunity and found that
women with premature ovarian failure were more likely to exhibit thyroid
peroxidase and parietal cell autoantibodies. Unexpectedly, use of the
commercially available test revealed that nearly one-third of normal control
women had ovarian antibodies. One half of young women with POF were found to
have antibodies, but the frequency of a positive test was not significantly
different from that in normal women. As expected, none of 26 men was found to
have ovarian antibodies. We were unable to improve the specificity of the
test and thus concluded that the method has poor specificity and is not a
reliable tool for the diagnosis of autoimmune ovarian failure. Our findings
underscore the need to demonstrate the specificity of any ovarian antibody
test before it is used clinically. Novosad JA, Kalantaridou SN, Tong ZB, Nelson LM. Ovarian antibodies as detected by indirect
immunofluorescence are unreliable in the diagnosis of autoimmune premature
ovarian failure: a controlled evaluation. BMC Womens Health 2003;3:2. Tong ZB, Gold L, De Pol
A, Vanevski K, Dorward H, Sena P, Palumbo C, Bondy CA, Nelson LM.
Developmental expression and subcellular localization of mouse MATER, an
oocyte-specific protein essential for early development. Endocrinology
2004;145:1427-1434. Premature ovarian failure, autoimmune
oophoritis, and steroidogenic cell autoantibodies Anasti,
Vanderhoof, Nelson; in collaboration with Bakalov, Calis We previously demonstrated that measuring
adrenal antibodies is an effective screening method by which to detect
asymptomatic autoimmune adrenal insufficiency in young women with spontaneous
POF. The standard ACTH stimulation test should be reserved to confirm adrenal
insufficiency in women who test positive for adrenal antibodies or those with
signs and symptoms of adrenal insufficiency. Evidence is accumulating to suggest that
autoimmune oophoritis and adrenal autoimmunity may represent a continuum of
one pathophysiologic process. We have been conducting an IRB-approved
protocol to investigate autoimmune oophoritis as a cause of 46,XX spontaneous
POF. We are studying the accuracy of steroidogenic cell antibodies in
predicting the presence of autoimmune oophoritis and collating results of the
antibody test with a gold standard: autoimmune oophoritis confirmed by
ovarian biopsy. Given that ascertainment bias has created uncertainty about
the true prevalence of autoimmune lymphocytic oophoritis as a mechanism of
POF, we are studying the prevalence of steroidogenic cell autoantibodies in
young women with 46,XX spontaneous POF who meet two primary criteria:
infertility and amenorrhea as a primary concern and otherwise general good
health. Nelson LM, Bakalov VK. Mechanisms of
follicular dysfunction in 46,XX spontaneous premature ovarian failure. Endocrinol
Metab Clin North Am 2003;32:613-637. Needs of young women with 46,XX spontaneous
premature ovarian failure Vanderhoof,
Nelson; in collaboration with Bakalov, Calis, Smith We are conducting clinical research to define
more fully other needs of young women with 46,XX spontaneous POF. In B6A
mice, neonatal thymectomy induces lacrimal gland autoimmunity as well as
autoimmune ovarian failure and provides a basis for an animal model of
Sjögren’s syndrome. To test the hypothesis that a similar association
may be present in a subset of women with 46,XX spontaneous POF, we are
collaborating with investigators at the National Eye Institute. We found an
association between ocular surface disease and POF that has not been reported
before. Keratoconjunctivitis sicca is defined as at least one symptom of dry
eye either occurring often or present all the time. Two major mechanisms of
keratoconjunctivitis are defined on the basis of either aqueous tear
deficiency or evaporative tear deficiency. A decreased volume of tear
production characterizes aqueous tear deficiency and may result from
autoimmunity directed against the lacrimal glands. A qualitative disturbance
in the tear film with resultant instability leads to increased evaporation
and dryness of the ocular surface and characterizes evaporative tear
deficiency, which is most frequently the result of meibomian gland disease.
Meibomian gland dysfunction leads to decreased lipid production, which
results in tear film instability. Interestingly, androgens, which are
deficient in women with POF, appear to play an important role in supporting
normal meibomian gland function. Compared
with age-matched control women, we found that young women with 46,XX
spontaneous POF have an increased prevalence and severity of both signs and
symptoms of ocular surface disease. Given that not all patients had dry eye,
it is possible that the dry eye phenotype signals a particular mechanism of
premature ovarian failure, such as autoimmunity. It is also possible that
endocrine factors, such as the androgen deficiency associated with POF, might
explain the association. We are planning additional studies to
characterize this pathology further
and determine its etiology. Adams Hillard PJ, Nelson LM. Adolescent girls,
the menstrual cycle, and bone health. J Pediatr Endocrinol Metab 2003;16:673-681. Gordon CM, Nelson LM. Amenorrhea and bone
health in adolescents and young women. Curr Opin Obstet Gynecol 2003;15:377-384. Smith JA, Vitale S, Reed GF, Grieshaber SA,
Goodman LA, Vanderhoof VH, Calis KA, Nelson LM. Dry eye signs and symptoms in
women with premature ovarian failure. Arch Ophthalmol
2004;122:151-156. COLLABORATORS Vladimir Bakalov, MD, Developmental
Endocrinology Branch, NICHD, Carolyn Bondy, MD,
Developmental Endocrinology Branch, NICHD, Karim A. Calis, DPharm, Pharmacy
Department, Warren Grant Magnuson Clinical Center, NIH, Bethesda, MD Anto de Pol, PhD, Department
of Anatomy and Histology, Janine A. Smith, MD, Division
of Epidemiology and Clinical Research, NEI, For
further information, contact nelsonl@mail.nih.gov |
|
