Introduction
Endometriosis, results in infertility in 50% infertile women [1]. Explanations given are
poor oocyte quality as well as low grade embryos associated with abnormal folliculogenesis
[2], with reduced chances of fertilization correlated with enhanced oxidative stress, high
reactive oxygen species (ROS) levels/local inflammation [3]. Particularly escalated amounts
of cytokines are found in follicular fluid (FF) of patients with Endometriosis might result in
ovulatory impairment [4]. Further Akila et al. reviewed how in the pathogenesis of ovarian
pathologies like Endometriosis and polycystic ovarian syndrome (PCOS) are affected by
enhanced ROS, enhanced oxidative stress in the ovary by concentrating on mural granulosa-
lutein cells of in vitro Fertilization (IVF) subjects. Synthesis of anti-oxidant enzymes like
peroxiredoxin 4, superoxide dismutase and catalase and oxidative stress damage response
proteins like aldehyde dehydrogenase 3, member A2 reduces with aging in human granulosa
lutein cells, that helps in an unbalance in ROS/anti-oxidants which modulate molecular injury
as well as changes in cellular functioning .Increased oxidative stress in the granulosa cells
associates with reduced expression of follicular stimulating hormone( FSH) receptor (FSHR)
as well as a dysregulated FSHR signalling pathway and thus might have a role in impaired
steroidogenic function as well as bad ovarian response to FSH in women who are aging. In case
of women having Endometriosis along with those with PCOS have<antioxidants producing
ability which may result in abnormal follicle formation as well as infertility. More investigations
of the signalling pathways in relation to cellular responses to oxidative stress might throw
light into molecular properties of these diseases and allow formation of new treating
strategies for increasing reproductive potential in these women. Kunitomi et al. [5] posited
that endoplasmic reticulum (ER) Stress is stimulated by great oxidative stress in granulose
cells in ovaries from Endometrioma and this modulates oxidative stress-stimulated apoptosis.
Crimson Publishers
Wings to the Research Short Communication
*Corresponding author: Kulvinder Kochar
Kaur, Centre for Human Reproduction,
India
Submission:
January 17, 2020
Published:
January 22, 2020
Volume 3 - Issue 4
How to cite this article: Kulvinder Kochar
K, Gautam A, Mandeep S. How Can We Op-
timize the Granulose Cell Function of Oo -
cytes from an Endometriosis Patient to Im-
prove the Reproductive Outcomes-A Short
Communication?. Perception in Reproduc-
tive Medicine.3(4). PRM.000570.2020.
DOI: 10.31031/PRM.2020.03.000570
Copyright@ Kulvinder Kochar Kaur, This
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ISSN: 2640-9666
245Perception in Reproductive Medicine
Abstract
Endometriosis, results in infertility in 50% infertile women. Explanations given are poor oocyte quality
as well as low grade embryos associated with abnormal folliculogenesis, with reduced chances of
fertilization correlated with enhanced oxidative stress, high reactive oxygen species (ROS) levels/local
inflammation. Particularly escalated amounts of cytokines are found in follicular fluid of follicles of
Endometriosis subjects. Here we further detail on the work going on in finding the role of granulosa cells
in Endometriosis subjects with regards to increased inflammation, alteration in cytokines in follicular
fluid that associates with follicular fluid in causing the oxidative stress, and how the upstream pathway
involving tumour necrosis factor alpha (TNFα) and nuclear factor kappa B( NFκB) that influences both
telomere length as well as telomerase activity, with shorter telomeres as well as reduced telomerase
activity associated with aging follicles as well as those observed in patients with premature ovarian
insufficiency (POI). Thus, this enhanced granulosa cell NFκB corresponds with inflammation found in FF
along with effect on telomeres. Ways of targeting it seems to be one answer in improving reproductive
potential of Endometriosis patients.
Keywords
Endometriosis; Poor oocyte quality; Oxidative stress; High reactive oxygen species (ROS);
NFκB; TNFα; Telomere length; Telomerase activity; POI
246
Perceptions Reprod Med
Copyright © Kulvinder Kochar Kaur
PRM.MS.ID.000570. 3(4).2020
Human granulosa-lutein cells (GLC’s) from Endometrioma patients
expressed great mRNA amounts correlated with unfolded protein
response (UPR). Additionally, amounts of phosphorylated ER Stress
sensor proteins, inositol-requiring enzyme (IRE1) and double
stranded RNA-activated protein kinase-like ER kinase (PERK), were
enhanced in granulosa cells from Endometrioma patients. Knowing
that ER Stress causes phosphorylation of ER Stress sensor proteins
and stimulates UPR, these observations point that these cells were
under ER Stress. H 2O2, that stimulates oxidative stress, enhanced
expression of UPR-related mRNA in cultured human GLC’s
with this action getting ameliorated by pre-treatment utilizing
tauroursodeoxycholic acid (TUDCA), that is an ER Stress inhibitor
utilized clinically. Therapy with H2O2 enhanced apoptosis as well as
action of pro- apoptotic factors caspase 8 as well as caspase 3 both
of which got ameliorated by TUDCA. This pointed that stimulated
ER Stress stimulated by oxidative stress in GCs in ovaries having
Endometrioma modulates apoptosis of these cells causing ovarian
dysfunction in Endometriosis patients [6].
Reviewing the quality of oocytes in relation to endometriosis,
Sanchez et al. [7] tried to concentrate on direct oocytes studied
instead of most studies concentrating on cumulus cells or FF
content. In summary It has been posited that morphological defects
seen that include i)cytoplasmic granularity as well as/or presence of
vacuoles might affect fertilization although limited predictive value
of these findings in view of restrictions of non-invasive techniques
with simple transmitted light microscopy along with subjectivity in
morphological analysis as well as morphology might be influenced
by other factors like ovarian stimulation or hormonal milieu. Goud
et al did functional studies examining immature oocytes obtained
from Endometriosis women as compared to control. They observed
that oocytes from Endometriosis women showed enhanced cortical
granule loss as well as ii) zona pellucida (ZP) hardening, probably
interfering with fertilization dissolution of the ZP and the ability
of embryo to undergo hatching and implantation (Figure1); [8,9].
Figure 1: Courtesy ref no.-7-Representative
morphological changes in oocytes from women
affected by endometriosis.
Further capacity of oocytes to undergo in vitro maturation
(IVM) to metaphase II stage was checked, observing a significant
reduction of number of germinal vesicles (GV) as well as metaphase
I (M1) oocytes could reach metaphase II stage in Endometriosis
group as compared to controls. iii)Since spindle structure needs
to coordinate the alignment as well as normal segregation of
homologous chromosomes and sister chromatids in 2 subsequent
meiotic division, disruption of meiotic spindle causes abnormal
chromosomes alignment and fertilization. Of the 2 methods by
which spindle morphology is studied polarized light microscopy
overcomes fixing problem of confocal microscopy. Barcelos et al.
checked spindle morphology following IVM comparing oocytes
obtained from Endometriosis patients (n=35) with oocytes from
control group with tubal factor infertility (n=19). Till recently
no significant differences were observed. Recently Goud et al.
using same IVM, observed a>percentage of abnormal spindles
in oocytes obtained from Endometriosis patients as compared to
ART secondary to male factor infertility (66.7% vs 16%, p<0.05).
Only study that observed spindle in mature oocytes unlike all
earlier ones on IVM ,failed to see any significant changes in
Endometriosis patients iv)Cytoplasm of mature oocytes have a very
high mitochondrial content as compared to other cell types, since
it can contain up to 105 mitochondria. The 1 st and only study that
examined correlation between cytoplasm ultrastructure of oocytes
and Endometriosis presence was conducted by Xu et al regarding
intra cytoplasmic sperm injection (ICSI). Using transmission
electron microscopy (TEM) 50MII oocytes from patients with
laparoscopically diagnosed minimal/mild Endometriosis
control found a >number of Endometriosis patients contained
decentralized chromatin with a voluminous nucleolus as compared
to control. Further oocytes from patients with Endometriosis had
both a > percentage of abnormal mitochondria (containing small/
swollen as well as blurred vacuoles) and in total lower quantity of
mitochondrial DNA (mtDNA) copies seen using quantitative PCR.
They concluded low mtDNA amount particularly shows reduced
oocyte quality with minimal/mild Endometriosis.
Sirtuins are a family of deacetylases which modify structural
proteins, metabolic enzymes, and histones for altering cellular
protein placement as well as function. In mammals, 7 Sirtuins,
that are related to functions like oxidative stress or metabolic
homeostasis correlated with increasing age, degeneration/
carcinoma. Gonzalez Fernandez et al. [10] explored gene expression
of Sirtuins by qRT-PCR in human mural granulosa-lutein cells (hGL)
from IVF subjects in various infertility diagnostic groups and in
oocyte donors (OD; Control grp). In Study 1 gene expression levels
of Sirtuins as well as association with age as well as IVF parameters
in women having no ovarian factor was done. They observed that
significantly>expression levels of SIRT1, SIRT2 as well as SIRT5
in patients ≥40yrs old as compared to OD and in women among
27-39yrs age with tubal/male factor and no ovarian factor (NOF).
Only SIRT2, SIRT5 and SIRT7 expression was associated with
age. In Study 2 gene expression of Sirtuins in poor responders
(PR), Endometriosis (EM)and PCOS was done. In contrast to NOF
Controls, they observed >, SIRT2 gene expression in all diagnostic
groups although SIRT3, SIRT5, SIRT6 and SIRT7 expression was >
only in PR. Associated with clinical parameters , SIRT1, SIRT6 and
SIRT7 correlated in a positive manner with FSH as well as LH doses
247
Perceptions Reprod Med
Copyright © Kulvinder Kochar Kaur
PRM.MS.ID.000570. 3(4).2020
given to EM patients. The number of mature oocytes obtained in PR
correlated in a positive manner with expression amounts of SIRT3,
SIRT4, SIRT5. Hence emphasizing on that cellular physiopathology
in PR’s follicles might be correlated with cumulative DNA damage
that points that future studies are required (Figure2); [8]. Since FF
surrounds the granulosa cell- oocyte complex and represents one of
the modulating factors in the inter cell conversation among the cells
within the follicle the substances present in FF are cytokines and
immune cells ,that includes IL-6.IL12, sHLA-G, macrophages, NK
cells and lymphocytes. These cells as well as cytokines may impact
the granulosa cell-oocyte complex, change in immune component
contents might be involved in alteration in folliculogenesis,
oocyte maturation, oocyte quality as well as ovulation. Moreover,
changes in these balances are probably responsible for immune
mediated conditions like Endometriosis. Prins et al., gave a
detailed evaluation on FF immune function, as well as FF substance
alterations in Endometriosis patients. Escalation of macrophages
in FF of Endometriosis patients as well as various cytokines have
been documented. The part played by particular immune cells
in FF and insight about the biological mode in healthy women as
well as Endometriosis patients is unknown. More studies in this
field will give us greater understanding in the role of FF immune
cells and the influence of change in these balances in patients with
Endometriosis [9].
Figure 2: Courtesy ref no.-8-Scheme of alterations in NOF and PR groups and possible Sirtuins’ roles. According
to our studies, NOF women between 18 to 38 years old may avoid OS damage by OSR, triggering a normal
signaling response and maintaining an equilibrated OS/OSR status (A). It is possible that this equilibrium
favors OS during pre-menopausal aging (B). In that case, OSR are not sufficient to protect cells from OS actions
and SIRT1, SIRT2 and SIRT5 gene expression increase would be required to recover homeostasis. Failing this
response, women poor responders show a different sirtuin pattern (C). In this group, women between 25 to
38 years old have an imbalance between OS and OSR similar to older NOF women. Cellular attempts to reach
homeostasis by increasing SIRT1, SIRT2 and SIRT5 gene expression are insufficient and it is necessary activate
protein, lipid and DNA repair mechanisms and others sirtuins’ expression. Despite the fact that SIRT6 and SIRT7
gene expression increase, cells cannot response to signaling and homeostasis cannot be recovered, leading to a
clinically poor response to follicle stimulation.
In follicular formation there is key role of granulosa cell [10].
In case of endometriotic subjects, abnormalities of granulosa cell
might interfere with oocyte maturation and result in poor oocyte
quality [11]. Telomerase was found as a biomarker of the potential
that germ cells possess [12]. Premature aging and decreased
fecundity were seen in mice having Telomerase deficiency [13].
Earlier Li et al. [14] revealed that telomerase activity (TA) in
granulosa cell (GTA), had a positive association with IVF treatment
Results
[14]. Healthy follicles showed > amounts of TA, as compared
to decreased GTA =>enhancement of atretic follicles [15]. Subjects
having subtle and biochemical premature ovarian insufficiency
(POI) further demonstrated reduced TA in their granulosa cells
[16,17]. Overall these observations point that GTA might work as
an ovarian function biomarker.
The effect of ovarian endometriosis on granulose cells
was recently studied by Li et al. [18], that correlates molecular
physiology with results in fertility. An efficient oocyte as well as
granulosa cell crosstalk taking place the ovarian follicles sees to it
that formation of a mature oocyte occurs for obtaining an embryo
having full competency resulting in a pregnancy that is viable. Li
et al. [18] described how internally endometriotic lesions present
on the ovarian tissue resulted in intrinsic injury by evaluating the
inflammatory paths as well as telomerase action within granulosa
cell. 80 women got enrolled prospectively having stage II-III
Endometriomas as well as 104 controls who were having oocyte
recovery utilizing artificial reproductive therapy (ART) therapy.
The 2 groups developed pregnancy (clinical)with equal chances,
that agrees with most of current literature and helps in giving
us assurance with regard to ART overcoming the problems in
endometriotic subjects. But emphasis has been paid by them on the
impaired results of folliculogenesis which takes place when lesions
are existing.
248
Perceptions Reprod Med
Copyright © Kulvinder Kochar Kaur
PRM.MS.ID.000570. 3(4).2020
Actually, the antral follicle count (AFC), luteinizing hormone
(LH) amounts as well as the number of oocytes recovered, and
mature oocytes all were < in their Endometriomas group. Stimulated
by these observations they tried to evaluate the molecular reasons
behind this effect on follicle formation via a number of repeated in
vitro studies where they separated granulosa cell from the follicular
fluid ,evaluated them for any basal inflammatory changes as well
as culturing them in the exogenous inflammatory stimulants added
for getting a response. Their findings were similar to the common
factors in such settings like the nuclear factor (NF) κB as well
as tumour necrosis factor alpha (TNF α) paths that seem to be
controlled separately in granulosa cell in endometriotic subjects
as compared to controls. Particularly action of NF κB in addition to
its 2 helpers IK κβ as well as IKB α was > in the granulosa cell from
the follicular fluid of endometriotic subjects as compared to healthy
cells. To find the upstream regulators of NF κB parts of granulosa
cell of endometriotic subjects. Their observation was that TNF α
found within the follicular fluid (FF) had a positive association
with the expression of NFκB in granulosa cell, a finding which was
later confirmed by crucial cell culture studies ,where TNFα therapy
directly escalated the excess of NF κB as well as IKB α. The biggest
importance of these experiments was the innovative understanding
of the telomerase enzyme action when endometriosis was existent
along with its associated inflammation. Recently trying to assess
telomere length as well as telomerase activity in granulosa cell of
patients with infertility has been on the rise that has turned to be a
good marker of oocyte competence. Telomeres represent conserved
areas at the distal part of chromosomes which aid in conferring
protection to genomic integrity.
Escalated mitotic action of granulosa cell as well as follicular
hormones lead to the shortened length of telomeres that has to
be restored by telomerase activity. Minimal but essential proof
has aided in the understanding that the activity of telomerase is
>in healthy as well as small follicles as compared to atretic larger
follicles and this activity of enzymes can be enhanced by estrogens
[18]. This telomeres length as well as telomerase enzyme activity
as far as theoretical explanation is that they represent divergence
but separate dynamics got detailed in particular situations ,Like
granulosa cell of women having a diagnosis of premature ovarian
failure(POF) had shorter telomeres as well as < telomerase activity
as compared to control ladies, while absence of normal telomerase
activity enhances the chances for women to have POF 11 times [19].
Though experiments of cellular modes with regards to telomere
structures within oocytes as well as granulosa cell might aid in
unfolding the underlying causes related to infertility, mostly little
work has been done in this field.
In 2017 Li et al. [18] utilized the niche, detailing the telomeres
length as well as telomerase activity in polycystic ovarian syndrome
(PCOS). Their observations were shorter telomeres but the
granulosa cell telomerase activity (GTA) was same in PCOS subjects
as compared to controls [19,20]. In this study, they found that GTA
in ovarian endometriotic subjects associated positively with the
number of mature oocytes, negatively with granulosa cell NF κB
activity and reduced following TNF α therapy. Greater information
regarding GTA dynamics was added by studies on (human
telomerase reverse transcriptase (hTERT), the catalytic subunit
of the telomerase enzyme was reduced with TNF α therapy and
enhanced by NFκB inhibitor. An essential observation of this study
although negative is that both GTA as well as hTERT were only little
lower in endometriotic subjects as compared to controls (p=0.16
and p=0.55 respectively) while NF κB inhibitor did not escalate
GTA in granulosa cell culture. It needs to be seen if lowering TNF α
activity or use of NFκB inhibitor might be of help in re-establishing
the hTERT activity needs to be studied further.
On the basis of in vitro findings, they posited a possible mode
where lesion led to escalation of FF TNFα stimulates NFκB cascade
activation in granulosa cell that in turn decreases telomerase
activity and effects physiologic increase in telomeres that is key
for folliculogenesis as well as oocyte quality. Important is follicular
TNFα levels was not separate in case as well as controls but the
in vivo findings here correlated with limited size sample size or
inclusion of earlier operated endometriotic subjects that might
have contribute to the complicated nature regarding this. There
is requirement for experiments detailing pathophysiology of
granulosa cell in endometriotic subjects and time to unveil why
subfertility in this disease both for patients as well as professionals
[21].
Conclusion
Thus trying to understand why infertility results in
Endometriosis patients lot of efforts have been put in originally
most studies concentrated on studying follicular fluid for finding
the reason of poor quality of oocytes among Endometriosis patients
where researchers observed enhanced oxidative stress as well as
ER Stress in cases of Endometriosis subjects.
Later deciding to study oocytes directly researchers observed
1. Altered mitochondrial numbers as well as abnormal
mitochondria along with reduced mitochondrial DNA in oocytes of
Endometriosis patients
2. Spindle abnormalities
3. ZP hardening of oocytes of Endometriosis patients
4. Abnormal spindle patterns and
5. Altered morphology in form of dark central granulation
by carrying out study on oocytes during IVM mostly.
Further the role of Sirtuins in effecting the alteration in cytokines
in FF associated with Endometriosis patients was emphasized as
reflecting which Sirtuins are associated with poor oocyte quality
with aging, PR as well as Endometriosis patients and PCOS subjects.
Li et al. [18] utilized the niche,detailin g the telomeres length as well
as telomerase activity in PCOS subjects where they found shorter
telomeres but the granulosa cell telomerase activity (GTA) was same
in PCOS subjects found that GTA in ovarian endometriotic subjects
associated positively with the number of mature oocytes, negatively
with granulosa cell NF κB activity and reduced following TNF α
therapy. Greater information regarding GTA dynamics was added
249
Perceptions Reprod Med
Copyright © Kulvinder Kochar Kaur
PRM.MS.ID.000570. 3(4).2020
by studies on hTERT , the catalytic subunit of the telomerase enzyme
was reduced with TNF α therapy and enhanced by NF κB inhibitor
.An essential observation of this study although negative ,is that
both GTA as well as hTERT were only little lower in endometriotic
subjects as compared to controls. On the basis of in vitro findings,
they posited a possible mode where lesion led to escalation of FF
TNFα stimulates NF κB cascade activation in granulosa cell that in
turn decreases telomerase activity and effects physiologic increase
in telomeres that is key for folliculogenesis as well as oocyte quality.
Important is follicular TNFα levels was not separate in case as well
as controls But the in vivo findings here correlated with limited
size sample size or inclusion of earlier operated endometriotic
subjects Further work is being needed to find why granulosa cells
are involved in Endometriosis patients ,studying a larger number
of cohort to try to get better possible therapies to reduce oxidative
stress and see to it that abnormal cytokines are prevented so that
we get optimum oocytes of good quality.
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