kir-hla

Question

Answer

Currently, with few exceptions, practitioners of assisted reproduction tend to attribute “unexplained and/or repeated” IVF failure(s), almost exclusively to poor embryo quality, advocating adjusted protocols for ovarian stimulation and/or gamete and embryo preparation as a potential remedy. The idea, having failed IVF, that all it takes to ultimately succeed is to keep trying the same recipe is over-simplistic.

The implantation process begins six or seven days after fertilization of the egg. At this time, specialized embryonic cells (i.e., trophoblasts), that later become the placenta begin growing into the uterine lining. When the trophoblast and the uterine lining meet, they, along with immune cells in the lining, become involved in a “cross talk” through mutual exchange of hormone-like substances called cytokines. Because of this complex immunologic interplay, the uterus can foster the embryo’s successful growth. Thus, from the earliest stage, the trophoblast establishes the very foundation for the nutritional, hormonal and respiratory interchange between mother and baby.  In this manner, the interactive process of implantation is not only central to survival in early pregnancy but also to the quality of life after birth.

There is an ever growing realization, recognition, and acceptance of the fact that uterine immunologic dysfunction can lead to immunologic implantation dysfunction (IID) with “unexplained” infertility, IVF failure, and recurrent pregnancy loss (RPL).

DIAGNOSIS 

Because immunologic problems may lead to implantation failure, it is important to properly evaluate women with risk factors such as:

• Unexplained or recurrent IVF failures
• Unexplained infertility or a family history of autoimmune diseases (e.g., rheumatoid arthritis, lupus erythematosus and hypothyroidism).
• Recurrent Pregnancy Loss (RPL)
• Endometriosis
• A personal or family history of autoimmune conditions, e.g., Rheumatoid Arthritis, Lupus erythematosus, autoimmune hypothyroidism (Hashimoto’s disease) etc.

            Considering its importance, it is not surprising that the failure of a properly functioning immunologic interaction during implantation has been implicated as a cause of recurrent miscarriage, late pregnancy fetal loss, IVF failure and infertility. A partial list of immunologic factors that may be involved in these situations includes:

• Activated natural killer cells (NKa) & the relevance of measuring Killer Cell immunoglobulin Receptors (KIR) and Human Leukocyte Antigens (HLA):

• Antiphospholipid antibodies (APA)
• Antithyroid antibodies (ATA/AMA)

1. A) ACTIVATED NATURAL KILLER CELLS (NKa) AND THEIR INTERRACTION WITH KILLER CELL IMMUNIGLOBULIN RECEPTORS (KIR) AND HLA..

Following ovulation and during early pregnancy, NK cells and T-cells comprise more than 80% of the lymphocyte-immune cells that frequent the uterine lining. These lymphocytes (white blood cells) journey from the bone marrow to the uterus and under hormonal regulation, proliferate there. After exposure to progesterone (due to induced /spontaneous exogenous administration), they begin to produce TH-1 and TH-2 cytokines. TH-2 cytokines are humoral in nature and induce the trophoblast (“root system of the embryo”) to permeate the uterine lining while TH-I cytokines induce a process referred to as apoptosis (cell suicide) thereby confining placental development to the inner part of the uterus. Optimal placental development (placentation) mandates that there be a balance between TH1 and TH-2 cytokines. Most of the cytokine production originates from NK cells (rather than from cytotoxic T-cells/Lymphocytes (CTL)). Excessive production/release of TH-1 cytokines, is toxic to the trophoblast and to endometrial cells, leading to programmed death/suicide (apoptosis) and subsequently to IID.

Functional NK cells reach a maximal concentration in the endometrium by about t day 6-7 days after exposure to progesterone …. This timing corresponds with when the embryo implants into the uterine lining (endometrium).

It is important to bear in mind that measurement of the concentration of blood NK cells has little or no relevance when it comes to assessing NK cell activation (NKa). Rather, it is the NK cell activation that matters. In fact, there are certain conditions (such as with endometriosis) where the NK cell blood concentration is below normal, but NK cell activation is markedly increased.

There are several methods by which NK cell activation (cytotoxicity) can be assessed in the laboratory. Methods such as immunohistochemical assessment of uterine NK cells and/or through measurement of uterine or blood TH-1 cytokines. However, the K-562 target cell blood test still remains the gold standard. With this test, NK cells, isolated from the woman’s blood using Flow Cytometry are incubated in the presence of specific “target cells”. The percentage (%) of “target cells” killed is then quantified. More than 12% killing suggests a level of NK cell activation that usually requires treatment.

Currently, there are less than a half dozen Reproductive Immunology Reference Laboratories in the U.S.A that are capable of performing the K-562 target cell test reliably.

There exists a pervasive but blatant misconception on the part of many, that the addition of IL or IVIg to a concentration of NK cells could have an immediate down-regulatory effect on NK cell activity. Neither IVIg nor IL is capable of significantly suppressing already activated “functional NK cells”. They are believed to work through “regulating” NK cell progenitors which only thereupon will start to propagate down-regulated NK cells. Thus, testing for a therapeutic effect would require that the IL/IVIg infusion be done about 14 days prior to ovulation or progesterone administration…  in order to allow for a sufficient number of normal (non-activated) “functional” NK cell” to be present at the implantation site when the embryos are transferred.

Failure to recognize this reality has, in our opinion, established an erroneous demand by practicing IVF doctors, that Reproductive Immunology Reference Laboratories report on NK cell activity before and again, immediately following laboratory exposure to IVIg and/or IL in different concentrations. Allegedly, this is to allow the treating physician to report back to their patient(s) on whether an IL or IVIG infusion will be effective in downregulating their Nka.  But, since already activated NK cells (NKa) cannot be deactivated in the laboratory, effective NKa down-regulation can only be adequately accomplished through deactivation of NK cell “progenitors /parental” NK cells in order to allow them thereupon, to s propagate normal “functional” NK cells and his takes about 10-14 days, such practice would be of little clinical benefit. This is because even if blood were to be drawn 10 -14 days after IL/IVIg treatment it would require at least an additional 10 -14days to receive results from the laboratory, by which time it would be far too late to be of practical value  

The relevance of measuring Killer Cell immunoglobulin Receptors (KIR) and Human Leukocyte Antigens (HLA).

HLA (human leukocyte antigen) proteins, also known as MHC (major histocompatibility complex) proteins, are a group of proteins found on the surface of cells in the body. They play a critical role in the immune system by presenting foreign substances, such as proteins from viruses or bacteria, to immune cells so that they can be recognized and destroyed.  

HLA proteins are highly variable and diverse, with many different types and variations found within the human population. This diversity allows the immune system to recognize and respond to a wide range of foreign substances, and also plays a role in transplant rejection, as the immune system can recognize and attack cells that express HLA proteins that are different from its own.

There are two main types of HLA proteins: class I and class II. Class I HLA proteins are found on the surface of most cells in the body and present antigens to CD8+ T cells, while class II HLA proteins are found primarily on immune cells and present antigens to CD4+ T cells. The interaction between HLA proteins and T cells is critical for the recognition and destruction of foreign substances by the immune system, and abnormalities in HLA expression or function can lead to immune system dysfunction and disease.

HLA (human leukocyte antigen)-C proteins on the surface of the embryo’s trophoblast (root system) are involved in embryo implantation by interacting with immune cells, such as uterine natural killer (NK) cells that play a critical role in the process.

During implantation, the developing embryo must attach itself to the uterine lining, a process that can be hindered by the maternal immune system, which may recognize the embryo as foreign and attempt to reject it. However, HLA-C proteins expressed on the surface of the trophoblast cells, which are the outermost layer of the developing embryo, can interact with maternal immune cells and modulate their activity. In fact, this  interaction between HLA proteins on trophoblast cells and maternal immune cells, particularly NK cells, plays a critical role in successful implantation. Specifically, HLA-C, which is a type of HLA protein expressed on the surface of trophoblast cells, has been implicated in regulating NK cell activity during implantation. It is thought that HLA-C on trophoblast cells interacts with KIR (killer cell immunoglobulin-like receptor) proteins on maternal NK cells, leading to the suppression of NK cell activity and the promotion of successful implantation. 

The exact mechanisms by which KIRs and HLA-C molecules interact and contribute to  embryo implantation are not yet fully understood, but several hypotheses have been proposed.

1. One hypothesis is that KIRs on maternal NK cells recognize and bind to HLA-C molecules on the surface of fetal trophoblast cells, which are the cells that make up the outer layer of the developing embryo. This interaction is thought to promote the invasion of trophoblast cells into the maternal endometrium, which is necessary for successful implantation.
2. Another hypothesis is that KIRs on maternal NK cells may recognize and bind to HLA-C molecules on the surface of immune cells in the maternal endometrium, leading to the suppression of immune responses that could interfere with implantation. This could include the suppression of inflammatory responses and the promotion of the development of a specialized type of immune cell known as regulatory T cells, which can help to prevent the rejection of the developing embryo.

While the interactions between KIRs and HLA-C molecules likely play a critical role in the complex interplay between the immune system and early pregnancy, helping to ensure the successful implantation and development of the embryo, further research is needed to fully understand the mechanisms by which these molecules contribute to implantation and early pregnancy.

1. ANTIPHOSPHOLIPID ANTIBODIES:

 Many women who experience “unexplained” IVF failure, women with RPL, those with a personal or family history of autoimmune diseases such as lupus erythematosus, rheumatoid arthritis, scleroderma, and dermatomyositis (etc.)  as well as women who have endometriosis (“silent” or overt) test positive for APAs. More than 30 years ago, we were the first to propose that women who test positive for APA’s be treated with a mini-dose heparin to improve IVF implantation and thus birth rates. This approach was based upon research that suggested that heparin repels APAs from the surface of the trophoblast (the embryo’s “root system) thereby reducing its ant-implantation effects.  We subsequently demonstrated that such therapy only improved IVF outcome in women whose APAs were directed against two specific IgG and/or IgM phospholipids [i.e., phosphatidylethanolamine (PE) and phosphatidylserine (PS)].  More recently low dosage heparin therapy has been supplanted using longer acting low molecular weight heparinoids such as Lovenox and Clexane.   It is very possible that APAs alone do not cause IID but that their presence might help to identify a population at risk due to concomitant activation of uterine natural killer cells (Nka) which through excessive TH-1 cytokine production causes in IID: This is supported by the following observations:

• The presence of female APAs in cases of male factor cases appears to bear no relationship to IID.
• Only APA positive women who also test positive for abnormal NK activity appear to benefit from selective immunotherapy with intralipid/IVIg/ steroids.
• Most APA positive women who have increased NK cell activity also harbor IgG or IgM phosphatidylethanolamine (PE) and phosphatidylserine (PS) antibodies.

1. ANTITHYROID ANTIBODIES: (ATA).

 A clear relationship has been established between ATA and reproductive failure (especially recurrent miscarriage and infertility).

Between 2% and 5% of women of the childbearing age have reduced thyroid hormone activity (hypothyroidism). Women with hypothyroidism often manifest with reproductive failure i.e., infertility, unexplained (often repeated) IVF failure, or recurrent pregnancy loss (RPL). The condition is 5-10 times more common in women than in men. In most cases hypothyroidism is caused by damage to the thyroid gland resulting from of thyroid autoimmunity (Hashimoto’s disease) caused by damage done to the thyroid gland by antithyroglobulin and antimicrosomal auto-antibodies. 

The increased prevalence of hypothyroidism and thyroid autoimmunity (TAI) in women is likely the result of a combination of genetic factors, estrogen-related effects, and chromosome X abnormalities.  This having been said, there is significantly increased incidence of thyroid antibodies in non-pregnant women with a history of infertility and recurrent pregnancy loss and thyroid antibodies ^can be present asymptomatically in women without them manifesting with overt clinical or endocrinologic evidence of thyroid disease. In addition, these antibodies may persist in women who have suffered from hyper- or hypothyroidism even after normalization of their thyroid function by appropriate pharmacological treatment. The manifestations of reproductive dysfunction thus seem to be linked more to the presence of thyroid autoimmunity (TAI) than to clinical existence of hypothyroidism and treatment of the latter does not routinely result in a subsequent improvement in reproductive performance.

It follows, that if antithyroid autoantibodies are associated with reproductive dysfunction they may serve as useful markers for predicting poor outcome in patients undergoing assisted reproductive technologies.

Some years back, I reported on the fact that 47% of women who harbor thyroid autoantibodies, regardless of the absence or presence of clinical hypothyroidism, have activated uterine natural killer cells (NKa) cells and cytotoxic lymphocytes (CTL) and that such women often present with reproductive dysfunction. We demonstrated that appropriate immunotherapy with IVIG or intralipid (IL) and steroids, subsequently often results in a significant improvement in reproductive performance in such cases.

The fact that almost 50% of women who harbor antithyroid antibodies do not have activated CTL/NK cells suggests that it is NOT the antithyroid antibodies themselves that cause reproductive dysfunction. The activation of CTL and NK cells that occurs in half of the cases with TAI is probably an epiphenomenon with the associated reproductive dysfunction being due to CTL/NK cell activation that damages the early “root system” (trophoblast) of the implanting embryo. We have shown that treatment of those women who have thyroid antibodies + NKa/CTL using IL/steroids, improves subsequent reproductive performance while women with thyroid antibodies who do not harbor NKa/CTL do not require or benefit from such treatment

TEATMENT OF IID:

The mainstay of treatment involves the selective use of:

• Intralipid (IL) infusion
• IVIg therapy
• Corticosteroids (Prednisone/dexamethasone)
• Heparinoids (Lovenox/Clexane)

Intralipid (IL) Therapy: 

IL is a suspension of soybean lipid droplets in water and is primarily used as source of parenteral nutrition. When administered intravenously, IL provides essential fatty acids, linoleic acid (LA), an omega-6 fatty acid, and alpha-linolenic acid (ALA), an omega-3 fatty acid.     

It is thought that fatty acids within the emulsion serve as ligands that activate peroxisome proliferator-activated receptors (PPARs) expressed by the NK cells. This is believed to decrease NK cell cytotoxic activity, and thereby enhance implantation A growing number of IVF programs, including ours, perform egg retrieval under conscious sedation using Propofol, a short acting hypnotic agent.

            Whatever the exact mechanism of action might be, Intralipid acts primarily to suppress NK cell over-production of TH-I cytokines. It exerts a modulating effect on certain immune cellular mechanisms largely by down-regulating cytotoxic /activated natural killer cells (NKa). This effect is enhanced through the concomitant administration of corticosteroids such as dexamethasone, prednisolone and prednisone which augment immune modulation of T cells. The combined effect of IL + steroid therapy suppresses pro-inflammatory cellular TH1 cytokines such as interferon gamma and TNF-alpha that are produced in excess by activated NK cells and cytotoxic lymphocytes/T-cells (CTL).   IL will, in about 80% of cases, successfully down-regulate activated natural killer cells (NKa) over a period of 2-3 weeks. It is likely to be just as effective as IVIg in this respect but at a fraction of the cost and with a far lower incidence of side-effects. Its effect lasts for ~ 4-6 weeks when administered in early pregnancy.

Intralipid is a suspension of soybean lipid droplets in water and is primarily used as source of parenteral nutrition. When administered intravenously, IL provides essential fatty acids, linoleic acid (LA), an omega-6 fatty acid, and alpha-linolenic acid (ALA), an omega-3 fatty acid.     

It is thought that fatty acids within the emulsion serve as ligands that activate peroxisome proliferator-activated receptors (PPARs) expressed by the NK cells. This is believed to decrease NK cell cytotoxic activity, and thereby enhance implantation A growing number of IVF programs, including ours, perform egg retrieval under conscious sedation using Propofol, a short acting hypnotic agent.

Whatever the exact mechanism of action might be, Intralipid acts primarily to suppress NK cell over-production of TH-I cytokines. It exerts a modulating effect on certain immune cellular mechanisms largely by down-regulating cytotoxic /activated natural killer cells (NKa). This effect is enhanced through the concomitant administration of corticosteroids such as dexamethasone, prednisolone and prednisone which augment immune modulation of T cells. The combined effect of IL + steroid therapy suppresses pro-inflammatory cellular TH1 cytokines such as interferon gamma and TNF-alpha that are produced in excess by activated NK cells and cytotoxic lymphocytes/T-cells (CTL).   IL will, in about 80% of cases, successfully down-regulate activated natural killer cells (NKa) over a period of 2-3 weeks. It is likely to be just as effective as IVIg in this respect but at a fraction of the cost and with a far lower incidence of side-effects. Its effect lasts for ~ 4-6 weeks when administered in early pregnancy.

            Can laboratory testing be used to assess for an immediate effect of IL on Nka suppression?  Since the downregulation of NKa through IL (or IVIg) therapy can take several weeks to become measurable, it follows that there is really no benefit in trying to assess the potential efficacy of such treatment by retesting NKa in the laboratory after adding IL (or IVIg) to the cells being tested.

IVIg Therapy:

Until about a decade ago, the only effective and available way (in the US) to down-regulate activated NK cells was through the intravenous administration of a blood product known as immunoglobulin-G (IVIg). The fear (albeit unfounded) that the administration of this product might lead to the transmission of viral infections such as HIV and hepatitis C, plus the high cost of IVIG along with the fact that significant side effects occurred about 20% of the time, led to bad press and bad publicity for the entire field of reproductive immunology. It was easier for RE’s to simply say “I don’t believe IVIg works” and thereby avoid risk and bad publicity. But the thousands of women who had babies because of NK cell activity being downregulated through its use, attests to IVIg’s efficacy. But those of us who felt morally obligated to many desperate patients who would not conceive without receiving IVIg were facing an uphill battle. The bad press caused by fear mongering took its toll and spawned a malicious controversy. It was only through the introduction of IL less (about 15-20 years ago ), that the tide began to turn in favor of those patients who required low cost, safe and effective immunotherapy to resolve their IID.

 Corticosteroid Therapy (e.g., Prednisone, and Dexamethasone):

Corticosteroid therapy has become a mainstay in the treatment of most women undergoing IVF. It is believed by most to enhance implantation due to an overall immunomodulatory effect. Corticosteroids reduce TH-1 cytokine production by CTL. When given in combination with IL or IVIG they augment the implantation process. The prednisone or dexamethasone therapy must commence (along with IL/IVIg) 10-14 days prior to egg retrieval and continue until pregnancy is discounted or until the 10th week of pregnancy.

 Heparinoid Therapy:

There is compelling evidence that the subcutaneous administration of low molecular heparin (Clexane, Lovenox) once daily, (starting with the onset of ovarian stimulation) can improve IVF birthrate in women who test positive for APAs and might prevent later pregnancy loss when used to treat certain thrombophilias (e.g., homozygous MTHFR mutation)

What About Baby Aspirin? In our opinion, aspirin has little (if any) value when it comes to IID, and besides, it could even reduce the chance of success. The reason for this is that aspirin thins the blood and increases the potential to bleed. This effect can last for up to a week and could complicate an egg retrieval procedure or result in “concealed” intrauterine bleeding at the time of embryo transfer, thereby potentially compromising IVF success.

TH-1 Cytokine Blockers (Enbrel, Humira):

TH-1 cytokine blockers, (Enbrel and Humira) are in our opinion relatively ineffective in the IVF setting. There has to date been no convincing data to support their use. However, these blockers could have a role in the treatment of a threatened miscarriage thought to be due to CTL/NK activation, but not for IVF. The reason is that the very initial phase of implantation requires a cellular response involving TH-1 cytokines. To block them completely (rather than simply restore a TH-1:TH-2 balance as occurs with IL therapy) so very early on could compromise rather than benefit implantation.

Leukocyte Immunization Therapy (LIT):

The subcutaneous injection of the male partner’s lymphocytes to the mother is thought to enhance the ability for the mother’s decidua (uterus) to recognize the DQ alpha matching embryo as “self” or “friend” and thereby avert its rejection. LIT has been shown to up-regulate Treg cells and thus down-regulate NK cell activation thereby improving decidual TH-1:TH-2 balance. Thus, there could be a therapeutic benefit from such therapy. However, the same benefit can be achieved through the use of IL plus corticosteroids. Besides, IL is much less expensive, and the use of LIT is prohibited by law in the U.S.A.

There are two categories of immunologic implantation dysfunction (IID) linked to NK cell activation (NKa).

1. AUTOIMMUNE , IMMUNOLOGIC IMPLANTATION DYSFUNCTION

Autoimmune Implantation Dysfunction: Here, the woman will often have a personal or family history of autoimmune conditions such as Rheumatoid arthritis, Lupus Erythematosus, and thyroid autoimmune activity (e.g., Hashimoto’s disease) etc. Autoimmune as well as in about one third of cases of endometriosis, regardless of severity.  Autoimmune sometimes also occurs in the absence of a personal or family history of autoimmune disease.

When it comes to treating  NKa in  IVF cases complicated by autoimmune implantation dysfunction,  the combination of daily oral dexamethasone commencing with the onset of ovarian stimulation and continuing until the 10th week of pregnancy, combined with an initial infusion of IL (100ml, 20% Il dissolved in 500cc of saline solution, 10-14  days prior to PGT-normal embryo transfer and repeated once more (only), as  soon as the blood pregnancy test is positive), the anticipated chance of a viable pregnancy occurring within 2 completed IVF attempts (including fresh + frozen ET’s)  in women under 39Y (who have normal ovarian reserve)  is approximately  65%.

1. ALLOIMMUNE, IMMUNOLOGIC IMPLANTATION DYSFUNCTION

Alloimmune Implantation Dysfunction: Here, NK cell activation results from uterine exposure to an embryo derived through fertilization by a spermatozoon that shares certain genotypic (HLA/DQ alpha) similarities with that of the embryo recipient.

Partial DQ alpha/HLA match:  Couples who upon genotyping are shown to share only one DQ alpha/HLA gene are labeled as having a “partial match”. The detection of a “partial match” in association with NKa puts the couple at a considerable disadvantage with regard to IVF outcome. It should be emphasized however, that in the absence of associated Nka, DQ alpha/HLA matching whether “partial” or “total (see below) will NOT cause an IID. Since we presently have no way of determining which embryo carries a matching paternal DQ alpha gene, it follows that each embryo transferred will have about half the chance of propagating a viable pregnancy. Treatment of a partial DQ alpha/HLA match (+ Nka) involves the same IL, infusion as for autoimmune-Nka with one important caveat, namely that here we prescribe oral prednisone as adjunct therapy (rather than dexamethasone) and the IL infusion is repeated every 2-4 weeks following the diagnosis of pregnancy and continued until the 24th week of gestation. Additionally, (as alluded to elsewhere) in such cases we transfer a single (1) embryo at a time. This is because, the likelihood is that one out of two embryos will “match” and we are fearful that if we transfer >1 embryo, and one transferred embryos “matches” it could cause further activation of uterine NK cells and so prejudice the implantation of all transferred embryos. Here it should be emphasized that if associated with Nka, a matching embryo will still be at risk of rejection even in the presence of Intralipid (or IVIg) therapy.

Total (complete) DQ alpha Match:   Here the husband’s DQ alpha genotype matches both of that of his partner’s. While this occurs very infrequently, a total alloimmune (DQ alpha) match with accompanying Nka, means that the chance of a viable pregnancy resulting in a live birth at term, is unfortunately greatly diminished.  Several instances in our experience have required the use of a gestational surrogate.

It is indeed unfortunate that so many patients are being denied the ability to go from “infertility to family” simply because (for whatever reason) so many reproductive specialists refuse to embrace the role of immunologic factors in the genesis of intractable reproductive dysfunction. Hopefully this will change, and the sooner the better.

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ADDITIONAL INFORMATION:

I am attaching online links to two E-books which I recently  co-authored with  my partner at SFS-NY  (Drew Tortoriello MD)……. for your reading pleasure:

1.From In Vitro Fertilization to Family: A Journey with Sher Fertility Solutions (SFS) “

http://sherfertilitysolutions.com/sher-fertility-solutions-ebook.pdf

1. “Recurrent Pregnancy Loss and Unexplained IVF Failure: The Immunologic Link

https://drive.google.com/file/d/1iYKz-EkAjMqwMa1ZcufIloRdxnAfDH8L/view

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