Understanding Immunologic Implantation Dysfunction Part 2: A Rational Basis for Selective Intralipid & IVIg Immunotherapy in IVF
Alloimmune Implantation Dysfunction
Every human being has two DQ-alpha genes. One is contributed by the father and the other by the mother. In a small percentage of patients undergoing IVF, paternal-maternal DQ-alpha gene similarities occur.In such cases, following repeated exposures to such genetically matching embryos, this will provoke activation of the decidual immune system. In most cases, through the mechanisms described above, this will lead to NK/CTL activation and reproductive failure (i.e.; infertility, and pregnancy loss).We refer to this phenomenon as alloimmune implantation dysfunction.
This is how alloimmune implantation dysfunction happens:Immunogenetically triggered HLA-G signaling by the embryo leads to a reduction in Treg cells, and eventually to a destabilization of NK/CTLs with domination of TH-1 over TH-2 activity. The severity with which this occurs determines whether total implantation failure will occur, or whether there remains enough residual trophoblastic activity to allow the pregnancy to limp along until the nutritional supply can no longer meet the demands of the pregnancy, at which point miscarriage or pregnancy loss occurs.
With paternal-maternal DQ alpha matching, it often takes several pregnancies for natural killer cell activation to build to the point that a woman with alloimmune implantation dysfunction will present with clinical evidence of implantation dysfunction. Sometimes it starts off with one or two pregnancies surviving to the birth of a baby, whereupon NK cell activity later starts to build, leading to one or more subsequent early miscarriages. Eventually the NK cell/CTL activity is so high that subsequent pregnancies can be lost before the woman is even aware that she was pregnant at all. At this point she is often diagnosed with secondary “unexplained” infertility.
Autoimmune Implantation Dysfunction:
With autoimmune implantation dysfunction, NK cell activation is already well established by the time the embryo reaches the uterus. Accordingly, in such cases the pregnancy is usually lost before its presence can be established by a blood pregnancy test or an early ultrasound examination (i.e., it presents as a negative pregnancy test or a chemical gestation).
So how is autoimmune implantation dysfunction established?The initialrecognition of the non-DQ alpha matching embryo as “friend” or “self” sets the stage for the cells/tissues of our bodies not coming under immune attack. However under certain circumstances, genetic, infective, toxic and degenerative influences can result in our own body’s proteins coming to be regarded as “non-self” (“foe”). When this happens the immune system starts to produce antibodies that are directed against our body’s own proteins. These so called autoantibodies then start attacking the body’s own cells/tissues/organs, creating pathologic states (diseases) such as can be seen with certain (autoimmune) diseases (e.g.,lupus erythematosus, autoimmune hypothyroidism [Hashimoto’s disease] and rheumatoid arthritis).
There are also certain reproductive diseases such as endometriosis, where cell membrane phospholipids are often altered by the disease process, and then combine with proteins to evoke the production of so called antiphospholipid antibodies (APAs)Certain types of APAs can both directly damage the trophoblast and can also lead to a reduction of Treg lymphocytes, culminating in activation of NK/CTLs.
This type of reaction, albeit due to a predisposition to autoimmune diseases such as lupus erythematosus, Hashimoto’s disease, etc., or reproductive conditions such as endometriosis, is referred to as autoimmune implantation dysfunction. Autoimmune implantation dysfunction is much more common than alloimmune implantation dysfunction. In fact, it is probably responsible for more than 85% of reproductive failure attributable to immunologic implantation dysfunction. The most common autoantibodies involved are:
1) antiphospholipid antibodies (APA)
2) antithyroid antibodies (ATA)
3) antiovarian antibodies (AOA)
Since autoimmune implantation dysfunction is often genetically transmitted, it is not surprising that this condition is more likely to exist in women who have a family (or personal) history of primary autoimmune diseases such as lupus erythematosus, scleroderma, clinical or subclinical hypothyroidism, rheumatoid arthritis, etc. Reactionary (secondary) autoimmunity can occur in conjunction with any medical condition associated with widespread tissue damage. One such gynecologic condition is endometriosis.
As previously stated, autoimmune implantation dysfunction is usually immediately lethal to the implanting embryo and accordingly most often presents as “unexplained “ infertility and/or “unexplained” IVF failure, rather than as miscarriage.This is because NK/CTL activation is present prior to implantation and as such, the embryo’s root system is severely damaged from the get-go. Autoimmune implantation dysfunction isreadily amenable to reversal through timely, appropriately administered, selective immunotherapy (see below).
Diagnosing Immunologic Implantation Dysfunction:
Whether alloimmune or autoimmune in origin, it is only once specialized immune cells in the uterine lining known as Natural Killer (NK) Cells and Cytotoxic Lymphocytes (CTL), become activated and TH-1 cytokine dominance is established that IID occurs. Thus, a full evaluation of immunologic implantation dysfunction requires that DQ alpha, APA, ATA, as well as NK/CTL activation be evaluated. This involves highly specialized blood testing and possibly also endometrial tests that can only be performed in a handful of reproductive immunology laboratories in the United States.
Alloimmune ID is diagnosed by testing the blood of both the male and female partners for matching DQ alpha genes. A sufficient degree of matching clinches the diagnosis. Since matching DQ alphas will rarely cause reproductive failure unless there is concomitant NK/CTL cell activation, it is important to test the embryo recipient for NK cell activation (the K-562 target cell) test and CTL activation (by a blood immunophenotype and HLA-DR measurement). Some reproductive immunologists might also test blood Treg cell concentration and/or recommend an endometrial biopsy to histolochemically evaluate uterine NK cells or assess the local TH-1/TH-2 balance. The performance of blood TH-1 and TH-2 cytokines to assess for TH-1 dominance is controversial and is of unproven value.
Treating Immunologic Implantation Dysfunction
In the United States, effective treatment of NK/CTL activation associated with either alloimmune or autoimmune implantation dysfunction requires the administration of Intralipid or IVIG. Such treatment is usually much more likely to be successful in the case of autoimmune implantation dysfunction where the NK/CTL activation is present in advance of the uterus being exposed to the embryo. It is not nearly as effective for the treatment of alloimmune implantation dysfunction where a DQ alpha matching embryo will exert a sustained activation of NK/CTLs over several months of gestation. It is presently not yet possible to identify paternal DQ alpha in the embryo. Accordingly, in cases where the paternal DQ alpha gene only matches with one of the mother’s DQ alphas (i.e. a partialmatch) there is a one-out-of-two chance that a transferred embryowill inadvertently be a match with at least one of the mother’s DQ alpha genes. Thus Intralipid or IVIG therapy will only prove half as likely to propagate a viable pregnancy in cases of partial DQ alpha matching as it can achieve in the treatment of NK/CTL activation associated with autoimmune implantation dysfunction.
For this reason, I prefer to transfer only one (rather than multiple) embryo at a time in such cases,for fear of there being one DQ alpha matching embryo in the mix and so “muddying the waters” for the non-DQ alpha matching that otherwise might have propagated a healthy baby.
A real problem arises in cases of a complete DQ alpha match, where both paternal DQ alpha genes match with at least one of the mother’s DQ alphas.Here, every embryo will express a paternal DQ alpha gene that matches that of the mother’s. In such cases, Intralipid and/or IVIG therapy will rarely work. The reason is that such treatment cannot match the sustained provocation of NK/CTL activity brought about by an ever-present DQ alpha “clash.” In cases of complete DQ alpha matching (with associated NK/CTL activation), where all the embryos will inevitably carry one or both paternal DQ alphas that match the mother, there is in my opinion little hope of success, even with Intalipid/IVIG/steroid therapy. In such cases, gestational surrogacy or the use of non-DQ alpha matching, donor sperm may offer the only reasonable chance of a successful IVF outcome.
Some patients ask whether using an egg donor might not offer another solution in such cases. The answer is no! The matchup is between the paternal DQ alpha contribution (in the sperm) and the mother’s uterus. It is not between the sperm and the egg.
IVIG/IL therapy should preferably always be administered in combination with corticosteroids at an adequate dosage, starting 7-14 days prior to planned embryo transfer. With alloimmune implantation dysfunction shuch treatment should be repeated every 2-4 weeks through the 1st half of pregnancy. The goal is to down-regulate NK /CTL activation and thereby reinstate a TH-1: TH-2 cytokine balance in advance of a “competent” non- DQ alpha matching embryo reaching the uterus. When it comes to autoimmune implantation dysfunction Intralipid and/or IVIG (with corticosteroids) need only be administered twice; (once, 7-14 days prior to embryo transfer, and the second administratio should be given when the beta hCG blood level has shown evidence of an appropriate rise, thereby suggesting that healthy implantation is likely to be in progress). Supplementation with heparinoid (see below) is indicated when there is evidence of concomitant APA’s
Heparinoid Therapy: There is compelling evidence that the subcutaneous administration of heparin twice daily or low molecular heparin (Clexane, Lovenox) once daily, (starting with the onset of ovarian stimulation and continued until the end of the 1st trimester), can improve IVF birth rates in women who test positive for APAs.
What About Taking a Baby Aspirin a Day?In my opinion, aspirin has little if any value when it comes to IID, and besides, 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 resulting in “concealed” intrauterine bleeding at the time of embryo transfer, thereby potentially compromising IVF success.
IVIg and Intralipid Therapy: In the past, the only effective way to accomplish the aforementioned immunologic down-regulation was through the intravenous administration of a blood product known as immunoglobulin-G (IVIg). However, the administration of a blood product raised understandable concern with regard to the possible transmission of viral infections such as HIV and hepatitis C.
Several years ago, researchers at SIRM and its (then) affiliate reproductive immunology program in Chicago, IL reported on the use of Intralipid (IL), a synthetic product which, upon being administered intravenously a week or longer prior to embryo transfer, elicits a similar down-regulatory effect on Nk / CTL activation as IVIg. We subsequently conducted confirmatory internal trials, and in 2007 I began prescribing IL preferentially for patients with CTL/NK activation.. To date we have treated more than 400 cases in this way and results have been very encouraging. Against this background I have now all but abandoned the use of IVIg for immunologic implantation dysfunction associated with NK/CTL activation, supplanting it with IL. On very rare occasions, where IL alone does not achieve the desired result I might recommend combining IVIg with IL therapy.
IVIg is very expensive and in about 20% of cases its use is indeed associated with immediate and delayed side effects and complications. Intralipid, on the other hand (provided that it is prescribed and administered appropriately), is virtually devoid of risk and/or significant side effects. It is also safe to the developing conceptus and it comes at a fraction of the cost of IVIg.
Corticosteroid Therapy (Prednisone, Prednisilone and Dexamethasone): Corticosteroid therapy has become a mainstay in the treatment of most women undergoing IVF. It is believed by most to enhance implantation overall. This is more than likely to an overall immunomodulatory effect. Some IVF programs prescribe daily oral methyl prednisilone (Medrol) while others prefer prednisone or dexamethasone, commencing a week or two prior to egg retrieval and continuing until pregnancy is discounted or until after the ultrasound confirmation of pregnancy.
TH-1 Blockers (Enbrel, Humira): I was one of the first to suggest using the TH-1 cytokine blocker, Enbrel (and Humira) forNK cell activation, only to find it to be relatively ineffective in the IVF setting. To date, as far as I am aware, there have not been any convincing reports showing TH-1 blockers to be of real benefit in patients undergoing IVF. These blockers might well have a role in the treatment of a threatened miscarriage thought to be due to CTL/NK activation, but in my opinion, not in the IVF setting. The reason is that the very initial stage of embryo implantation requires a cellular response involving TH-1 cytokines. To block them (rather than simply restore a TH1: TH-2 balance as occurs with IL or IVIg therapy) so very early could, in my opinion, compromise rather than benefit implantation.
Leukocyte Immunization Therapy (LIT): The subcutaneous injection of husbands 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 the decidual TH1: TH-2 balance.Thus, there could be a therapeutic benefit from such therapy. However, in my opinion, such benefit is no greater than can be achieved through the use of IL plus corticosteroids. Besides, Intralipid is much less expensive and the use of LIT is prohibited by law in the United States.
The evaluation for immunologic dysfunction as well as other factors that can affect implantation should form part of the evaluation of patients preparing to undergo IVF, and especially so in women with endometriosis, recurrent pregnancy loss (RPL), women with a personal or family history of autoimmune conditions, and women with “unexplained” infertility or unexplained IVF failure(s).