Report from Juneau Biosciences

Way back in the distant and hazy past of 2009 I wrote about a company called Juneau Biosciences who were looking to recruit women with endometriosis for genetic research study. Well the results are in and they have released a preliminary report on what they have found.

The report states that they have found mutations in an imprinted gene called NLRP2 that are more common in women with endometriosis. What does this mean? Well, that will be the subject of todays blogpost.

First of all we need to understand what an imprinted gene is and why they are important. I’ve wrote before about genes, what they are and how they work, but what are imprinted genes? Normally a child inherits two ‘active’ copies of each gene, one from the mother and one from the father. However in some cases one of the genes, from either the father or the mother, can be switched off or ‘imprinted’ meaning that the child only has one working copy of the gene. This makes imprinted genes more ‘vulnerable’ because normally there would be two working copies of each gene, so if one copy gets mutated or stops working, there is a backup copy. With imprinted genes there is no backup, so if that gene has an important function (like preventing a cell becoming cancerous, for example) then there is a greater risk of a deleterious effect occurring.

Onto the next question, what does NLRP2 gene do and why is that relevant to endometriosis? The products of NLRP genes, in general, have a role in regulating the immune system and inflammation, which may be their most relevant known function in endometriosis. In particular NLRP2 has been shown to inhibit some key mediators of inflammation. Endometriosis is characterised by an increase in inflammation, both around the lesions and throughout the whole body (it is even thought that this might contribute to the fatigue many women with endometriosis experience). Also, I have written previously about how women with endo are at a higher risk of certain inflammatory and immune conditions, like inflammatory bowel disease, allergies and asthma to name a few. So finding alterations in a gene that is involved in inflammation and the immune system is potentially quite intriguing.

It could be tempting to suggest that this new finding could go some way to explaining why there is excess inflammation in endometriosis. However the sheer number of factors that contribute to the regulation of inflammation in endometriosis is huge (and still not fully understood) so exactly how significant a single factor is remains to be seen (in any case, the exact role of NLRP2 in general has been poorly characterised). Another point is that we need to know how these mutations in the NLRP2 gene affect the function of the protein it produces.

So there is a way still to go before this research can be translated into something relevant for the women living with endometriosis, but all progress needs a starting point, and this is a pretty good starting point. 

Endometriosis Awareness Month - Part III

Endometriosis is a puzzling disease, there are still many unanswered question surrounding its origin, who gets it and why. In this way it makes studying endometriosis like exploring the world in the 17^th century, there is a sense of undiscovered territory to explore, but rather than large wooden ships and subjugating natives, we have theories and hypotheses to test with science. Some of those theories prove worth exploring, some have a little, a lot, or no evidence to support them. Creating new theories sometimes seems like muddying the water and complicated an already complicated subject, but it is only by coming up with and testing new ideas, we get closer to the truth (however, all ideas must be testable and all tests must be fair, objective and subject to scrutiny by peer review, something pseudoscience always fails at).

With that in mind I’m going to be doing a bit of theorising myself in this week’s blog post. A big part of my research is examining the role that inflammation plays in endometriosis, specifically what controls inflammation in endometriotic and normal endometrial tissue. Part of this research involves looking into the initial causes of inflammation, and one thing in particular has caught my attention recently and that is bacteria.

Some types of bacteria are essential for our health, without them we would become very ill indeed and several of our organs have their own population of micro-organisms that help them function correctly. The gut and the vagina are two good examples, the gut in particular contains between 500 and 1000 different species of bacteria, numbering in the trillions of individual micro-organisms. Interestingly, the harmless bacteria that naturally populate the vagina actually help prevent infections by more harmful bacterial types. But sometimes disruption of the natural order of our internal microflora can lead to harmful effects.

Now I’m not falling into the trap of confusing endometriosis with endometritis and I’m certainly not suggesting that endometriosis is an infection or caused by an infection. Rather bacteria may play a hitherto under-recognised role in inflammation and the generation of painful symptoms in endometriosis.

How might bacteria contribute to endometriosis? To clarify I’m talking about a specific type of bacteria, called Gram-negative bacteria, which is a group of bacteria including E.coli, one of the better known species of bacteria. Why these organisms are important is because of something they secrete, namely lipopolysaccharides (LPS). LPS are essentially toxins the bacteria produce that are responsible for making you ill, but they are also powerful stimulants for inflammation and this is the key point of interest.

To start with we need to know which bacteria are normally present in the uterus and how this differs in women with endometriosis. A study published in 2014 investigated this very phenomena and found that several bacteria types, especially E.coli, were increased in the endometrium of women with endometriosis (see the figure below)

The solid white boxes represent the levels of micro-organisms found in the endometrium of women without endo, the dashed boxes represent the levels in women with endo.Figure source: http://humrep.oxfordjournals.org/content/29/11/2446.long

The solid white boxes represent the levels of micro-organisms found in the endometrium of women without endo, the dashed boxes represent the levels in women with endo.

What we can see from this is that there are several types of micro-organism found at increased levels in the endometrium of women with endometriosis, in particular a large increase in E.coli. Following on from this further studies found that LPS was found at a much higher concentration in the menstrual fluid and peritoneal fluid of women with endo as you can see if you click this link and look at figures C and D (the white bars represent the levels of LPS in women without endo, the black bars are women with endo). 

The increase in LPS in the menstrual fluid can be attributed to the increase in E.coli in the endometrium, but what about the peritoneal fluid? This can be explained by retrograde menstruation, where menstrual fluid is passed upwards through the fallopian tubes and out into the peritoneal cavity. Retrograde menstruation is a natural event in the female body during menstruation, occurring in as much as 90% of women and it was long thought that this was the root cause of endo, with endometrial cells shed during a period being passed into the peritoneal cavity where they implant and grow. This theory has since fell from favour somewhat as more evidence accumulates against it being the cause of endo, but there may be a role for retrograde menstruation in endometriosis, just perhaps not what was previously thought.

It seems plausible then that increased levels of E.coli in the endometrium lead to higher concentrations of LPS in the menstrual blood, which can get refluxed into the peritoneal cavity by retrograde menstruation, increasing the concentration of LPS in the peritoneal fluid, which can be in close/direct contact with endometriotic lesions. The next step is to assess what can happen when

LPS interacts with endometriosis.

Some studies have looked into this and found that LPS can stimulate endometriotic cells to release factors, like prostaglandin E2 (PGE2) and tumour necrosis factor (TNFα)  which promote inflammation and stimulate pain signals (PGE2 has been implicated in a number of important facets for endometriosis survival including cell growth, inhibition cell destruction and hormone production). This would lead to a heightened inflammatory state around endometriotic lesions and in the normal endometrium, possibly contributing to symptoms frequently associated with endometriosis, such as chronic pelvic pain and excessively painful periods. The whole process can be summed up on the diagram below.

Original image from https://edc2.healthtap.com/ht-staging/user_answer/reference_image/7081/large/Uterus.jpeg?1386669522

The final question, which we don’t have an answer to yet, is why E.coli and other micro-organisms are increased in the endometrium of women with endo.  It may be due to alterations of vaginal acidity leading to easier colonisation of the uterus by bacteria, or dysfunction of the immune cells in the uterus of women with endo resulting in them not being able to keep micro-organisms in check? Also, what effect would restoring the normal balance of uterine micro-organisms have and how can this be achieved? There are a lot of issues that need to be addressed here, but hopefully this will be an area of investigation that yields positive results in terms of relief from painful symptoms.

Highlights from WCE 2014 - Part 2

Let’s continue our exploration through the World Congress on Endometriosis 2014 and we’re going to delve into some of the research about what makes women with endo different from those without and how this could give us clues as to what causes endo in the first place.

A team from Australia made an interesting discovery regarding stem cells and endometriosis. You have probably heard about stem cells before, but why would they be of interest in endometriosis? Stem cells are the precursors to the different types of cells in your body and are mostly of use during the very early part of your development when you were a foetus growing new organs. But they still have some use as an adult, for example, inside the uterus there are a population of stem cells that your body uses to regrow the endometrium after each menstruation, which are unsurprisingly referred to as endometrial stem cells. If these cells can grow endometrium and endometriosis is endometrium-like tissue, it becomes clear how these stem cells could play a role in endometriosis. Some researchers believe that genetic changes associated with endometriosis result in some endometrial stem cells becoming displaced during embryo development, which go on to produce endometriotic lesions as a girl approaches adolescence. Others believe these stem cells are shed into the pelvic cavity by retrograde menstruation (where the menstrual blood goes into the pelvic cavity) and implant around the pelvis and then develop into endometriotic lesions.

This investigation by the Australian team looked at the number of endometrial stem cells in the blood, menstrual blood and peritoneal fluid of women with and without endometriosis. What they found was that, although the amount of peritoneal fluid was similar between the two groups, the number of viable endometrial stem cells in the peritoneal fluid was massively higher in women with endo. So how did those cells get there? Retrograde menstruation is a likely explanation, but they found no difference in the amount of stem cells in the menstrual blood between women with and without endo.  It could be that the immune system of women with endo doesn’t clear the refluxed stem cells and they just accumulate or maybe there is some other way these cells are getting into the pelvic cavity, at this moment nobody knows for sure.

Speaking of peritoneal fluid, a group from the US and Brazil analysed the peritoneal fluid looking for inflammatory factors that are related to endometriosis associated pain. What they found was that dyspareunia (painful sex), non-cyclic pain and infertility were not related to the inflammatory factors they were studying. What they did find though was that certain inflammatory factors were associated with dysmenorrhea (excessively painful periods). This has some potentially very interesting implications, particularly as dysmenorrhea is the most common symptom of endometriosis. This suggests that dysmenorrhea is caused by areas of chronic inflammation around the sites of endometriosis regardless of stage or location. If it were possible to find out how these inflammatory factors are being produced and find a way to reduce the level of these factors, in the future this could be a new way of treating the pain associated with endo. 

More highlights on the way soon...