Chronic Histiocytic Intervillositis: Study Proposal

15 Nov

            I have updated the e-book work in progress, but I still need to improve the formatting and navigation. I have renamed the “page” as “Chronic Histiocytic Intervillositis”. It is not yet the time to create an open source digital placental pathology book. In writing the draft, I did see how important it is to have many case  illustrations, even better if they could be whole slides. I think for pathologists to understand CHIV, they need to see a broad sample of the overlying pathologies and of the difficulties in assigning percentage borders to the diagnosis.

I still want to find participants for a multi-institutional study of CHIV. As with the stillbirth study, I hope to pilot a study at Magee after I start there in February. A draft of the proposal for the study is in the  “Massive Chorionic Intervillositis” page. I am also posting same draft proposal below on this blog. I still need to add references, and the proposal is incomplete. I am open to comments and suggestions. Thanks. 

Draft of a Proposal to Study CHIV

Background: 

            The lesion is defined by a consensus to have clusters of monocytes in more than 5% of the intervillous space. The monocyte clusters should contain at least 80% monocytes. There  may be heterogeneity in the distribution of intervillous monocytes. The lesion has an association with increased perivillous fibrinoid and villitis of unknown etiology. There is no clear association of obstetrical outcome with these histological features, although there is some evidence that monocytes filling more than 50% of the intervillous space are associated with more severe outcomes.

            Associated clinical outcomes include a high incidence of fetal loss at all gestations, but greater in the first and second trimester, fetal growth restriction, and recurrence in multiple pregnancies. The growth restriction is often early onset and may be associated with oligohydramnios. There may be an elevation of maternal serum alkaline phosphatase above normal pregnancy values.

            An immune origin of the lesion has been hypothesized. There may be an association with maternal autoimmune disease, especially anti-phospholipid syndrome, and with anti-HLA antibodies. The microvillous border of syncytiotrophoblast can be immunostained with c4d, a marker of antibody initiated fixation of complement. 

            Many treatment regimens have been used to prevent recurrent fetal loss, and anecdotally have resulted in a live born infant. These have included combinations of low dose aspirin, low molecular weight heparin, prednisone and hydroxychloroquine. No treatments have been demonstrated to be superior. 

            There is no standard pre-delivery method to diagnosis the lesion in an index pregnancy. Measures of early onset growth restriction are consistent with the lesion in pregnancies after a primary histologic diagnosis. The histologic lesions show variety and it is possible that the lesion is a common pathway of different etiologies. Only one, malaria, has been specifically identified. A better understanding of the pathogenesis of the lesion is needed.

            The goal remains to find a specific test for the lesion prior to delivery, and an effective treatment. Even though the lesion is infrequent (less than .5% prevalence), it can cause recurrent fetal losses in some mothers. 

Aims of the study

            Part 1: Retrospective study of the histology: 

  1. Develop a quantifiable method of measuring intervillous monocytes, perivillous fibrin/fibrinoid, and VUE
  2. Utilize CD 68, anti T cell, and c4d staining on cases and develop quantifiable measures.
  3. Correlate the quantified measures of part 1.2  with obstetrical outcomes: first trimester fetal death, second trimester fetal death, third trimester fetal death, fetal growth restriction in the second trimester, fetal growth restriction in the third trimester, history of recurrent pregnancy loss, and history of recurrent CHIV. 
  4. Correlate quantified histologic measures with treatment, and if possible from placental samples from the same patient before and after treatment.

            Part 2: Prospective study of mothers with a history of previous CHIV or with early onset severe fetal growth restriction.

  1. Obtain maternal serum at first visit, at time of delivery, and before and after start of treatment to test for markers of the disease including alkaline phosphatase, serum complement panel, and red cell c4d. 
  2. Perform an auto-antibody panel including anti-phospholipid and anti-HLA
  3. Save serum to explore other markers of monocyte activation, of syncytial trophoblast injury, or of auto/allo-antibodies to trophoblast antigens
  4. In addition to routine specimen processing, prepare tissue of further basic research on CHIV including frozen placental tissues, and monocyte extraction from placenta

Part 3: Prospective Clinical trial

  1. Trial comparison of at least two therapy regimes against historical controls 

Methods:

Part 1.1 

            The slides from cases of previously diagnosed CHIV (and gestation matched controls) are scanned and areas are selected that do not contain lesions or non-placental tissue. The size of the areas on each sample slide are calculated. The number of intervillous monocytes, foci of VUE, and area of pervillous fibrinoid are calculated for each area and summed area of each case. A shared software solution will be developed to use image analysis to perform this procedure. The range of values for the measured variables for each case in different slides of the same sample will also be recorded.

Part 1.2 

            From the same cases above, additional slides will be cut for immuno-staining with CD68, T-cell markers, and c4d along with controls. The same procedures will be used to select areas to evaluate as in part 1.1 . Then, software will be developed to count each of the CD68 cells in the intervillous space, the T-cells in the villi, and linear extent of c4d staining along the villous surface.

Part 1.3

            The various histological measures will be compared to the major clinical outcomes:  first trimester fetal death, second trimester fetal death, third trimester fetal death, fetal growth restriction in the second trimester, fetal growth restriction in the third trimester, history of recurrent pregnancy loss, and history of recurrent CHIV. Statistical analysis will look at independence of the variables, and the best cluster of variables to “predict” the clinical outcome and, if possible, using ROC analysis to create a diagnostic score.

Part 1.4 

            Using the best cluster of variables to “predict” outcome, the measure of these variables in the specimens before and after treatment in an individual patient are tested against the null hypothesis that treatment did not alter the diagnostic score. 

Part 2.1

            The serum values will be compared to controls without evidence of early growth restriction, or history of CHIV, and to cases with evidence of early growth restriction with and without the diagnosis of CHIV. The goal is to find a correlation of the serum markers with the diagnosis of CHIV.

Part 2.2

            These antibody screening will be from routine clinical laboratory procedures. The prevalence of such antibodies in CHIV will be calculated. In addition, cases with autoantibodies will be stratified in comparisons with obstetrical outcomes, measures of alloantigen response, and of treatment outcomes in part 3.

Part 2.3 and part 2.4 

            Future studies into the pathogenesis of the disease depend on researcher initiative. A sample proposed study that hypothesized an alloantibody to a paternal microvillous antigen, could utilize frozen section slides of placentas including those from the patients and controls. An Fc receptor blocker would be applied to the slides, and then CHIV and control serums applied to the slides. They would then be rinsed, and a fluorescent labeled anti-human IgG would be applied. Positive fluorescent staining would be evidence of specific anti-trophophoblast antibody if the control serums were negative. Further studies could be designed to identify the antigen.

Part 3: The high recurrence of fetal death in mothers with identified CHIV in a prior pregnancy precludes an untreated group given anecdotal reports of successful treatment. A panel of obstetricians would decide on the best way to approach comparing randomly assigned treatment groups. The results of the study would also be stratified by various anatomic and clinical pathological variables elucidated in parts 1 and 2. 

Statistical analysis:

Institutional resources:

Sample patient consent:

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: