Complement activation and regulation in preeclampsia and hemolysis, elevated liver enzymes, and low platelet count syndrome.

The complement system is critical to human health owing to its central role in host defense and innate immunity. During pregnancy, the complement system must be appropriately regulated to allow for immunologic tolerance to the developing fetus and placenta. Although some degree of complement activation can be seen in normal pregnancy, the fetus seems to be protected in part through the placental expression of complement regulatory proteins, which inhibit complement activation at different steps along the complement activation cascade. In women who develop preeclampsia and hemolysis, elevated liver enzymes, and low platelet count syndrome, there is a shift toward increased complement activation and decreased complement regulation. There is an increase in placental deposition of C5b-9, which is the terminal effector of classical, lectin, and alternative complement pathways. C5b-9 deposition stimulates trophoblasts to secrete soluble fms-like tyrosine kinase-1, which sequesters vascular endothelial growth factor and placental growth factor. Pathogenic mutations or deletions in complement regulatory genes, which predispose to increased complement activation, have been detected in women with preeclampsia and hemolysis, elevated liver enzymes, and low platelet count syndrome. Before the disease, biomarkers of alternative complement pathway activation are increased; during active disease, biomarkers of terminal complement pathway activation are increased. Urinary excretion of C5b-9 is associated with preeclampsia with severe features and distinguishes it from other hypertensive disorders of pregnancy. Taken together, existing data link preeclampsia and hemolysis, elevated liver enzymes, and low platelet count syndrome with increased activation of the terminal complement pathway that, in some cases, may be influenced by genetic alterations in complement regulators. These findings suggest that the inhibition of the terminal complement pathway, possibly through C5 blockade, may be an effective strategy to treat preeclampsia and hemolysis, elevated liver enzymes, and low platelet count syndrome, but this strategy warrants further evaluation in clinical trials.

Is the presence of antiphospholipid antibodies a poor prognostic factor for patients with hemolysis, elevated liver enzymes, and low platelet count syndrome?

BACKGROUND: The characteristics of antiphospholipid syndrome-associated hemolysis, elevated liver enzymes, and low platelet count syndrome are poorly described, likely because of the low frequency of this combination of syndromes. OBJECTIVE: This study aimed to compare the characteristics and prognosis of hemolysis, elevated liver enzymes, and low platelet count syndrome in patients with and without antiphospholipid syndrome. STUDY DESIGN: In this multicenter, case-control study, adult women diagnosed with hemolysis, elevated liver enzymes, and low platelet count syndrome before 34 weeks' gestation and who were also tested for antiphospholipid antibodies according to international diagnostic recommendations were included. Cases labeled "HELLP-APS+" were defined as patients who fulfilled the international classification criteria for antiphospholipid syndrome; they were retrospectively recruited by screening the 672 patients with antiphospholipid syndrome in our antiphospholipid syndrome database. Control cases labeled "HELLP-APS-" were defined as patients who did not fulfill the criteria for antiphospholipid syndrome; they were retrospectively recruited from our hospital admission database. RESULTS: Overall, 71 patients were included (mean age, 30±5 years), with 23 patients in the hemolysis, elevated liver enzymes, and low platelet count syndrome with antiphospholipid syndrome group and 48 patients in the hemolysis, elevated liver enzymes, and low platelet count syndrome without antiphospholipid syndrome group. The live birth rate was significantly lower for patients with hemolysis, elevated liver enzymes, and low platelet count with antiphospholipid syndrome than for those with hemolysis, elevated liver enzymes, and low platelet count syndrome without antiphospholipid syndrome (43.5% vs 89.4%; P<.001). The patients with hemolysis, elevated liver enzymes, and low platelet count syndrome with antiphospholipid syndrome gave birth prematurely more often than the patients without antiphospholipid syndrome (24 weeks' gestation; 22.0-28.0 weeks vs 30 weeks' gestation; 27.0-33.0 weeks; P<.001). Among the patients with hemolysis, elevated liver enzymes, and low platelet count syndrome with antiphospholipid syndrome, 39% required an induced abortion owing to hemolysis, elevated liver enzymes, and low platelet count syndrome severity vs 8.5% of the patients with hemolysis, elevated liver enzymes, and low platelet count syndrome without antiphospholipid syndrome (P=.006). The intensive care unit admission rate was 61.9% in patients with hemolysis, elevated liver enzymes, and low platelet count syndrome with antiphospholipid syndrome, which was significantly higher than the rate of 27.7% in patients with hemolysis, elevated liver enzymes, and low platelet count syndrome without antiphospholipid syndrome (P=.007). None of the mothers died. CONCLUSION: Our results suggest that the presence of antiphospholipid syndrome is a poor prognostic factor for both the mother and fetus in patients with hemolysis, elevated liver enzymes, and low platelet count syndrome.

The effect of therapeutic plasma exchange on management of HELLP Syndrome: The report of 47 patients.

BACKGROUND AND OBJECTIVES: HELLP syndrome is a life-threatening condition that may potentially cause complications during pregnancy. If not diagnosed and treated quickly, HELLP syndrome may lead to serious complications both for the mother and the baby. The aim of this study was to determin the effectiveness of therapeutic plasma exchange (TPE) for treatment of Class-I HELLP syndrome. MATERIALS AND METHODS: Laboratory results from 47 patients with Class-I HELLP syndrome patients who underwent TPE between 2011 and 2020 were recorded before and after the procedure. A central venous catheter was inserted, and TPE was performed in patients who had not responded to delivery, steroid, and supportive therapy (blood products, anti-hypertensive therapy, intravenous fluid administration, and antibiotics) within 24 hours after the diagnosis of Class I HELLP syndrome according to the Mississippi Criteria. RESULTS: The average age of patients was 33 ± 4.7 years (range; 21-39 years). A mean of 5 (range; 4 to 6) TPE sessions were performed. There was a statistically significant decrease in total bilirubin, lactic dehydrogenase, aspartate aminotransferase, and alanine aminotransferase levels in all patients, whereas a significant increase in platelet count was observed (p < 0.05). Furthermore, clinical and laboratory improvement was achieved. CONCLUSION: In all patients with HELLP syndrome, a dramatically clinical and laboratory improvement occurred after TPE. Our study suggests that postpartum use of TPE within 24 hours is an efficient treatment option for Class-I HELLP syndrome.

Fas ligand neutralization attenuates hypertension, endothelin-1, and placental inflammation in an animal model of HELLP syndrome.

Neutralization of FasL is linked to suppression of hypertension, placental inflammation, and endothelin system activation in an animal model of hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome. During HELLP syndrome the placenta has been reported to serve as the primary source of Fas ligand (FasL), which has an impact on inflammation and hypertension during pregnancy and is dysregulated in women with severe preeclampsia and HELLP syndrome. We hypothesize that neutralization of FasL during pregnancy in an animal model of HELLP syndrome decreases inflammation and placental apoptosis, improves endothelial damage, and improves hypertension. On gestational day (GD) 12, rats were chronically infused with placental antiangiogenic factors sFlt-1 and sEng to induce HELLP syndrome. To neutralize FasL, MFL4 or FasL antibody was infused into a subset of HELLP or normal pregnant rats on GD13. IgG infusion into another group of NP and HELLP rats on GD13 was used as a control for FasL antibody, and all rats were euthanized on GD19 after blood pressure measurement. Plasma and placentas were collected to assess inflammation, apoptosis, and the degree of placental debris activation of endothelial cells. Administration of MFL4 to HELLP rats significantly decreased blood pressure compared with untreated HELLP rats and HELLP rats infused with IgG and improved the biochemistry of HELLP syndrome. Both circulating and placental FasL were significantly attenuated in response to MFL4 infusion, as were levels of placental and circulating TNFα when compared with untreated HELLP rats and HELLP rats infused with IgG. Endothelial cells exposed to placental debris and media from HP + MFL4 rats secreted significantly less endothelin-1 compared with stimulated endothelial cells from HELLP placentas. Neutralization of FasL is associated with decreased MAP and improvement in placental inflammation and endothelial damage in an animal model of HELLP syndrome.

Recurrent Placental Transcriptional Profile With a Different Histological and Clinical Presentation: A Case Report.

Statistically, patients with severe pregnancy complications are at risk of recurrent complications, but it is less understood if patients present with similar or different placental pathologies in subsequent pregnancies. In this case report, we describe 2 consecutive adverse pregnancies in the same woman 4 years apart. The first pregnancy was diagnosed as early-onset preeclampsia and hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome, with placental maternal vascular malperfusion features, such as syncytial knots and accelerated villous maturity. In contrast, the second pregnancy was associated with normotensive fetal growth restriction and placental "immunological" lesions, such as massive perivillous fibrin deposition and chronic intervillositis. However, based on the expression of FLT1, LIMCH1, and TAP1 by quantitative polymerase chain reaction, the placentas from both pregnancies were found to exhibit an "immunological" transcriptional signature. This suggests that this small panel of gene expression markers may be able to predict the future reoccurrence of an immunological placental pathology despite no histological evidence within the first pregnancy. These results call for more studies looking at paired pregnancies of individuals with recurrent obstetric complications and confirm the importance of assessing matched transcriptional and histopathological placental information.

The Complement Alternative Pathway and Preeclampsia.

PURPOSE OF REVIEW: Significant and intricate immune adaptations are essential for the establishment and maintenance of normal pregnancy. Preeclampsia is a morbid, potentially life-threatening disease for both mother and neonate that occurs uniquely in pregnancy, at least in part, due to maternal immune maladaptation. We aim to review the literature that focuses on case reports, diagnostic approaches, and treatment strategies for disorders of the complement alternative pathway (CAP) as related to preeclampsia. RECENT FINDINGS: There is evidence of complement dysregulation in preeclampsia and HELLP syndrome, similar to that observed in a few rare types of thrombotic microangiopathies. Complement dysregulation may be identified with functional laboratory testing as well as genetic testing. Increased utilization of a standardized diagnostic approach to establish whether persistent and/or severe cases of preeclampsia and HELLP syndrome are complement-mediated may lead to development of future treatment strategies, such as complement-targeted therapy.

Differentiation of ICOS+ and ICOS- recent thymic emigrant regulatory T cells (RTE T regs) during normal pregnancy, pre-eclampsia and HELLP syndrome.

Two different subsets of naturally occurring regulatory T cells (nTregs), defined by their expression of the inducible co-stimulatory (ICOS) molecule, are produced by the human thymus. To examine the differentiation of ICOS(+) and ICOS(-) CD45RA(+) CD31(+) recent thymic emigrant (RTE) T regs during normal pregnancy and in the presence of pre-eclampsia or haemolysis elevated liver enzymes low platelet (HELLP)-syndrome, we used six-colour flow cytometric analysis to determine the changes in the composition of the ICOS(+) and ICOS(-) T reg pools with CD45RA(+) CD31(+) RTE T regs, CD45RA(+) CD31(-) mature naive (MN) T regs, CD45RA(-) CD31(+) and CD45RA(-) CD31(-) memory Tregs. With the beginning of pregnancy until term, we observed a strong differentiation of both ICOS(+) and ICOS(-) CD45RA(+) CD31(+) RTE, but not CD45RA(+) CD31(-) MN T regs, into CD45RA(-) CD31(-) memory T regs. At the end of pregnancy, the onset of spontaneous term labour was associated with a significant breakdown of ICOS(+) CD45RA(-) CD31(-) memory T regs. However, in the presence of pre-eclampsia, there was a significantly increased differentiation of ICOS(+) and ICOS(-) CD45RA(+) CD31(+) RTE T regs into CD45RA(-) CD31(+) memory T regs, wherein the lacking differentiation into CD45RA(-) CD31(-) memory T regs was partially replaced by the increased differentiation of ICOS(+) and ICOS(-) CD45RA(+) CD31(-) MN Tregs into CD45RA(-) CD31(-) memory T regs. In patients with HELLP syndrome, this alternatively increased differentiation of CD45RA(-) CD31(-) MN T regs seemed to be exaggerated, and presumably restored the suppressive activity of magnetically isolated ICOS(+) and ICOS(-) T regs, which were shown to be significantly less suppressive in pre-eclampsia patients, but not in HELLP syndrome patients. Hence, our findings propose that the regular differentiation of both ICOS(+) and ICOS(-) CD45RA(+) CD31(+) RTE T regs ensures a healthy pregnancy course, while their disturbed differentiation is associated with the occurrence of pre-eclampsia and HELLP syndrome.

Pregnancy-associated diseases are characterized by the composition of the systemic regulatory T cell (Treg) pool with distinct subsets of Tregs.

Dysregulations concerning the composition and function of regulatory T cells (T(regs)) are assumed to be involved in the pathophysiology of complicated pregnancies. We used six-colour flow cytometric analysis to demonstrate that the total CD4(+) CD127(low+/-) CD25(+) forkhead box protein 3 (FoxP3)(+) T(reg) cell pool contains four distinct T(reg) subsets: DR(high+) CD45RA(-), DR(low+) CD45RA(-), DR(-) CD45RA(-) T(regs) and naive DR(-) CD45RA(+) T(regs). During the normal course of pregnancy, the most prominent changes in the composition of the total T(reg) cell pool were observed between the 10th and 20th weeks of gestation, with a clear decrease in the percentage of DR(high+) CD45RA(-) and DR(low+) CD45RA(-) T(regs) and a clear increase in the percentage of naive DR(-) CD45RA(+) T(regs). After that time, the composition of the total T(reg) cell pool did not change significantly. Its suppressive activity remained stable during normally progressing pregnancy, but decreased significantly at term. Compared to healthy pregnancies the composition of the total T(reg) cell pool changed in the way that its percentage of naive DR(-) CD45RA(+) T(regs) was reduced significantly in the presence of pre-eclampsia and in the presence of preterm labour necessitating preterm delivery (PL). Interestingly, its percentage of DR(high+) CD45RA(-) and DR(low+) CD45RA(-) T(regs) was increased significantly in pregnancies affected by pre-eclampsia, while PL was accompanied by a significantly increased percentage of DR(-) CD45RA(-) and DR(low+) CD45RA(-) T(regs). The suppressive activity of the total T(reg) cell pool was diminished in both patient collectives. Hence, our findings propose that pre-eclampsia and PL are characterized by homeostatic changes in the composition of the total T(reg) pool with distinct T(reg) subsets that were accompanied by a significant decrease of its suppressive activity.

[Antiphospholipid syndrome and pregnancy]. / Antifoszfolipid-szindróma és a terhesség.

Antiphospholipid syndrome is characterized by arterial and venous thromboembolic events and persistent laboratory evidence of antiphospholipid antibodies. Obstetric complications such as recurrent miscarriage, early delivery, oligohydramnios, prematurity, intrauterine growth restriction, fetal distress, fetal or neonatal thrombosis, pre-eclampsia/eclampsia, and HELLP syndrome are also hallmarks of antiphospholipid syndrome. This syndrome is one of the diseases associated with the most severe thrombotic risk. Changes in the hemostatic system during normal pregnancy also result in a hypercoagulable state resulting in elevated thrombotic risk. Thromboembolic events are responsible of the vast majority of maternal and fetal deaths. Administration of appropriate thromboprophylaxis helps prevent thromboembolic complications during pregnancy in women with antiphospholipid syndrome and also give birth to healthy children. It is important to centralize the medication and management of these patients. It helps in the thoughtful care of these pregnant women encountering serious problems.

Neonatal nephrotic syndrome associated with placental transmission of proinflammatory cytokines.

Although there are clinical data suggesting a direct relationship between neonatal nephrotic syndrome and placental transfer of proinflammatory cytokines from mothers with HELLP syndrome, there is no direct evidence that these inflammatory cytokines are pathogenic. Here, the first human model of placental transfer of proinflammatory cytokines from a mother with HELLP syndrome to a newborn, resulting in neonatal nephrotic syndrome is described. Forty-eight hours after delivery, the neonate developed nephrotic syndrome and abnormalities in renal function which resolved completely during the 5 days following the initiation of therapy with hydrocortisone, albumin, and furosemide. The newborn's cord blood showed increased concentrations of interleukin (IL)-1ß, IL-6, and tumor necrosis factor alpha that were identical to those found in the mother's serum. Hydrocortisone therapy was discontinued after a 2-week course. Clinical and laboratory improvements were associated with a marked decline in serum cytokine levels, indicating that the proinflammatory cytokines were pathogenic. The neonate remained in remission with no recurrence of nephrotic syndrome during 12 months of follow-up. These findings demonstrate that the placental transmission of circulating cytokines causing HELLP syndrome occurred during pregnancy and may have resulted in nephrotic syndrome in the neonate.

[Role of plasmapheresis in immunological kidney diseases. Experience from 1050 completed plasmapheresis treatment sessions]. / A plazmaferézis szerepe immunológiai etiológiájú vesebetegségekben. Tapasztalataink 1050 elvégzett feréziskezelés kapcsán.

UNLABELLED: Plasmapheresis is an effective treatment modality in several immunological kidney diseases. It is also indicated in certain neurological and hematological abnormalities, and some other diseases. AIMS: In this study the indications and outcomes of the plasma exchange treatments performed in the Plasmapheresis Unit of the authors during the last 12 years are summarized, and the findings are compared to those published in the literature. The procedure, mechanisms of action and adverse effects are also briefly discussed. METHODS: Between 1999 and 2010 authors completed 1050 plasma exchanges in 195 patients with an average 5.4 (1-20) treatments/person. In the 78 males and 117 females (age 57±16 years) the indications were as follows: 47% anti-cytoplasmic antibody-associated vasculitis, 4% anti-glomerular basement membrane disease, 3% rapidly progressing immunocomplex glomerulonephritis, 11% severe complications of systemic lupus erythematosus, 1% treatment resistant focal segmental glomerular sclerosis, 5% hemolytic uremic syndrome, 13% complications of multiple myeloma, 4% HELLP syndrome, 10% neurological diseases, and 2% other abnormalities. RESULTS: Plasmapheresis, completed as part of combined immunosuppressive treatment, resulted in remarkable improvements in patients with anti-cytoplasmic antibody-associated vasculitis. Out of the 91 patients, 54 needed urgent dialysis on admission, and renal replacement therapy could be discontinued in 44% of them. Renal functions in those patients who did not need dialysis also improved significantly, and pulmonary hemorrhage ceased in all affected subjects. Survival of the patients with anti-glomerular basement membrane diseases was 100%. The treatment significantly improved the renal function in rapidly progressive lupus nephritis, and all the 5 cases of lupus cerebritis were successfully cured. The results showed less effectiveness in therapy resistant focal segmental glomerular sclerosis and in rapidly progressing immunocomplex glomerulonephritis. Plasmapheresis proved to be very efficient in cases with the primary hemolytic uremic syndrome, and each patient with HELLP syndrome recovered completely. The outcome of those with multiple myeloma was less favorable, although hyperviscosity was rapidly and effectively decreased by the plasmapheresis. The treatment improved the conditions of almost all patients with neurological diseases. DISCUSSION: According to these findings plasmapheresis treatment, introduced by proper indications, effectively improves the outcomes of several diseases. Early diagnosis and immediate introduction of the plasmapheresis are very important - in conjunction with the appropriate therapy of the underlying diseases.

Abnormal expression of the costimulatory molecule B7-H4 in placental chorionic villous and decidual basalis tissues of patients with preeclampsia and HELLP syndrome.

BACKGROUND: B7-H4, a checkpoint molecule of the B7 family, regulates a broad spectrum such as T-cell activation, cytokine secretion, tumour progression, and invasion capacities. Our previous data revealed that soluble B7-H4 (sB7-H4) blood serum levels are elevated in women at high risk for the hypertensive pregnancy disorder preeclampsia (PE) in the first trimester, as well as in patients with confirmed early/late-onset PE. AIM: We here aim to investigate the expression pattern of B7-H4 in placental tissues of PE and HELLP Syndrome versus control group. METHODS: B7-H4 protein expression and localization were investigated by immunoblotting and co-immunohistochemistry in placental chorionic villous and decidual basalis tissues. RESULTS: B7-H4 protein was prominently expressed at the cell membrane, in the cytoplasm of the syncytiotrophoblast (STB) and interstitial extravillous trophoblast (EVT). B7-H4 protein levels in placental chorionic villous tissue were significantly higher in women with early-onset/late-onset PE and HELLP, while it was decreased in decidual basalis tissues of early-onset PE and HELLP compared with controls. CONCLUSION: B7-H4 was inversely expressed in placental chorionic villous and decidual basalis tissues of PE and HELLP patients. The increase in B7-H4 in the STB in PE and HELLP may lead to excessive apical expression and release of soluble B7-H4 in the maternal circulation. In contrast, the decrease in B7-H4 in decidual basalis tissues could be related to the decrease in invasion ability of the EVT in PE. Thus, the current results strongly suggest that B7-H4 is involved in the pathogenesis of PE and HELLP.

Innate and Adaptive Immune Responses in HELLP Syndrome.

Innate and adaptive immune involvement in hemolysis, elevated liver enzymes and low platelet (HELLP) syndrome is an understudied field, although it is of high clinical importance. This syndrome implies a risk of serious morbidity and mortality to both the mother and the fetus during pregnancy. It was proposed that HELLP syndrome occurs in a circulatory inflammatory milieu, that might in turn participate in a complex interplay between the secreted inflammatory immunomodulators and immune cell surface receptors. Meanwhile, reported immune cell attenuation during HELLP may consequently lead to a prolonged immunoactivation and tissue damage. In this regard, learning more about the immune components of this syndrome should widen the understanding of the HELLP pathophysiology and eventually enable development of novel immune-based therapeutics. This review aims to summarize and discuss the recent and previous findings of the innate and adaptive immune responses during HELLP in order to update the current knowledge of the immune involvement in HELLP pathogenesis.

Complement-Mediated Disorders in Pregnancy.

Complement-mediated disorders in pregnancy span a large spectrum and have been implicated in all three complement pathways: classical, lectin, and alternative. Our understanding of these disorders in recent years has advanced due to a better understanding of complement regulatory proteins, such as complement factor H, complement factor I, membrane cofactor protein, and thrombomodulin that particularly affect the alternative complement pathway. Enthusiasm in genotyping for mutations that encode these proteins has allowed us to study the presence of genetic variants which may predispose women to develop conditions such as pregnancy-associated hemolytic uremic syndrome (P-aHUS), thrombotic thrombocytopenic purpura, preeclampsia/hemolysis, elevated liver enzymes, low platelets (HELLP), systemic lupus erythematosus/antiphospholipid syndrome, and peripartum cardiomyopathy. The advent of the anti-C5-antibody eculizumab to quench the complement cascade has already proven in small case series to improve maternal kidney outcomes in complement-mediated obstetric catastrophes such as P-aHUS and HELLP. In this review, we will detail the pathogenesis behind these complement-mediated pregnancy disorders, the role of complement variants in disease phenotype, and the most up-to-date experience with eculizumab in this population.

Pregnancy and catastrophic antiphospholipid syndrome.

Antiphospholipid syndrome (APS) is clearly related to maternal morbidity. The most characteristic feature is pregnancy loss; however, several other serious complications had been reported including fetal growth restriction, uteroplacental insufficiency, fetal distress, pre-eclampsia, and HELLP syndrome. Herein, we review the different aspects of obstetric APS features, with special emphasis on its life-threatening variant known as catastrophic APS (Asherson's syndrome) and its relationship with a thrombotic microangiopathy such as HELLP syndrome.

Placental sFLT1 is associated with complement activation and syncytiotrophoblast damage in preeclampsia.

The immune complement system protects against pathogens; however, excess activation results in disease like hemolytic uremic syndrome, a clinical imitator of preeclampsia. Vascular endothelial factor (VEGF) protects against aberrant complement activation and is inhibited by soluble fms-like tyrosine kinase-1 (sFLT1) in other organs. We hypothesize that sFLT1 promotes complement-mediated placental damage through VEGF inhibition in preeclampsia. Objective: Quantify placental complement activity and sFLT1 expression in preeclampsia, and the subgroup of preeclampsia with hemolysis elevated liver enzymes low platelets (HELLP) syndrome. Methods: Placental complement activation marker C4d, membrane attack complex (MAC), and sFLT1 expression was quantified using immunofluores cence microscopy. Results: Placentas from 18 controls, 25 preeclampsia, including 6 cases of HELLP syndrome were identified. Placental C4d expression was greater in PE (median 6.4 [IQR: 5.1, 8.3]) compared to controls (4.4 [3.6, 5.5]; p = 0.003). MAC expression was also increased in preeclampsia compared to controls (6.5 [5.8, 8.7]; 5.4 [2.9, 5.9], p = 0.001). Placental sFLT1 expression was also higher in preeclampsia (p <0.0001). C4d and MAC were strongly correlated with sFLT1 levels in the placenta (R = 0.72; p < 0.0001 and R = 0.59; p = 0.01, respectively). Complement and sFLT1 expression was elevated in HELLP compared to preeclampsia without laboratory abnormalities, but this difference did not reach statistical significance. Conclusion: Increased placental complement activation and damage was seen in preeclampsia and correlates with sFLT1 expression. Our findings support the importance of the complement pathway in preeclampsia.

Complement Activation and Thrombotic Microangiopathies.

BACKGROUND AND OBJECTIVES: Atypical hemolytic uremic syndrome is a form of thrombotic microangiopathy caused by dysregulation of the alternative complement pathway. There is evidence showing complement activation in other thrombotic microangiopathies. The aim of this study was to evaluate complement activation in different thrombotic microangiopathies and to monitor treatment response. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Complement activation was assessed by exposing endothelial cells to sera or activated-patient plasma-citrated plasma mixed with a control sera pool (1:1)-to analyze C5b-9 deposits by immunofluorescence. Patients with atypical hemolytic uremic syndrome (n=34) at different stages of the disease, HELLP syndrome (a pregnancy complication characterized by hemolysis, elevated liver enzymes, and low platelet count) or severe preeclampsia (n=10), and malignant hypertension (n=5) were included. RESULTS: Acute phase atypical hemolytic uremic syndrome-activated plasma induced an increased C5b-9 deposition on endothelial cells. Standard and lower doses of eculizumab inhibited C5b-9 deposition in all patients with atypical hemolytic uremic syndrome, except in two who showed partial remission and clinical relapse. Significant fibrin formation was observed together with C5b-9 deposition. Results obtained using activated-plasma samples were more marked and reproducible than those obtained with sera. C5b-9 deposition was also increased with samples from patients with HELLP (all cases) and preeclampsia (90%) at disease onset. This increase was sustained in those with HELLP after 40 days, and levels normalized in patients with both HELLP and preeclampsia after 6-9 months. Complement activation in those with malignant hypertension was at control levels. CONCLUSIONS: The proposed methodology identifies complement overactivation in patients with atypical hemolytic uremic syndrome at acute phase and in other diseases such as HELLP syndrome and preeclampsia. Moreover, it is sensitive enough to individually assess the efficiency of the C5 inhibition treatment.

Eculizumab in pregnancy: a narrative overview.

Pregnancy can be a dangerous trigger for patients with paroxysmal nocturnal hemoglobinuria (PNH), atypical hemolytic uremic syndrome (aHUS), or hemolysis, elevated liver enzymes and low platelet (HELLP) syndrome. Due to the possibility of several serious complications, pregnancy is somewhat discouraged in the presence of the above diseases. Eculizumab is a humanized antibody that may dramatically change the clinical course of PNH, aHUS and HELLP syndrome. However, data on the safety of eculizumab in pregnancy are scarce. In this narrative overview, we summarize current evidence on the use of eculizumab during pregnancy in women with PNH, aHUS and HELLP syndrome. Eculizumab is not present in breast milk, and the levels observed in umbilical cord blood samples are not sufficient to affect the concentrations of complement in newborns. Therefore, eculizumab may be regarded as safe in pregnancy. Nonetheless, given that data on eculizumab in pregnancy are limited, it is not possible to completely exclude risks for both mother and fetus in treating PNH, aHUS and HELLP syndrome.