Quantification of Calcyclin and Heat Shock Protein 90 in Sera from Women with and without Preeclampsia by Mass Spectrometry

Deciphering the immunological interactions: targeting preeclampsia with Hydroxychloroquine's biological mechanisms

Preeclampsia (PE) is a complex pregnancy-related disorder characterized by hypertension, followed by organ dysfunction and uteroplacental abnormalities. It remains a major cause of maternal and neonatal morbidity and mortality worldwide. Although the pathophysiology of PE has not been fully elucidated, a two-stage model has been proposed. In this model, a poorly perfused placenta releases various factors into the maternal circulation during the first stage, including pro-inflammatory cytokines, anti-angiogenic factors, and damage-associated molecular patterns into the maternal circulation. In the second stage, these factors lead to a systemic vascular dysfunction with consecutive clinical maternal and/or fetal manifestations. Despite advances in feto-maternal management, effective prophylactic and therapeutic options for PE are still lacking. Since termination of pregnancy is the only curative therapy, regardless of gestational age, new treatment/prophylactic options are urgently needed. Hydroxychloroquine (HCQ) is mainly used to treat malaria as well as certain autoimmune conditions such as systemic lupus and rheumatoid arthritis. The exact mechanism of action of HCQ is not fully understood, but several mechanisms of action have been proposed based on its pharmacological properties. Interestingly, many of them might counteract the proposed processes involved in the development of PE. Therefore, based on a literature review, we aimed to investigate the interrelated biological processes of HCQ and PE and to identify potential molecular targets in these processes.

Interaction of S100A6 Protein with the Four-Helical Cytokines

S100 is a family of over 20 structurally homologous, but functionally diverse regulatory (calcium/zinc)-binding proteins of vertebrates. The involvement of S100 proteins in numerous vital (patho)physiological processes is mediated by their interaction with various (intra/extra)cellular protein partners, including cell surface receptors. Furthermore, recent studies have revealed the ability of specific S100 proteins to modulate cell signaling via direct interaction with cytokines. Previously, we revealed the binding of ca. 71% of the four-helical cytokines via the S100P protein, due to the presence in its molecule of a cytokine-binding site overlapping with the binding site for the S100P receptor. Here, we show that another S100 protein, S100A6 (that has a pairwise sequence identity with S100P of 35%), specifically binds numerous four-helical cytokines. We have studied the affinity of the recombinant forms of 35 human four-helical cytokines from all structural families of this fold to Ca2+-loaded recombinant human S100A6, using surface plasmon resonance spectroscopy. S100A6 recognizes 26 of the cytokines from all families of this fold, with equilibrium dissociation constants from 0.3 nM to 12 µM. Overall, S100A6 interacts with ca. 73% of the four-helical cytokines studied to date, with a selectivity equivalent to that for the S100P protein, with the differences limited to the binding of interleukin-2 and oncostatin M. The molecular docking study evidences the presence in the S100A6 molecule of a cytokine-binding site, analogous to that found in S100P. The findings argue the presence in some of the promiscuous members of the S100 family of a site specific to a wide range of four-helical cytokines. This unique feature of the S100 proteins potentially allows them to modulate the activity of the numerous four-helical cytokines in the disorders accompanied by an excessive release of the cytokines.

S100A6 Protein-Expression and Function in Norm and Pathology

S100A6, also known as calcyclin, is a calcium-binding protein belonging to the S100 protein family. It was first identified and purified more than 30 years ago. Initial structural studies, focused mostly on the mode and affinity of Ca²⁺ binding and resolution of the resultant conformational changes, were soon complemented by research on its expression, localization and identification of binding partners. With time, the use of biophysical methods helped to resolve the structure and versatility of S100A6 complexes with some of its ligands. Meanwhile, it became clear that S100A6 expression was altered in various pathological states and correlated with the stage/progression of many diseases, including cancers, indicative of its important, and possibly causative, role in some of these diseases. This, in turn, prompted researchers to look for the mechanism of S100A6 action and to identify the intermediary signaling pathways and effectors. After all these years, our knowledge on various aspects of S100A6 biology is robust but still incomplete. The list of S100A6 ligands is growing all the time, as is our understanding of the physiological importance of these interactions. The present review summarizes available data concerning S100A6 expression/localization, interaction with intracellular and extracellular targets, involvement in Ca²⁺-dependent cellular processes and association with various pathologies.

A Study of Heat Shock Protein 90 and Serum CCL21 Expression in Pregnant Women with Preeclampsia

Objective

The purpose of the study was to determine the significance of heat shock protein 90 (HSP 90) and serum chemokine ligand 21 (CCL-21) in pregnant women with preeclampsia (PE).

Methods

From June 2021 to June 2022, the study enrolled 100 women undergoing obstetric examinations and delivering in our hospital; 50 PE patients undergoing routine obstetric examinations and delivering during the same period were enrolled in the research group; according to the severity, they were divided into mild PE and severe PE groups, while 50 healthy pregnant women undergoing obstetric examinations and delivering in our hospital during the same period were enrolled in the control group. In a subsequent analysis, serum levels of CCL-21 and HSP90 were compared between the two groups, and the correlation among CCL-21, HSP 90, and PE severity was analyzed.

Results

An overall total of 50 patients with PE were enrolled in the study, which included 32 patients with mild PE and 18 patients with severe PE. Patients with severe PE had lower mean arterial pressure (MAP), HSP 90, and CCL21 index levels than those with mild PE; MAP, HSP 90, and CCL21 in the severe PE group were higher than those in the mild PE group, but the difference was not statistically significant; In the research group, MAP was weakly correlated with HSP90 concentration and CCL21 concentration, with correlation coefficients of 0.33 and 0.30, respectively, and the correlation analysis was significant.

Conclusion

Patients with PE showed significantly increased serum concentrations of HSP90 and CCL-21, but a significant difference did not exist between mild and severe PE. In addition, there was a weak relationship between HSP90 and CCL-21 concentrations in PE patients and MAP, suggesting that HSP90 and CCL-21 play an instrumental role in the pathogenesis of PE, although more studies are needed to clarify the exact mechanisms.

Circulating heat shock protein 27 (HSPB1) levels in prediction of pre-eclampsia: A pilot study

OBJECTIVE

To determine whether circulating heat shock proteins HSP27/HSPB1 and HSP90α/HSPC1 may be useful for early prediction of the occurrence of pre-eclampsia in asymptomatic women.

METHODS

We have measured by ELISA the levels of HSPB1, HSPC1, and placental protein 13 (PP13) in serum samples from 44 women in the first trimester (10-12 weeks) and second trimester (17-20 weeks) of pregnancy. Western blot and immunohistochemistry for HSPB1 and HSPC1 were performed.

RESULTS

HSPB1 serum levels were higher in women with pre-eclampsia than in normotensive pregnant women at the first and second trimester (P = 0.003), whereas PP13 levels decreased in women with pre-eclampsia only in the first trimester of gestation (P = 0.021). We also observed higher HSPB1 levels in patients with early-onset pre-eclampsia in the first and second trimester (P = 0.014).

CONCLUSION

This pilot study points out that circulating HSPB1 levels in first and second trimester might be useful for predicting the occurrence of pre-eclampsia in asymptomatic women. Further validation studies are needed to finally establish this protein as a candidate predictive biomarker of pre-eclampsia.

S100A6, Calumenin and Cytohesin 2 as Biomarkers for Cutaneous Involvement in Systemic Sclerosis Patients: A Case Control Study

BACKGROUND

Systemic sclerosis (Ssc) is an autoimmune disease with incomplete known physiopathology. There is a high number of candidate proteomic biomarkers for Ssc that have not yet been confirmed on independent Ssc cohorts. The aim of the study was to confirm circulating S100A6, calumenin, and cytohesin 2 as biomarkers for Ssc.

METHODS

53 Ssc patients and 26 age- and gender-matched controls were included. Serum S100A6, calumenin, and cytohesin 2 were evaluated with commercial ELISA kits. Associations between serum expression and clinical Ssc characteristics were evaluated.

RESULTS

Serum calumenin, S100A6, and cytohesin 2 were higher in Ssc patients compared to controls. Calumenin associated with extensive cutaneous fibrosis, frequency of Raynaud phenomenon, and low complement level, and had a tendency to be higher in Ssc patients with pulmonary fibrosis. S100A6 correlated with the number of active digital ulcers. Serum cytohesin 2 levels were higher in patients with teleangiectasia and associated with pulmonary artery pressure.

CONCLUSIONS

Serum calumenin, S100A6, and cytohesin 2 were confirmed as biomarkers on an independent group of Ssc patients. Calumenin had the best predictive capacity for cutaneous Ssc manifestations. Future studies are needed to evaluate the prognostic value of these biomarkers and evaluate them as possible therapeutic targets.

Cerebrospinal Fluid of Preeclamptic and Normotensive Pregnant Women Compared to Nonpregnant Women Analyzed with Mass Spectrometry

Preeclampsia is a pregnancy-specific multiorgan disorder in which impaired placental functioning and excessive oxidative stress play an important role. We previously showed distinct differences between cerebrospinal fluid proteins in patients with preeclampsia and normotensive pregnant women. An additional group of nonpregnant women was included to study the presence of pregnancy-related proteins in normotensive and preeclamptic pregnancies and whether pregnancy-related proteins were associated with preeclampsia. Cerebrospinal fluid samples were tryptically digested and subsequently measured with a nano-LC-tribrid Orbitrap mass spectrometry system. Proteins were identified by shotgun proteomic analysis based on a data-dependent acquisition method. Proteins identified in preeclampsia, normotensive pregnant controls, and nonpregnant groups were compared to the Progenesis method according to the criteria as previously described and with a secondary analysis using a Scaffold method including Benjamini-Hochberg correction for multiple testing. For preeclampsia, the Progenesis and the Scaffold method together identified 15 (eight proteins for both analyses with one overlap) proteins that were significantly different compared to normotensive control pregnancies. Three of these 15 proteins, which were elevated in cerebrospinal fluid of preeclamptic women, were described to be pregnancy proteins with a calcium-binding function. Using two analysis methods (Progenesis and Scaffold), four out of 15 differential proteins were associated with pregnancy, as described in the literature. Three out of the four pregnancy-related proteins were elevated in preeclampsia. Furthermore, the contribution of elevated (n = 4/15) and downregulated (n = 2/15) calcium-binding proteins in preeclampsia is remarkably high (40%) and needs to be elucidated further.

Quantification of Calcyclin and Heat Shock Protein 90 in Sera from Women with and without Preeclampsia by Mass Spectrometry

PURPOSE

The objective of present study is to determine serum levels and placental distribution of two interacting proteins calcyclin and heat shock protein 90 in preeclampsia.

EXPERIMENTAL DESIGN

Maternal serum levels of calcyclin and heat shock protein 90 are compared throughout pregnancy from the first trimester till term among women with preeclampsia (n = 43) and age-matched normotensive pregnant controls (n = 46). A serum-based 2D LC-MS assay using Parallel Reaction Monitoring is applied to quantify both calcyclin and heat shock protein 90.

RESULTS

Serum levels of calcyclin are significantly lower in patients with preeclampsia in the second trimester of pregnancy as compared to controls (p < 0.05). Serum levels of heat shock protein 90 are significantly higher in patients with preeclampsia in the third trimester as compared to controls (p < 0.001).

CONCLUSION AND CLINICAL RELEVANCE

Both interacting proteins calcyclin and heat shock protein 90 are notably changed in preeclamptic patients compared to controls. Calcyclin is already decreased before the onset of preeclampsia in the second trimester and HSP90 is strongly increased in the third trimester. This suggests that these proteins may play a role in the pathogenesis of preeclampsia and ought to be investigated in large cohort studies as molecular biomarkers.