Impression Cytology Is a Non-invasive and Effective Method for Ocular Cell Retrieval of Zika Infected Babies: Perspectives in OMIC Studies

Multiomics Approach Reveals Serum Biomarker Candidates for Congenital Zika Syndrome

The Zika virus (ZIKV) can be vertically transmitted, causing congenital Zika syndrome (CZS) in fetuses. ZIKV infection in early gestational trimesters increases the chances of developing CZS. This syndrome involves several pathologies with a complex diagnosis. In this work, we aim to identify biological processes and molecular pathways related to CZS and propose a series of putative protein and metabolite biomarkers for CZS prognosis in early pregnancy trimesters. We analyzed serum samples of healthy pregnant women and ZIKV-infected pregnant women bearing nonmicrocephalic and microcephalic fetuses. A total of 1090 proteins and 512 metabolites were identified by bottom-up proteomics and untargeted metabolomics, respectively. Univariate and multivariate statistical approaches were applied to find CZS differentially abundant proteins (DAP) and metabolites (DAM). Enrichment analysis (i.e., biological processes and molecular pathways) of the DAP and the DAM allowed us to identify the ECM organization and proteoglycans, amino acid metabolism, and arachidonic acid metabolism as CZS signatures. Five proteins and four metabolites were selected as CZS biomarker candidates. Serum multiomics analysis led us to propose nine putative biomarkers for CZS prognosis with high sensitivity and specificity.

Quantitation of Pax-6 protein in ocular impression cytology samples using an electrochemiluminescence immunoassay

Paired box protein Pax-6 (oculothrombin) is a transcription factor that plays an important regulatory role in ocular, brain, and pancreatic development. Mutations of the PAX6 gene cause aniridia and Peters anomaly. Reduction in Pax-6 protein is also associated with ocular diseases such as dry eye. An electrochemiluminescence immunoassay method using the Meso Scale Discovery platform was developed to measure Pax-6 protein levels in corneal epithelial cells obtained by impression cytology. Impression cytology involves harvesting ocular epithelial cells by applying a polyethersulfone membrane patch briefly to the ocular surface using a commercially available EYEPRIM™ device. The epithelial cells that adhere to the membrane patch of the EYEPRIM™ device provide a biological sample which can be assayed for Pax-6 protein levels. Assay development identified an antibody pair capable of detecting purified recombinant Pax-6 protein produced in mammalian cells. The optimized assay has a dynamic range of 24 pg mL^-1 to 100,000 pg mL^-1 and a lower limit of quantification of 24 pg mL^-1. Assay selectivity was demonstrated using either HeLa or HEK293 cells transfected with inhibitory RNA. Finally, the method was validated by measuring Pax-6 protein levels in impression cytology acquired samples obtained using the EYEPRIM™ device from rabbit cornea.

Proteomics of ZIKV infected amniotic fluids of microcephalic fetuses reveals extracellular matrix and immune system dysregulation

During pregnancy, the vertical transmission of the Zika virus (ZIKV) can cause some disorders in the fetus, called Congenital Zika Syndrome (CZS). Several efforts have been made to understand the molecular mechanism of the CZS. However, the study of CZS pathogenesis through infected human samples is scarce. Therefore, the main goal of this study is to identify and understand the biological processes affected by CZS development. We analyzed by a shotgun proteomic approach the amniotic fluid of pregnant women infected with Zika carrying microcephalic (MC⁺ ) or non-microcephalic (Z⁺ ) fetuses compared to Zika negative controls (CTR). Several groups of extracellular matrix (ECM) proteins were dysregulated in the Z⁺ and MC⁺ patients, triggering an opposite dysregulation. The down-regulation of the ECM proteins in the MC⁺ groups can be another factor that contributes to CZS. On the contrary, the Z⁺ group could be developing a neuroprotective response through ECM proteins up-regulation. The neutrophil degranulation process was disrupted in the Z⁺ and MC⁺ groups, where the MC⁺ groups showed a complex dysregulation. These results suggest that the microcephalic phenotypes are modulated by a down-regulation of the ECM and the impairment of the innate immune system processes.

The impact of Zika virus exposure on the placental proteomic profile

Zika virus (ZIKV) infection has caused severe unexpected clinical outcomes in neonates and adults during the recent outbreak in Latin America, particularly in Brazil. Congenital malformations associated with ZIKV have been frequently reported; nevertheless, the mechanism of vertical transmission and the involvement of placental cells remains unclear. In this study, we applied quantitative proteomics analysis in a floating explant model of chorionic villi of human placental tissues incubated with ZIKV and with ZIKV pre-adsorbed with anti-ZIKV envelope protein. Proteomic data are available via ProteomeXchange with identifier PXD025764. Altered levels of proteins were involved in cell proliferation, apoptosis, inflammatory processes, and the integrin-cytoskeleton complex. Antibody-opsonized ZIKV particles differentially modulated the pattern of protein expression in placental cells; this phenomenon may play a pivotal role in determining the course of infection and the role of mixed infections. The expression of specific proteins was also evaluated by immunoperoxidase assays. These data fill gaps in our understanding of early events after ZIKV placental exposure and help identify infection control targets.

Ocular Surface and Conjunctival Cytology Findings in Patients With Confirmed COVID-19

PURPOSE

To assess the effect of severe acute respiratory syndrome coronavirus-2 infection on the conjunctiva and tear film.

METHODS

Thirty-eight patients with confirmed COVID-19 and 31 healthy controls were included in this prospective and observational study. Individuals with COVID-19 formed the patient group, and healthy individuals formed the control group. Conjunctival impression cytology (CIC), TBUT, Schirmer II test, and ocular surface disease index were evaluated in all participants.

RESULTS

No significant difference was observed regarding the mean age and gender between the groups (P=0.786 and P=0.122, respectively). The mean TBUT and Schirmer II test results did not differ between the two groups (P=0.496 and P=0.447, respectively). The CIC results revealed decreased density and cell size of goblet cells and moderate to high enlargement, squamous changes, and increased nucleocytoplasmic ratio in nongoblet epithelial cells in the COVID-19 group compared with the control group. Based on the Nelson classification in CIC samples, 60.6% of the COVID-19 group and 19.4% of the control group had changes consistent with grade 2 or above. The presence of neutrophils in CIC was significantly higher in the COVID-19 group (P<0.001), whereas the presence of lymphocyte was similar between the two groups (P=0.247).

CONCLUSION

This study revealed the pathological conjunctival alterations in patients with COVID-19 and demonstrated that pathological ocular surface alterations may present even at the beginning of COVID-19 without clinically significant ocular manifestation.

Cellular Imprinting Proteomics Assay: A Novel Method for Detection of Neural and Ocular Disorders Applied to Congenital Zika Virus Syndrome

Congenital Zika syndrome was first described due to increased incidence of congenital abnormalities associated with Zika virus (ZIKV) infection. Since the eye develops as part of the embryo central nervous system (CNS) structure, it becomes a specialized compartment able to display symptoms of neurodegenerative diseases and has been proposed as a noninvasive approach to the early diagnosis of neurological diseases. Ocular lesions result from defects that occurred during embryogenesis and can become apparent in newborns exposed to ZIKV. Furthermore, the absence of microcephaly cannot exclude the occurrence of ocular lesions and other CNS manifestations. Considering the need for surveillance of newborns and infants with possible congenital exposure, we developed a method termed cellular imprinting proteomic assay (CImPA) to evaluate the ocular surface proteome specific to infants exposed to ZIKV during gestation compared to nonexposure. CImPA combines surface cells and fluid capture using membrane disks and a large-scale quantitative proteomics approach, which allowed the first-time report of molecular alterations such as neutrophil degranulation, cell death signaling, ocular and neurological pathways, which are associated with ZIKV infection with and without the development of congenital Zika syndrome, CZS. Particularly, infants exposed to ZIKV during gestation and without early clinical symptoms could be detected using the CImPA method. Lastly, this methodology has broad applicability as it could be translated in the study of several neurological diseases to identify novel diagnostic biomarkers. Data are available via ProteomeXchange with identifier PXD014038.