Markedly Reduced Expression of Annexin A2 Is Associated with Hypofibrinolysis and Provoked and Unprovoked Venous Thromboembolism

Introduction: Recent evidence indicates that plasma hypofibrinolysis, as measured by clot lysis times (CLT) at or above the 90th percentile, can double the risk of venous thromboembolism (VTE). To our knowledge, there are no studies on the role of cell surface fibrinolysis in thrombosis. Annexin A2 (A2) is a calcium dependent, phospholipid binding protein that forms a heterotetramer with S100A10 (A2-S100A10)2 on the surface of endothelial cells (ECs). This complex serves as a co-receptor for plasminogen and tissue plasminogen activator (tPA), and increases the catalytic efficiency of tPA-dependent cell surface plasmin generation by 60-fold. In mouse studies, global knockout of the annexin A2 gene (Anxa2) is associated with fibrin accumulation and impaired clearance of arterial thrombi. In addition, there are several examples of the regulatory role of A2 in fibrinolysis in human diseases such as antiphospholipid antibody syndrome, cerebral venous thrombosis, and sickle cell disease. In the current study, we aimed to explore the potential role of the A2 system and cell surface based fibrinolysis in the development of VTE. Methods: Study subjects included patients 18-65 years old with history of VTE and healthy controls. Subjects were classified as having provoked or unprovoked VTE based on the presence or absence of identifiable environmental risk factors. Peripheral blood mononuclear cells (PBMCs) were isolated from whole blood collected in EDTA tubes, and used as a surrogate for ECs. Assays performed on PBMCs included determination of the rate of tPA-dependent cell surface plasmin generation using a fluorogenic substrate and analysis of CLT in the presence of phospholipid vesicles. Because A2 accounts for approximately 50% of cell surface based plasmin generation on both ECs and PBMCs, we analyzed total A2 protein expression relative to GAPDH in whole cell lysates of PBMCs using semi-quantitative western blotting. Additional assays included quantitative RT-PCR and ANXA2 gene sequencing. Statistical analysis was performed using one-way ANOVA followed by Tukey's multiple comparisons test. Results: Overall, 116 subjects with VTE (76 with provoked and 40 with unprovoked VTE) and 87 healthy controls were studied between September 2010 and May 2019. Plasma based clot lysis assays revealed that the mean CLT for subjects with VTE was significantly longer than that for healthy controls (37.5 versus 30.7 minutes, p=0.0001). Additionally, the mean rate of cell surface plasmin generation was significantly reduced in subjects with VTE as compared with healthy controls (0.33 RFU/min2 versus 0.49 RFU/min2, p=0.0021). Moreover, none of the 60 healthy controls (0%), but 18 of the 107 subjects with thrombosis (17%) had cell surface plasmin generating capacity in the lowest 10th percentile. In protein expression studies, we observed that none of the 21 healthy controls (0%), but 5 of 41 subjects with thrombosis (12%) had A2 expression in the lowest 10th percentile for the group; 4 of 18 (22%) of those with unprovoked VTE and 1 of 23 (4%) of those with provoked VTE fell into the lowest decile for protein expression. For plasmin generating capacity, 8 of 36 (22%) of subjects with unprovoked VTE and 10 of 71 (14%) of those with provoked VTE occupied the lowest decile. Probing of western blots of samples obtained on two separate occasions several months apart with A2 epitope-specific antibodies revealed abnormalities within either the tPA binding N-terminal tail or C-terminal core domain in proximity to the plasminogen binding site. Neither quantitative RT-PCR nor ANXA2 gene sequencing of selected samples revealed abnormalities in either mRNA or genomic DNA that could explain the reduced A2 expression. Conclusion: These data confirm findings previously reported by Lisman that plasma hypofibrinolysis is associated with VTE and may represent an independent risk factor for VTE. Additionally, we demonstrate for the first time that impaired cell surface based fibrinolysis and aberrations in A2 protein expression are associated with both provoked and unprovoked VTE, and may represent a novel risk factor for thrombosis. Possible explanations for reduced A2 expression include dysfunctional translation of mRNA into protein or post-translational proteolysis of the translated protein. Compromise of the A2-based fibrinolytic system may represent a previously unrecognized contributor to thrombophilia in VTE. Disclosures Ruisi: BMY: Equity Ownership; EMD, subsidiary of Merck KGaA: Employment. De Sancho:Apellis Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees.

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Levels of Circulating TIMP-2 and MMP2-TIMP2 Complex Are Decreased in Squamous Cervical Carcinoma

Obstetrics and Gynecology International ◽

10.1155/2010/179351 ◽

2010 ◽

Vol 2010 ◽

pp. 1-3 ◽

Cited By ~ 3

Author(s):

Talvensaari-Mattila Anne ◽

Turpeenniemi-Hujanen Taina

Keyword(s):

Cervical Carcinoma ◽

Matrix Metalloproteinase 2 ◽

Healthy Controls ◽

Matrix Degradation ◽

Serum Samples ◽

Study Population ◽

The Mean ◽

Natural Tissue ◽

Squamous Cervical Carcinoma

Background. The role of matrix metalloproteinase-2 and -9 (MMP-2, MMP-9) in matrix degradation and metastasis has been described in various tumors. Their action is inhibited by their natural tissue inhibitor molecules TIMP-1 and -2.Methods. The study population consisted of 12 squamous cervical carcinoma patients and 27 healthy volunteer control patients. MMP-9, MMP-2-TIMP-2 complex, TIMP-1, and TIMP-2 were analyzed from serum samples using enzyme-linked immunoassay (ELISA).Results. The mean levels of serum TIMP-2 and of MMP-2-TIMP-2 complex were higher in healthy controls compared to patients with a malignant tumor. Serum TIMP-2 values decreased significantly from healthy controls (median 323 g/l, range 305–342 g/l) to malignant (median 136 g/l, range 120–151 g/l) squamous cervical carcinoma patients . Also, serum proMMP2-TIMP2 complex values decreased from control patients to squamous cervical carcinoma patients .Conclusion. This paper shows that the levels of circulating TIMP-2 and that of MMP-2-TIMP-2 complex are lower in squamous cervical carcinoma patients than in healthy women.

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Reduced Expression of Annexin A2 is Associated with Impaired Cell Surface Fibrinolysis and Venous Thromboembolism

Blood ◽

10.1182/blood.2020008123 ◽

2021 ◽

Author(s):

Hannah Fassel ◽

Huigen Chen ◽

Mary Ruisi ◽

Neha Kumar ◽

Maria T DeSancho ◽

...

Keyword(s):

Risk Factor ◽

Venous Thromboembolism ◽

Cell Surface ◽

Mononuclear Cells ◽

Annexin A2 ◽

Clot Lysis ◽

Mrna Levels ◽

Peripheral Blood Mononuclear ◽

Intravascular Thrombosis

Reduced plasma fibrinolysis has been identified as a potential risk factor for venous thromboembolism (VTE), but the role of cell surface fibrinolysis in VTE is unknown. The annexin A2/S100A10 complex serves as a co-receptor for plasminogen and tissue plasminogen activator (tPA), augmenting plasmin generation by 60-fold on the endothelial cell surface. Several studies in both mice and humans support the concept that A2 regulates fibrin homeostasis and intravascular thrombosis in vivo. Here, we examined A2 protein expression and function in 115 adult subjects with venous thromboembolism (VTE) and 87 healthy controls. Using peripheral blood mononuclear cells (PBMCs) as a surrogate for endothelial cells, we found a 41% mean decrease in cell surface tPA-dependent fibrinolytic activity in subjects who had a positive personal and family history of VTE, but tested negative for known inherited thrombophilias. A2 protein was reduced on average by 70%, and mRNA levels by 30%, but neither decrease correlated with anticoagulant therapy. [Sentence omitted] Neither cell A2 protein nor cell surface plasmin generation correlated with plasma-based clot lysis times, suggesting that the plasma and cell surface fibrinolytic systems operate independently of one another. These data suggest that reduced expression of annexin A2 protein is associated with cell surface hypofibrinolysis and may represent a novel risk factor for inherited thrombophilia.

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Hyperaggregability Of Platelets In Cancer, Especially In Reference To Genesis Of DIC

10.1055/s-0038-1653313 ◽

1981 ◽

Author(s):

H Yamazaki ◽

Y Yahara ◽

T Motomiya ◽

K Tanoue ◽

I Isohisa ◽

...

Keyword(s):

Cancer Patients ◽

Time Course ◽

Mean Value ◽

Activated Partial Thromboplastin Time ◽

Healthy Controls ◽

Triggering Mechanism ◽

Coagulation Abnormalities ◽

Activated Platelets ◽

The Mean

To clarify the role of platelets in the genesis of DIC in cancer, platelets of cancer patients with and without DIC were examined. Patients studied were 29 cases with cancer in stomach, 17 in lung, 7 in pancreas, 6 in liver (hepatoma), 6 in throat, nose and jaw, 2 in the gall bladder and bilary duct, 2 in uterus and 1 each in the small bowel, rectum and prostate, and 1 each with osteosarcoma, mesothelioma and chorionepithelioma. All patients were in stage 3 or 4. 105 healthy controls were also studied. They were evaluated on a scale of coagulation abnormalities, one point was given for each of the following criteria full-filled, and the score (0 to 4) was used. 1. Platelet count<150xl03Anl. 2. Prothrombin time prolonged more than 1 sec over control and/or activated partial thromboplastin time prolonged more than 10 sec over control. 3. Fibrinogen<250 mg/dl (mean fibrinogen value of the cancer patients minus 1 SD). 4. FDP>20 µg/ml. The patients were distributed with 27 % for score 0, 38 % for 1, 20 % for 2, 7 % for 3 and 8 % for 4. Degrees of abnormality in groups with scores of 3 and 4 were significant when compared to scores 0 and 1, but score 2 was not clearly distinguishable. Platelet mode volume in score 4 was smaller than the other groups. Platelet aggregation by adrenaline and ADP decreased in score 3 and 4, while it increased significantly in score 0 and 1 respectively (P<0.01 -0.05). The mean value of plasma β-TG in the cancer patients as a whole (44±24 ng/ml) was significantly higher than that of control (22±13 ng/ml)(P<0.01). PF4 showed the same tendency. During the time course of the disease, hyperaggrega- bility of platelets associated with increases in β-TG and PF4 was observed before an appearance of DIC syndrome in several cases. The results suggest the existence of hyperfunction of platelets in cancer patients and the possibility of triggering mechanism of such activated platelets in the genesis of DIC in cancer.

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Dysfunction of annexin A2 contributes to hyperglycaemia-induced loss of human endothelial cell surface fibrinolytic activity

Thrombosis and Haemostasis ◽

10.1160/th12-12-0944 ◽

2013 ◽

Vol 109 (06) ◽

pp. 1070-1078 ◽

Cited By ~ 16

Author(s):

Zhanyang Yu ◽

Xiang Fan ◽

Ning Liu ◽

Min Yan ◽

Zhong Chen ◽

...

Keyword(s):

Endothelial Cells ◽

Endothelial Cell ◽

Cell Surface ◽

Protein Expression ◽

Plasminogen Activator ◽

Fibrinolytic Activity ◽

Annexin A2 ◽

Tissue Type ◽

Endothelial Cell Surface ◽

Pai 1

SummaryHyperglycaemia impairs fibrinolytic activity on the surface of endothelial cells, but the underlying mechanisms are not fully understood. In this study, we tested the hypothesis that hyperglycaemia causes dysfunction of the endothelial membrane protein annexin A2, thereby leading to an overall reduction of fibrinolytic activity. Hyperglycaemia for 7 days significantly reduced cell surface fibrinolytic activity in human brain microvascular endothelial cells (HBMEC). Hyperglycaemia also decreased tissue type plasminogen activator (t-PA), plasminogen, and annexin A2 mRNA and protein expression, while increasing plasminogen activator inhibitor-1 (PAI-1). No changes in p11 mRNA or protein expression were detected. Hyperglycaemia significantly increased AGE-modified forms of total cellular and membrane annexin A2. The hyperglycemia-associated reduction in fibrinolytic activity was fully restored upon incubation with recombinant annexin A2 (rA2), but not AGE-modified annexin A2 or exogenous t-PA. Hyperglycaemia decreased t-PA, upregulated PAI-1 and induced AGE-related disruption of annexin A2 function, all of which contributed to the overall reduction in endothelial cell surface fibrinolytic activity. Further investigations to elucidate the underlying molecular mechanisms and pathophysiological implications of A2 derivatisation might ultimately lead to a better understanding of mechanisms of impaired vascular fibrinolysis, and to development of new interventional strategies for the thrombotic vascular complications in diabetes.

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CD137 Expression Is Enhanced in EBV-Infected T or NK Cells by Viral Protein LMP1 and Mediates Anti-Apoptotic Intracellular Signaling through NF-ĸB Activation.

Blood ◽

10.1182/blood.v114.22.1929.1929 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1929-1929

Author(s):

Ayako Arai ◽

Ken-ichi Imadome ◽

Mayumi Takahashi ◽

Koichi Naka ◽

Tetsuya Fukuda ◽

...

Keyword(s):

Cell Surface ◽

Nk Cells ◽

Intracellular Signaling ◽

Mononuclear Cells ◽

Nk Cell ◽

Jurkat Cells ◽

Rt Pcr ◽

Infected Cells ◽

Ebv Dna

Abstract Abstract 1929 Poster Board I-952 Epstein-Barr virus (EBV) can infect not only B cells but also T or NK cells uncommonly and causes lymphoid malignancies, such as extranodal NK/T-cell lymphoma nasal type (ENKL), aggressive NK-cell leukemia, and EBV-positive T/NK-cell lymphoproliferative disease (EBV-T/NK-LPD), which is also known as chronic active EBV infection. However, why and how EBV infects T or NK cells and the mechanism of action responsible for these EBV-induced malignancies have not been elucidated to date. To clarify the molecular mechanism underlying development of EBV-T/NK-LPD, we focused on costimulatory receptor CD137, which is expressed on the surface of activated T cells and plays a pivotal role in their proliferation, survival, and differentiation. We investigated CD137 expression on the surface of EBV-infected T/NK cells (EB-T/NK cells) by flow cytometry. First, three EBV-positive T and NK cell lines, SNT8, SNK6, and SNT16, were obtained for examination. These cell lines had been established from primary lesions of ENKL patients (SNT8 and SNK6) and peripheral blood of an EBV-T/NK-LPD patient (SNT16). CD137 expression was confirmed on the cell surface of these cells, whereas the EBV-negative T and NK cell line, Jurkat and KHYG1 cells, respectively, were negative for CD137. Next, we investigated expression on the surface of EB-T/NK cells derived from EBV-T/NK-LPD patients. EBV-T/NK-LPD was diagnosed according to the following criteria: presence of persistent infectious mononucleosis-like symptoms, elevation of EBV-DNA titer in the peripheral blood (PB), and detection of EBV-infected T or NK cells. To detect the infected cells, we isolated peripheral mononuclear cells and divided them into CD19-, CD4-, CD8-, or CD56-positive fractions using antibody-conjugated magnetic beads. Next, we measured the EBV-DNA titer of each fraction by quantitative RT-PCR. Nine patients (aged 8–41 years; 4 male, 5 female; 4 T and 5 NK cell types) were diagnosed with EBV-T/NK-LPD. Then, we examined surface CD137 expression of the infected cells of each patient. Expression was detected in 7 of 9 patients. Control cells (PB mononuclear cells of a healthy donor, who was negative for EBV-DNA titer in the PB) did not express the molecule. We also examined transcription of CD137 mRNA by RT-PCR assay and detected it in all the 12 EB-T/NK-cell samples described above. From these results we concluded that CD137 expression was induced at the level of both mRNA and protein in EB-T/NK cells. To investigate the molecular mechanism of CD137 overexpression in EBV-T/NK cells, we examined the influence of viral proteins on CD137 expression. EB-T/NK cells express EBV-encoded proteins, including LMP1, LMP2A, LMP2B, and EBNA1 (latency type 2). We cotransfected expression plasmids for these proteins with a luciferase reporter plasmid containing the CD137 gene promoter in Jurkat cells and performed a luciferase assay. LMP1 significantly upregulated the CD137 promoter activity, although the other molecules did not. Furthermore, in a transient expression assay of these viral proteins using Jurkat cells, transcription of endogenous mRNA of CD137 was upregulated only in the LMP1 transfectant. These results indicate that LMP1 may transactivate CD137 transcription and expression in EBV-T/NK cells. Next, we investigated the role of CD137 in developing EBV-T/NK-LPD. We cultured the above-mentioned CD137-expressing EBV-T/NK cells on CHO cells that stably express human CD137L on the cell surface. NF-ĸB activation was detected in CD137-positive EBV-T/NK cells that were cocultured with CD137L-expressing CHO cells. We confirmed that both p50 and p52 translocated to the nucleus, indicating that both canonical and non-canonical pathways for NF-ĸB activation were activated downstream of CD137. Finally, we investigated the role of CD137-mediated NF-ĸB activation in the development of EBV-T/NK-LPD. We cocultured EB-T/NK cells on CHO-wt or CHO-CD137L with VP-16 for 48 h and determined apoptosis by measuring DiCO6 uptake. We noted that stimulation of CD137 significantly suppressed VP-16-induced apoptosis of these cells. Together, these results indicate that EBV-infected T/NK-cells express CD137 on the cell surface, which may be induced by LMP1 and activate the anti-apoptotic intracellular signaling pathway through NF-ĸB activation. This pathway may contribute to immortalization of the infected cells and development of EBV-T/NK-LPD. Disclosures: No relevant conflicts of interest to declare.

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Role of Annexin A2 isoform 2 on the aggregative growth of dermal papillae cells

Bioscience Reports ◽

10.1042/bsr20180971 ◽

2018 ◽

Vol 38 (6) ◽

Author(s):

Jing Gu ◽

Yinni Ma ◽

Lijia Yang ◽

Feng Wang ◽

Cao Lei ◽

...

Keyword(s):

Western Blot ◽

Mrna Expression ◽

Expression Vector ◽

Dermal Papilla ◽

Annexin A2 ◽

Expression Level ◽

Rt Pcr ◽

Aggregative Growth ◽

Dermal Papillae

The dermal papilla is a major component of hair, which signals the follicular epithelial cells to prolong the hair growth process. Human Annexin A2 was preliminarily identified by two-dimensional gel electrophoresis (2-DE), MALDI-TOF-MS and database searching. The aim of the present study was to explore the role of Annexin A2 in the aggregative growth of dermal papillae cells (DPC). Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot were adopted to detect the expression of Annexin A2. And siRNA technique was used to suppress the expression of Annexin A2. Construction of over-expression vector was used to up-regulate the expression of Annexin A2. Cell Counting Kit 8 (CCK-8) and proliferating cell nuclear antigen (PCNA) were taken to detect the proliferation of DPC. The expression of Annexin A2 mRNA was up-regulated in passage 3 DPC compared with passage 10 DPC by RT-PCR. In line with the results at the mRNA level, Western blot analysis revealed that Annexin A2 isoform 2 was up-regulated significantly in passage 3 DPC compared with passage 10 DPC. The Annexin A2 isoform 2 siRNA was synthesized and transfected into passage 3 DPC. RT-PCR data showed the mRNA expression of Annexin A2 isoform 2 was suppressed in passage 3 DPC. Western blot results showed the expression level of Annexin A2 isoform 2 and PCNA were suppressed in passage 3 DPC. CCK-8 results showed that the proliferation of passage 3 DPC was suppressed (P < 0.05). Recombinant plasmid PLJM-Annexin A2 isoform 2-expression vector were constructed and were transfected into passage 10 DPC. RT-PCR data showed the mRNA expression of Annexin A2 isoform 2 was up-regulated in passage 10 DPC. Western blot results showed the expression level of annexin A2 isoform 2 and PCNA were up-regulated in passage 10 DPC. CCK-8 assay showed the proliferation of DPC was stimulated compared with control group (*P < 0.05). Our study proved that Annexin A2 isoform 2 may participate in regulating the proliferation of DPC and may be related to aggregative growth of dermal papilla cells. Therefore, our study suggests that Annexin A2 may be linked to hair follicle growth cycle.

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Serum Carnitine in Patients on Continuous Ambulatory Peritoneal Dialysis (CAPD)

Peritoneal Dialysis International ◽

10.1177/089686088100200105 ◽

1981 ◽

Vol 2 (1) ◽

pp. 11-12 ◽

Cited By ~ 6

Author(s):

Pablo Amair ◽

Agis Gregoriadis ◽

Helen Rodela ◽

Raymond Ogilvie ◽

Ramesh Khanna ◽

...

Keyword(s):

Peritoneal Dialysis ◽

Continuous Ambulatory Peritoneal Dialysis ◽

Healthy Controls ◽

Carnitine Supplementation ◽

Serum Triglycerides ◽

Significant Difference ◽

The Mean

Serum carnitine and serum triglycerides were measured in 45 patients on CAPD and in 14 healthy controls. There was no significant difference between the mean carnitine levels in the two groups. Furthermore, there was no correlation between serum carnitine and serum triglycerides. Our data cast some doubt on the role of carnitine in the development of hypertriglyceridemia in patients on CAPD and on the need for carnitine supplementation in these patients.

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Tyrosine 23 Phosphorylation-Dependent Cell-Surface Localization of Annexin A2 Is Required for Invasion and Metastases of Pancreatic Cancer

PLoS ONE ◽

10.1371/journal.pone.0019390 ◽

2011 ◽

Vol 6 (4) ◽

pp. e19390 ◽

Cited By ~ 104

Author(s):

Lei Zheng ◽

Kelly Foley ◽

Lanqing Huang ◽

Ashley Leubner ◽

Guanglan Mo ◽

...

Keyword(s):

Pancreatic Cancer ◽

Cell Surface ◽

Annexin A2 ◽

Surface Localization ◽

Dependent Cell ◽

Cell Surface Localization

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Tacrolimus reverses the pemphigus vulgaris serum-enhanced expression of desmoglein in HaCaT cells

10.21203/rs.2.16901/v1 ◽

2019 ◽

Author(s):

zhimin xie ◽

Qiaolin Pan ◽

Xucheng Shen ◽

Yi Zhang ◽

Xiangnong Dai ◽

...

Keyword(s):

Cell Surface ◽

Protein Expression ◽

Cell Model ◽

Pemphigus Vulgaris ◽

Hacat Cells ◽

Hacat Keratinocytes ◽

Mrna Transcription ◽

Rt Pcr ◽

Enhanced Expression ◽

A Cell

Abstract Pemphigus vulgaris (PV) is associated with autoantibodies against desmoglein (Dsg), including Dsg1 and Dsg3. However, the precise mechanism by which acantholysis occurs in response to PV-IgG and the effect of tacrolimus for PV remain unclear.Method To co-culture human HaCaT keratinocytes with DMEM medium containing 5% PV-sera to establish a cell model of pemphigus that can determine the effect of PV-sera and tacrolimus on Dsg mRNA transcription and protein expression in HaCaT cells. Dsg protein expression in HaCaT cells was evaluated by Western blotting and Dsg mRNA transcription by real-time PCR (RT-PCR). The distribution of Dsg1 and Dsg3 in HaCaT cells was determined by indirect immunofluorescence (IIF).Results The application of 5% PV serum resulted in an increase in the transcription and expression levels of Dsg1 and Dsg3, whereas tacrolimus suppressed Dsg1 and Dsg3 expression. Tacrolimus inhibited PV serum-induced disruption of cell−cell contacts. Tacrolimus also downregulated the expression of Dsg1and Dsg3 compared with the PV group. IIF revealed that the linear deposits of Dsg1 on the surface of HaCaT cells in the PV-sera group disappeared and were replaced by granular and agglomerated fluorescent particles on the cell surface, whereas the Dsg3 linear deposits still existed, but this effect could be reversed by tacrolimus.Conclusion The Dsg3 antibody disrupts desmosome junctions by inducing endocytosis, resulting in desmosomal dissociation. Tacrolimus could reverse PV serum-induced enhancement Dsg expression in HaCaT cells.

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Infants have lower RT-PCR cycle threshold for SARS-CoV-2 in comparison with older children and adults

10.1101/2021.04.20.21255059 ◽

2021 ◽

Author(s):

Marcia Polese-Bonatto ◽

Ivaine Tais Sauthier Sartor ◽

Fernanda Hammes-Varela ◽

Gabriela Luchiari Tumioto Gianinni ◽

Thais Raupp Azevedo ◽

...

Keyword(s):

Viral Load ◽

Significant Role ◽

Signs And Symptoms ◽

Viral Dynamics ◽

Older Children ◽

Rt Pcr ◽

Pcr Assay ◽

Cycle Threshold ◽

The Mean

Background: The viral dynamics and the role of children in the spread of SARS-CoV-2 are not completely understood. Our aim was to evaluate how RT-PCR Ct values among children with confirmed SARS-CoV-2 compared with that of adult subjects. Methods: Patients (aged from 2 months to ≤18 years, and adults) with signs and symptoms of acute SARS-CoV-2 infection for less than 7 days, were prospectively enrolled in the study from May to November 2020. All participants performed RT-PCR assay for SARS-CoV-2 detection; Ct values of ORF1ab, N, and S gene-targets, and the average of all the three probes were used as surrogates of viral load. Results: Of the total of 376 participants with confirmed SARS-CoV-2 infection there were 21 infants, 62 children and 293 adults. The RT-PCR Ct values of children under 18 were not significantly different from that of adults, as observed by the analyzed probes (namely ORF1ab, N, and S), and by the mean of all 3 gene-targets. However, infants had significantly lower Ct values compared to children and adults (P = 0.044). Discussion: Ct values for children were not significantly different than that of adults with positive SARS-CoV-2. Interestingly, infants had even lower Ct values when compared to older children and adults. Although viral load is not the only determinant of transmission, infants may play a significant role in the spread of SARS-CoV-2 in the community, especially if or when this population returns to regular daycare activities.

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