Role of Vascular Endothelial Growth Factor (VEGF) in the Neurological Manifestations of Dengue: A Preliminary Study

The Role of Growth Factors in the Pathogenesis of Dengue: A Scoping Review

Growth factors (GFs) have a role in tissue repair and in the modulation of the expression of inflammatory cells in damage caused by pathogens. This study aims to systematize the evidence on the role of GFs in the pathogenesis of dengue. This scoping review considered all published peer-reviewed studies in the MEDLINE and Embase databases. Ultimately, 58 studies that analyzed GFs in dengue patients, published between 1998 and 2021, were included. DENV-2 infection and secondary infection were more frequent in the patients studied. ELISA and multiplex immunoassay (Luminex) were the most used measurement techniques. Increased levels of vascular endothelial growth factor, granulocyte–macrophage colony-stimulating factor, granulocyte colony-stimulating factor, transforming growth factor beta, and hepatocyte growth factor as well as reduced levels of platelet-derived growth factor and epidermal growth factor were observed in severe dengue in most studies. Vascular endothelial growth factor and hepatocyte growth factor were identified as biomarkers of severity. In addition, there is evidence that the dengue virus can use the growth factor pathway to facilitate its entry into the cell and promote its viral replication. The use of tyrosine kinase inhibitors is an alternative treatment for dengue that is being studied.

The predictive and diagnostic accuracy of vascular endothelial growth factor and pentraxin-3 in severe dengue

This study aimed to evaluate vascular endothelial growth factor (VEGF) and pentraxin 3 (PTX-3) as predictive and diagnostic markers in differentiating severe dengue from non-severe dengue. The study was conducted in Ampang Health Clinic, Ampang Hospital and Serdang Hospital. The plasma levels of VEGF and PTX-3 were compared between severe dengue and non-severe dengue by ELISA from the day of presentation until discharged. Multiple logistic regression was used to develop predictive and diagnostic models by incorporating other clinical parameters. The receiver operating characteristics (ROC) analysis was used to assess the accuracy of the biomarkers and the developed models. Eighty-two patients were recruited, 29 with severe dengue and four died. The Area Under the Curve (AUC) was statistically significant in VEGF as diagnostic marker at Day 2 and 3 of illness with sensitivity of 80.00%-100.00% and specificity of 76.47%-80.00%. The predictive model with AUC of 0.84 (p < 0.01) has a sensitivity of 100.00% and specificity of 79.25% for predicting severe dengue. The diagnostic model with AUC of 0.71 (p < 0.01) has a sensitivity of 76.19% and specificity of 73.58% for diagnosing severe dengue. The AUC for PTX-3 was not statistically significant. VEGF may be used in combination with other clinical parameters to predict the severity of the disease. As a single biomarker, it may be used as an adjunct investigation to support the diagnosis of severe dengue. PTX-3 was not able to differentiate severe dengue from non-severe dengue.

Meta-analysis of biomarkers for severe dengue infections

BACKGROUND

Dengue viral infection is an acute infection that has the potential to have severe complications as its major sequela. Currently, there is no routine laboratory biomarker with which to predict the severity of dengue infection or monitor the effectiveness of standard management. Hence, this meta-analysis compared biomarker levels between dengue fever (DF) and severe dengue infections (SDI) to identify potential biomarkers for SDI.

METHODS

Data concerning levels of cytokines, chemokines, and other potential biomarkers of DF, dengue hemorrhagic fever, dengue shock syndrome, and severe dengue were obtained for patients of all ages and populations using the Scopus, PubMed, and Ovid search engines. The keywords "(IL1* or IL-1*) AND (dengue*)" were used and the same process was repeated for other potential biomarkers, according to Medical Subject Headings terms suggested by PubMed and Ovid. Meta-analysis of the mean difference in plasma or serum level of biomarkers between DF and SDI patients was performed, separated by different periods of time (days) since fever onset. Subgroup analyses comparing biomarker levels of healthy plasma and sera controls, biomarker levels of primary and secondary infection samples were also performed, as well as analyses of different levels of severity and biomarker levels upon infection by different dengue serotypes.

RESULTS

Fifty-six studies of 53 biomarkers from 3,739 dengue cases (2,021 DF and 1,728 SDI) were included in this meta-analysis. Results showed that RANTES, IL-7, IL-8, IL-10, IL-18, TGF-b, and VEGFR2 levels were significantly different between DF and SDI. IL-8, IL-10, and IL-18 levels increased during SDI (95% CI, 18.1-253.2 pg/mL, 3-13 studies, n = 177-1,909, I2 = 98.86%-99.75%). In contrast, RANTES, IL-7, TGF-b, and VEGFR2 showed a decrease in levels during SDI (95% CI, -3238.7 to -3.2 pg/mL, 1-3 studies, n = 95-418, I2 = 97.59%-99.99%). Levels of these biomarkers were also found to correlate with the severity of the dengue infection, in comparison to healthy controls. Furthermore, the results showed that IL-7, IL-8, IL-10, TGF-b, and VEGFR2 display peak differences between DF and SDI during or before the critical phase (day 4-5) of SDI.

DISCUSSION

This meta-analysis suggests that IL-7, IL-8, IL-10, TGF-b, and VEGFR2 may be used as potential early laboratory biomarkers in the diagnosis of SDI. This can be used to predict the severity of dengue infection and to monitor the effectiveness of treatment. Nevertheless, methodological and reporting limitations must be overcome in future research to minimize variables that affect the results and to confirm the findings.

Is VEGF a marker of severity of scrub typhus infection?

Vascular endothelial growth factor (VEGF) and its receptors have been reported as severity markers of septicemia. Scrub typhus (ST) results in multi-organ dysfunction but the role of VEGF has not been evaluated. We report VEGF and its receptors in ST and its correlation with severity, outcome and laboratory findings. Thirty patients with ST diagnosed by solid phase immune chromatographic assay and Weil-Felix tests were included. Their clinical details, Glasgow Coma Scale (GCS), SOFA and modified Rankin Scale (mRS) scores and laboratory findings were noted. VEGF, VEGFR1 and VEGFR2 were done by ELISA at admission and repeated at 1 month. Outcome was defined at 1 month. Serum VEGF and VEGF-R1 levels were significantly higher and VEGFR2 was significantly lower in the ST patients compared to the controls. These levels significantly improved at 1 month. VEGF level correlated with SOFA score (p = 0.05) and SGPT (p = 0.04). VEGFR1 correlated with hemoglobin (p = 0.04), platelet count (p = 0.03), serum CK (p = 0.001), weakness (p = 0.04) and mRS score (p = 0.04). VEGFR2 did not correlate with any clinical or laboratory parameters. All the patients recovered with doxycycline. Serum VEGF and VEGFR1 levels increased in ST and suggest disease severity but do not predict outcome.

Neurological manifestations of scrub typhus

OBJECTIVE

To evaluate the neurological manifestations of scrub typhus and correlate their clinical, EEG and MRI findings.

METHODS

A cross-sectional study over 2 years included patients with scrub typhus diagnosed by solid phase immunochromatographic assay or Weil-Felix test. A detailed clinical evaluation including Glasgow Coma Scale (GCS) was documented. Blood counts, chemistry, ECG, chest radiograph, cerebrospinal fluid (CSF), EEG and cranial MRI were performed. Outcome on discharge and at 1 month were categorised into good and poor based on modified Rankin Scale.

RESULTS

Thirty-seven patients with ages ranging between 3 and 71 years were included; 51% of whom were females. All patients had fever and myalgia. Thirty-one (84%) patients had impaired consciousness, and six were deeply comatose (GCS score ≤8). Eight patients presented with status epilepticus. MRI revealed meningeal enhancement in only 1/25 (4%) patient and EEG showed generalised slowing in 6/28 (21.4%). Among 31 patients with altered sensorium, CSF studies were conducted on 28. Nineteen patients had meningoencephalitis and 9 encephalopathy, but no significant differences were observed in clinical, laboratory, EEG and MRI findings. All patients responded within 48 h to doxycycline and had good recovery at 1 month. Patients with low GCS score had significantly more focal neurological deficit (r=0.5; p=0.002), longer hospital stay (r=-0.4; p=0.03) and more disability on discharge (r=-0.4; p=0.01).

CONCLUSIONS

Meningoencephalitis/encephalopathy may be seen in two-third of patients with scrub typhus. Scrub typhus should be included in the differential diagnosis of febrile encephalopathy.