Renal Injury in DENV-4 Fatal Cases: Viremia, Immune Response and Cytokine Profile

Severe dengue in the intensive care unit

Dengue fever is considered the most prolific vector-borne disease in the world, with its transmission rate increasing more than eight times in the last two decades. While most cases present mild to moderate symptoms, 5% of patients can develop severe disease. Although the mechanisms are yet not fully comprehended, immune-mediated activation leading to excessive cytokine expression is suggested as a cause of the two main findings in critical patients: increased vascular permeability that may shock and thrombocytopenia, and coagulopathy that can induce hemorrhage. The risk factors of severe disease include previous infection by a different serotype, specific genotypes associated with more efficient replication, certain genetic polymorphisms, and comorbidities such as diabetes, obesity, and cardiovascular disease. The World Health Organization recommends careful monitoring and prompt hospitalization of patients with warning signs or propensity for severe disease to reduce mortality. This review aims to update the diagnosis and management of patients with severe dengue in the intensive care unit.

Prevalence, Characteristics, and Outcomes Associated with Acute Kidney Injury among Adult Patients with Severe Dengue in Mainland China

Acute kidney injury (AKI) can occur in adult patients with severe dengue (SD) and have serious clinical outcomes. This study aimed to determine the prevalence, characteristics, risk factors, and clinical outcomes of AKI in adult patients with SD; the correlation of dengue virus (DENV) serological and virological profiles with AKI; and the clinical features of patients with severe AKI who received renal replacement treatment (RRT). This multicenter study was conducted in Guangdong Province, China, between January 2013 and November 2019. A total of 242 patients were evaluated, of which 85 (35.1%) developed AKI and 32 (13.2%) developed severe AKI (stage 3). Patients with AKI had a higher fatality rate (22.4% versus 5.7%; P < 0.001) and longer length of hospital stay (median: 13 versus 9 days; P < 0.001). Independent risk factors for AKI were hypertension (odds ratio [OR]: 2.03; 95% CI: 1.10-3.76), use of nephrotoxic drugs (OR: 1.90; 95% CI: 1.00-3.60), respiratory distress (OR: 4.15; 95% CI: 1.787-9.632), high international normalized ratio (INR) levels (OR: 6.44; 95% CI: 1.89-21.95), and hematuria (OR: 2.12; 95% CI: 1.14-3.95). There was no significant association between DENV serological and virological profiles and the presence or absence of AKI. Among patients with severe AKI, those who received RRT had a longer length of hospital stay and similar fatality rate. Hence, adult patients with SD should be closely monitored for the development of AKI to enable timely and appropriate therapy.

Primary infection of BALB/c mice with a dengue virus type 4 strain leads to kidney injury

BACKGROUND

Dengue is a disease caused by dengue virus (DENV-1 through -4). Among the four serotypes, DENV-4 remains the least studied. Acute kidney injury is a potential complication of dengue generally associated with severe dengue infection.

OBJECTIVES

The goal of this study was to investigate the alterations caused by experimental dengue infection in the kidney of adult BALB/c mice.

METHODS

In this study, BALB/c mice were infected through the intravenous route with a DENV-4 strain, isolated from a human patient. The kidneys of the mice were procured and subject to histopathological and ultrastructural analysis.

FINDINGS

The presence of the viral antigen was confirmed through immunohistochemistry. Analysis of tissue sections revealed the presence of inflammatory cell infiltrate throughout the parenchyma. Glomerular enlargement was a common find. Necrosis of tubular cells and haemorrhage were also observed. Analysis of the kidney on a transmission electron microscope allowed a closer look into the necrotic tubular cells, which presented nuclei with condensed chromatin, and loss of cytoplasm.

MAIN CONCLUSIONS

Even though the kidney is probably not a primary target of dengue infection in mice, the inoculation of the virus in the blood appears to damage the renal tissue through local inflammation.

Immunopathology of Renal Tissue in Fatal Cases of Dengue in Children

Dengue virus (DENV) infection represents a worldwide public health concern and can cause damage to multiple organs, including the kidney. In this work, we investigated the histopathological changes caused by dengue virus infection along with the detection of inflammatory mediators, cytokines, and cell expression patterns in the renal tissue of three fatal cases in children. Hematoxylin and Eosin staining was performed to analyze these histopathological changes. Immunohistochemistry allowed for the detection of immunological inflammatory markers in renal tissues that were quantified and further analyzed. Vascular congestion, edema and glomerular infiltrate were observed in the three cases, in addition to the thickening of the matrix area around the glomerular capillaries and mononuclear infiltrate associated with vascular congestion in the medullary region. The renal tissues exhibited collagen deposition and high expression of CD68⁺ Mø, CD8⁺ T, CD56⁺ cells and MMP-9, and the cytokine profile was mainly characterized by the expression of IFN-γ and TNF-α. Additionally, the expression of RANTES, VEGFR-2 and VCAM-1 were observed. The replication of DENV was evidenced by the detection of the NS3 protein. These results contributed to clarifying the main factors that may be involved in changes in the renal tissue of fatal cases of dengue in children.

Subsets of Cytokines and Chemokines from DENV-4-Infected Patients Could Regulate the Endothelial Integrity of Cultured Microvascular Endothelial Cells

Introduction: It is a consensus that inflammatory mediators produced by immune cells contribute to changes in endothelial permeability in dengue. We propose to relate inflammatory mediators seen in dengue patients with the in vitro alteration of endothelial cells (ECs) cultured with serum from these patients. Methods: Patients with mild (DF) to moderate and severe dengue (DFWS/Sev) were selected. ELISA quantified inflammatory mediators. Expression of adhesion molecules and CD147 were evaluated in the ECs cultured with the patient’s serum by flow cytometry. We assessed endothelial permeability by measuring transendothelial electrical resistance in cocultures of ECs with patient serum. Results: Dengue infection led to an increase in inflammatory mediators—the IL-10 distinguished DF from DFWS/Sev. There were no changes in CD31, CD54, and CD106 but decreased CD147 expression in ECs. DFWS/Sev sera induced a greater difference in endothelial permeability than DF sera. Correlation statistical test indicated that low IL-10 and IFN-γ and high CCL5 maintain the integrity of ECs in DF patients. In contrast, increased TNF, IFN-γ, CXCL8, and CCL2 maintain EC integrity in DFWS/Sev patients. Conclusions: Our preliminary data suggest that a subset of inflammatory mediators may be related to the maintenance or loss of endothelial integrity, reflecting the clinical prognosis.

Immunocompetent Mice Infected by Two Lineages of Dengue Virus Type 2: Observations on the Pathology of the Lung, Heart and Skeletal Muscle

Dengue virus (DENV) infection by one of the four serotypes (DENV-1 to 4) may result in a wide spectrum of clinical manifestations, with unpredictable evolution and organ involvement. Due to its association with severe epidemics and clinical manifestations, DENV-2 has been substantially investigated. In fact, the first emergence of a new lineage of the DENV-2 Asian/American genotype in Brazil (Lineage II) in 2008 was associated with severe cases and increased mortality related to organ involvement. A major challenge for dengue pathogenesis studies has been a suitable animal model, but the use of immune-competent mice, although sometimes controversial, has proven to be useful, as histological observations in infected animals reveal tissue alterations consistent to those observed in dengue human cases. Here, we aimed to investigate the outcomes caused by two distinct lineages of the DENV-2 Asian/American genotype in the lung, heart and skeletal muscle tissues of infected BALB/c mice. Tissues were submitted to histopathology, immunohistochemistry, histomorphometry and transmission electron microscopy (TEM) analysis. The viral genome was detected in heart and skeletal muscle samples. The viral antigen was detected in cardiomyocytes and endothelial cells of heart tissue. Heart and lung tissue samples presented morphological alterations comparable to those seen in dengue human cases. Creatine kinase serum levels were higher in mice infected with both lineages of DENV-2. Additionally, statistically significant differences, concerning alveolar septa thickening and heart weight, were observed between BALB/c mice infected with both DENV-2 lineages, which was demonstrated to be an appropriate experimental model for dengue pathogenesis studies on lung, heart and skeletal muscle tissues.

Different Profiles of Cytokines, Chemokines and Coagulation Mediators Associated with Severity in Brazilian Patients Infected with Dengue Virus

The incidence of dengue in Latin America has increased dramatically during the last decade. Understanding the pathogenic mechanisms in dengue is crucial for the identification of biomarkers for the triage of patients. We aimed to characterize the profile of cytokines (IFN-γ, TNF-α, IL-1β, IL-6, IL-18 and IL-10), chemokines (CXCL8/IL-8, CCL2/MCP-1 and CXCL10/IP-10) and coagulation mediators (Fibrinogen, D-dimer, Tissue factor-TF, Tissue factor pathway inhibitor-TFPI and Thrombomodulin) during the dengue-4 epidemic in Brazil. Laboratory-confirmed dengue cases had higher levels of TNF-α (p < 0.001), IL-6 (p = 0.005), IL-10 (p < 0.001), IL-18 (p = 0.001), CXCL8/IL-8 (p < 0.001), CCL2/MCP-1 (p < 0.001), CXCL10/IP-10 (p = 0.001), fibrinogen (p = 0.037), D-dimer (p = 0.01) and TFPI (p = 0.042) and lower levels of TF (p = 0.042) compared to healthy controls. A principal component analysis (PCA) distinguished between two profiles of mediators of inflammation and coagulation: protective (TNF-α, IL-1β and CXCL8/IL-8) and pathological (IL-6, TF and TFPI). Lastly, multivariate logistic regression analysis identified high aspartate aminotransferase-to-platelet ratio index (APRI) as independent risk factors associated with severity (adjusted OR: 1.33; 95% CI 1.03–1.71; p = 0.027), the area under the receiver operating characteristics curve (AUC) was 0.775 (95% CI 0.681–0.869) and an optimal cutoff value was 1.4 (sensitivity: 76%; specificity: 79%), so it could be a useful marker for the triage of patients attending primary care centers.

Brazilian Dengue Virus Type 2-Associated Renal Involvement in a Murine Model: Outcomes after Infection by Two Lineages of the Asian/American Genotype

Dengue virus type 2 (DENV-2) is, traditionally, the most studied serotype due to its association with explosive outbreaks and severe cases. In Brazil, almost 20 years after the first introduction in the 1990s, a new lineage (Lineage II) of the DENV-2 Asian/American genotype emerged and caused an epidemic with severe cases and hospitalizations. Severe dengue includes multiple organ failure, and renal involvement can be potentially related to increased mortality. In order to better understand the role of DENV infection in renal injury, here we aimed to investigate the outcomes of infection with two distinct lineages of DENV-2 Asian/American genotype in the kidney of a murine model. BALB/c mice were infected with Lineages I and II and tissues were submitted to histopathology, immunohistochemistry, histomorphometry and ultrastructural analysis. Blood urea nitrogen (BUN) was detected in blood sample accessed by cardiac puncture. A tendency in kidney weight increase was observed in mice infected with both lineages, but urea levels, on average, were increased only in mice infected with Lineage II. The DENV antigen was detected in the tissue of mice infected with Lineage II and morphological changes were similar to those observed in human dengue cases. Furthermore, the parameters such as organ weight, urea levels and morphometric analysis, showed significant differences between the two lineages in the infected BALB/c, which was demonstrated to be a suitable experimental model for dengue pathophysiology studies in kidneys.