Study of interleukin-6 and interleukin-8 levels in patients with neurological manifestations of dengue

Age-specific dynamics of neutralizing antibodies, cytokines, and chemokines in response to La Crosse virus infection in mice

La Crosse virus (LACV) is a primary cause of pediatric arboviral encephalitis in the United States, particularly affecting children aged 16 years or younger. This age-related susceptibility extends to murine models, where weanling mice (3 weeks old) succumb to LACV infection, while adults (≥6 weeks old) demonstrate resistance. Despite its clinical relevance, the host immune response to LACV is not fully understood. In this study, we investigated the roles of neutralizing antibodies (nAbs), cytokines, and chemokines in weanling and adult mice following infection with 5 × 105 plaque-forming units (PFU) of LACV. Weanling mice demonstrated early disease onset with elevated peripheral viremia, but passive transfer of adult serum, confirmed to have nAbs, to naïve weanlings prior to infection completely rescued them from death. Moreover, adult mice had increased Th1 cytokines, Th9/Th17/Th22/Treg cytokines, and many chemokines. In contrast, weanlings had higher Th2 cytokines, correlating with symptoms onset. Flow cytometry and intracellular cytokine staining further demonstrated that weanling mice produced higher levels of IL-4 by CD4+ and CD8+ T cells compared to adults, regardless of infection status. Conversely, LACV-infected adult mice had increased IFN-γ production by CD8+ T cells compared to uninfected controls. Finally, the adoptive transfer of splenocytes from immune adult mice to naïve weanlings delayed neurological symptoms and improved survival. In conclusion, this study links nAbs and cytokine and chemokine responses to protective immunity in adult mice, contrasting with the pathogenesis seen in weanlings. These findings underscore the importance of further research into innate and adaptive immune mechanisms during LACV infection.IMPORTANCELa Crosse virus (LACV) is a primary cause of pediatric encephalitis in the United States, with an impact on children aged 16 years or younger. This age-related susceptibility is recapitulated in mouse models, where young mice succumb to LACV-induced disease, while adults demonstrate resistance. Our understanding of host responses to LACV remains underexplored. This study sheds light on the dynamics of neutralizing antibodies (nAbs), cytokines, and chemokines following LACV infection in both adult and weanling mice. Our study reveals age-specific variations in viremia, neutralizing antibody titers, survivability, and levels of cytokines and chemokines. Adult mice exhibit significantly elevated levels of Th1 cytokines, contrasting with elevated levels of Th2 cytokines observed in weanling mice, often coinciding with the onset of symptoms. These data reveal age-specific dynamics in cytokines and chemokines associated with protective versus pathogenic immunity, emphasizing the need for further studies on innate and adaptive immunity.

Dengue-Associated Acute Necrotizing Encephalopathy Is an Acute Necrotizing Encephalopathy Variant Rather than a Mimic: Evidence From a Systematic Review

BACKGROUND

Bilateral hemorrhagic thalamic lesions in dengue encephalitis resemble lesions seen in acute necrotizing encephalopathy (ANE). We investigate whether dengue-associated ANE (DANE) should be considered an ANE variant or a mimic.

METHODS

Systematic review of dengue encephalitis literature from PubMed and SCOPUS (inception to December 31, 2022). Diagnostic criteria for ANE, acute encephalitis (AE), acute disseminated encephalomyelitis (ADEM), and infection-triggered encephalopathy syndromes were applied.

RESULTS

Data on 162 patients (median age 20 [0.4 to 79] years; 69 [42.3%] female; 72 [44.4%] aged ≤18 years) from 103 articles were analyzed. DANE (62, 38.3%) was the commonest, followed by AE (56, 34.6%) and ADEM (27, 16.7%). The main clinical features were fever (100%), thrombocytopenia (79.0%), headache (57.8%), and seizures (43.7%). Patients with DANE had earlier neurological deterioration (3.5 [1 to 8] vs 5 [1 to 14] days in other encephalitis syndromes, P = 0.0127), seizures (54.2% vs 37.4%, P = 0.0471), higher cerebrospinal fluid (CSF) protein (0.92 [0.18 to 4.8] vs 0.73 [1 to 16] g/L, P = 0.0469), thalamic (100% vs 8.0%) and hemorrhagic brain lesions (73.3% vs 7.5%, P < 0.0001). CSF pleocytosis and positive CSF dengue IgM/viral polymerase chain reaction were reported in 66.7% and 78.6% with DANE. Mortality was 16.1% in DANE, and 40.6% of survivors had disability. High-risk ANE severity scores predicted poor outcomes (positive predictive value 64.3% [95% confidence interval 38.8% to 83.7%]).

CONCLUSION

DANE differs from other dengue encephalitis syndromes and is clinicoradiologically indistinguishable from sporadic ANE with sufficient evidence to be considered an ANE variant.

Zika virus infection suppresses CYP24A1 and CAMP expression in human monocytes

Monocytes are the primary targets of Zika virus (ZIKV) and are associated with ZIKV pathogenesis. Currently, there is no effective treatment for ZIKV infection. It is known that 1,25-dihydroxy vitamin D3 (VitD3) has strong antiviral activity in dengue virus-infected macrophages, but it is unknown whether VitD3 inhibits ZIKV infection in monocytes. We investigated the relationship between ZIKV infection and the expression of genes of the VitD3 pathway, as well as the inflammatory response of infected monocytes in vitro. ZIKV replication was evaluated using a plaque assay, and VitD3 pathway gene expression was analyzed by RT-qPCR. Pro-inflammatory cytokines/chemokines were quantified using ELISA. We found that VitD3 did not suppress ZIKV replication. The results showed a significant decrease in the expression of vitamin D3 receptor (VDR), cytochrome P450 family 24 subfamily A member 1 (CYP24A1), and cathelicidin antimicrobial peptide (CAMP) genes upon ZIKV infection. Treatment with VitD3 was unable to down-modulate production of pro-inflammatory cytokines, except TNF-α, and chemokines. This suggests that ZIKV infection inhibits the expression of VitD3 pathway genes, thereby preventing VitD3-dependent inhibition of viral replication and the inflammatory response. This is the first study to examine the effects of VitD3 in the context of ZIKV infection, and it has important implications for the role of VitD3 in the control of viral replication and inflammatory responses during monocyte infection.

Neurological Manifestations of Perinatal Dengue

Dengue viruses (DENVs) are single-stranded RNA viruses belonging to the family Flaviviridae. There are four distinct antigenically related serotypes, DENVs types 1, 2, 3, and 4. These are all mosquito-borne human pathogens. Congenital dengue disease occurs when there is mother-to-fetus transmission of the virus and should be suspected in endemic regions in neonates presenting with fever, maculopapular rash, and thrombocytopenia. Although most of the infected infants remain asymptomatic, some can develop clinical manifestations such as sepsis-like illness, gastric bleeding, circulatory failure, and death. Neurological manifestations include intracerebral hemorrhages, neurological malformations, and acute focal/disseminated encephalitis/encephalomyelitis. Dengue NS1Ag, a highly conserved glycoprotein, can help the detection of cases in the viremic stage. We do not have proven specific therapies yet; management is largely supportive and is focused on close monitoring and maintaining adequate intravascular volume.

Mechanisms of Neuroinvasion and Neuropathogenesis by Pathologic Flaviviruses

Flaviviruses are present on every continent and cause significant morbidity and mortality. In many instances, severe cases of infection with flaviviruses involve the invasion of and damage to the central nervous system (CNS). Currently, there are several mechanisms by which it has been hypothesized flaviviruses reach the brain, including the disruption of the blood-brain barrier (BBB) which acts as a first line of defense by blocking the entry of many pathogens into the brain, passing through the BBB without disruption, as well as travelling into the CNS through axonal transport from peripheral nerves. After flaviviruses have entered the CNS, they cause different neurological symptoms, leading to years of neurological sequelae or even death. Similar to neuroinvasion, there are several identified mechanisms of neuropathology, including direct cell lysis, blockage of the cell cycle, indication of apoptosis, as well as immune induced pathologies. In this review, we aim to summarize the current knowledge in the field of mechanisms of both neuroinvasion and neuropathogenesis during infection with a variety of flaviviruses and examine the potential contributions and timing of each discussed pathway.

Molecular Mechanism and Role of Japanese Encephalitis Virus Infection in Central Nervous System-Mediated Diseases

The Japanese encephalitis virus (JEV) is the most common cause of neurodegenerative disease in Southeast Asia and the Western Pacific region; approximately 1.15 billion people are at risk, and thousands suffer from permanent neurological disorders across Asian countries, with 10-15 thousand people dying each year. JEV crosses the blood-brain barrier (BBB) and forms a complex with receptors on the surface of neurons. GRP78, Src, TLR7, caveolin-1, and dopamine receptor D2 are involved in JEV binding and entry into the neurons, and these receptors also play a role in carcinogenic activity in cells. JEV binds to GRP78, a member of the HSP70 overexpressed on malignant cells to enter neurons, indicating a higher chance of JEV infection in cancer patients. However, JEV enters human brain microvascular endothelial cells via an endocytic pathway mediated by caveolae and the ezrin protein and also targets dopamine-rich areas for infection of the midbrain via altering dopamine levels. In addition, JEV complexed with CLEC5A receptor of macrophage cells is involved in the breakdown of the BBB and central nervous system (CNS) inflammation. CLEC5A-mediated infection is also responsible for the influx of cytokines into the CNS. In this review, we discuss the neuronal and macrophage surface receptors involved in neuronal death.

Serum IL-18 Is a Potential Biomarker for Predicting Severe Dengue Disease Progression

Background. Dengue virus (DENV) infection is the most common arboviral disease that affects tropical and subtropical regions. Based on the clinical hallmarks, the different severities of patients range from mild dengue fever (MDF) to severe dengue diseases (SDDs) and include dengue hemorrhagic fever or dengue shock syndrome. These are commonly associated with cytokine release syndrome (CRS). The types and levels of cytokines/chemokines, which are suppressed or enhanced, are varied, indicating CRS's pathogenic and host defensive effects. Principal Finding. In this study, we created an integrated and precise multiplex panel of cytokine/chemokine assays based on our literature analysis to monitor dengue CRS. A 24-plex panel of cytokines/chemokines was evaluated to measure the plasma levels of targeting factors in dengue patients with an MDF and SDD diagnosis without or with comorbidities. As identified in sixteen kinds of cytokines/chemokines, ten were significantly (P < 0.05) (10/16) increased, one was significantly (P < 0.01) (1/16) decreased, and five were potentially (5/16) altered in all dengue patients (n = 30) in the acute phase of disease onset. Compared to MDF, the levels of IL-8 (CXCL-8) and IL-18 in SDD were markedly (P < 0.05) increased, accompanied by positively increased IL-6 and TNF-α and decreased IFN-γ and RANTES. With comorbidities, SDD significantly (P < 0.01) portrayed elevated IL-18 accompanied by increased IL-6 and decreased IFN-α2 and IL-12. In addition, decreased platelets were significantly (P < 0.05) associated with increased IL-18. Significance. These results demonstrate an efficient panel of dengue cytokine/chemokine assays used to explore the possible level of CRS during the acute phase of disease onset; also, we are the first to report the increase of IL-18 in severe dengue with comorbidity compared to severe dengue without comorbidity and mild dengue.

Correlation of serotype-specific strain in patients with dengue virus infection with neurological manifestations and its outcome

INTRODUCTION

Neurological manifestation of dengue virus infection is a rare entity. Serotypes commonly associated with neurological manifestation are DENV-2 and DENV-3. We plan to detect the serotypes related to the neurological presentation in dengue infection and its correlation with different neurological complications and outcome.

METHODS

In this case-control study, consecutive dengue cases with different neurological manifestations were enrolled along with age and sex-matched controls (dengue patients without neurological complication). Serotyping using RT-PCR of samples of cases and controls were done. Level of correlation was analyzed with various parameters and outcomes.

RESULTS

In cases out of 33 samples, 6 sample serotypes were detected, which were composed of DENV-1 (n = 2) and DENV-2 (n = 4). In controls, DENV-1 (n = 5), DENV-2 (n = 6), and DENV-3 (n = 3) were detected. When statistically correlated, no significant association was found in cases and controls with dengue virus serotype. The frequency of serotype 2 was higher in hypokalemic paralysis cases than non-hypokalemic paralysis cases and the difference was significant (p < 0.05). The outcome was good (mRS < 3) in all the cases where serotypes were detected, but on statistical correlation, it was not found significant (p > 0.05).

CONCLUSION

DENV-1 and DENV-2 are associated with neurological manifestation of dengue infection, which is different from the existing literature, where DENV-2 and DENV-3 are reported. The detection of DENV serotype will help in predicting and best management of neurological complication. The serotype 2 of dengue virus is more commonly associated with dengue-associated hypokalemic paralysis than other neurological complication (p < 0.05). There is no significant association of serotypes with outcome or mortality.

Current Understanding of the Pathogenesis of Dengue Virus Infection

The pathogenesis of dengue virus infection is attributed to complex interplay between virus, host genes and host immune response. Host factors such as antibody-dependent enhancement (ADE), memory cross-reactive T cells, anti-DENV NS1 antibodies, autoimmunity as well as genetic factors are major determinants of disease susceptibility. NS1 protein and anti-DENV NS1 antibodies were believed to be responsible for pathogenesis of severe dengue. The cytokine response of cross-reactive CD4+ T cells might be altered by the sequential infection with different DENV serotypes, leading to further elevation of pro-inflammatory cytokines contributing a detrimental immune response. Fcγ receptor-mediated antibody-dependent enhancement (ADE) results in release of cytokines from immune cells leading to vascular endothelial cell dysfunction and increased vascular permeability. Genomic variation of dengue virus and subgenomic flavivirus RNA (sfRNA) suppressing host immune response are viral determinants of disease severity. Dengue infection can lead to the generation of autoantibodies against DENV NS1antigen, DENV prM, and E proteins, which can cross-react with several self-antigens such as plasminogen, integrin, and platelet cells. Apart from viral factors, several host genetic factors and gene polymorphisms also have a role to play in pathogenesis of DENV infection. This review article highlights the various factors responsible for the pathogenesis of dengue and also highlights the recent advances in the field related to biomarkers which can be used in future for predicting severe disease outcome.

Alkaloids of Abuta panurensis Eichler: In silico and in vitro study of acetylcholinesterase inhibition, cytotoxic and immunomodulatory activities

Natural products obtained from species of the genus Abuta (Menispermaceae) are known as ethnobotanicals that are attracting increasing attention due to a wide range of their pharmacological properties. In this study, the alkaloids stepharine and 5-N-methylmaytenine were first isolated from branches of Abuta panurensis Eichler, an endemic species from the Amazonian rainforest. Structure of the compounds was elucidated by a combination of 1D and 2D NMR spectroscopic and MS and HRMS spectrometric techniques. Interaction of the above-mentioned alkaloids with acetylcholinesterase enzyme and interleukins IL-6 and IL-8 was investigated in silico by molecular docking. The molecules under investigation were able to bind effectively with the active sites of the AChE enzyme, IL-6, and IL-8 showing affinity towards the proteins. Along with the theoretical study, acetylcholinesterase enzyme inhibition, cytotoxic, and immunomodulatory activity of the compounds were assessed by in vitro assays. The data obtained in silico corroborate the results of AChE enzyme inhibition, the IC50 values of 61.24μM for stepharine and 19.55μM for 5-N-methylmaytenine were found. The compounds showed cytotoxic activity against two tumor cell lines (K562 and U937) with IC50 values ranging from 11.77 μM to 28.48 μM. The in vitro assays revealed that both alkaloids were non-toxic to Vero and human PBMC cells. As for the immunomodulatory activity, both compounds inhibited the production of IL-6 at similar levels. Stepharine inhibited considerably the production of IL-8 in comparison to 5-N-methylmaytenine, which showed a dose dependent action (inhibitory at the IC50 dose, and stimulatory at the twofold IC50 one). Such a behavior may possibly be explained by different binding modes of the alkaloids to the interleukin structural fragments. Occurrence of the polyamine alkaloid 5-N-methylmaytenine was reported for the first time for the Menispermaceae family, as well as the presence of stepharine in A. panurensis.

Highlights for Dengue Immunopathogenesis: Antibody-Dependent Enhancement, Cytokine Storm, and Beyond

Infection with dengue virus (DENV) can lead to a wide spectrum of clinical presentations, ranging from asymptomatic infection to death. It is estimated that the disease manifests only in 90 million cases out of the total 390 million yearly infections. Even though research has not yet elucidated which are the precise pathophysiological mechanisms that trigger severe forms of dengue, the infection elicits a critical immune response significant for dengue pathogenesis development. Understanding how the immune response to DENV is established and how it can resolve the infection or turn into an immunopathology is of great importance in DENV research. Currently, studies have extensively debated 2 hypotheses involving immune response: antibody-dependent enhancement and cytokine storm. However, despite its undeniable importance in severe forms of the disease, these 2 hypotheses are based on a primed immune status resulting from previous heterologous infection, abstaining them from explaining the severe forms of dengue in naive immune subjects, for example. Thus, it seems that a more intricate arrangement of causes and conditions must be achieved to severe dengue to occur. Among them, the cytokine network signature elicited, in association with viral aspects deserves special attention regarding the establishment of infection and evolution to pathogenesis. In this work, we intend to shed light on how those elements contribute to severe dengue development.

Hyperlipidemia, statin use and dengue severity

Multiple in vitro and mice model studies suggest statins may attenuate dengue severity. However, little is known about statin use and dengue severity in adult dengue patients with hyperlipidemia. We conducted a retrospective cohort study from 2004–2008 and 2012–2013 in Tan Tock Seng Hospital, Singapore on adult dengue patients with hyperlipidemia, comparing those with and without statin usage at hospitalization in terms of primary outcome of dengue hemorrhagic fever (DHF) or shock syndrome (DSS), and severe dengue (SD). Of 13,975 subjects screened, 257 dengue patients were included; 191 (74.3%) were statin users and 66 (25.7%) were non-users. Compared with non-users, statin use was not associated with decreased risk of DHF/DSS (adjusted risk ratio [aRR] = 0.66, 95%confidence interval [CI]: 0.41–1.08, P = 0.10) and SD (aRR = 1.43, 95%CI: 0.84–2.43, P = 0.19). Therefore, statin usage had minimal effect on dengue severity in our study population in Singapore.

ZIKV Infection Induces an Inflammatory Response but Fails to Activate Types I, II, and III IFN Response in Human PBMC

The recent epidemic in the Americas caused by Zika virus (ZIKV), Asian lineage, spurred the research towards a better understanding of how ZIKV infection affects the host immune response. The aim of this study was to evaluate the effects of Asian and East African ZIKV strain infection on the induction of IFN and proinflammatory and Th2 cytokines in human PBMC. We reported a slight modulation of type II IFN in PBMC exposed to Asian strain, but not to African strain, and a complete lack of type I and III IFN induction by both strains, suggesting the ability of ZIKV to evade the IFN system not only inhibiting the antiviral IFN response but also IFN production. Moreover, we highlighted a polyfunctional immune activation only in PBMC exposed to Asian strain, due to the induction of an inflammatory profile (IL-6, IL-8) and of a Th9 (IL-9) response. Overall, our data show a different ability of the ZIKV Asian strain, with respect to the African strain, to activate host immune response that may have pathogenetic implications for virus spread in vivo, including mother-to-child transmission and induction of severe fetal complications, as birth defects and neurological disorders.