The combination of valacyclovir with an anti-TNF alpha antibody increases survival rate compared to antiviral therapy alone in a murine model of herpes simplex virus encephalitis

Modelling viral encephalitis caused by herpes simplex virus 1 infection in cerebral organoids

Herpes simplex encephalitis is a life-threatening disease of the central nervous system caused by herpes simplex viruses (HSVs). Following standard of care with antiviral acyclovir treatment, most patients still experience various neurological sequelae. Here we characterize HSV-1 infection of human brain organoids by combining single-cell RNA sequencing, electrophysiology and immunostaining. We observed strong perturbations of tissue integrity, neuronal function and cellular transcriptomes. Under acyclovir treatment viral replication was stopped, but did not prevent HSV-1-driven defects such as damage of neuronal processes and neuroepithelium. Unbiased analysis of pathways deregulated upon infection revealed tumour necrosis factor activation as a potential causal factor. Combination of anti-inflammatory drugs such as necrostatin-1 or bardoxolone methyl with antiviral treatment prevented the damages caused by infection, indicating that tuning the inflammatory response in acute infection may improve current therapeutic strategies.

Neurological risks and benefits of cytokine-based treatments in coronavirus disease 2019: from preclinical to clinical evidence

Immunodeficiency and hyperinflammation are responsible for the most frequent and life-threatening forms of coronavirus disease 2019 (COVID-19). Therefore, cytokine-based treatments targeting immuno-inflammatory mechanisms are currently undergoing clinical scrutiny in COVID-19-affected patients. In addition, COVID-19 patients also exhibit a wide range of neurological manifestations (neuro-COVID), which may also benefit from cytokine-based treatments. In fact, such drugs have shown some clinical efficacy also in neuroinflammatory diseases. On the other hand, anti-cytokine drugs are endowed with significant neurological risks, mainly attributable to their immunodepressant effects. Therefore, the aim of the present manuscript is to briefly describe the role of specific cytokines in neuroinflammation, to summarize the efficacy in preclinical models of neuroinflammatory diseases of drugs targeting these cytokines and to review the clinical data regarding the neurological effects of these drugs currently being investigated against COVID-19, in order to raise awareness about their potentially beneficial and/or detrimental neurological consequences.

Immunomodulatory Strategies in Herpes Simplex Virus Encephalitis

Herpes simplex virus 1 (HSV-1) can be responsible for life-threatening HSV encephalitis (HSE). The mortality rate of patients with HSE who do not receive antiviral treatment is 70%, with most survivors suffering from permanent neurological sequelae. The use of intravenous acyclovir together with improved diagnostic technologies such as PCR and magnetic resonance imaging has resulted in a reduction in the mortality rate to close to 20%. However, 70% of surviving patients still do not recover complete neurological functions. Thus, there is an urgent need to develop more effective treatments for a better clinical outcome. It is well recognized that cerebral damage resulting from HSE is caused by viral replication together with an overzealous inflammatory response. Both of these processes constitute potential targets for the development of innovative therapies against HSE. In this review, we discuss recent progress in therapy that may be used to ameliorate the outcome of patients with HSE, with a particular emphasis on immunomodulatory agents. Ideally, the administration of adjunctive immunomodulatory drugs should be initiated during the rise of the inflammatory response, and its duration should be limited in time to reduce undesired effects. This critical time frame should be optimized by the identification of reliable biomarkers of inflammation.

Roles of HSV-1 infection-induced microglial immune responses in CNS diseases: friends or foes?

Microglia, as brain-resident macrophages, are the first line of defense against brain invading pathogens. Further, their dysfunction has been recognized to be closely associated with mounting CNS diseases. Of note, chronic HSV-1 infection leads to the persistent activation of microglia, which elicit a comprehensive response by generating certain factors with neurotoxic and neuroprotective effects. CNS infection with HSV-1 results in herpes simplex encephalitis and herpes simplex keratitis. Microglial immune response plays a crucial role in the development of these diseases. Moreover, HSV-1 infection is strongly associated with several CNS diseases, especially Alzheimer's disease and schizophrenia. These CNS diseases can be effectively ameliorated by eliciting an appropriate immune response, such as inhibition of microglial proliferation and activation. Therefore, it is crucial to reassess the positive and negative roles of microglia in HSV-1 CNS infection for a more comprehensive and detailed understanding of the relationship between microglia and CNS diseases. Hence, the present review focuses on the dual roles of microglia in mediating HSV-1 CNS infection, as well as on the strategy of targeting microglia to ameliorate CNS diseases. Further research in this field can help comprehensively elucidate the dual role of the microglial immune response in HSV-1 CNS infection, providing a theoretical basis for identifying therapeutic targets against overactive microglia in CNS diseases and HSV-1 infection.

Both IRF3 and especially IRF7 play a key role to orchestrate an effective cerebral inflammatory response in a mouse model of herpes simplex virus encephalitis

The impact of a deficiency in interferon regulatory factor (IRF)3 and IRF7 was evaluated in an herpes simplex virus encephalitis (HSE) model. Compared to wild type (WT), the mortality rates of infected IRF3^-/- and IRF7^-/- mice were higher and associated with increased brain viral titers. At a critical time post-infection, IRF7^-/- mice exhibited a deficit in IFN-β production. At a later time point, levels of type I IFNs and cytokines were increased in brains of both deficient mice compared to WT. Our results suggest that IRF3, and especially IRF7, are important for an effective control of inflammatory responses during HSE.

Herpes Simplex Encephalitis: an Update

PURPOSE OF REVIEW

The goal of this review is to provide an update on current thinking regarding herpes simplex encephalitis (HSE), emphasizing new information about pathogenesis, diagnosis, and immune responses. Specific questions to be addressed are the following: (1) Is there a genetic predisposition to HSE? (2) What clinical approaches have the greatest impact on improving the long-term outcomes in patients with HSE? And (3) are there immune-mediated mechanisms that may account for relapsing HSE?

RECENT FINDINGS

Toll-like receptor 3 (TLR 3) plays an important role in innate immune responses, including generation of interferons. Multiple single-gene errors in TLR 3 interferon pathways have recently been described in children that result in increased susceptibility to HSE. Conversely, studies in both animal models and humans indicate that both cytolytic viral replication and immune-mediated responses (including cytotoxic T lymphocytes and immune mechanisms mediated by TLR 2) contribute to the pathology of HSV, suggesting possible new therapeutic approaches. In terms of treatment, data clearly indicate that a longer duration between onset of symptoms and initiation of effective antiviral therapy correlates directly with less favorable clinical outcome. Recurrent or relapsing HSE may occasionally occur, but recent observations indicate that many instances of "relapsing HSE", especially in children, are more often anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis triggered by the antecedent HSV infection. Innate immune responses are critical for defense against HSV; genetic defects in this system may predispose patients to HSE. During acute HSE, exuberant immune responses may contribute to the CNS pathology, suggesting that selective immunosuppressive therapy, coupled with potent antiviral drugs, may eventually play a role in the therapeutic management of HSV. While overall clinical outcomes of HSE remain suboptimal, the initiation of high-dose acyclovir therapy as early as possible in the course of the illness provides the best chance for a patient to survive with minimal neurologic damage. Distinguishing relapsing HSE from autoimmune anti-NMDAR antibody encephalitis is critically important because therapeutic approaches will be very different.

BAI1 Orchestrates Macrophage Inflammatory Response to HSV Infection-Implications for Oncolytic Viral Therapy

Purpose: Brain angiogenesis inhibitor (BAI1) facilitates phagocytosis and bacterial pathogen clearance by macrophages; however, its role in viral infections is unknown. Here, we examined the role of BAI1, and its N-terminal cleavage fragment (Vstat120) in antiviral macrophage responses to oncolytic herpes simplex virus (oHSV).Experimental Design: Changes in infiltration and activation of monocytic and microglial cells after treatment of glioma-bearing mice brains with a control (rHSVQ1) or Vstat120-expressing (RAMBO) oHSV was analyzed using flow cytometry. Co-culture of infected glioma cells with macrophages or microglia was used to examine antiviral signaling. Cytokine array gene expression and Ingenuity Pathway Analysis (IPA) helped evaluate changes in macrophage signaling in response to viral infection. TNFα-blocking antibodies and macrophages derived from Bai1^-/- mice were used.Results: RAMBO treatment of mice reduced recruitment and activation of macrophages/microglia in mice with brain tumors, and showed increased virus replication compared with rHSVQ1. Cytokine gene expression array revealed that RAMBO significantly altered the macrophage inflammatory response to infected glioma cells via altered secretion of TNFα. Furthermore, we showed that BAI1 mediated macrophage TNFα induction in response to oHSV therapy. Intracranial inoculation of wild-type/RAMBO virus in Bai1^-/- or wild-type non-tumor-bearing mice revealed the safety of this approach.Conclusions: We have uncovered a new role for BAI1 in facilitating macrophage anti-viral responses. We show that arming oHSV with antiangiogenic Vstat120 also shields them from inflammatory macrophage antiviral response, without reducing safety. Clin Cancer Res; 23(7); 1809-19. ©2016 AACR.

Strychnos pseudoquina A. St. Hil.: a Brazilian medicinal plant with promising in vitro antiherpes activity

AIMS

To investigate the anti-HSV and anti-inflammatory effects of a standardized ethyl acetate extract (SEAE) prepared with the stem bark of Strychnos pseudoquina, along with two isolated compounds: quercetin 3-O-methyl ether (3MQ) and strychnobiflavone (SBF).

METHODS AND RESULTS

The mechanisms of action were evaluated by different methodological strategies. SEAE and SBF affected the early stages of viral infection and reduced HSV-1 protein expression. Both flavonoids elicited a concentration-dependent inhibition of monocyte chemoattractant protein-1 (MCP-1), whereas 3MQ reduced the chemokine release more significantly than SBF. Conversely, both compounds stimulated the production of the cytokines TNF-α and IL-1-β in LPS-stimulated cells, especially at the intermediate and the highest tested concentrations.

CONCLUSIONS

SEAE and SBF interfered with various steps of HSV replication cycle, mainly adsorption, postadsorption and penetration, as well as with β and γ viral proteins expression; moreover, a direct inactivation of viral particles was observed. Besides, both flavonoids inhibited MCP-1 selectively, a feature that may be beneficial for the development of new anti-HSV agents.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results indicated that the samples present anti-HSV and anti-inflammatory activities, at different levels, which is an interesting feature since cold and genital sores are accompanied by an inflammation process.

The effect of captopril on the expression of MMP-9 and the prognosis of neurological function in herpes simplex encephalitis mice

BACKGROUND AND PURPOSE

Early increased matrix metalloproteinase-9 (MMP-9) expression is involved in the evolution of herpes simplex encephalitis (HSE) by facilitating the development of cerebrovascular complications. However, the molecular mechanism underlying the detrimental effects of MMP-9 in HSE has not been elucidated. Recent research finds angiotensin II plays an important role in regulation of MMP-9 activity. The aim of this work was to identify the influence of angiotensin-converting enzyme inhibitor (ACEI) captopril on MMP-9 activation after herpes simplex virus 1 (HSV-1) infection.

METHODS

Animal models of HSE were established by intracerebral inoculation of HSV-1 into mice. Brain tissue ROS levels were measured by staining with dihydroethidium. MMP-9 protein expression was detected by immunofluorescence and brain water content was measured with dry-wet weight method. Neurological function score was quantified 5 d after HSV-1 infection. Microglial cells were treated with various concentrations of captopril. MMP-9 gelatinolytic activity in the supematant of the cell cultures was assessed by zymography. RT-PCR was used to detect the mRNA expressions of p47phox and MMP-9.

RESULTS

Immunofluorescence showed that expression of MMP-9 in brain tissue was mainly presented in OX-42 positive microglia. Quantification of gelatinolytic activity by densitometry showed that expression of MMP-9 in microglia was significantly increased after HSV-1 infection and inhibited by captopril treatment. NADPH oxidase subunit p47phox and MMP-9 mRNA expression were significantly increased 6 h after HSV-1 infection, and were seen reduced after captopril treatment in dose dependence. Captopril also downregulated ROS and MMP-9 protein expression following encephalitis in vivo, and attenuated brain edema, and improved neurological function.

DISCUSSION

This compelling evidence suggests that MMP-9 is a key pathogenic factor within HSE. ACEI captopril could reduce the expression of MMP-9 mediated by ROS, then relieve cerebral edema and improve neurological function, which may lay a foundation for further basic research and clinical application.

Perispinal Delivery of CNS Drugs

Perispinal injection is a novel emerging method of drug delivery to the central nervous system (CNS). Physiological barriers prevent macromolecules from efficiently penetrating into the CNS after systemic administration. Perispinal injection is designed to use the cerebrospinal venous system (CSVS) to enhance delivery of drugs to the CNS. It delivers a substance into the anatomic area posterior to the ligamentum flavum, an anatomic region drained by the external vertebral venous plexus (EVVP), a division of the CSVS. Blood within the EVVP communicates with the deeper venous plexuses of the CSVS. The anatomical basis for this method originates in the detailed studies of the CSVS published in 1819 by the French anatomist Gilbert Breschet. By the turn of the century, Breschet's findings were nearly forgotten, until rediscovered by American anatomist Oscar Batson in 1940. Batson confirmed the unique, linear, bidirectional and retrograde flow of blood between the spinal and cerebral divisions of the CSVS, made possible by the absence of venous valves. Recently, additional supporting evidence was discovered in the publications of American neurologist Corning. Analysis suggests that Corning's famous first use of cocaine for spinal anesthesia in 1885 was in fact based on Breschet's anatomical findings, and accomplished by perispinal injection. The therapeutic potential of perispinal injection for CNS disorders is highlighted by the rapid neurological improvement in patients with otherwise intractable neuroinflammatory disorders that may ensue following perispinal etanercept administration. Perispinal delivery merits intense investigation as a new method of enhanced delivery of macromolecules to the CNS and related structures.

Infiltration Pattern of Blood Monocytes into the Central Nervous System during Experimental Herpes Simplex Virus Encephalitis

The kinetics and distribution of infiltrating blood monocytes into the central nervous system and their involvement in the cerebral immune response together with resident macrophages, namely microglia, were evaluated in experimental herpes simplex virus 1 (HSV-1) encephalitis (HSE). To distinguish microglia from blood monocyte-derived macrophages, chimeras were generated by conditioning C57BL/6 recipient mice with chemotherapy regimen followed by transplantation of bone morrow-derived cells that expressed the green fluorescent protein. Mice were infected intranasally with a sub-lethal dose of HSV-1 (1.2x10⁶ plaque forming units). Brains were harvested prior to and on days 4, 6, 8 and 10 post-infection for flow cytometry and immunohistochemistry analysis. The amounts of neutrophils (P<0.05) and «Ly6C^hi» inflammatory monocytes (P<0.001) significantly increased in the CNS compared to non-infected controls on day 6 post-infection, which corresponded to more severe clinical signs of HSE. Levels decreased on day 8 for both leukocytes subpopulations (P<0.05 for inflammatory monocytes compared to non-infected controls) to reach baseline levels on day 10 following infection. The percentage of «Ly6C^low» patrolling monocytes significantly increased (P<0.01) at a later time point (day 8), which correlated with the resolution phase of HSE. Histological analysis demonstrated that blood leukocytes colonized mostly the olfactory bulb and the brainstem, which corresponded to regions where HSV-1 particles were detected. Furthermore, infiltrating cells from the monocytic lineage could differentiate into activated local tissue macrophages that express the microglia marker, ionized calcium-binding adaptor molecule 1. The lack of albumin detection in the brain parenchyma of infected mice showed that the infiltration of blood leukocytes was not necessarily related to a breakdown of the blood-brain barrier but could be the result of a functional recruitment. Thus, our findings suggest that blood monocyte-derived macrophages infiltrate the central nervous system and may contribute, with resident microglia, to the innate immune response seen during experimental HSE.

Therapeutic effect of anti-feline TNF-alpha monoclonal antibody for feline infectious peritonitis

Feline infectious peritonitis virus (FIPV) replication in macrophages/monocytes induced tumor necrosis factor (TNF)-alpha production, and that the TNF-alpha produced was involved in aggravating the pathology of FIP. We previously reported the preparation of a feline TNF-alpha (fTNF-alpha)-neutralizing mouse monoclonal antibody (anti-fTNF-alpha mAb). This anti-fTNF-alpha mAb 2–4 was confirmed to inhibit the following fTNF-alpha-induced conditions in vitro. In the present study, we investigated whether mAb 2–4 improved the FIP symptoms and survival rate of experimentally FIPV-inoculated SPF cats. Progression to FIP was prevented in 2 out of 3 cats treated with mAb 2–4, whereas all 3 cats developed FIP in the placebo control group. Plasma alpha1-glycoprotein and vascular endothelial growth factor levels were improved by the administration of mAb 2–4, and the peripheral lymphocyte count also recovered. These results strongly suggested that the anti-fTNF-alpha antibody is effective for the treatment of FIP.

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Feline infectious peritonitis (FIP) is a coronavirus-induced fatal disease in cats.

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We investigated therapeutic effect of anti-fTNF-α mAb for experimental FIP infection.

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Anti-fTNF-α mAb improved the FIP symptoms and survival rate in 2 of 3 cats.

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Anti-fTNF-α mAb improved plasma AGP and VEGF level and lymphopenia.

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The results suggested the anti-fTNF-α mAb may be effective for the treatment of FIP.

Valacyclovir combined with artesunate or rapamycin improves the outcome of herpes simplex virus encephalitis in mice compared to antiviral therapy alone

Despite antiviral therapy, the mortality rate of herpes simplex virus encephalitis (HSE) remains high and many surviving patients harbor neurological sequelae. Although viral replication is responsible for substantial neurological damages, an exaggerated inflammatory response could also contribute to this process. Artesunate (ART) and rapamycin (RAPA) have shown some benefits in the treatment of herpes simplex virus infections. Herein, we evaluated the benefit of combining ART or RAPA with valacyclovir (VACV) in a murine model of HSE. Infected mice were treated with VACV (1mg/mL in drinking water) from day 3 post-infection (p.i.) combined or not with daily intraperitoneal administration of ART (30mg/kg) or RAPA (20mg/kg) from days 4 to 13 p.i. Viral load, infectious titers, cytokine and chemokine levels were measured in brain homogenates on days 5, 7 and 9. The survival rates of mice treated with VACV and ART or RAPA were higher than with VACV alone (71.9% versus 43.2% for ART and 66.7% versus 43.2% for RAPA; both P⩽0.05) but no significant difference was seen in the brain viral loads. Levels of IL-1β, IL-2 (both P⩽0.05), IL-6, IFN-γ (both P⩽0.01), CCL2 (P⩽0.01), CCL3 and CCL4 (both P⩽0.05) were reduced in mice treated with VACV combined with ART versus VACV alone. Levels of IL-6, IL-1β and IFN-γ slightly increased on day 7 in mice treated with VACV combined with RAPA compared to VACV alone and then decreased on day 9. Our results suggest that immunomodulatory compounds such as ART or RAPA could benefit antiviral therapy in HSE.

Innate immune response during herpes simplex virus encephalitis and development of immunomodulatory strategies

Herpes simplex viruses are large double-stranded DNA viruses. These viruses have the ability to establish a lifelong latency in sensory ganglia and to invade and replicate in the CNS. Apart from relatively benign mucosal infections, HSV is responsible for severe illnesses including HSV encephalitis (HSE). HSE is the most common cause of sporadic, potentially fatal viral encephalitis in Western countries. If left untreated, the mortality rate associated with HSE is approximately 70%. Despite antiviral therapy, the mortality is still higher than 30%, and almost 60% of surviving individuals develop neurological sequelae. It is suggested that direct virus-related and indirect immune-mediated mechanisms contribute to the damages occurring in the CNS during HSE. In this manuscript, we describe the innate immune response to HSV, the development of HSE in mice knock-out for proteins of the innate immune system as well as inherited deficiencies in key components of the signaling pathways involved in the production of type I interferon that could predispose individuals to develop HSE. Finally, we review several immunomodulatory strategies aimed at modulating the innate immune response at a critical time after infection that were evaluated in mouse models and could be combined with antiviral therapy to improve the prognosis of HSE. In conclusion, the cerebral innate immune response that develops during HSE is a "double-edged sword" as it is critical to control viral replication in the brain early after infection, but, if left uncontrolled, may also result in an exaggerated inflammatory response that could be detrimental to the host.

The Impact of Macrophage- and Microglia-Secreted TNFα on Oncolytic HSV-1 Therapy in the Glioblastoma Tumor Microenvironment

PURPOSE

Oncolytic herpes simplex viruses (oHSV) represent a promising therapy for glioblastoma (GBM), but their clinical success has been limited. Early innate immune responses to viral infection reduce oHSV replication, tumor destruction, and efficacy. Here, we characterized the antiviral effects of macrophages and microglia on viral therapy for GBM.

EXPERIMENTAL DESIGN

Quantitative flow cytometry of mice with intracranial gliomas (±oHSV) was used to examine macrophage/microglia infiltration and activation. In vitro coculture assays of infected glioma cells with microglia/macrophages were used to test their impact on oHSV replication. Macrophages from TNFα-knockout mice and blocking antibodies were used to evaluate the biologic effects of TNFα on virus replication. TNFα blocking antibodies were used to evaluate the impact of TNFα on oHSV therapy in vivo.

RESULTS

Flow-cytometry analysis revealed a 7.9-fold increase in macrophage infiltration after virus treatment. Tumor-infiltrating macrophages/microglia were polarized toward a M1, proinflammatory phenotype, and they expressed high levels of CD86, MHCII, and Ly6C. Macrophages/microglia produced significant amounts of TNFα in response to infected glioma cells in vitro and in vivo. Using TNFα-blocking antibodies and macrophages derived from TNFα-knockout mice, we discovered TNFα-induced apoptosis in infected tumor cells and inhibited virus replication. Finally, we demonstrated the transient blockade of TNFα from the tumor microenvironment with TNFα-blocking antibodies significantly enhanced virus replication and survival in GBM intracranial tumors.

CONCLUSIONS

The results of these studies suggest that FDA approved TNFα inhibitors may significantly improve the efficacy of oncolytic virus therapy.

Evasion of early antiviral responses by herpes simplex viruses

Besides overcoming physical constraints, such as extreme temperatures, reduced humidity, elevated pressure, and natural predators, human pathogens further need to overcome an arsenal of antimicrobial components evolved by the host to limit infection, replication and optimally, reinfection. Herpes simplex virus-1 (HSV-1) and herpes simplex virus-2 (HSV-2) infect humans at a high frequency and persist within the host for life by establishing latency in neurons. To gain access to these cells, herpes simplex viruses (HSVs) must replicate and block immediate host antiviral responses elicited by epithelial cells and innate immune components early after infection. During these processes, infected and noninfected neighboring cells, as well as tissue-resident and patrolling immune cells, will sense viral components and cell-associated danger signals and secrete soluble mediators. While type-I interferons aim at limiting virus spread, cytokines and chemokines will modulate resident and incoming immune cells. In this paper, we discuss recent findings relative to the early steps taking place during HSV infection and replication. Further, we discuss how HSVs evade detection by host cells and the molecular mechanisms evolved by these viruses to circumvent early antiviral mechanisms, ultimately leading to neuron infection and the establishment of latency.