Requirements for the Upregulation of Interleukin-6 by Herpes Simplex Virus-Infected Gingival Fibroblasts

Cetylpyridinium Chloride-Containing Mouthwashes Show Virucidal Activity against Herpes Simplex Virus Type 1

The oral cavity is particularly susceptible to viral infections that are self-recovering in most cases. However, complications may appear in severe cases and/or immunocompromised subjects. Cetylpyridinium chloride (CPC)-containing mouthwashes are able to decrease the infectivity of the SARS-CoV-2 virus by disrupting the integrity of the viral envelope. Here, we show that CPC, as the active ingredient contained in commercialized, exerts significant antiviral activity against enveloped viruses, such as HSV-1, but not against non-enveloped viruses, such as HPV. CPC-containing mouthwashes have been used as antiseptics for decades, and thus, they can represent a cost-effective measure to limit infection and spread of enveloped viruses infecting the oral cavity, aiding in reducing viral transmission.

Cetylpyridinium chloride blocks herpes simplex virus replication in gingival fibroblasts

Infections with herpes simplex viruses are lifelong and highly prevalent worldwide. Individuals with clinical symptoms elicited by HSVs may suffer from occasional or recurrent herpetic lesions in the orofacial and genital areas. Despite the existence of nucleoside analogues that interfere with HSV replication, such as acyclovir, these drugs are somewhat ineffective in treating skin lesions as topical formulations only reduce in one or few days the duration of the herpetic ulcers. Cetylpyridinium chloride (CPC) is a quaternary ammonium compound present in numerous hygiene products, such as mouthwashes, deodorants, aphtae-treating formulations and oral tablets as an anti-septic to limit bacterial growth. Some reports indicate that CPC can also modulate host signaling pathways, namely NF-κB signaling. Because HSV infection is modulated by NF-κB, we sought to assess whether CPC has antiviral effects against HSVs. Using wild-type HSV-1 and HSV-2, as well as viruses that are acyclovir-resistant or encode GFP reporter genes, we assessed the antiviral capacity of CPC in epithelial cells and human gingival fibroblasts expanded from the oral cavity and its mechanism of action. We found that a short, 10-min exposure to CPC added after HSV entry into the cells, significantly limited viral replication in both cell types by impairing viral gene expression. Interestingly, our results suggest that CPC blocks HSV replication by interfering with the translocation of NF-κB into the nucleus of HSV-infected cells. Taken together, these findings suggest that formulations containing CPC may help limit HSV replication in infected tissues and consequently reduce viral shedding.

Altered expression of cytokines in mice infected intranasally with two syncytial variants of Herpes simplex virus type 1

Immune evasion strategies are important for the onset and the maintenance of viral infections. Many viruses have evolved mechanisms to counteract or suppress the host immune response. We have previously characterized two syncytial (syn) variants of Herpes simplex 1 (HSV-1) strain F, syn14-1 and syn17-2, obtained by selective pressure with a natural carrageenan. These variants showed a differential pathology in vaginal and respiratory mucosa infection in comparison with parental strain. In this paper, we evaluated the modulation of immune response in respiratory mucosa by these HSV-1 variants. We observed altered levels of Tumor Necrosis Factor-α and Interleukin-6 in lungs of animals infected with the syn14-1 and syn17-2 variants compared with the parental strain. Also, we detected differences in the recruitment of immune cells to the lung in syn variants infected mice. Both variants exhibit one point mutation in the sequence of the gene of glycoprotein D detected in the ectodomain of syn14-1 and the cytoplasmic tail of syn17-2. Results obtained in the present study contribute to the characterization of HSV-1 syn variants and the participation of the cellular inflammatory response in viral pathogenesis.

Effects of herpes simplex virus type 1 infection on immune functions of human neutrophils

BACKGROUND AND OBJECTIVE

Herpesviruses may play roles in the development of periodontal diseases. This study analyzed the effects of herpes simplex virus type 1 (HSV-1) infection on neutrophil function. The effects of lipopolysaccharide (LPS) from the periodontal pathogen, Porphyromonas gingivalis, during HSV-1 infection were also determined.

MATERIAL AND METHODS

Purified HSV-1 was pretreated with buffer containing no serum, with HSV-1 immunoglobulin G (IgG)-positive serum (HSV-1 antiserum) or with control serum. Neutrophils were mock-infected or infected with the pretreated HSV-1. Viral binding and phagosome formation were detected using immunostaining. Intracellular reactive oxygen species (ROS) were determined using 2',7'-dichlorofluorescin diacetate and fluorometry. Leukotriene B(4) (LTB(4)) and interleukin-8 (IL-8) were detected using enzyme immunoassays. Release of matrix metalloproteinase-9 (MMP-9) was examined using gelatin zymography. Phosphorylation of Akt/glycogen synthase kinase-3 (GSK-3) was determined using western blotting.

RESULTS

HSV-1 bound directly to neutrophils and enhanced the release of MMP-9. HSV-1 immune complexes, formed in the HSV-1 antiserum, bound neutrophils and induced the formation of early phagosome more effectively than did HSV-1 alone. The relative levels of ROS and phosphorylation of Akt/GSK-3 were increased significantly in neutrophils after infection with HSV-1 immune complexes. Infection with HSV-1 and HSV-1 immune complexes also stimulated the production of inflammatory mediators, LTB(4) and IL-8. Moreover, LPS enhanced the HSV-1-stimulatory production of IL-8.

CONCLUSION

This study demonstrated differences in neutrophils infected with HSV-1 alone or with HSV-1 immune complexes, suggesting that opsonization of HSV-1 might enhance its effects on neutrophils. The in vitro findings suggest that HSV-1 infection may induce the inflammatory response and affect periodontal health.

Sensing herpes: more than toll

To launch an effective antiviral immune response, cells must recognize the virus, activate a cytokine response, and initiate inflammatory processes. Herpes simplex virus 1 (HSV-1) and HSV-2 are nuclear-replicating viruses composed of a double-stranded DNA genome plus glycoproteins that are incorporated into a lipid bilayer envelope that surrounds an icosahedral capsid. Several novel receptors that mediate innate recognition of HSV and that activate the innate immune response have been identified in recent years. The host-virus interactions that lead to type I interferon (IFN), type III IFN, and cytokine production include cellular recognition of viral envelope and structural proteins, recognition of viral genomic DNA and recognition of virus-derived double-stranded RNAs. Such RNAs can interact with cellular pattern-recognition receptors, including Toll-like receptors and a number of cytoplasmic and nuclear receptors for virus DNA and virus-derived RNAs. In this review, I present a systematic overview of innate cellular recognition of HSV infection that leads to immune activation, and I discuss the implications of the known cell-host interactions. In addition, I discuss the use of innate stimulation to improve anti-HSV treatment and vaccine response and I discuss future research aims.

PI3K/Akt signaling mediated apoptosis blockage and viral gene expression in oral epithelial cells during herpes simplex virus infection

Phosphatidylinositol 3-kinases (PI3Ks) function in the anti-apoptotic pathway, and are commonly exploited by various viruses to accomplish the viral life cycle. This study examined the role of the PI3K pathway in human oral epithelial cells following herpes simplex virus type 1 (HSV-1) infection. The results showed that HSV-1 induced the phosphorylation of Akt and glycogen synthase kinase 3 (GSK-3). Phosphorylation of Akt, but not GSK-3, induced by HSV-1 was PI3K-dependent. The expression of HSV-1 immediate-early genes may be involved in the initial phosphorylation of Akt and GSK-3. Inhibition of HSV-1-induced PI3K activity increased DNA fragmentation and cleavage of poly ADP-ribose polymerase (PARP), caspase 3 and caspase 7 compared with infected alone. Inhibition of PI3K attenuated the expression of HSV-1-infected cell protein 0 (ICP0), but not thymidine kinase (TK) and viral replication. Collectively, these data suggested that, in oral epithelial cells, the HSV-1-induced PI3K/Akt activation was involved in the regulation of apoptosis blockage and viral gene expression.

Macrophages and cytokines in the early defence against herpes simplex virus

Herpes simplex virus (HSV) type 1 and 2 are old viruses, with a history of evolution shared with humans. Thus, it is generally well-adapted viruses, infecting many of us without doing much harm, and with the capacity to hide in our neurons for life. In rare situations, however, the primary infection becomes generalized or involves the brain. Normally, the primary HSV infection is asymptomatic, and a crucial element in the early restriction of virus replication and thus avoidance of symptoms from the infection is the concerted action of different arms of the innate immune response. An early and light struggle inhibiting some HSV replication will spare the host from the real war against huge amounts of virus later in infection. As far as such a war will jeopardize the life of the host, it will be in both interests, including the virus, to settle the conflict amicably. Some important weapons of the unspecific defence and the early strikes and beginning battle during the first days of a HSV infection are discussed in this review. Generally, macrophages are orchestrating a multitude of anti-herpetic actions during the first hours of the attack. In a first wave of responses, cytokines, primarily type I interferons (IFN) and tumour necrosis factor are produced and exert a direct antiviral effect and activate the macrophages themselves. In the next wave, interleukin (IL)-12 together with the above and other cytokines induce production of IFN-gamma in mainly NK cells. Many positive feed-back mechanisms and synergistic interactions intensify these systems and give rise to heavy antiviral weapons such as reactive oxygen species and nitric oxide. This results in the generation of an alliance against the viral enemy. However, these heavy weapons have to be controlled to avoid too much harm to the host. By IL-4 and others, these reactions are hampered, but they are still allowed in foci of HSV replication, thus focusing the activity to only relevant sites. So, no hero does it alone. Rather, an alliance of cytokines, macrophages and other cells seems to play a central role. Implications of this for future treatment modalities are shortly considered.