Quercetin can reduce viral RNA level of O'nyong-nyong virus and resulting innate immune cytokine responses in cultured human synovial fibroblasts

The impact of arthritogenic viruses in oral tissues

Arthritis and periodontitis are inflammatory diseases that share several immunopathogenic features. The expansion in the study of virus-induced arthritis has shed light on how this condition could impact other parts of the human body, including the mouth. Viral arthritis is an inflammatory joint disease caused by several viruses, most notably the alphaviruses Chikungunya virus (CHIKV), Sindbis virus (SINV), Ross River virus (RRV), Mayaro virus (MAYV), and O'nyong'nyong virus (ONNV). These viruses can induce an upsurge of matrix metalloproteinases and immune-inflammatory mediators such as Interleukin-6 (IL6), IL-1β, tumor necrosis factor, chemokine ligand 2, and receptor activator of nuclear factor kappa-B ligand in the joint and serum of infected individuals. This can lead to the influx of inflammatory cells to the joints and associated muscles as well as osteoclast activation and differentiation, culminating in clinical signs of swelling, pain, and bone resorption. Moreover, several data indicate that these viral infections can affect other sites of the body, including the mouth. The human oral cavity is a rich and diverse microbial ecosystem, and viral infection can disrupt the balance of microbial species, causing local dysbiosis. Such events can result in oral mucosal damage and gingival bleeding, which are indicative of periodontitis. Additionally, infection by RRV, CHIKV, SINV, MAYV, or ONNV can trigger the formation of osteoclasts and upregulate pro-osteoclastogenic inflammatory mediators, interfering with osteoclast activation. As a result, these viruses may be linked to systemic conditions, including oral manifestations. Therefore, this review focuses on the involvement of alphavirus infections in joint and oral health, acting as potential agents associated with oral mucosal inflammation and alveolar bone loss. The findings of this review demonstrate how alphavirus infections could be linked to the comorbidity between arthritis and periodontitis and may provide a better understanding of potential therapeutic management for both conditions.

Miconia albicans (Melastomataceae) to treat Chikungunya viral infection: An effectual symptom-driven ethnomedicinal repurposing of an anti-inflammatory species?

ETHNOPHARMACOLOGICAL RELEVANCE

Miconia albicans (MA) is consumed all over the Brazilian territory as a remedy to treat rheumatoid arthritis and has been increasingly used to alleviate the deleterious symptoms caused by Chikungunya virus (CHIKV).

AIM OF THE STUDY

To investigate the effect of MA leaf and stem hydroethanolic extracts (LE and SE, respectively), their fractions enriched in triterpene acids or polyphenols as well isolated constituents, on CHIKV hosted in Vero cells.

MATERIALS AND METHODS

Polyphenol profiles of LE and SE were dereplicated by HPLC-DAD-ESI-MS/MS, aided by standards. Polyphenol-rich (LEx and SEx) and triterpenic acid-rich (LOH and SOH) fractions were obtained in Amberlite XAD-4 and alkalinized 95% ethanol (EtOH) extraction, respectively. TPC and TFC were assessed by colorimetric methods. Three representative flavonoids and two triterpenic acids were quantified by HPLC. CHIKV load suppression was evaluated in Vero cells by real-time qRT‒PCR at noncytotoxic concentrations.

RESULTS

Fifteen flavonoids were characterized in LE and SE. LEx presented isoquercitrin, quercitrin, rutin (0.49-1.51%) and quercetin. The TPC was 48 and 62 mg QE/g extract, and the TFC was 11.93 and 0.76 mg QE/g extract for LEx and SEx, respectively. LOH presented ursolic (15.3%) and oleanolic (8.0%) acids. A reduction (91-97%) in the CHIKV load was produced by the triterpene fraction, quercitrin and quercetin; the latter maintained the activity down to one twentieth of the tolerated concentration.

CONCLUSION

M. albicans contains flavonoids and triterpenic acids that are effective against CHIKV, which might justify its use to alleviate sequelae of CHIKV infection. However, further investigations on the species and its active constituents are needed.

The Synthetic Peptide GA-Hecate and Its Analogs Inhibit Multiple Steps of the Chikungunya Virus Infection Cycle In Vitro

Chikungunya virus (CHIKV) belongs to the Alphavirus genus and is responsible for significant outbreaks worldwide. Currently, there is no approved antiviral therapy against CHIKV. Bioactive peptides have great potential for new drug development. Here, we evaluated the antiviral activity of the synthetic peptide GA-Hecate and its analogs PSSct1905 and PSSct1910 against CHIKV infection. Initial screening showed that all three peptides inhibited the CHIKV replication cycle in baby hamster kidney fibroblast cells (BHK-21) and human hepatocarcinoma epithelial cells (Huh-7). GA-Hecate and its analog PSSct1905 were the most active, demonstrating suppression of viral infection by more than 91%. The analog PSSct1905 exhibited a protective effect in cells against CHIKV infection. We also observed that the analogs PSSct1905 and PSSct1910 affected CHIKV entry into both cell lines, inhibiting viral attachment and internalization. Finally, all tested compounds presented antiviral activity on the post-entry steps of CHIKV infection in all cells evaluated. In conclusion, this study highlights the potential of the peptide GA-Hecate and its analogs as novel anti-CHIKV compounds targeting different stages of the viral replication cycle, warranting the development of GA-Hecate-based compounds with broad antiviral activity.

Inflammatory Mesenchymal Stem Cells Express Abundant Membrane-Bound and Soluble Forms of C-Type Lectin-like CD248

CD248 (endosialin) belongs to a glycoprotein family that also includes thrombomodulin (CD141), CLEC14A, and CD93 (AA4) stem cell markers. We analyzed the regulated expression of CD248 in vitro using skin (HFFF) and synovial (FLS) mesenchymal stem cell lines, and in fluid and tissue samples of rheumatoid arthritis (RA) and osteoarthritis (OA) patients. Cells were incubated with either rhVEGF₁₆₅, bFGF, TGF-β1, IL1-β, TNF-α, TGFβ1, IFN-γ, or PMA (Phorbol ester). There was no statistically significant change in membrane expression. A soluble (s) form of cleaved CD248 (sCD248) was detected after cell treatment with IL1-β and PMA. Matrix metalloprotease (MMP) MMP-1 and MMP-3 mRNAs were significantly up-regulated by IL1-β and PMA. A broad MMP inhibitor blocked the release of soluble CD248. In RA synovial tissue, we identified CD90⁺ perivascular MSCs double-stained for CD248 and VEGF. High sCD248 levels were detected in synovial fluid from RA. In culture, subpopulations of CD90⁺ CD14^- RA MSCs were either identified as CD248⁺ or CD141⁺ cells but CD93^-. CD248 is abundantly expressed by inflammatory MSCs and shed in an MMP-dependent manner in response to cytokines and pro-angiogenic growth factors. Both membrane-bound and soluble CD248 (acting as a decoy receptor) may contribute to RA pathogenesis.

Antiviral Activity of Quercetin Hydrate against Zika Virus

Zika virus (ZIKV) has re-emerged in recent decades, leading to outbreaks of Zika fever in Africa, Asia, and Central and South America. Despite its drastic re-emergence and clinical impact, no vaccines or antiviral compounds are available to prevent or control ZIKV infection. This study evaluated the potential antiviral activity of quercetin hydrate against ZIKV infection and demonstrated that this substance inhibits virus particle production in A549 and Vero cells under different treatment conditions. In vitro antiviral activity was long-lasting (still observed 72 h post-infection), suggesting that quercetin hydrate affects multiple rounds of ZIKV replication. Molecular docking indicates that quercetin hydrate can efficiently interact with the specific allosteric binding site cavity of the NS2B-NS3 proteases and NS1-dimer. These results identify quercetin as a potential compound to combat ZIKV infection in vitro.

Deciphering the Role of Schwann Cells in Inflammatory Peripheral Neuropathies Post Alphavirus Infection

Old world alphaviruses (e.g., chikungunya) are known to cause severe acute and chronic debilitating arthralgia/arthritis. However, atypical neurological manifestations and, in particular, unexpected cases of acute inflammatory Guillain-Barre syndrome (GBS) have been associated with the arthritogenic alphaviruses. The pathogenesis of alphavirus-associated GBS remains unclear. We herein addressed for the first time the role of Schwann cells (SC) in peripheral neuropathy post-alphaviral infection using the prototypical ONNV alphavirus model. We demonstrated that human SC expressed the recently identified alphavirus receptor MxRA8 and granting viral entry and robust replication. A canonical innate immune response was engaged by ONNV-infected SC with elevated gene expression for RIG-I, MDA5, IFN-β, and ISG15 and inflammatory chemokine CCL5. Transcription levels of prostaglandin E2-metabolizing enzymes including cPLA2α, COX-2, and mPGES-1 were also upregulated in ONNV-infected SC. Counterintuitively, we found that ONNV failed to affect SC regenerative properties as indicated by elevated expression of the pro-myelinating genes MPZ and MBP1 as well as the major pro-myelin transcription factor Egr2. While ONNV infection led to decreased expression of CD55 and CD59, essential to control complement bystander cytotoxicity, it increased TRAIL expression, a major pro-apoptotic T cell signal. Anti-apoptotic Bcl2 transcription levels were also increased in infected SC. Hence, our study provides new insights regarding the remarkable immunomodulatory role of SC of potential importance in the pathogenesis of GBS following alphavirus infection.

The mechanism of the anti-inflammatory effect of Oldenlandia diffusa on arthritis model rats: a quantitative proteomic and network pharmacologic study

BACKGROUND

In China, Oldenlandia diffusa (OD) has been prescribed as a therapeutic herb for rheumatoid arthritis (RA). We previously conducted a preliminary study of the anti-inflammatory effect of OD, and the purpose of this study is to further investigate its mechanism.

METHODS

We performed a quantitative proteomic analysis of synovium, identified the differentially expressed proteins, and performed bioinformatics analyses. With the help of network pharmacology, we aimed to find the key synovial proteins which OD or its key compound might influence. To verify the result, liquid chromatography-mass spectrometry (LC-MS) was applied to quantify and qualify the absorbable potential compounds of OD. The anti-inflammatory effect was evaluated by morphological, histopathological, and cytokine analyses. Target proteins were observed by immunohistochemistry (IHC) and enzyme-linked immunosorbent assay (ELISA).

RESULTS

MMP3 and CAV1 were identified as 2 of the differentially expressed proteins in RA synovium, and might be influenced by quercetin, the active compound of OD. MMP3 might be altered through atherosclerosis signaling, while CAV1 might be altered through caveolar-mediated endocytosis signaling. According to our verification, quercetin was identified as the absorbed and effective compound of OD, and it could exert an anti-inflammatory effect on the collagen-induced arthritis (CIA) model, including serum cytokine expression, synovial hyperplasia and lymphocyte infiltration, articular cartilage lesion. Quercetin could also down-regulate the synovial expression of MMP3 and CAV1, and could exert better effects at a high dose.

CONCLUSIONS

Quercetin was the main active compound of OD in the treatment of RA. OD might alleviate inflammatory responses in CIA rats by suppressing the expression of MMP3 and CAV1 through quercetin, and at a high dose, quercetin could exert a better anti-inflammatory effect.

Emodin from Aloe inhibits Swine acute diarrhea syndrome coronavirus in cell culture

Swine acute diarrhea syndrome coronavirus (SADS-CoV) is an emerging swine enteropathogenic coronavirus that causes severe diarrhea in neonatal piglets, leading to serious economic losses to the pig industries. At present, there are no effective control measures for SADS, making an urgent need to exploit effective antiviral therapies. Here, we confirmed that Aloe extract (Ae) can strongly inhibit SADS-CoV in Vero and IPI-FX cells in vitro. Furthermore, we detected that Emodin from Ae had anti-SADS-CoV activity in cells but did not impair SADS-CoV infectivity directly. The time-of-addition assay showed that Emodin inhibits SADS-CoV infection at the whole stages of the viral replication cycle. Notably, we found that Emodin can significantly reduce virus particles attaching to the cell surface and induce TLR3 (p < 0.001), IFN-λ3 (p < 0.01), and ISG15 (p < 0.01) expressions in IPI-FX cells, indicating that the anti-SADS-CoV activity of Emodin might be due to blocking viral attachment and the activation of TLR3-IFN-λ3-ISG15 signaling axis. These results suggest that Emodin has the potential value for the development of anti-SADS-CoV drugs.

Malaria abrogates O'nyong-nyong virus pathologies by restricting virus infection in nonimmune cells

O'nyongnyong virus (ONNV) is a re-emerging alphavirus previously known to be transmitted by main malaria vectors, thus suggesting the possibility of coinfections with arboviruses in co-endemic areas. However, the pathological outcomes of such infections remain unknown. Using murine coinfection models, we demonstrated that a preexisting blood-stage Plasmodium infection suppresses ONNV-induced pathologies. We further showed that suppression of viremia and virus dissemination are dependent on Plasmodium-induced IFNγ and are associated with reduced infection of CD45- cells at the site of virus inoculation. We further proved that treatment with IFNγ or plasma samples from Plasmodium vivax-infected patients containing IFNγ are able to restrict ONNV infection in human fibroblast, synoviocyte, skeletal muscle, and endothelial cell lines. Mechanistically, the role of IFNγ in restricting ONNV infection was confirmed in in vitro infection assays through the generation of an IFNγ receptor 1 α chain (IFNγR1)-deficient cell line.

Antiinflammatory phytochemicals against virus-induced hyperinflammatory responses: Scope, rationale, application, and limitations

Uncontrolled inflammatory responses or cytokine storm associated with viral infections results in deleterious consequences such as vascular leakage, severe hemorrhage, shock, immune paralysis, multi-organ failure, and even death. With the emerging new viral infections and lack of effective prophylactic vaccines, evidence-based complementary strategies that limit viral infection-mediated hyperinflammatory responses could be a promising approach to limit host tissue injury. The present review emphasizes the potentials of antiinflammatory phytochemicals in limiting hyperinflammatory injury caused by viral infections. The predominant phytochemicals along with their mechanism in limiting hyperimmune and pro-inflammatory responses under viral infection have been reviewed comprehensively. How certain phytochemicals can be effective in limiting hyper-inflammatory response indirectly by favorably modulating gut microbiota and maintaining a functional intestinal barrier has also been presented. Finally, we have discussed improved systemic bioavailability of phytochemicals, efficient delivery strategies, and safety measures for effective antiinflammatory phytotherapies, in addition to emphasizing the requirement of tightly controlled clinical studies to establish the antiinflammatory efficacy of the phytochemicals. Collectively, the review provides a scooping overview on the potentials of bioactive phytochemicals to mitigate pro-inflammatory injury associated with viral infections.

Emodin from Aloe Inhibits Porcine Reproductive and Respiratory Syndrome Virus via Toll-Like Receptor 3 Activation

Porcine reproductive and respiratory syndrome virus (PRRSV) causes severe reproductive failure in sows and respiratory diseases in growing and finishing pigs and results in great economic losses to the swine industry. Although vaccines are available, PRRSV remains a major threat to the pig farms. Thus, there is an urgent need to develop antiviral drugs to compensate for vaccines. In this study, we report that Aloe extract (Ae) can strongly inhibit PRRSV in Marc-145 cells and porcine alveolar macrophages lines (iPAMs) in vitro. Furthermore, we identified a novel anti-PRRSV molecule, Emodin, from Ae by high-performance liquid chromatography (HPLC). Emodin exerted its inhibitory effect through targeting the whole stages of PRRSV infectious cycle. Moreover, we also found that Emodin can inactivate PRRSV particles directly. Notably, we confirmed that Emodin was able to significantly induce Toll-like receptor 3 (TLR3) (p < 0.01), IFN-α (p < 0.05) and IFN-β expression in iPAMs, indicating that induction of antiviral agents via TLR3 activation by Emodin might contribute to its anti-PRRSV effect. These findings imply that the Emodin from Aloe could hamper the proliferation of PRRSV in vitro and might constitute a new approach for treating PRRSV infection.