Dauricine combined with clindamycin inhibits severe pneumonia co-infected by influenza virus H5N1 and Streptococcus pneumoniae in vitro and in vivo through NF-κB signaling pathway

Dauricine attenuates ovariectomized-induced bone loss and RANKL-induced osteoclastogenesis via inhibiting ROS-mediated NF-κB and NFATc1 activity

BACKGROUND

Osteoclast plays an important role in maintaining the balance between bone anabolism and bone catabolism. The abnormality of osteoclast is closely related to osteolytic bone diseases such as osteoporosis, rheumatoid arthritis and tumor bone metastasis.

PURPOSE

We aim to search for natural compound that may suppress osteoclast formation and function.

STUDY DESIGN

In this study, we assessed the impact of Dauricine (Dau) on the formation and function of osteoclasts in vitro, as well as its potential in preventing bone loss in an ovariectomy mouse model in vivo.

METHODS

Multiple in vitro experiments were carried out, including osteoclastogenesis, podosomal belt formation, bone resorption assay, RNA-sequencing, real-time quantitative PCR, ROS level detection, surface plasmon resonance assay, luciferase assay and western blot. To verify the effect in vivo, an ovariectomized mouse model (OVX model) was constructed, and bone parameters were measured using micro-CT and histology. Furthermore, metabolomics analysis was performed on blood serum samples from the OVX model.

RESULTS

In vitro experiments demonstrated that Dau inhibits RANKL-induced osteoclastogenesis, podosomal belt formation, and bone resorption function. RNA-sequencing results revealed that Dau significantly suppresses genes related to osteoclast. Functional enrichment analysis indicated that Dau's inhibition of osteoclasts may be associated with NF-κB signaling pathway and reactive oxygen metabolism pathway. Molecular docking, surface plasmon resonance assay and western blot analysis further confirmed that Dau inhibits RANKL-induced osteoclastogenesis by modulating the ROS/NF-κB/NFATc1 pathway. Moreover, administration of Dau to OVX-induced mice validated its efficacy in treating bone loss disease.

CONCLUSION

Dau prevents OVX-induced bone loss by inhibiting osteoclast activity and bone resorption, potentially offering a new approach for preventing and treating metabolic bone diseases such as osteoporosis. This study provides innovative insights into the inhibitory effects of Dau in an in vivo OVX model and elucidates the underlying mechanism.

An alkaloid from Menispermum dauricum, dauricine mediates Ca2+ influx and inhibits NF-κB pathway to protect chondrocytes from IL-1β-induced inflammation and catabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Dauricine (DA) is a natural plant-derived alkaloid extracted from Menispermum dauricum. Menispermum dauricum has been used in traditional Chinese medicine as a classic remedy for rheumatoid arthropathy and is believed to be effective in alleviating swelling and pain in the limbs.

AIM OF THE STUDY

Osteoarthritis (OA) is a classic degenerative disease involving chondrocyte death, and there is still a lack of effective therapeutic agents that can reverse the progression of the disease. Here we explored the therapeutic effects of DA against OA and further explored the mechanism.

MATERIALS AND METHODS

The effect of DA on cell viability was assessed by CCK-8. IL-1β-treated mouse chondrocytes were used as an in vitro model of OA, and apoptosis was detected by flow cytometry. QRT-PCR, western blotting, cell staining, and immunofluorescence were used to detect relevant inflammatory factors and cartilage-specific expression. RNA sequencing was used to identify pertinent signaling pathways. The therapeutic effect of DA was verified by micro-CT, histological analysis and immunohistochemical analysis in a mouse OA model.

RESULTS

DA demonstrated a high safety profile on chondrocytes, significantly reversing the inflammatory response induced by IL-1β, and promoting factors associated with cartilage regeneration. Moreover, DA exhibited a significant protective effect on the knee joints of mice undergoing ACLT-DMM, effectively preventing cartilage degeneration and subchondral bone tissue destruction. These positive therapeutic effects were achieved through the modulation of the NF-κB pathway and the Ca2+ signaling pathway by DA.

CONCLUSION

Being derived from a traditional herb, DA exhibits remarkable therapeutic potential and safety in OA treatment, presenting a promising option for patients dealing with osteoarthritis.

Research progress on pharmacological effects and mechanisms of cepharanthine and its derivatives

Cepharanthine (CEP) is a bisbenzylisoquinoline alkaloid compound found in plants of the Stephania genus, which has biological functions such as regulating autophagy, inhibiting inflammation, oxidative stress, and apoptosis. It is often used for the treatment of inflammatory diseases, viral infections, cancer, and immune disorders and has great clinical translational value. However, there is no detailed research on its specific mechanism and dosage and administration methods, especially clinical research is limited. In recent years, CEP has shown significant effects in the prevention and treatment of COVID-19, suggesting its potential medicinal value waiting to be discovered. In this article, we comprehensively introduce the molecular structure of CEP and its derivatives, describe in detail the pharmacological mechanisms of CEP in various diseases, and discuss how to chemically modify and design CEP to improve its bioavailability. In summary, this work will provide a reference for further research and clinical application of CEP.

Herbal Compounds Dauricine and Isoliensinine Impede SARS-CoV-2 Viral Entry

Targeting viral entry has been the focal point for the last 3 years due to the continued threat posed by SARS-CoV-2. SARS-CoV-2's entry is highly dependent on the interaction between the virus's Spike protein and host receptors. The virus's Spike protein is a key modulator of viral entry, allowing sequential cleavage of ACE2 at the S1/S2 and S2 sites, resulting in the amalgamation of membranes and subsequent entry of the virus. A Polybasic insertion (PRRAR) conveniently located at the S1/S2 site can also be cleaved by furin or by serine protease, TMPRSS2, at the cell surface. Since ACE2 and TMPRSS2 are conveniently located on the surface of host cells, targeting one or both receptors may inhibit receptor-ligand interaction. Here, we show that Dauricine and Isoliensinine, two commonly used herbal compounds, were capable of inhibiting SARS-CoV-2 viral entry by reducing Spike-ACE2 interaction but not suppressing TMPRSS2 protease activity. Further, our biological assays using pseudoviruses engineered to express Spike proteins of different variants revealed a reduction in infection rates following treatment with these compounds. The molecular modeling revealed an interconnection between R403 of Spike protein and both two compounds. Spike mutations at residue R403 are critical, and often utilized by ACE2 to gain cell access. Overall, our findings strongly suggest that Dauricine and Isoliensinine are effective in blocking Spike-ACE2 interaction and may serve as effective therapeutic agents for targeting SARS-CoV-2's viral entry.

Dauricine alleviates cognitive impairment in Alzheimer's disease mice induced by D-galactose and AlCl3 via the Ca2+/CaM pathway

Alzheimer's disease (AD) is a common neurodegenerative disease in the elderly. Dysregulation of intracellular Ca2+ homeostasis plays a critical role in the pathological development of AD. Dauricine (DAU) is a bisbenzylisoquinoline alkaloid isolated from Menispermum dauricum DC., which can prevent the influx of extracellular Ca2+ and inhibit the release of Ca2+ from the endoplasmic reticulum. DAU has a potential for anti-AD. However, it is unclear whether DAU can exert its anti-AD effect in vivo by regulating the Ca2+ related signaling pathways. Here, we investigated the effect and mechanism of DAU on D-galactose and AlCl3 combined-induced AD mice based on the Ca2+/CaM pathway. The results showed that DAU (1 mg/kg and 10 mg/kg for 30 days) treatment attenuated learning and memory deficits and improved the nesting ability of AD mice. The HE staining assay showed that DAU could inhibit the histopathological alterations and attenuate neuronal damage in the hippocampus and cortex of AD mice. Studies on the mechanism indicated that DAU decreased the phosphorylation of CaMKII and Tau and reduced the formation of NFTs in the hippocampus and cortex. DAU treatment also reduced the abnormally high expression of APP, BACE1, and Aβ1-42, which inhibited the deposition of Aβ plaques. Moreover, DAU could decrease Ca2+ levels and inhibit elevated CaM protein expression in the hippocampus and cortex of AD mice. The molecular docking results showed that DAU may have a high affinity with CaM or BACE1. DAU has a beneficial impact on pathological changes in AD mice induced by D-galactose and AlCl3 and may act by negative regulation of the Ca2+/CaM pathway and its downstream molecules such as CaMKII and BACE1.

Dauricine exhibits anti-inflammatory property against acute ulcerative colitis via the regulation of NF-κB pathway

We aim to investigate the therapeutic effect of dauricine on ulcerative colitis (UC). Our results indicated that dauricine attenuated the reduction of colonic length, weight loss, disease activity index, colonic tissue damage, and inflammatory cytokine levels in dextran sulfate sodium mice. In addition, dauricine reduced lipopolysaccharide-induced inflammation in HT-29 cells. Mechanically, dauricine docked with p65, a member of nuclear transcription factor kappaB (NF-κB) family, through which reduced the inflammatory cytokine release from HT-29 cells. Together, the above results inferred that dauricine had therapeutic effect for UC by suppressing NF-κB pathway, which provided a promising mean for UC treatment.

Human microbiomes in cancer development and therapy

Colonies formed by bacteria, archaea, fungi, and viral groups and their genomes, metabolites, and expressed proteins constitute complex human microbiomes. An increasing evidences showed that carcinogenesis and disease progression were link to microbiomes. Different organ sources, their microbial species, and their metabolites are different; the mechanisms of carcinogenic or procancerous are also different. Here, we summarize how microbiomes contribute to carcinogenesis and disease progression in cancers of the skin, mouth, esophagus, lung, gastrointestinal, genital, blood, and lymph malignancy. We also insight into the molecular mechanisms of triggering, promoting, or inhibiting carcinogenesis and disease progress induced by microbiomes or/and their secretions of bioactive metabolites. And then, the strategies of application of microorganisms in cancer treatment were discussed in detail. However, the mechanisms by which human microbiomes function are still poorly understood. The bidirectional interactions between microbiotas and endocrine systems need to be clarified. Probiotics and prebiotics are believed to benefit human health via a variety of mechanisms, in particular, in tumor inhibition. It is largely unknown how microbial agents cause cancer or how cancer progresses. We expect this review may open new perspectives on possible therapeutic approaches of patients with cancer.

The association between serum complement C3a and severity in patients with community-acquired pneumonia

Background

A few studies found that the complement system may be involved in the onset and progression of community-acquired pneumonia (CAP). However, the role of the complement system in CAP was obscure. The goal of this study was to analyze the association of serum complement C3a with CAP severity scores based on a cross-sectional study.

Methods

All 190 CAP patients and 95 control subjects were enrolled. Demographic information and clinical data were extracted. Peripheral blood samples were collected on admission.

Results

Serum complement C3a on admission was elevated in CAP patients compared with healthy subjects. The level of complement C3a was gradually elevated in parallel with CAP severity scores (CURB-65, CRB-65, PSI, SMART-COP, and CURXO). Complement C3a was positively correlated with blood routine parameters, renal function markers, and inflammatory cytokines in CAP patients. Furthermore, multivariate linear and logistic regression models found that serum complement C3a on admission was positively associated with CAP severity scores. Mechanistic research suggested that complement system inhibition alleviated Streptococcus pneumoniae-induced upregulation of IL-1β, TNF-α, IL-6, and CRP in MLE-12 cells.

Conclusions

Serum complement C3a on admission is positively associated with the severity of CAP patients. Inhibiting complement system attenuates S. pneumoniae-elevated secretion of inflammatory cytokines in pulmonary epithelial cells, indicating that complement C3a is involved in the pathophysiology of CAP. Serum complement C3a may serve as an earlier diagnostic biomarker for CAP.

Bioactivity and In Silico Studies of Isoquinoline and Related Alkaloids as Promising Antiviral Agents: An Insight

Viruses are widely recognized as the primary cause of infectious diseases around the world. The ongoing global pandemic due to the emergence of SARS-CoV-2 further added fuel to the fire. The development of therapeutics becomes very difficult as viruses can mutate their genome to become more complex and resistant. Medicinal plants and phytocompounds could be alternative options. Isoquinoline and their related alkaloids are naturally occurring compounds that interfere with multiple pathways including nuclear factor-κB, mitogen-activated protein kinase/extracellular-signal-regulated kinase, and inhibition of Ca²⁺-mediated fusion. These pathways play a crucial role in viral replication. Thus, the major goal of this study is to comprehend the function of various isoquinoline and related alkaloids in viral infections by examining their potential mechanisms of action, structure-activity relationships (SAR), in silico (particularly for SARS-CoV-2), in vitro and in vivo studies. The current advancements in isoquinoline and related alkaloids as discussed in the present review could facilitate an in-depth understanding of their role in the drug discovery process.

5-Methoxyflavone-induced AMPKα activation inhibits NF-κB and P38 MAPK signaling to attenuate influenza A virus-mediated inflammation and lung injury in vitro and in vivo

Influenza-related acute lung injury (ALI) is a life-threatening condition that results mostly from uncontrolled replication of influenza virus (IV) and severe proinflammatory responses. The methoxy flavonoid compound 5-methoxyflavone (5-MF) is believed to have superior biological activity in the treatment of cancer. However, the effects and underlying mechanism of 5-MF on IV-mediated ALI are still unclear. Here, we showed that 5-MF significantly improved the survival of mice with lethal IV infection and ameliorated IV-mediated lung edema, lung histological changes, and inflammatory cell lung recruitment. We found that 5-MF has antiviral activity against influenza A virus (IAV), which was probably associated with increased expression of radical S-adenosyl methionine domain containing 2 (RSAD2) and suppression of endosomal acidification. Moreover, IV-infected A549 cells with 5-MF treatment markedly reduced proinflammatory mediator expression (IL-6, CXCL8, TNF-α, CXCL10, CCL2, CCL3, CCL4, GM-CSF, COX-2, and PGE₂) and prevented P-IKBα, P-P65, and P-P38 activation. Interestingly, we demonstrated that 5-MF treatment could trigger activation of AMP-activated protein kinase (AMPK)α in IV-infected A549 cells, as evidenced by activation of the AMPKα downstream molecule P53. Importantly, the addition of AMPKα blocker compound C dramatically abolished 5-MF-mediated increased levels of RSAD2, the inhibitory effects on H1N1 virus-elicited endosomal acidification, and the suppression expression of proinflammatory mediators (IL-6, TNF-α, CXCL10, COX-2 and PGE₂), as well as the inactivation of P-IKBα, P-P65, and P-P38 MAPK signaling pathways. Furthermore, inhibition of AMPKα abrogated the protective effects of 5-MF on H1N1 virus-mediated lung injury and excessive inflammation in vivo. Taken together, these results indicate that 5-MF alleviated IV-mediated ALI and suppressed excessive inflammatory responses through activation of AMPKα signaling.

External stimuli-responsive gasotransmitter prodrugs: Chemistry and spatiotemporal release

Gasotransmitters like nitric oxide, carbon monoxide, and hydrogen sulfide with unique pleiotropic pharmacological effects in mammals are an emerging therapeutic modality for different human diseases including cancer, infection, ischemia-reperfusion injuries, and inflammation; however, their clinical translation is hampered by the lack of a reliable delivery form, which delivers such gasotransmitters to the action site with precisely controlled dosage. The external stimuli-responsive prodrug strategy has shown tremendous potential in developing gasotransmitter prodrugs, which affords precise temporospatial control and better dose control compared with endogenous stimuli-sensitive prodrugs. The promising external stimuli employed for gasotransmitter activation range from photo, ultrasound, and bioorthogonal click chemistry to exogenous enzymes. Herein, we highlight the recent development of external stimuli-mediated decaging chemistry for the temporospatial delivery of gasotransmitters including nitric oxide, carbon monoxide, hydrogen sulfide and sulfur dioxide, and discuss the pros and cons of different designs.

Regulation of Microglia-Activation-Mediated Neuroinflammation to Ameliorate Ischemia-Reperfusion Injury via the STAT5-NF-κB Pathway in Ischemic Stroke

Inflammatory reaction after ischemia-reperfusion contributes significantly to a worsened prognosis, and microglia activation is the main resource of inflammation in the nervous system. Targeting STAT5 has been shown to be a highly effective anti-inflammatory therapy; however, the mechanism by which the STAT5 signaling pathway regulates neuroinflammation following brain injury induced by ischemia-reperfusion remains unclear. Dauricine is an effective agent in anti-inflammation and neuroprotection, but the mechanism by which dauricine acts in ischemia-reperfusion remained unknown. This study is the first to find that the anti-inflammation mechanism of dauricine mainly occurs through the STAT5-NF-κB pathway and that it might act as a STAT5 inhibitor. Dauricine suppresses the inflammation caused by cytokines Eotaxin, KC, TNF-α, IL-1α, IL-1β, IL-6, IL-12β, and IL-17α, as well as inhibiting microglia activation. The STAT5b mutant at Tyr-699 reverses the protective effect of dauricine on the oxygen-glucose deprivation-reperfusion injury of neurons and reactivates the P-NF-κB expression in microglia. These results suggest that dauricine might be able to suppress the neuroinflammation and protect the neurons from the injury of post-ischemia-reperfusion injury via mediating the microglia activation through the STAT5-NF-κB pathway. As a potential therapeutic target for neuroinflammation, STAT5 needs to be given further attention regarding its role in ischemic stroke.

Menisperdaurines A-W, structurally diverse isoquinoline alkaloids from Menispermum dauricum and their dopamine D1 receptor activities

A total of 33 structurally diverse isoquinoline alkaloids were isolated from the rhizomes of Menispermum dauricum, including seventeen benzylisoquinoline analogues (menisperdaurines A-Q, 1-17), five protoberberine analogues (menisperdaurines R-V, 18-22), a quaternary phenanthrene alkaloid (menisperdaurine W, 23) and ten known compounds (24-33). Compound structures, including absolute configurations, were determined by extensive spectroscopic methods, quantum chemical calculations of chemical shifts, and calculated and experimental electronic circular dichroism (ECD) data. Compounds 1-5 were glycosidic benzylisoquinolines with glucose moieties attached at the C-12 position. Compound 8 was the first example that was isolated from the rhizomes of Menispermum dauricum, benzylisoquinoline and an aromatic unit connected by a sugar bridge. Compounds were evaluated for their inhibitory effects on the dopamine D1 receptor. Compounds 1, 8, 21, 24 and 29 showed potent D1 antagonistic activities, with IC₅₀ values ranging from 1.0 to 4.5 μM. Compound 1 exhibited the highest antagonistic activity with an IC₅₀ value of 1.0 ± 0.2 μM.

Dauricine Attenuates Vascular Endothelial Inflammation Through Inhibiting NF-κB Pathway

Endothelial cells are the fundamental components of blood vessels that regulate several physiological processes including immune responses, angiogenesis, and vascular tone. Endothelial dysfunction contributes to the development of various diseases such as acute lung injury, and endothelial inflammation is a vital part of endothelial dysfunction. Dauricine is an extract isolated from Menispermum dauricum DC, a traditional Chinese medical plant that can be used for pharyngitis. In this work, we found that IL-1β-induced overexpression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin was inhibited by dauricine in primary human umbilical vein endothelial cells (HUVECs). Correspondingly, adhesion of human acute monocytic leukemia cell line (THP-1) to HUVECs was decreased by dauricine. Further studies showed that dauricine inhibited the activation of nuclear factor-κB (NF-κB) pathway in HUVECs stimulated with IL-1β. In vivo, dauricine protected mice from lipopolysaccharide (LPS)-induced acute lung injury. In lung tissues, the activation of NF-κB pathway and the expression of its downstream genes (ICAM-1, VCAM-1, and E-selectin) were decreased by dauricine, consistent with what was found in vitro. In summary, we concluded that dauricine could alleviate endothelial inflammation by suppressing NF-κB pathway, which might serve as an effective candidate for diseases related with endothelial inflammation.

Evodiamine Enhanced the Anti-Inflammation Effect of Clindamycin in the BEAS-2B Cells Infected with H5N1 and Pneumoniae D39 Through CREB-C/EBPβ Signaling Pathway

Pneumonia is a pulmonary disease among children. Evodiamine, a traditional Chinese medicine, is known for anti-inflammatory effect. This study aimed to investigate the impact of evodiamine on severe pneumonia-like cells and the underlying mechanism involved. H5N1 and pneumoniae D39 was used to induce severe pneumonia-like conditions in BEAS-2B cells. The cell viability in BEAS-2B cells after treatments with 0, 20, 40, 60, 80, and 100 μM evodiamine was examined using MTT assays. The protein concentrations of inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1β, and Toll-like receptors (TLRs) were measured by enzyme-linked immunosorbent assay methods and the protein and mRNA changes in C/EBPβ/CREB were measured using Real Time-quantitative polymerase chain reaction and Western blot methods. Our results revealed that Evodiamine significantly decreased TNF-α, IL-6, and IL-1β in BEAS-2B cells. Moreover, evodiamine markedly reduced TLR2,3,4 protein expression and the phosphorylated protein of C/EBPβ and CREB. Besides, evodiamine combined with clindamycin exerted more significant effects than clindamycin alone. Taken together, our results demonstrated that evodiamine enhanced the anti-inflammation effect of clindamycin in the BEAS-2B cells infected with H5N1 and pneumoniae D39 through CREB-C/EBPβ signaling pathway.

An Integrated Strategy for the Detection, Dereplication, and Identification of DNA-Binding Biomolecules from Complex Natural Product Mixtures

A fundamental factor in natural product drug discovery programs is the necessity to identify the active component(s) from complex chemical mixtures. Whereas this has traditionally been accomplished using bioassay-guided fractionation, we questioned whether alternative techniques could supplement and, in some cases, even supplant this approach. We speculated that a combination of ligand-fishing methods and modern analytical tools (e.g., LC-MS and online natural product databases) offered a route to enhance natural product drug discovery. Herein, a candidate solution referred to as the lickety-split ligand-affinity-based molecular angling system (LLAMAS) is described. This approach utilizes an ultrafiltration-based LC-PDA-MS/MS-guided DNA-binding assay in combination with the (i) Global Natural Products Social Molecular Networking, (ii) Dictionary of Natural Products, and (iii) SciFinder platforms to identify DNA binders in complex chemical mixtures. LLAMAS was initially vetted in tests using known small-molecule DNA binders and then optimized to a 96-well plate-based format. A set of 332 plant samples used in traditional Chinese medicine was screened for DNA-binding activity with LLAMAS, resulting in the identification of seven DNA-binding molecules, including berberine (12), palmatine (13), coptisine (14), fangchinoline (15), tetrandrine (16), daurisoline (17), and dauricine (18). These results demonstrate that LLAMAS is an effective natural product discovery platform for the efficient identification and dereplication of DNA-binding molecules from complex mixtures.

Analgesic bisbenzylisoquinoline alkaloids from the rhizoma of Menispermum dauricum DC

Fifteen new bisbenzylisoquinoline alkaloids (1-15) were isolated from the rhizome of Menispermum dauricum DC. Compounds 1-9 were new N-oxides of dauricine-type alkaloids. Compounds 10-14 were rare tail-to-tail quaternary alkaloids. Their structures were characterized by comprehensive analysis of spectroscopic data, and absolute configurations were established from electronic circular dichroism (ECD) data and ECD calculations. Compounds were assayed on analgesic-related G-protein coupled receptors (GPCRs) including dopamine D1 and D2 receptors, opioid Mu receptor and muscarinic M3 receptor. Compound 1 showed high affinity and selective antagonistic activity on the M3 receptor with an IC₅₀ value of 2.2 ± 0.5 μM; compound 15 exhibited the highest antagonistic affinity among the evaluated compounds on Mu (IC₅₀ = 1.1 ± 0.6 μM) and it also acted as a D1 receptor antagonist (IC₅₀ = 8.8 ± 2.9 μM). These findings expanded the existing library of bisbenzylisoquinoline alkaloids and provided new structures for the related future drug design and synthesis.

Research Progress on Anti-Inflammatory Effects and Mechanisms of Alkaloids from Chinese Medical Herbs

As the spectrum of diseases keeps changing and life pace keeps going faster, the probability and frequency of diseases caused by human inflammatory reactions also keep increasing. How to develop effective anti-inflammatory drugs has become the hotspot of researches. It has been found that alkaloids from Chinese medical herbs have anti-inflammatory, analgesic, antitumor, anticonvulsant, diuretic, and antiarrhythmic effects, among which the anti-inflammatory effect is very prominent and commonly used in the treatment of rheumatoid arthritis, ankylosing spondylitis, and other rheumatic immune diseases, but its mechanism of action has not been well explained. Based on this, this paper will classify alkaloids according to structural types and review the plant sources, applicable diseases, and anti-inflammatory mechanisms of 16 kinds of alkaloids commonly used in clinical treatment, such as berberine, tetrandrine, and stephanine, with the aim of providing a reference for drug researches and clinical applications.

Medicinal chemistry strategies toward host targeting antiviral agents

Direct‐acting antiviral agents (DAAs) represent a class of drugs targeting viral proteins and have been demonstrated to be very successful in combating viral infections in clinic. However, DAAs suffer from several inherent limitations, including narrow‐spectrum antiviral profiles and liability to drug resistance, and hence there are still unmet needs in the treatment of viral infections. In comparison, host targeting antivirals (HTAs) target host factors for antiviral treatment. Since host proteins are probably broadly required for various viral infections, HTAs are not only perceived, but also demonstrated to exhibit broad‐spectrum antiviral activities. In addition, host proteins are not under the genetic control of viral genome, and hence HTAs possess much higher genetic barrier to drug resistance as compared with DAAs. In recent years, much progress has been made to the development of HTAs with the approval of chemokine receptor type 5 antagonist maraviroc for human immunodeficiency virus treatment and more in the pipeline for other viral infections. In this review, we summarize various host proteins as antiviral targets from a medicinal chemistry prospective. Challenges and issues associated with HTAs are also discussed.

Downregulation of FSTL‑1 attenuates the inflammation injury during Streptococcus pneumoniae infection by inhibiting the NLRP3 and TLR4/NF‑κB signaling pathway

Streptococcus pneumoniae‑induced pneumonia is a common disease and major cause of community‑acquired pneumonia. Previous studies have shown that Follistatin‑like protein 1 (FSTL‑1) serves important roles in regulating the inflammatory response. The present study aimed to investigate the effect of FSTL‑1 on the inflammatory response during S. pneumoniae infection using in vitro and in vivo models. ELISAs were used to detect the production of interleukin (IL)‑1β, tumor necrosis factor‑α and IL‑6. Western blotting and reverse transcription‑quantitative PCR were performed to determine the protein and mRNA expression of these factors. The results of the present study indicated that S. pneumoniae infection triggered a strong proinflammatory response and a high level of FSTL‑1 expression in mouse bone marrow‑derived macrophages. Moreover, FSTL‑1 may be required for the production of inflammatory factors during S. pneumoniae infection by regulating nucleotide oligomerization domain‑like receptor protein 3 in vitro and in vivo. In addition, it was found that the Toll‑like receptor 4/nuclear factor‑κB signaling pathway was involved in the inflammatory response regulated by FSTL‑1. The findings of the present study suggested that FSTL‑1 plays an important role in the inflammatory response during S. pneumoniae infection, providing a potential therapeutic target for reducing morbidity and mortality in patients with pneumonia.

Evidence that a primary anti-viral stimulation of the immune response by OM-85 reduces susceptibility to a secondary respiratory bacterial infection in mice

BACKGROUND

Viral respiratory infections may promote bacterial super-infection decreasing the host immune response efficiency. However, using a mice model we recently demonstrated that preventive treatment with the bacterial extract OM-85 reduces the susceptibility to a secondary Streptococcus (S.) pneumoniae infection after influenza virus (I.V.) challenge.

METHODS

To better characterize the efficacy of OM-85 against S. pneumoniae super-infection, a post-hoc analysis was conducted, comparing efficacy (survival) and morbidity signs (clinical score, body temperature and weight loss) in the OM-85 and the control (BLANC) groups of mice after: a) I.V. infection; b) primary S. pneumoniae infection and c) post-I.V. S. pneumoniae super-infection.

RESULTS

After a sublethal I.V. dose, all mice stayed alive at day 5 and no differences in morbidity signs were detected between the OM-85 and the BLANC groups. However, OM-85 pretreatment led to a significantly reduction of the viral load in the lung on day 5 post viral infection and, on day 10, reduced neutrophilic inflammation while increasing influenza-specific CD8 + T-cell proportion in the airways. Conversely to viral infection, exposure to S. pneumoniae induced a dramatic reduction of survival, with no mice surviving on day 3 post infection in the BLANC group, whereas a partial protective effect was observed in OM-85 pre-treated mice (20% of mice surviving at day 3, and 10% at day 4 and 5). The morbidity data substantiated the survival results. Interestingly, in the "super-infection" study, when mice were exposed to a sublethal I.V. dose followed by a secondary S. pneumoniae infection, all mice died by day 4 in the BLANC group. In contrast, in the OM-85 treated group, the survival rate was 70% at day 4 and still 50% at day 5, with positive effects on the clinical scores and on the body temperature already detectable at days 1 and 2.

CONCLUSIONS

The efficacy of OM-85 pre-treatment against S. pneumoniae super-infection reflects a strong and immediate immune reaction from the host, an event that can be explained in part by a "non-specific" activation of the immune system, a positive "immune effect" of the general OM-85- induced immune response against I.V.