The global battle against COVID-19 continues to demand innovative and efficacious treatments capable of addressing the challenges posed by rapidly evolving viral variants and escalating drug resistance. In this context, recent research published in Acta Pharmaceutica Sinica B unveils a pioneering approach that simultaneously targets the viral papain-like protease (PLpro) and the host receptor-interacting protein kinase 1 (RIPK1), demonstrating pronounced antiviral and anti-inflammatory synergy in a mouse model of SARS-CoV-2 infection. These findings could revolutionize therapeutic strategies against severe COVID-19.

SARS-CoV-2’s ability to propagate unabated hinges on intricate viral-host interactions and immune dysregulation, notably the cytokine storm, which often dictates disease severity and patient outcomes. Contemporary antiviral agents primarily focus on viral polymerase and spike protein targets, but emerging drug resistance and variant-associated escape mechanisms necessitate alternative approaches. The papain-like protease (PLpro) of SARS-CoV-2 represents a less conventional, yet highly druggable target essential for viral polyprotein processing and antagonism of host innate immunity.

Concurrently, RIPK1, a crucial signaling mediator in host cells, orchestrates inflammatory cascades and necroptosis pathways, which are implicated in the hyperinflammatory responses characterizing severe COVID-19 cases. Viral exploitation of RIPK1 not only facilitates viral replication but accelerates cytokine storms, aggravating pulmonary damage. Thus, RIPK1 stands as a promising host-directed therapeutic target that could mitigate inflammation and viral load concomitantly.

The research team employed robust high-throughput screening methodologies to discover potent and selective small-molecule inhibitors against both PLpro and RIPK1. Their efforts culminated in the identification of two lead compounds, SHY1643 targeting PLpro and QY1892 targeting RIPK1. These inhibitors exhibit high specificity and favorable pharmacokinetic profiles, critical parameters for advancing preclinical development.

In in vivo studies using a SARS-CoV-2-infected mouse model, administration of SHY1643 and QY1892 individually resulted in significant, yet moderate, reductions in viral titers and inflammatory cytokines. Remarkably, combined treatment with these inhibitors produced a synergistic therapeutic effect, dramatically diminishing viral loads and attenuating cytokine release syndrome, thereby preventing severe lung pathology. This synergistic efficacy underlines the therapeutic advantage of simultaneously modulating viral enzymatic activity and host inflammatory pathways.

Mechanistically, SHY1643 inhibits PLpro by competitively binding to its catalytic domain, thereby obstructing viral polyprotein cleavage and impairing viral replication. QY1892’s inhibitory action on RIPK1 curtails kinase-mediated signaling pathways responsible for propagating pro-inflammatory cytokine production and programmed necrosis, which are hallmarks of severe systemic inflammation in COVID-19. The dual blockade of viral replication and host inflammation presents a compelling case for combination therapy.

This study’s insights address an unmet clinical need for effective treatments that circumvent the limitations of existing antivirals and immunosuppressants. The robust preclinical data offer a proof-of-concept that dual targeting of viral and host factors can yield superior therapeutic benefits. Moreover, the selective nature of the inhibitors minimizes off-target effects, potentially translating into favorable safety profiles for future clinical trials.

The discovery pipeline integrating high-throughput screening, structural biology, and in vivo validation exemplifies a multidisciplinary approach in antiviral drug development. Such methodologies enable rapid identification and optimization of lead compounds with desirable pharmacodynamics and pharmacokinetics against emerging infectious diseases. The PLpro and RIPK1 inhibitors described represent promising candidates for further medicinal chemistry refinement and regulatory evaluation.

Importantly, the study emphasizes that viral proteases like PLpro constitute underexplored antiviral targets that complement established modalities focusing on polymerases or spike proteins. Meanwhile, targeting host molecules such as RIPK1 leverages the host-pathogen interface to temper deleterious immune responses without directly exerting selective pressure on the virus, thereby reducing the likelihood of resistance development.

While the findings are promising, challenges remain in translating these preclinical successes into clinical practice. Pharmacological characterization, dosage optimization, and comprehensive safety assessments in larger animal models and human subjects will be essential. Additionally, evaluating efficacy across diverse SARS-CoV-2 variants and in patients with varying disease severities will determine the clinical utility of this combination therapy.

Looking forward, the dual-inhibitor strategy delineated by this research holds potential not only for COVID-19 but also for other viral diseases where host inflammation exacerbates disease progression. It underscores the paradigm shift towards combination therapies that simultaneously target virus and host factors, heralding a new era in antiviral treatment design.

In summary, this groundbreaking study by Shan and colleagues marks a significant advance in COVID-19 therapeutics by demonstrating that concurrent inhibition of SARS-CoV-2 PLpro and host RIPK1 synergistically reduces viral replication and cytokine-mediated inflammation. This novel combination therapy approach offers a promising avenue to mitigate severe COVID-19 outcomes and enriches the antiviral arsenal against this relentless pandemic.

Subject of Research: Discovery and preclinical evaluation of synergistic inhibitors targeting SARS-CoV-2 PLpro and host RIPK1 for COVID-19 therapy.

Article Title: Discovery of SARS-CoV-2 PLpro inhibitors and RIPK1 inhibitors with synergistic antiviral efficacy in a mouse COVID-19 model

News Publication Date: Not specified

Web References:

• Journal homepage: http://www.imm.ac.cn/
• Chinese Pharmaceutical Association: http://www.cpa.org.cn/Index.html
• Article DOI: http://dx.doi.org/10.1016/j.apsb.2025.09.026
• Acta Pharmaceutica Sinica B on ScienceDirect: https://www.sciencedirect.com/journal/acta-pharmaceutica-sinica-b

References:
Hengyue Shan, Yuzheng Zhou, Ying Qin, Taijie Guo, Xiao Zhang, Huaijiang Xiang, Qinyang He, Chen Shi, Dekang Li, Jingli Liu, Chunting Qi, Shi Chen, Jiajia Dong, Gang Xu, Ying Li, Zheng Zhang, Li Tan, Acta Pharmaceutica Sinica B, Volume 16, Issue 1, 2026, Pages 387-405.

Keywords: SARS-CoV-2, COVID-19, PLpro, RIPK1, Infectious diseases, Cytokine storm, Small molecule inhibitors, Combination therapy.

The entry of SARS-CoV-2 into human cells relies heavily on the angiotensin-converting enzyme 2 (ACE2) receptor, which is abundant in the heart and blood vessels. While ACE2 is crucial for regulating various cardiovascular functions, its interaction with the virus leads to detrimental effects. Upon infection, the virus displaces ACE2 from endothelial cells, disrupting the renin-angiotensin system and resulting in vasoconstriction, increased blood pressure, and heightened inflammation. The ensuing damage is not merely localized but extends throughout the cardiovascular system, promoting acute inflammatory responses that significantly elevate the risk of myocardial injury.

One major pathway implicated in the exacerbation of ACS is the cytokine storm, a hyper-inflammatory reaction characterized by excessive production of pro-inflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α). These cytokines are known to activate platelets, leading to thrombus formation and destabilization of atherosclerotic plaques. The severity of inflammation can also lead to microvascular dysfunction, further compromising myocardial perfusion and increasing the likelihood of adverse cardiac events. Understanding this cascade of inflammatory responses presents new avenues for therapeutic intervention that could mitigate the cardiovascular consequences associated with SARS-CoV-2 infection.

Moreover, hypoxic conditions often present during severe COVID-19 infections can exacerbate these inflammatory phenomena, creating a vicious cycle of injury. Hemodynamic instability due to the systemic effects of the virus compounds the risk of ACS, emphasizing the urgent need for comprehensive strategies addressing both viral and cardiovascular health. This dual focus is especially critical in managing patients who already have underlying cardiovascular conditions, who are consequently more vulnerable to the complications posed by SARS-CoV-2.

In efforts to mitigate these complications, recent research into therapeutic options has gained traction. Among these strategies, modulation of the ACE2 receptor has emerged as a point of focus for innovative treatments. While traditional ACE inhibitors and angiotensin receptor blockers (ARBs) remain under scrutiny due to their potential to upregulate ACE2 expression, emerging evidence points towards alternative therapeutic agents that may confer cardioprotective effects without exacerbating the viral entry process.

Melatonin has been highlighted in recent studies as a promising adjunct therapy in this context. By enhancing nitric oxide bioavailability, melatonin stabilizes arterial plaques and reduces oxidative stress, thereby providing a protective effect during viral-induced inflammation. The implementation of such novel agents in clinical practice could spell a shift in how physicians approach the treatment of patients presenting with ACS as a complication of COVID-19.

Ayurvedic and traditional Chinese medicine (TCM) approaches have also gained attention for their potential to address both viral replication and cardiovascular impairment. The pharmacological properties of various herbal compounds, such as licorice and honeysuckle, showcase their ability to inhibit viral entry and mitigate cytokine storms effectively. Licorice’s glycyrrhizic acid exhibits antiviral properties while simultaneously protecting against oxidative damage through the modulation of key cellular signaling pathways. The integrative use of these natural products alongside conventional therapies might represent a holistic approach towards managing the multifactorial impacts of COVID-19 and its cardiovascular sequelae.

While herbal medicine presents significant benefits, innovative non-herbal pharmacological interventions are also under investigation. Recent findings suggest the efficacy of peptide fusion inhibitors like EK1C4 and IL-1 antagonists such as anakinra in reducing thromboembolic events and the incidence of ACS in patients battling the severe manifestations of COVID-19. Particularly, anakinra has shown promise in curbing hyperinflammation, correlating with improved survival outcomes during severe COVID-19 cases.

Nanotechnology also represents a groundbreaking frontier in the management of COVID-19 and its associated complications. Nanoparticle platforms have revolutionized vaccine delivery systems, enhancing the stability and efficacy of mRNA vaccines like those developed by Pfizer-BioNTech and Moderna. These lipid nanoparticles not only protect the mRNA from enzymatic degradation but also optimize immune response elicitation. Additionally, alternative nanoparticles such as nanoceria and silver nanoparticles are being explored for their antioxidative properties and ability to hinder viral replication.

As the field advances, future directions must include clinical trials to establish standardized dosages for herbal formulations, thereby validating their safety and efficacy in larger populations. Detailed mechanistic studies utilizing emerging imaging technologies like cryo-electron microscopy could elucidate the interactions between herbal compounds and viral receptors. Moreover, optimizing nanoparticle delivery and enhancing target-specific mechanisms will grant greater precision in therapy, ultimately improving patient outcomes in the context of viral-induced cardiovascular disease.

With these diverse strategies contributing to the fight against SARS-CoV-2, the collective promise of phytomedicine and advanced therapeutic modalities heralds a new paradigm in addressing the multifaceted complications of COVID-19. Bridging traditional medical knowledge with cutting-edge science offers an integrated approach that prioritizes safety, efficacy, and patient-centered care in the evolving landscape of post-pandemic cardiology. Adapting to these paradigms will be paramount in redefining therapeutic strategies while ensuring comprehensive care for patients grappling with both viral infections and cardiovascular challenges.

Understanding the interplay between SARS-CoV-2 and acute coronary syndrome is crucial as we navigate the complexities of treating affected patient populations. Education, research, and innovative approaches are essential in overcoming the cardiovascular ramifications of viral infections amidst the ongoing challenges presented by the COVID-19 pandemic.

Subject of Research: The relationship between SARS-CoV-2 infection and acute coronary syndrome (ACS)
Article Title: Potential of Phytomedicine in Benefiting Both Long COVID and Acute Coronary Syndromes: A State-of-the-art Review
News Publication Date: 13-May-2025
Web References: Exploratory Research and Hypothesis in Medicine
References: doi:10.14218/ERHM.2024.00043
Image Credits: Credit: Qing Liu, Rongyuan Yang, Xiao Jiang, Yiran Lu, Yu Ding

Keywords

COVID-19, acute coronary syndrome, ACE2, phytomedicine, nanotechnology, herbal medicine, cytokine storm, inflammation, cardiovascular disease, therapeutic strategies.