The Crosstalk Between Viral Infection and The NLRP3 Inflammasome

The inflammatory response is the foundation and a critical component of innate immunity. It serves as a vital defense mechanism, enabling the body to rapidly recognize and resist the invasion of foreign pathogenic microorganisms through a spontaneous immune reaction. Through pattern recognition receptors (PRRs), the host can effectively identify pathogen-associated molecular patterns (PAMPs) from microbes like bacteria and viruses, as well as damage-associated molecular patterns (DAMPs) released by injured cells. This allows for swift identification and resistance against pathogenic invasions, fulfilling a cellular surveillance function. As one of the most important protein complexes in innate immunity, the NLRP3 inflammasome—a large multi-protein complex—is among the most extensively studied inflammasomes. It assembles in response to pathogenic invasion or other danger signals and is crucial for the processing and release of pro-inflammatory mediators. This process helps the body distinguish between “self” and “non-self” and plays a significant role in both inflammatory and antiviral responses, thereby maintaining the host’s internal homeostasis. However, under certain conditions, immune regulation can become dysregulated, leading to an inflammatory response that is either too weak or too strong. This imbalance between pro-inflammatory and anti-inflammatory states can ultimately result in disease and tissue damage. Notably, not all viral infections activate the inflammasome. The activation mechanism of the NLRP3 inflammasome remains unclear and is even a subject of debate. On one hand, viruses are recognized by the host’s innate immune system, which can activate the NLRP3 inflammasome to mobilize immune and inflammatory responses for antiviral defense. Upon viral infection, the host receptor protein NLRP3 recognizes inflammatory signals, recruits the adapter protein ASC, and forms an inflammasome complex with pro-caspase-1. This triggers a cascade of activation events that initiate the innate immune response. Strategies involved in this process include altering intracellular and extracellular ion concentrations, affecting host cell energy metabolism, and directly interacting with components of the NLRP3 inflammasome to regulate its activation. On the other hand, viruses have evolved multiple strategies to inhibit NLRP3 inflammasome activation and evade immune responses. These include regulating NLRP3 ubiquitination and degradation, inhibiting the assembly and activation of the NLRP3 inflammasome, and modulating its effector functions. Furthermore, while NLRP3 inflammasome activation upon viral infection helps clear the virus and is crucial for antiviral defense, viruses can also evade this immune mechanism to facilitate their own replication and proliferation. A deeper understanding of the interplay between inflammasome activation and viral replication will contribute to the precise and effective prevention and treatment of currently incurable viral diseases. Therefore, this article will focus on the complex interactions between viral infection and the NLRP3 inflammasome. It will review recent advances in understanding virus-induced NLRP3 inflammasome activation and the immune evasion strategies viruses employ by modulating NLRP3 inflammasome activity, with the ultimate goal of fundamentally controlling viral replication in the host. In-depth research in this area will not only enhance our understanding of viral pathogenesis but also provide new strategies for clinical antiviral therapy and drug development.