Toll-like receptor 3 (TLR3) initiates antiviral and inflammatory responses exclusively through the adaptor protein TRIF (TIR-domain-containing adapter-inducing interferon-β). In contrast, MyD88 (myeloid differentiation primary response 88), a central adaptor for most other TLRs, is traditionally considered dispensable for TLR3 signaling. Here, we demonstrate that MyD88 directly contributes to TLR3-mediated NF-κB activation and cytokine production in macrophages. Bone marrow-derived macrophages (BMDMs) from MyD88 deficient mice exhibited significantly attenuated NF-κB activation in response to the TLR3 agonist polyinosinic–polycytidylic acid (poly(I:C)) compared to wild-type cells, as evidenced by the reduced phosphorylation of NF-κB p65 and IκBα, as well as IκBα degradation. Consistently, pro-inflammatory cytokine production, including IL-6, TNF-α, and IFN-β, was attenuated in MyD88-deficient BMDMs in vitro following stimulation by poly(I:C) or poly(A:U), another TLR3 agonist. Blood concentrations of IL-6, TNF-α, and IFN-β were significantly reduced in both TRIF-deficient mice and MyD88-deficient mice challenged by the i.p. injection of poly(I:C). Mechanistic analyses revealed that MyD88 physically associates with activated TLR3 upon poly(I:C) stimulation, and that TLR3 engagement triggered MyD88 oligomerization, which was absent in TLR3 or TRIF deficient macrophages. Our findings highlight a previously unrecognized dual-adaptor mechanism for TLR3, wherein MyD88 recruitment amplifies NF-κB signaling dynamics by bridging TLR3 to the canonical NF-κB activation cascade and robust cytokine induction. This study expands the paradigm of TLR3 signaling by establishing MyD88 as a direct contributor to TLR3-driven innate immune responses, offering new insight into cross-talk between MyD88-dependent and -independent pathways.

The Salmonella enterica serovar Typhimurium (ST) mutant lacking the msbB gene (ΔmsbB) has been widely studied as a candidate for attenuated bacterial vectors in therapeutic applications. Deletion of msbB results in LPS with under-acylated lipid A, which lowers endotoxicity while maintaining structural integrity. This attenuation has traditionally been attributed to reduced TLR4 activation due to weaker interaction between the modified lipid A and TLR4. In our study, we confirmed that ΔmsbB ST was less lethal than wild-type (WT) ST in a mouse sepsis model. However, this difference persisted even in TLR4- and caspase-11-deficient mice, suggesting that LPS signaling is not the primary determinant of virulence. In vitro, bone marrow–derived macrophages (BMDMs) from TLR4- or caspase-11-deficient mice showed only modest reductions in ST-induced cell death and cytokine production. Importantly, ΔmsbB ST behaved similarly to WT ST in these assays, further indicating that LPS-mediated signaling is not central to the observed attenuation. Our previous studies showed that ST-induced mortality in mice is primarily mediated through NLRC4 activation. Using qPCR and immunoblotting, we found that expression of NLRC4 activators was diminished in the ΔmsbB strain. Additionally, the mutant exhibited increased outer membrane permeability—likely contributing to its heightened antibiotic sensitivity—and reduced motility due to lower flagellin protein levels. In summary, the attenuation of virulence observed in the ΔmsbB strain is not directly due to altered LPS–TLR4 interactions, but rather an indirect effect of diminished expression of virulence factors that activate the NLRC4 inflammasome.

To analyze the characteristics of CDR3 of TCRbeta on CD8+ T cells in chronic hepatitis B patients. Eight patients with chronic hepatitis B (ALT more than 2 ULN) were enrolled in this study. CD8+ T cells were isolated from peripheral blood. RT-PCR was proformed to amplify the CDR3 of TCRbeta, and the PCR products were sequenced and analyzed. The chronic hepatitis B patients showed obvious clonal expansion of T cell, and three perturbation patterns of T cell expansion were showed in the CDR3 of TCRbeta, including monoclonicity, oligoclonicity and skewed peak patterns. The number of perturbation families of CD8+ subpopulation was significantly higher than that of CD8- subpopulation (10.6+/-4.7 vs. 4.1+/-3.1, t = 6.619, P less than 0.01). In 3 out of 8 patients, the number of perturbation families of CD8+ subpopulation was also higher than that of PBMCs without depleting CD8+ subpopulation. The characteristics of CDR3 of TCRbeta may help to understand the inflammatory response in CHB patients.

B-type natriuretic peptide (BNP) is a cardiac-derived vasodilator and a well-established biomarker for heart failure. Elevated BNP and its cleavage product N-terminal proBNP (NT-proBNP) also predict adverse outcomes in acute coronary syndromes and other cardiovascular diseases. However, it remains unclear whether BNP directly contributes to cardiovascular disease pathogenesis, such as by promoting thrombosis, or merely serves as a biomarker. We investigated the effect of BNP on platelets in vitro and thrombosis in vivo. Incubation of platelets with BNP significantly increased intracellular cGMP levels and enhanced platelet aggregation, granule secretion, spreading, and clot retraction in vitro. We further identified that platelets express the receptor for BNP, natriuretic peptide receptor-A (NPRA). The effects of BNP on cGMP production and platelet activation were abolished in NPRA-deficient platelets. Using FeCl₃ carotid injury-induced arterial thrombosis model and a thromboplastin-induced pulmonary embolism model, we found that BNP administration accelerated thrombus formation in wild-type mice. Moreover, NPRA-deficient mice exhibited prolonged tail bleeding times and delayed arterial occlusion following vascular injury. BNP injection failed to promote thrombosis in NPRA-deficient mice. Our study demonstrates that BNP promotes platelet activation and enhances arterial thrombosis and thromboembolism via NPRA signaling. These findings suggest that BNP may not only serve as a biomarker of cardiovascular disease, but may also contribute directly to thrombotic risk, providing a potential mechanistic link between elevated cGMP levels and thrombosis.