METHODS: An initial study showed that PMX53, an antagonist of C5aR1 in normal C57BL6/J (wild type, WT) mice reduced heart rate (HR) and appeared to have a protective effect on the heart following induced sepsis. C5aR1 knockout (CD88-/-) mice had a lower HR than wild type mice, even during sham surgery. A model to assess heart rate variability (HRV) in anesthetized mice was developed to assess the effects of inhibiting the β1-adrenoreceptor (β1-AR) in a randomized crossover study design.
RESULTS: HR and LF Norm were constitutively lower and SDNN and HF Norm constitutively higher in the CD88-/- compared with WT mice (P< 0.001 for all outcomes). Administration of atenolol (2.5 mg/kg) reduced the HR and increased HRV (P< 0.05, respectively) in the wild type but not in the CD88-/- mice. There was no shift of the sympathovagal balance post-atenolol in either strains of mice (P> 0.05), except for the reduced LF/HF (Lower frequency/High frequency) ratio (P< 0.05) at 60 min post-atenolol, suggesting increased parasympathetic tone of the heart due to the effect of atenolol administration. The HR of the WT mice were lower post atenolol compared to the CD88-/- mice (P = 0.001) but the HRV of CD88-/- mice were significantly increased (P< 0.05), compared with WT mice.
CONCLUSION: Knockout of the C5aR1 attenuated the effect of β1-AR in the heart, suggesting an association between the β1-AR and C5aR1, although further investigation is required to determine if this is a direct or causal association.
RESULTS: Our findings showed that in vivo model of C. neoformans infection demonstrated induction of abundant IL-17A secretion. By examining the lung bronchoalveolar lavage fluid (BALF), mediastinal lymph node (mLN) and spleen of the IL-17A-EGFP reporter mice, we showed that intranasal inoculation with C. neoformans promoted leukocytes lung infiltration. A large proportion (~ 50%) of the infiltrated CD4+ helper T cell population secreted EGFP, indicating vigorous TH17 activity in the C. neoformans-infected lung. The infection study in IL-17A-KO mice, on the other hand, revealed that absence of IL-17A marginally boosted fungal burden in the lung and accelerated the mouse death.
CONCLUSION: Therefore, our data suggest that IL-17A is released predominantly from TH17 cells in vivo, which plays a supporting role in the protective immunity against C. neoformans infection.
RESULTS: Here, we describe a luciferase/luciferin (XenoLuc) assay that could specifically measure changes in the proliferation of cancer cells in the co-culture system using two modified NPC patient-derived tumour xenograft (PDTXs) cells: Xeno284-gfp-luc2 and XenoB110-gfp-luc2. Through this assay, we are able to show that the growth of NPC xenograft cells in both two-dimensional (2D) and three-dimensional (3D) models was enhanced when co-cultured with normal human dermal fibroblasts (NHDFs). In addition, potential applications of this assay in in vitro drug or inhibitor screening experiments are also illustrated.
CONCLUSIONS: XenoLuc assay is specific, sensitive, rapid and cost-effective for measuring the growth of luciferase-expressing cells in a co- or multiple-culture system. This assay may also be adapted for tumour microenvironment studies as well as drug screening experiments in more complex 3D co-culture systems.
METHODS: We assessed the relationship between STRN status in humans (HyperPATH cohort) and SSBP and on volume regulated systems in humans and a striatin knockout mouse (STRN+/-).
RESULTS: The previously identified association between a striatin risk allele and systolic SSBP was demonstrated in a new cohort (P = 0.01). The STRN-SSBP association was significant for the combined cohort (P = 0.003; β = +5.35 mm Hg systolic BP/risk allele) and in the following subgroups: normotensives, hypertensives, men, and older subjects. Additionally, we observed a lower epinephrine level in risk allele carriers (P = 0.014) and decreased adrenal medulla phenylethanolamine N-methyltransferase (PNMT) in STRN+/- mice. No significant associations were observed with other volume regulated systems.
CONCLUSIONS: These results support the association between a variant of striatin and SSBP and extend the findings to normotensive individuals and other subsets. In contrast to most salt-sensitive hypertensives, striatin-associated SSBP is associated with normal plasma renin activity and reduced epinephrine levels. These data provide clues to the underlying cause and a potential pathway to achieve, specific, personalized treatment, and prevention.
BACKGROUND: Formyl peptide receptors (FPRs) play pivotal roles in the regulation of innate immunity and host defense. The FPRs include three family members: FPR1, FPR2/ALX, and FPR3. The activation of FPR1 by its high-affinity ligand, N-formyl-methionyl-leucyl-phenylalanine (fMLF) (a bacterial chemoattractant peptide), triggers intracellular signaling in immune cells such as neutrophils and exacerbates inflammatory responses to accelerate the clearance of microbial infection. Notably, fMLF has been demonstrated to induce intracellular calcium mobilization and chemotaxis in platelets that are known to play significant roles in the regulation of innate immunity and inflammatory responses. Despite a plethora of research focused on the roles of FPR1 and its ligands such as fMLF on the modulation of immune responses, their impact on the regulation of hemostasis and thrombosis remains unexplored.
OBJECTIVE: To determine the effects of fMLF on the modulation of platelet reactivity, hemostasis, and thrombus formation.
METHODS: Selective inhibitors for FPR1 and Fpr1-deficient mice were used to determine the effects of fMLF and FPR1 on platelets using various platelet functional assays.
RESULTS: N-formyl-methionyl-leucyl-phenylalanine primes platelet activation through inducing distinctive functions and enhances thrombus formation under arterial flow conditions. Moreover, FPR1 regulates normal platelet function as its deficiency in mouse or blockade in human platelets using a pharmacological inhibitor resulted in diminished agonist-induced platelet activation.
CONCLUSION: Since FPR1 plays critical roles in numerous disease conditions, its influence on the modulation of platelet activation and thrombus formation may provide insights into the mechanisms that control platelet-mediated complications under diverse pathological settings.