Chemiluminescence response and adherence of neutrophils to cultured endothelial cells--influence of immunoglobulin G

Mechanisms of action of intravenous immunoglobulin in septic encephalopathy

Acute brain dysfunction associated with sepsis is a serious complication that results in morbidity and mortality. Intravenous immunoglobulin (IVIg) treatment is known to alleviate behavioral deficits in the experimentally induced model of sepsis. To delineate the mechanisms by which IVIg treatment prevents neuronal dysfunction, an array of immunological and apoptosis markers was investigated. Our results suggest that IVIgG and IgGAM administration ameliorates neuronal dysfunction and behavioral deficits by reducing apoptotic cell death and glial cell proliferation. IgGAM treatment might suppress classical complement pathway by reducing C5a activity and proapoptotic NF-κB and Bax expressions, thereby, inhibiting major inflammation and apoptosis cascades. Future animal model experiments performed with specific C5aR and NF-κB agonists/antagonists or C5aR-deficient mice might more robustly disclose the significance of these pathways. C5a, C5aR, and NF-κB, which were shown to be the key molecules in brain injury pathogenesis in sepsis, might also be utilized as potential targets for future treatment trials of septic encephalopathy.

Myeloperoxidase genetic polymorphisms and susceptibility to Kawasaki disease in Taiwanese children

BACKGROUND/PURPOSE

The aim of this study was to investigate the myeloperoxidase (MPO) -463G>A polymorphism in Kawasaki disease (KD) patients, and the relationship between gene polymorphism and MPO levels.

METHODS

A total of 334 KD children and 492 sex-matched controls were assayed for polymorphism analysis. TaqMan assays were used for genotyping. MPO was measured in 37 KD patients and 42 febrile controls.

RESULTS

A significant linear trend of KD risk was found to be related to the G/G genotype (p_{linear trend} = 0.032). The combined genotypes (G/A and A/A) of MPO -463G>A were associated with a significantly decreased KD risk compared to the G/G genotype [adjusted odds ratios (AOR) = 0.71, 95% confidence interval (CI): 0.52-0.99, p = 0.040]. In addition, KD patients with A allele were associated with a significantly decreased KD risk as compared to those with G allele (AOR = 0.73, 95% CI: 0.54-0.98, p = 0.033). MPO levels were significantly elevated in KD patients in preintravenous immunoglobulin (pre-IVIG) stage compared to febrile controls (p = 0.002). KD patients in pre-IVIG stage had significantly higher MPO levels than febrile controls in terms of G/G genotype (p = 0.003) and G allele (p < 0.001). KD patients with A allele had significantly lower MPO levels than those with G allele in post-IVIG acute stage (p = 0.042). However, there was no significant difference of individual MPO change for KD patients from pre- to post-IVIG stage in terms of genotypes (p = 0.837) or alleles (p = 0.631).

CONCLUSION

Our results suggest that G allele of MPO -463G>A polymorphism is a potential genetic marker for KD risk in Taiwanese children.

Intravenous immunoglobulin counteracts oxidative stress in Kawasaki disease

Oxidative stress (OS) appears to play a pivotal role in many medical conditions. This study aimed to investigate whether OS is associated with Kawasaki disease (KD) or not, and if so, then to determine whether the mechanism of intravenous immunoglobulin therapy (IVIG) is associated with scavenging reactive oxygen species. Results show a significant difference between patients with KD and those with febrile illnesses (p = 0.018) in terms of OS, as assessed by the d-ROMs/BAP ratio, an arbitrary index comprising derivatives of reactive oxygen metabolites (d-ROMs) relative to a biologic antioxidant potential (BAP). Furthermore, children with KD had a significantly decreased d-ROMs/BAP ratio after IVIG (p = 0.011). Interestingly, the d-ROMs/BAP ratio decreased in 12 of 14 patients with KD who defervesced after IVIG, whereas all but one patient who did not defervesce showed an increase in this ratio. In conclusion, OS plays an important role in the pathogenesis of acute KD. Because IVIG therapy relieves OS by augmenting BAP, an assessment of OS in the acute phase of KD may be useful for early recognition of the necessity to perform additional IVIG treatment. Further study to elucidate this point would be worthwhile.

Targeting Adhesion Molecules as a Potential Mechanism of Action for Intravenous Immunoglobulin

Background— Intravenous immunoglobulin (IVIg) therapy has been shown to have therapeutic benefit in more than 50 inflammatory and immune-related diseases; however, the potential benefit of IVIg in cardiovascular disease is more limited, in part because our understanding of the mechanisms underlying the effects of IVIg in innate immunity is incomplete.

Methods and Results— In this study, a systematic assessment of the role of IVIg in leukocyte recruitment was completed with an in vitro flow-chamber system and in vivo intravital microscopy in a feline ischemia-reperfusion model system. IVIg treatment of blood resulted in a profound decrease in recruitment of either immobilized P-selectin or E-selectin due to direct effects of IVIg on the leukocyte (not substratum). Similar results were observed on endothelium treated with histamine, which induces P-selectin–dependent rolling and β 2 -integrin–dependent adhesion. IVIg reduced P-selectin glycoprotein ligand-1 (PSGL-1) antibody binding to PSGL-1 on leukocytes. Use of a β 2 -integrin–dependent static assay to bypass selectin-dependent recruitment revealed some inhibitory effectiveness (60%), which suggests that the majority of the effects of IVIg were due to selectin inhibition, with some inhibition of integrin function. In vivo intravital microscopy revealed a potent inhibitory effect of IVIg on P-selectin–dependent rolling and β 2 -integrin–dependent adhesion that led to reduced leukocyte recruitment and vascular dysfunction in postischemic microvessels.

Conclusions— Our data demonstrate that IVIg has direct inhibitory effects on leukocyte recruitment in vitro and in vivo through inhibition of selectin and integrin function.