Regulation of the expression of Fc gamma receptor on circulating neutrophils and monocytes in Kawasaki disease

Role of FcγRIII in the nasal cavity of BALB/c mice in the primary amebic meningoencephalitis protection model

Different mechanisms of the host immune response against the primary amebic meningoencephalitis (PAM) in the mouse protection model have been described. It has been proposed that antibodies opsonize Naegleria fowleri trophozoites; subsequently, the polymorphonuclear cells (PMNs) surround the trophozoites to avoid the infection. FcγRs activate signaling pathways of adapter proteins such as Syk and Hck on PMNs to promote different effector cell functions which are induced by the Fc portion of the antibody-antigen complexes. In this work, we analyzed the activation of PMNs, epithelial cells, and nasal passage cells via the expression of Syk and Hck genes. Our results showed an increment of the FcγRIII and IgG subclasses in the nasal cavity from immunized mice as well as Syk and Hck expression was increased, whereas in the in vitro assay, we observed that when the trophozoites of N. fowleri were opsonized with IgG anti-N. fowleri and interacted with PMN, the expression of Syk and Hck was also increased. We suggest that PMNs are activated via their FcγRIII, which leads to the elimination of the trophozoites in vitro, while in the nasal cavity, the adhesion and consequently infection are avoided.

The neutrophil: A key resourceful agent in immune‐mediated vasculitis

The term "vasculitis" refers to a group of rare immune-mediated diseases characterized by the dysregulated immune system attacking blood vessels located in any organ of the body, including the skin, lungs, and kidneys. Vasculitides are classified according to the size of the vessel that is affected. Although this observation is not specific to small-, medium-, or large-vessel vasculitides, patients show a high circulating neutrophil-to-lymphocyte ratio, suggesting the direct or indirect involvement of neutrophils in these diseases. As first responders to infection or inflammation, neutrophils release cytotoxic mediators, including reactive oxygen species, proteases, and neutrophil extracellular traps. If not controlled, this dangerous arsenal can injure the vascular system, which acts as the main transport route for neutrophils, thereby amplifying the initial inflammatory stimulus and the recruitment of immune cells. This review highlights the ability of neutrophils to "set the tone" for immune cells and other cells in the vessel wall. Considering both their long-established and newly described roles, we extend their functions far beyond their direct host-damaging potential. We also review the roles of neutrophils in various types of primary vasculitis, including immune complex vasculitis, anti-neutrophil cytoplasmic antibody-associated vasculitis, polyarteritis nodosa, Kawasaki disease, giant cell arteritis, Takayasu arteritis, and Behçet's disease.

Nanomedicine for acute respiratory distress syndrome: The latest application, targeting strategy, and rational design

Acute respiratory distress syndrome (ARDS) is characterized by the severe inflammation and destruction of the lung air-blood barrier, leading to irreversible and substantial respiratory function damage. Patients with coronavirus disease 2019 (COVID-19) have been encountered with a high risk of ARDS, underscoring the urgency for exploiting effective therapy. However, proper medications for ARDS are still lacking due to poor pharmacokinetics, non-specific side effects, inability to surmount pulmonary barrier, and inadequate management of heterogeneity. The increased lung permeability in the pathological environment of ARDS may contribute to nanoparticle-mediated passive targeting delivery. Nanomedicine has demonstrated unique advantages in solving the dilemma of ARDS drug therapy, which can address the shortcomings and limitations of traditional anti-inflammatory or antioxidant drug treatment. Through passive, active, or physicochemical targeting, nanocarriers can interact with lung epithelium/endothelium and inflammatory cells to reverse abnormal changes and restore homeostasis of the pulmonary environment, thereby showing good therapeutic activity and reduced toxicity. This article reviews the latest applications of nanomedicine in pre-clinical ARDS therapy, highlights the strategies for targeted treatment of lung inflammation, presents the innovative drug delivery systems, and provides inspiration for strengthening the therapeutic effect of nanomedicine-based treatment.

A Retrospective Cohort Study of Intravenous Immunoglobulin Therapy in the Acute Phase of Kawasaki Disease: The Earlier, the Better?

Background

Although intravenous immunoglobulin (IVIG) is expected to prevent coronary artery abnormalities of Kawasaki disease (KD) in the acute phase, the timing and effectiveness of IVIG remain to be determined. The association of timing of IVIG administration in KD patients with coronary artery abnormalities is evaluated in this cohort study.

Methods

We systematically studied KD patients from two participating institutions between 2015 and 2017. To reveal the effectiveness of IVIG treatment, these patients were classified into four groups regarding the time of IVIG treatment. Primary outcome was coronary artery abnormalities by echo at diagnosis and 12 months follow-up; secondary outcomes included inflammatory markers.

Results

A total of 1281 patients were included in this study. The best time of IVIG treatment cut-off values in 12 months follow-up for predicting coronary artery abnormalities was days 7.5 of illness onset. According to the best time of IVIG treatment cut-off values, all patients were classified into 4 groups. Group 1 was defined as earlier IVIG treatment administration on days ≤4 of the illness (n = 77). Group 2 was defined with days 5-7 (n = 817), group 3 with days 8-10 (n = 249), group 4 with days >10 (n = 138). A greater proportion of IVIG-resistant KD patients were group 4 than the other three groups, and there were significant differences (p < 0.05). The incidence of coronary artery lesions (CALs) and coronary artery aneurysms (CAAs) in group 3 and group 4 was higher than that in group 1 (p < 0.05) and group 2 (p < 0.05) during a 12-month follow-up. Additionally, the incidence of CALs in group 1 was higher than that in group 2 but without statistical significance (p > 0.05). The OR was significantly higher for those who started IVIG administration more than 7 days from the onset was positively associated with the occurrence of CALs (OR, 5.3; 95% CI, 2.0-13.9) and CAAs (OR, 13.5; 95% CI, 2.9-14.1) 12 months after initial onset. Multivariate regression revealed that the timing of IVIG treatment and IVIG-resistance was independent risk factors of CALs.

Conclusions

IVIG treatment less than 7 days after illness onset are found to be sufficient for preventing developing coronary artery abnormalities in KD patients. Earlier IVIG treatment administration within 4 days may not increase the higher incidence of coronary artery abnormalities and IVIG resistance (Chinese Clinical Trial Registry:ChiCTR1800015800).

Long-Term Hypermethylation of FcγR2B in Leukocytes of Patients with Kawasaki Disease

The Fc gamma receptor family contains several activating receptors and the only inhibitory receptor, FcγR2B. In this study, we investigated the dynamic methylation change of FcγR2B in different stages of Kawasaki disease (KD). We enrolled a total of 116 participants, which included patients with febrile diseases as controls and KD patients. Whole blood cells of KD patients were collected prior to intravenous immunoglobulin (IVIG) treatment (KD1), three to seven days after IVIG (KD2), three weeks after IVIG treatment (KD3), six months after IVIG (KD4), and one year after IVIG treatment (KD5). In total, 76 KD patients provided samples in every stage. Leukocytes of controls were also recruited. We performed DNA extraction and pyrosequencing. FcγR2B methylation levels were higher in KD3 compared to both the controls and KD1. A significantly higher methylation of FcγR2B was found in KD5 when compared with KD1. FcγR2B methylation levels in the IVIG-resistant group were lower than those in the IVIG-responsive group at KD1-3 (p = 0.004, 0.004, 0.005 respectively). This study is the first to report the dynamic change of FcγR2B methylation and to demonstrate long-term hypermethylation one year after disease onset. Hypomethylation of FcγR2B is associated with IVIG resistance.

Identification of increased expression of activating Fc receptors and novel findings regarding distinct IgE and IgM receptors in Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is associated with expression and methylation of Fc gamma receptor genes. We characterized immunoglobulin A (IgA), IgE, IgG, and IgM receptor expression levels in KD.

METHODS

Fc receptor expression levels were characterized using GeneChip Human Transcriptome Array 2.0 (HTA 2.0) with 18 KD patients, 18 non-febrile controls, and 18 febrile controls. Another 48 control individuals and 46 patients with KD were measured using pyrosequencing for the methylation levels.

RESULTS

The mRNA expression levels of FCER1A and FCER2 were significantly lower in KD patients than in non-febrile controls and then rose following treatments with intravenous immunoglobulin (IVIG). Expression levels of FCER1G increased compared to the non-febrile subjects and then subsided after IVIG. FCER1A methylation was significantly lower among KD patients and even lower in KD patients with IVIG resistance. HTA analysis revealed higher mRNA levels of FCAR, FCGR1C, and FCGR2A in KD patients. FCMR mRNA expression levels were significantly lower in KD patients. FCMR expression levels rose after IVIG treatment. After IVIG, FCGR1A, B, and C decreased even lower than the febrile controls.

CONCLUSION

This is the first study indicating that IgA, IgE, IgG, and IgM receptors are associated with KD. We highlighted potential biomarkers related to Fc receptors and their regulation.

Neutrophils and Macrophages as Targets for Development of Nanotherapeutics in Inflammatory Diseases

Neutrophils and macrophages are major components of innate systems, playing central roles in inflammation responses to infections and tissue injury. If they are out of control, inflammation responses can cause the pathogenesis of a wide range of diseases, such as inflammatory disorders and autoimmune diseases. Precisely regulating the functions of neutrophils and macrophages in vivo is a potential strategy to develop immunotherapies to treat inflammatory diseases. Advances in nanotechnology have enabled us to design nanoparticles capable of targeting neutrophils or macrophages in vivo. This review discusses the current status of how nanoparticles specifically target neutrophils or macrophages and how they manipulate leukocyte functions to inhibit their activation for inflammation resolution or to restore their defense ability for pathogen clearance. Finally, we present a novel concept of hijacking leukocytes to deliver nanotherapeutics across the blood vessel barrier. This review highlights the challenges and opportunities in developing nanotherapeutics to target leukocytes for improved treatment of inflammatory diseases.

Prevention of vascular inflammation by nanoparticle targeting of adherent neutrophils

Inflammatory diseases such as acute lung injury and ischaemic tissue injury are caused by the adhesion of a type of white blood cell--polymorphonuclear neutrophils--to the lining of the circulatory system or vascular endothelium and unchecked neutrophil transmigration. Nanoparticle-mediated targeting of activated neutrophils on vascular endothelial cells at the site of injury may be a useful means of directly inactivating neutrophil transmigration and hence mitigating vascular inflammation. Here, we report a method employing drug-loaded albumin nanoparticles, which efficiently deliver drugs into neutrophils adherent to the surface of the inflamed endothelium. Using intravital microscopy of tumour necrosis factor-α-challenged mouse cremaster post-capillary venules, we demonstrate that fluorescently tagged albumin nanoparticles are largely internalized by neutrophils adherent to the activated endothelium via cell surface Fcɣ receptors. Administration of albumin nanoparticles loaded with the spleen tyrosine kinase inhibitor, piceatannol, which blocks 'outside-in' β2 integrin signalling in leukocytes, detached the adherent neutrophils and elicited their release into the circulation. Thus, internalization of drug-loaded albumin nanoparticles into neutrophils inactivates the pro-inflammatory function of activated neutrophils, thereby offering a promising approach for treating inflammatory diseases resulting from inappropriate neutrophil sequestration and activation.

The involvement of Fc gamma receptor gene polymorphisms in Kawasaki disease

Kawasaki disease is an acute febrile syndrome in infancy, characterized by vasculitis of medium-sized arteries. Without treatment the disease can lead to coronary artery lesions (CAL) in approximately 25% of the children. Therapy consists of intravenous immunoglobulins (IVIG), leading to a decrease of complications to 5-16%. Little is known about the working mechanisms of IVIG. In this study we evaluated the involvement of Fcgamma receptors (FcgammaRs) in Kawasaki disease by the determination of the frequency of known single nucleotide polymorphisms (SNPs) in the genes coding for the FcgammaRs and compared this with frequencies in a cohort of healthy controls. There was no difference in the distribution of the functionally relevant genotypes for FcgammaRIIa-131H/R, FcgammaRIIb-232I/T, FcgammaRIIIa-158 V/F and FcgammaRIIIb-NA1/NA2 between the patient group and the healthy controls. Furthermore, there were no polymorphisms linked to the disease severity as indicated by the absence or development of CAL during the disease. Altered transcription or expression of FcgammaR on specific cell types of the immune system may still play a role in susceptibility and treatment success, but at a level different from the functional SNPs in FcgammaR genes tested in this study.

The CD14+ CD16+ blood monocytes: their role in infection and inflammation

Blood monocyte subpopulations have been defined in man initially, and the two major types of monocytes are the CD14++ CD16- and the CD14+ CD16+ monocytes. These cells have been shown to exhibit distinct phenotype and function, and the CD14+ CD16+ were labeled proinflammatory based on higher expression of proinflammatory cytokines and higher potency in antigen presentation. The current review describes these properties, including the relationship to dendritic cells, and summarizes the host of publications about CD14+ CD16+ monocytes in inflammation and infectious disease in man, all of which suggest a crucial role of these cells in the disease processes. The review also covers the more recent description of homologues of these cells in other model species, which is expected to better define the role of monocyte subsets in disease.

Neutrophilic involvement in the damage to coronary arteries in acute stage of Kawasaki disease

BACKGROUND

There has been no morphological evidence that polymorphonuclear leukocytes (PMNL) infiltrate the coronary arterial lesions of acute Kawasaki disease (KD) patients, although clinical data indicate the activation of PMNL.

METHODS

The experimental materials consisted of eight autopsy patients who died during the acute phase of KD. Duration of the illness ranged from 6 to 32 days. The tissues were fixed and embedded in paraffin. Hematoxylin and eosin, elastica van Gieson and azan-Mallory stainings were performed for routine histological examination. In addition, antibodies to CD3, CD20, CD68 and neutrophil elastase were used for immunohistochemistry to identify infiltrating cells in arterial lesions.

RESULTS

The inflammatory cells that appeared in the coronary arterial lesions were mainly composed of macrophages in all patients. In addition, numerous neutrophils were also identified in the coronary arterial lesions of the patients who died 10 days after the onset of KD. Neutrophilic infiltration reached a peak earlier than the peaks of CD68+ macrophages, CD3+ T lymphocytes and CD20+ B lymphocytes.

CONCLUSIONS

These results suggest that neutrophils are involved in the damage occurring to coronary arteries in the early stage of KD. Vasodilation might occur as a result of injury to vascular walls caused by neutrophils, as well as macrophages.

Expression of IL-8 in Kawasaki disease

We investigated, by Northern blotting, ELISA, and a chemotaxis assay, the expression of IL-8 mRNA, the production of IL-8 protein, and the biological activity of mononuclear cells (MNC), polymorphonuclear neutrophils (PMN) and plasma, respectively, from patients with Kawasaki disease (KD) who received intravenous immunoglobulin (IVIG). IL-8 mRNA expression by MNC and PMN, the level of IL-8 protein, and the neutrophil chemoattractant activity within plasma were all increased in the acute phase of KD, and were significantly elevated following IVIG therapy. The level of chemotactic activity of neutrophils, but not that of monocytes, in response to F-met-leu-phe was decreased in patients with KD after IVIG. The increased expression of IL-8 in PMN and MNC, the increased plasma level of IL-8 and the decreased level of neutrophil chemotactic activity of the patients who received IVIG therapy might inhibit the accumulation of neutrophils at the sites of inflammation, and may thus reduce the risk of aneurysm formation.