Effects of human soluble BAFF synthesized in Escherichia coli on CD4+ and CD8+ T lymphocytes as well as NK cells in mice

Secoemestrin C Ameliorates Psoriasis-like Skin Inflammation in Mice by Suppressing the TNF-α/NF-κB Signaling Pathway

OBJECTIVE

Secoemestrin C (SC), an epitetrathiodioxopiperazine isolated from Aspergillus nidulans, has been previously reported to have immunomodulatory and hepatoprotective effects against acute autoimmune hepatitis. However, the effect of SC on regulating the inflammation and its underlying mechanisms in the pathogenesis of psoriasis remain unclear. This study aimed to evaluate the effects of SC on inflammatory dermatosis both in vitro and in vivo.

METHODS

In vitro, HaCaT cells were induced with tumor necrosis factor-alpha (TNF-α, 10 ng/mL) to establish an inflammatory injury model, and the expression of nuclear transcription factor-κB (NF-κB) pathway components was measured using qRT-PCR and Western blotting. An in vivo mouse model of imiquimod (IMQ)-induced psoriasis-like skin inflammation was used to evaluate the effectiveness of SC in alleviating psoriasis.

RESULTS

SC significantly blocked the activation of NF-κB signaling in TNF-α-stimulated HaCaT cells. In addition, systemic and local administration of SC improved psoriatic dermatitis in the IMQ-induced mouse model. SC reduced skin scale and significantly inhibited the secretion of inflammatory factors in skin lesions.

CONCLUSION

The protective effect of SC against psoriatic-associated inflammation reveals its potential therapeutic value for treating psoriasis.

Single-cell transcriptomics reveal a hyperacute cytokine and immune checkpoint axis after cardiac arrest in patients with poor neurological outcome

BACKGROUND

Most patients hospitalized after cardiac arrest (CA) die because of neurological injury. The systemic inflammatory response after CA is associated with neurological injury and mortality but remains poorly defined.

METHODS

We determine the innate immune network induced by clinical CA at single-cell resolution.

FINDINGS

Immune cell states diverge as early as 6 h post-CA between patients with good or poor neurological outcomes 30 days after CA. Nectin-2+ monocyte and Tim-3+ natural killer (NK) cell subpopulations are associated with poor outcomes, and interactome analysis highlights their crosstalk via cytokines and immune checkpoints. Ex vivo studies of peripheral blood cells from CA patients demonstrate that immune checkpoints are a compensatory mechanism against inflammation after CA. Interferon γ (IFNγ)/interleukin-10 (IL-10) induced Nectin-2 on monocytes; in a negative feedback loop, Nectin-2 suppresses IFNγ production by NK cells.

CONCLUSIONS

The initial hours after CA may represent a window for therapeutic intervention in the resolution of inflammation via immune checkpoints.

FUNDING

This work was supported by funding from the American Heart Association, Brigham and Women's Hospital Department of Medicine, the Evergreen Innovation Fund, and the National Institutes of Health.

Distinct binding mode of BAFF antagonist antibodies belimumab and tabalumab, analyzed by computer simulation

B cell-activating factor (BAFF) can bind with specific receptors to activate signalling pathways associated with the B cell activation. Belimumab and tabalumab are anti-BAFF (B cell depleting) monoclonal antibodies, with therapeutic efficacy demonstrated for the treatment of autoimmune disorders, while belimumab was approved by FDA in 2011 as a targeted therapy for systemic lupus erythematosus (SLE) and exhibited better clinical outcome than tabalumab. In this investigation, the combination modes of BAFF-belimumab and BAFF-tabalumab complexes were simulated in silico to better understand the reason for the comparative inhibitory difference between belimumab and tabalumab. The structures of belimumab and tabalumab were constructed through homology modelling. The combination mode of BAFF-belimumab complex was analyzed by molecular dynamics simulation, while that of BAFF-tabalumab complex was analyzed by protein-protein docking following the molecular dynamics simulation. Both belimumab and tabalumab were bound with BAFF at the same hydrophobic center to which the natural receptors of BAFF bind as well. Belimumab heavy chain components I51, F54, K58, D100, D101, L102, L103, and P105 and R27, Y30, K49, and S65 of belimumab light chain contribute to the BAFF-belimumab interaction mainly via hydrogen bonds, salt bridges, and hydrophobic interactions. More importantly, belimumab could bind to L83 of BAFF and produce steric hindrance with the adjacent BAFF trimers, while tabalumab could not. Therefore, our results indicated that belimumab has a better clinical outcome compared with tabalumab mainly because belimumab could bind to L83 of BAFF and interfere the formation of a BAFF 60-mer, besides mediating inhibition of the interaction of BAFF with its receptors.

The effects of B-cell-activating factor on the population size, maturation and function of murine natural killer cells

The role of B-cell-activating factor (BAFF) in B-lymphocyte biology has been comprehensively studied, but its contributions to innate immunity remain unclear. Natural killer (NK) cells form the first line of defense against viruses and tumors, and have been shown to be defective in patients with systemic lupus erythematosus (SLE). The link between BAFF and NK cells in the development and progression of SLE remains unstudied. By assessing NK cell numbers in wild-type (WT), BAFF^-/- (BAFF deficient), BAFF-R^-/- (BAFF receptor deficient), TACI^-/- (transmembrane activator and calcium modulator and cyclophilin ligand interactor deficient), BCMA^-/- (B-cell maturation antigen deficient) and BAFF transgenic (Tg) mice, we observed that BAFF signaling through BAFF-R was essential for sustaining NK cell numbers in the spleen. However, according to the cell surface expression of CD27 and CD11b on NK cells, we found that BAFF was dispensable for NK cell maturation. Ex vivo and in vivo models showed that NK cells from BAFF^-/- and BAFF Tg mice produced interferon-γ and killed tumor cells at a level similar to that in WT mice. Finally, we established that NK cells do not express receptors that interact with BAFF in the steady state or in the BAFF Tg mouse model of SLE. Our findings demonstrate that BAFF has an indirect effect on NK cell homeostasis and no effect on NK cell function.

Regulatory effect of Act1 on the BAFF pathway in B-cell malignancy

The aim of the present study was to ascertain whether nuclear factor (NF)-κB Activator 1 (Act1) was involved in B cell-activating factor (BAFF) regulation in B-cell malignancy. The human B-cell malignancy cell lines Raji, Daudi and BALL-1 were cultured and the expression of BAFF receptor (BAFF-R) mRNA and protein was analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting, respectively. NF-κB signaling was also assessed using western blotting. Act1 silencing was performed using Act1 small interfering RNA. BAFF-R levels were assessed using flow cytometry. It was demonstrated that BAFF-R was upregulated in all three cell lines and RT-qPCR, and western blotting confirmed these results. Act1 overexpression was demonstrated to induce BAFF-R upregulation, whereas Act1 knockdown resulted in BAFF-R downregulation. Furthermore, the NF-κB pathway was activated by Act1 overexpression and inhibited following Act1 knockdown. The results of the present study demonstrated that Act1 can regulate BAFF via targeting NF-κB signaling, which suggests that Act1 may be a promising therapeutic target for the treatment of B-cell malignancy.

Antigen-adjuvant effects of icariin in enhancing tumor-specific immunity in mastocytoma-bearing DBA/2J mice

Cancer immunotherapy has attracted much attention in recent years because of the ability of immune system to identify tumor cells and limit their growth. Icariin (ICA) is a natural flavonoid glucoside isolated from Epimedium plants and has shown a variety of pharmacological activities such as anti-inflammatory effects, immunological regulation and anticancer potency. Furthermore, it has immunoadjuvant effects on enhancing Th1-immune response, suggesting that ICA may serve as an adjuvant for cancer immunotherapy. In this study, we used P815 mouse mastocytoma tumor model and immunized them with P815AB peptide and/or ICA. Our results demonstrated that ICA could increase the cytotoxic T lymphocytes (CTL) response for P815AB peptide on the tumor-bearing DBA/2J mice. In addition, the percentage of CD4⁺CD8⁺/CD3⁺CD69⁺/CD69⁺NKG2D⁺ positive cells in splenocytes of the tumor-bearing mice all significantly increased after combined immunization with ICA and P815AB peptide. This illustrated that ICA could enhance the immunogenicity of P815AB and improve the ability of T cells and CTLs in recognizing the tumor cells. Moreover, ICA improved the function of peritoneal macrophages with effects of inhibition on tumor growth. Besides, we discussed the possible mechanism of ICA to enhance body immunity by detecting the expression level of MHC-I and related genes in B16-F10 and RMA/S cells. The results suggested that ICA has the potential to up-regulate LMP/TAP related molecules and induce the expression of MHC-I, which increase the immune surveillance and keep cancer in remission. In conclusion, ICA showed an anti-tumor effect both in vitro and in vivo and may be an effective antigen adjuvant for cancer treatment by enhancing tumor-specific immunity.

Significance of BAFF/APRIL Expression and Their Receptors in Pediatric Patients With Acute Lymphoblastic Leukemia

In this study, we investigated the mRNA expression and protein levels of B-cell activating factor (BAFF)/a proliferation-inducing ligand (APRIL) and their receptors in acute lymphoblastic leukemia (ALL) cell lines and pediatric patients with ALL using real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blotting. The location and level of the BAFF/APRIL proteins in ALL cell lines were also detected by immunofluorescence cytochemistry and flow cytometry. Correlations between plasma protein levels of BAFF/APRIL and primary clinical parameters were analyzed. We found that BAFF/APRIL was highly expressed in pediatric ALL patients and ALL cell lines. The BAFF/APRIL proteins were located on the cell membrane, and the proportion of positive cells and mean fluorescence intensity were significantly higher than in the healthy control group (P<0.05). The mRNA expression and protein levels of BAFF/APRIL and their receptors in untreated ALL children were significantly higher than in healthy controls (P<0.05) as well as were significantly reduced in the remission group (P<0.05). The plasma protein levels of BAFF/APRIL were positively correlated with the white blood cell count, lactate dehydrogenase, and serum ferritin. Abnormal levels of BAFF/APRIL in pediatric ALL suggest that BAFF/APRIL are associated with the development and progression of ALL in children and may provide information for the development of BAFF-based and APRIL-based targeted therapies.

The Role of the Fibroblast in Inflammatory Upper Airway Conditions

Upper airway inflammation is one of the most frequent health care presentations. This is perhaps not surprising with our exposure to a myriad of environmental microbes, pollutants, and allergens. The precise pathophysiological mechanisms that cause persistent, exaggerated, upper airway inflammation rather than acute resolving illness remain unclear. Analysis of upper airway specimens identifies specific inflammatory cells, cytokine signatures, and fibrotic airway remodeling. Recent research has highlighted the role of stromal cells in the generation and persistence of chronic inflammation. Rather than simply being scaffolding or extracellular matrix-secreting cells on which organ systems are built, stromal cells including fibroblasts and osteocytes have their own independent immunologic functions. Here, we review the emerging inflammatory roles of upper airway fibroblasts, the majority of which appear to influence immune cell chemotaxis and amplify the inflammatory response.