Alternative NF-κB signaling controls peripheral homeostasis and function of regulatory T cells

The Peptide/Antibody-Based Surface Decoration of Calcium Phosphate Nanoparticles Carrying siRNA Influences the p65 NF-κB Protein Expression in Inflamed Cells In Vitro

Earlier studies with nanoparticles carrying siRNA were restricted to investigating the inhibition of target-specific protein expression, while almost ignoring effects related to the nanoparticle composition. Here, we demonstrate how the design and surface decoration of nanoparticles impact the p65 nuclear factor-kappa B (NF-κB) protein expression in inflamed leucocytes and endothelial cells in vitro. We prepared silica-coated calcium phosphate nanoparticles carrying encapsulated siRNA against p65 NF-κB and surface-decorated with peptides or antibodies. We show that RGD-decorated nanoparticles are efficient in down-regulating p65 NF-κB protein expression in endothelial cells as a result of an enhanced specific cellular binding and subsequent uptake of nanoparticles. In contrast, nanoparticles decorated with IgG (whether specific or not for CD69) are efficient in down-regulating p65 NF-κB protein expression in T-cells, but not in B-cells. Thus, an optimized nanoparticle decoration with xenogenic IgG may stimulate a specific cellular uptake. In summary, the composition of siRNA-loaded calcium phosphate nanoparticles can either weaken or stimulate p65 NF-κB protein expression in targeted inflamed leucocytes and endothelial cells. In general, unveiling such interactions may be very useful for the future design of anti-p65 siRNA-based nanomedicines for treatment of inflammation-associated diseases.

NF-κB in Cancer Immunity: Friend or Foe?

The emergence of immunotherapies has definitely proven the tight relationship between malignant and immune cells, its impact on cancer outcome and its therapeutic potential. In this context, it is undoubtedly critical to decipher the transcriptional regulation of these complex interactions. Following early observations demonstrating the roles of NF-κB in cancer initiation and progression, a series of studies converge to establish NF-κB as a master regulator of immune responses to cancer. Importantly, NF-κB is a family of transcriptional activators and repressors that can act at different stages of cancer immunity. In this review, we provide an overview of the selective cell-intrinsic contributions of NF-κB to the distinct cell types that compose the tumor immune environment. We also propose a new view of NF-κB targeting drugs as a new class of immunotherapies for cancer.

A recombinant protein rLZ-8, originally extracted from Ganoderma lucidum, ameliorates OVA-induced lung inflammation by regulating Th17/Treg balance

Asthma is one of the most common chronic and inflammatory respiratory diseases, which is estimated to affect 1-10% of the population in different regions across the world. Previous studies have shown that recombinant Ling-Zhi 8 (rLZ-8), an immunoregulatory protein originally extracted from Ganoderma lucidum, plays multiple roles in regulating murine immune cells, including T cells. Here, we examined whether rLZ-8 would ameliorate pulmonary inflammation in a model of asthma-like mice. We found that rLZ-8 significantly inhibited the lung inflammation and reduced infiltration of inflammatory cells, including dendritic cells and eosinophils, in OVA-induced asthmatic mice. It also deceased IL-17A level but increased IL-10 level in bronchoalveolar lavage fluid (BALF) while reducing RORγt mRNA expression and enhancing Foxp3 mRNA level in the lung tissue. Flow cytometry studies demonstrated that rLZ-8 remarkably down-regulated Th17 cells but upregulated Foxp3⁺ regulatory T (Treg) cells, rather than influencing Th1 versus Th2 cells. Experiments in vitro also showed that rLZ-8 suppressed murine CD3⁺ T cell proliferation and reduced the frequency of Th17 cells while promoting the differentiation of CD4⁺ Foxp3⁺ Tregs. Moreover, rIL-8 similarly altered human Th17/Treg generation or their balance in vitro. Finally, we found that rLZ-8 suppressed signaling pathways of both STAT3 and NF-κB (P100/P52) in murine lung tissue as well as cultured T cells. Thus, we have demonstrated that rLZ-8 attenuates pulmonary inflammation through regulating the balance of Th17/Treg cells in OVA-induced asthmatic mice and that rLZ-8 may be a potential therapeutic agent for the treatment of asthma in clinic.

RelB regulates the homeostatic proliferation but not the function of Tregs

Background

RelB, a member of the NF-κB family, plays a critical role in the development of T cells. However, the role of RelB in Foxp3⁺ regulatory T cells (Tregs) remains controversial.

Results

Using a bone marrow chimeric mouse model, we demonstrated that the expansion of Foxp3⁺ Tregs in vivo could be mediated by extrinsic mechanisms. RelB plays an important role in inhibiting the homeostatic proliferation of Tregs, but not their survival. Even with the heightened expansion, RelB^−/− Treg cells displayed normal suppressive function in vitro. Among the expanded populations of Treg cells, most were nTreg cells; however, the population of iTregs did not increase. Mechanistically, RelB seems to regulate Treg proliferation independently of the signal transducer and activator of transcription 5 (STAT5) pathway.

Conclusions

These data suggest that RelB regulates Treg proliferation independently of the STAT5 pathway, but does not alter the function of Tregs. Further studies are warranted to uncover such mechanisms.