Inhibition of Sprouty2 polarizes macrophages toward an M2 phenotype by stimulation with interferon γ and Porphyromonas gingivalis lipopolysaccharide

Ginsenoside Rg5 promotes wound healing in diabetes by reducing the negative regulation of SLC7A11 on the efferocytosis of dendritic cells

Background: ginsenoside Rg5 is a rare ginsenoside with known hypoglycemic effects in diabetic mice. This study aimed to explore the effects of ginsenoside Rg5 on skin wound-healing in the Leprdb/db mutant (db/db) mice (C57BL/KsJ background) model and the underlying mechanisms.

Methods

Seven-week-old male C57BL/6J, SLC7A11-knockout (KO), the littermate wild-type (WT), and db/db mice were used for in vivo and ex vivo studies.

Results

Ginsenoside Rg5 provided through oral gavage in db/db mice significantly alleviated the abundance of apoptotic cells in the wound areas and facilitated skin wound healing. 50 μM ginsenoside Rg5 treatment nearly doubled the efferocytotic capability of bone marrow-derived dendritic cells (BMDCs) from db/db mice. It also reduced NF-κB p65 and SLC7A11 expression in the wounded areas of db/db mice dose-dependently. Ginsenoside Rg5 physically interacted with SLC7A11 and suppressed the cystine uptake and glutamate secretion of BMDCs from db/db and SLC7A11-WT mice but not in BMDCs from SLC7A11-KO mice. In BMDCs and conventional type 1 dendritic cells (cDC1s), ginsenoside Rg5 reduced their glycose storage and enhanced anaerobic glycolysis. Glycogen phosphorylase inhibitor CP-91149 almost abolished the effect of ginsenoside Rg5 on promoting efferocytosis. Conclusion: ginsenoside Rg5 can suppress the expression of SLC7A11 and inhibit its activity via physical binding. These effects collectively alleviate the negative regulations of SLC7A11 on anaerobic glycolysis, which fuels the efferocytosis of dendritic cells. Therefore, ginsenoside Rg5 has a potential adjuvant therapeutic reagent to support patients with wound-healing problems, such as diabetic foot ulcers.

Application of biomaterials in periodontal tissue repair and reconstruction in the presence of inflammation under periodontitis through the foreign body response: Recent progress and perspectives

Periodontitis would cause dental tissue damage locally. Biomaterials substantially affect the surrounding immune microenvironment through treatment-oriented local inflammatory remodeling in dental periodontitis. This remodeling process is conducive to wound healing and periodontal tissue regeneration. Recent progress in understanding the foreign body response (FBR) and immune regulation, including cell heterogeneity, and cell-cell and cell-material interactions, has provided new insights into the design criteria for biomaterials applied in treatment of periodontitis. This review discusses recent progress and perspectives in the immune regulation effects of biomaterials to augment or reconstruct soft and hard tissue in an inflammatory microenvironment of periodontitis.

Intersection between macrophages and periodontal pathogens in periodontitis

Periodontitis is a chronic infectious disease characterized by loss of periodontal attachment and resorption of alveolar bone. Dysregulated oral microbial community is the initial factor of periodontitis and causes excessive infiltration of immune cells in periodontal tissues. Macrophage, as an important part of the innate immune system, interacts continually with oral pathogens. Macrophages can recognize and phagocytize pathogens and apoptotic neutrophils and produce the specialized pro-resolving mediators (SPMs) playing an important role in maintaining the homeostasis of tissue microenvironment. However, macrophages may also induce abnormal immune responses with the overstimulation from pathogens, leading to the destruction of periodontal tissues and alveolar bone. Looking for targeted drugs that can regulate the activities of oral pathogens and the functions of macrophages provides a new idea for periodontitis treatment. This review summarizes the interaction between macrophages and periodontal pathogens in periodontitis, focusing on the pro-inflammation and anti-inflammation phenotypes of macrophages, and briefly concludes potential new methods of periodontitis therapy targeted at oral pathogens and macrophages.

Genetic Basis of Response of Ghanaian Local Chickens to Infection With a Lentogenic Newcastle Disease Virus

Newcastle disease (ND) is a global threat to domestic poultry, especially in rural areas of Africa and Asia, where the loss of entire backyard local chicken flocks often threatens household food security and income. To investigate the genetics of Ghanaian local chicken ecotypes to Newcastle disease virus (NDV), in this study, three popular Ghanaian chicken ecotypes (regional populations) were challenged with a lentogenic NDV strain at 28 days of age. This study was conducted in parallel with a similar study that used three popular Tanzanian local chicken ecotypes and after two companion studies in the United States, using Hy-line Brown commercial laying birds. In addition to growth rate, NDV response traits were measured following infection, including anti-NDV antibody levels [pre-infection and 10 days post-infection (dpi)], and viral load (2 and 6 dpi). Genetic parameters were estimated, and two genome-wide association study analysis methods were used on data from 1,440 Ghanaian chickens that were genotyped on a chicken 600K Single Nucleotide Polymorphism (SNP) chip. Both Ghana and Tanzania NDV challenge studies revealed moderate to high (0.18 – 0.55) estimates of heritability for all traits, except viral clearance where the heritability estimate was not different from zero for the Tanzanian ecotypes. For the Ghana study, 12 quantitative trait loci (QTL) for growth and/or response to NDV from single-SNP analyses and 20 genomic regions that explained more than 1% of genetic variance using the Bayes B method were identified. Seven of these windows were also identified as having at least one significant SNP in the single SNP analyses for growth rate, anti-NDV antibody levels, and viral load at 2 and 6 dpi. An important gene for growth during stress, CHORDC1 associated with post-infection growth rate was identified as a positional candidate gene, as well as other immune related genes, including VAV2, IL12B, DUSP1, and IL17B. The QTL identified in the Ghana study did not overlap with those identified in the Tanzania study. However, both studies revealed QTL with genes vital for growth and immune response during NDV challenge. The Tanzania parallel study revealed an overlapping QTL on chromosome 24 for viral load at 6 dpi with the US NDV study in which birds were challenged with NDV under heat stress. This QTL region includes genes related to immune response, including TIRAP, ETS1, and KIRREL3. The moderate to high estimates of heritability and the identified QTL suggest that host response to NDV of local African chicken ecotypes can be improved through selective breeding to enhance increased NDV resistance and vaccine efficacy.

Controlling TIME: How MNK Kinases Function to Shape Tumor Immunity

A number of studies have clearly established the oncogenic role for MAPK-interacting protein kinases (MNK) in human malignancies. Modulation of MNK activity affects translation of mRNAs involved in cancer development, progression, and resistance to therapies. As a result, there are ongoing efforts to develop and evaluate MNK inhibitors for cancer treatment. However, it is important to recognize that MNK activity also plays an important role in regulating the innate and adaptive immune systems. A better understanding of the role of MNK kinases and MNK-mediated signals in regulating the immune system could help mitigate undesired side effects while maximizing therapeutic efficacy of MNK inhibitors. Here, we provide a systematic review on the function of MNK kinases and their substrates in immune cells.

Osteoclastogenesis in periodontal diseases: Possible mediators and mechanisms

BACKGROUND

Periodontitis is the inflammation of the tooth-supporting structures and is one of the most common diseases of the oral cavity. The outcome of periodontal infections is tooth loss due to a lack of alveolar bone support. Osteoclasts are giant, multi-nucleated, and bone-resorbing cells that are central for many osteolytic diseases, including periodontitis. Receptor activator of nuclear factor-kB ligand (RANKL) is the principal factor involved in osteoclast differentiation, activation, and survival. However, under pathological conditions, a variety of pro-inflammatory cytokines secreted by activated immune cells also contribute to osteoclast differentiation and activity. Lipopolysaccharide (LPS) is a vital component of the outer membrane of the Gram-negative bacteria. It binds to the Toll-like receptors (TLRs) expressed in many cells and elicits an immune response.

HIGHLIGHTS

The presence of bacterial LPS in the periodontal area stimulates the secretion of RANKL as well as other inflammatory mediators, activating the process of osteoclastogenesis. RANKL, either independently or synergistically with LPS, can regulate osteoclastogenesis, while LPS alone cannot. MicroRNA, IL-22, M1/M2 macrophages, and memory B cells have recently been shown to modulate osteoclastogenesis in periodontal diseases.

CONCLUSION

In this review, we summarize the mechanism of osteoclastogenesis accompanying periodontal diseases at the cellular level. We discuss a) the effects of LPS/TLR signaling and other cytokines on RANKL-dependent and -independent mechanisms involved in osteoclastogenesis; b) the recently identified role of several endogenous factors such as miRNA, IL-22, M1/M2 macrophages, and memory B cells in regulating osteoclastogenesis during periodontal pathogenesis.

Silencing of long isoforms of nuclear factor erythroid 2 like 1 primes macrophages towards M1 polarization

Macrophages are a major component of the immune system and play an important role in regulating the magnitude, duration, and quality of the inflammatory response. Dissecting the functions of transcription factors regulating macrophage activation is important for understanding the inflammatory responses. Nuclear factor erythroid 2 like 1 (NFE2L1, also known as Nrf1) is a CNC-bZIP protein, which has multiple isoforms. While the exact physiological functions of various isoforms of NFE2L1 are still under investigation, accumulating evidence indicate that long isoforms of NFE2L1 (NFE2L1(L)) are important regulators in the antioxidant response, proteasome homeostasis and inflammation. In this study, we found that NFE2L1(L) was upregulated in response to LPS stimulation in RAW264.7 macrophages. Stable knockdown of Nfe2l1(L) (Nfe2l1(L)-KD) in RAW264.7 cells resulted in increased expression of multiple genes indicative of M1 polarization, including Il6, Il1β, Cox2, and Ccl2, under both resting and LPS-challenged conditions. In addition, lentiviral shRNA-mediated silencing of NFE2L1(L) in human monocytic SC and THP1 cells also significantly increased mRNA expression of IL6, IL1β, and TNFα. Furthermore, transient silence of NFE2L1(L) in primary human monocytes isolated from peripheral blood by nucleofection with small interfering RNA resulted in increased expression of IL6 and TNFα. Analysis of the key transcription factors involved in M1 polarization revealed that Nfe2l1(L)-KD RAW264.7 cells have increased mRNA and protein expression and phosphorylation of STAT1 and STAT3 under both resting and M1 polarized conditions. Activation of the NFκB, ERK1/2 and p38 pathways in response to LPS was not affected by the reduction of NFE2L1(L). Moreover, Nfe2l1(L)-KD cells were found to have elevated levels of intracellular ROS, but macrophage M1 polarization induced by Nfe2l1(L) silence was independent of ROS accumulation. Collectively, our results show that knockdown of Nfe2l1(L) leads macrophages to M1 polarization by disinhibition of STAT1/3, and not through the NFκB, ERK1/2 and/or p38 signaling pathways. These findings indicate that NFE2L1(L) functions as a negative regulator of M1 polarization and pro-inflammatory response in macrophages.

Caffeic acid phenethyl ester attenuates lipopolysaccharide-stimulated proinflammatory responses in human gingival fibroblasts via NF-κB and PI3K/Akt signaling pathway

Periodontal diseases often begin with chronic gingival inflammation, which causes the destruction of periodontal tissues. Inflammatory immune responses from host cells to bacteria, such as Porphyromonas gingivalis (P. gingivalis), cause periodontal degradation. Human gingival fibroblasts (HGFs) are the major cells in periodontal soft tissues. When stimulated by lipopolysaccharide (LPS), HGFs could secrete several pro-inflammatory cytokines and chemokines, such as interleukins (ILs) IL-6, IL-8, inducible nitric oxide synthase (iNOS), and cyclooxygenase 2 (COX-2). Caffeic acid phenethyl ester (CAPE) is the main active component of propolis, which is collected by honeybees from different plants and known for its anti-inflammatory effects. The anti-inflammatory effects of CAPE on the LPS-induced HGFs were demonstrated in this study. HGFs were pretreated with CAPE (10, 20, and 30µm) for 1h, followed by LPS stimulation (1μg/ml) for 24h. Enzyme-linked immunosorbent assay, Western blot analysis, and immunofluorescence staining were used to evaluate the production of IL-6, IL-8, iNOS, and COX-2, as well as the activation of TLR4-mediated NF-κB, PI3K/AKT, and MAPK signaling pathways. The results indicated that CAPE inhibits LPS-induced IL-6, IL-8, iNOS, and COX-2 production in a dose-dependent manner. Moreover, CAPE suppresses LPS-induced TLR4/MyD88 and nuclear factor kappa B (NF-κB) activation. In addition, phosphatidylinositol 3 kinase (PI3K) and protein kinase B (AKT) phosphorylation was inhibited by CAPE. These results demonstrated that CAPE could be effective for treating of periodontal diseases.