TLR9 transcriptional regulation in response to double-stranded DNA viruses

Metal-polyDNA nanoparticles reconstruct osteoporotic microenvironment for enhanced osteoporosis treatment

Current clinical approaches to osteoporosis primarily target osteoclast biology, overlooking the synergistic role of bone cells, immune cells, cytokines, and inorganic components in creating an abnormal osteoporotic microenvironment. Here, metal-polyDNA nanoparticles (Ca-polyCpG MDNs) composed of Ca2+ and ultralong single-stranded CpG sequences were developed to reconstruct the osteoporotic microenvironment and suppress osteoporosis. Ca-polyCpG MDNs can neutralize osteoclast-secreted hydrogen ions, provide calcium repletion, promote remineralization, and repair bone defects. Besides, the immune-adjuvant polyCpG in MDNs could induce the secretion of osteoclastogenesis inhibitor interleukin-12 and reduce the expression of osteoclast function effector protein to inhibit osteoclast differentiation, further reducing osteoclast-mediated bone resorption. PPi4- generated during the rolling circle amplification reaction acts as bisphosphonate analog and enhances bone targeting of Ca-polyCpG MDNs. In ovariectomized mouse and rabbit models, Ca-polyCpG MDNs prevented bone resorption and promoted bone repair by restoring the osteoporotic microenvironment, providing valuable insights into osteoporosis therapy.

Harnessing dendritic cells for innovative therapeutic cancer vaccines

PURPOSE OF REVIEW

The clinical activity of new immunotherapies in cancer, such as anti-Programmed cell death 1 (PD-1)/Programmed death-ligand 1, has revealed the importance of the patient's immune system in controlling tumor development. As in infectious diseases, dendritic cells (DCs) are critical for inducing immune responses in cancer. Unfortunately, autologous DC-based vaccines have not yet demonstrated their clinical benefit. Here, we review recent research using allogeneic DCs as alternatives to autologous DCs to develop innovative therapeutic cancer vaccines.

RECENT FINDINGS

A novel approach using an allogeneic plasmacytoid dendritic cell (PDC) line as an antigen presentation platform showed great potency when used to prime and expand antitumor-specific CD8+ T cells in vitro and in vivo in a humanized mouse model. This PDC platform, named PDC∗vac, was first evaluated in the treatment of melanoma with encouraging results and is currently being evaluated in the treatment of lung cancer in combination with anti-PD-1 immunotherapy.

SUMMARY

Therapeutic cancer vaccines are of particular interest because they aim to help patients, to mount effective antitumor responses, especially those who insufficiently respond to immune checkpoint inhibitors. The use of an allogeneic plasmacytoid DC-based platform such as PDC∗vac could greatly potentiate the efficacy of these new immunotherapies.

Lipopolysaccharides increase the risk of colorectal cancer recurrence and metastasis due to the induction of neutrophil extracellular traps after curative resection

BACKGROUND

Intra-abdominal infection after curative surgery for colorectal cancer is a serious complication associated with an increased risk of recurrence. Lipopolysaccharides (LPS)-an essential component of the cell wall of Gram-negative bacteria-were found to exert a protumorigenic effect by stimulating the inflammatory pathology and formation of neutrophil extracellular traps (NETs). This study was conducted to test whether LPS-induced formation of NETs promotes the development of cancer and metastasis.

METHODS

The clinical characteristics, incidence of relapse, and serum myeloperoxidase-DNA complexes of 40 patients with infection and 40 patients without infection after curative surgery were analyzed. The effects of LPS on the induction of NETs were evaluated in a mouse model of colorectal cancer and liver metastasis. The toll-like receptor 9 (TLR9)-a DNA receptor-was knocked down to assess its effect on the mitogen-activated protein kinase pathway and activities implicated in the formation of NETs.

RESULTS

Analysis of the clinical data obtained from these patients showed the significant relation of the formation of NETs and incidence of metastasis and survival rates. Subsequent in vitro experiments revealed an increased level of citrullinated-histone H3 and myeloperoxidase-DNA in LPS-injected mice with colorectal cancer. In the mimic metastatic model, injection of LPS enhanced the metastatic capacity, which was then attenuated by DNase I. This suggested that the formation of NETs was activated by LPS. Injection of TLR9-knockdown HCT116 cells in mice, followed by induction through LPS, mitigated the level of citrullinated-histone H3 and myeloperoxidase-DNA. This finding implied that the formation of NETs was suppressed.

CONCLUSION

These findings shed light on the mechanism underlying the relationship between the elevated rate of colorectal cancer recurrence in patients who underwent surgery and the incidence of infection. This mechanism involves the protumorigenic activities of LPS-induced formation of NETs. The NETs which could be mediated by the TLR9 and the mitogen-activated protein kinase signaling pathway.

Functional Polymorphisms and Gene Expression of TLR9 Gene as Protective Factors for Nasopharyngeal Carcinoma Severity and Progression

Nasopharyngeal carcinoma (NPC) is a disease that is closely associated with EBV infection. Toll-like receptor 9 is an important factor mediating the interaction between EBV and the host immune response. Any genetic (single nucleotide polymorphisms, SNPs) or expression variation in TLR9 gene may modify the ability of the receptor to respond correctly to viral infection as in NPC. This study is aimed at evaluating the effect of TLR9 functional polymorphisms (TLR9-1486 T/C and TLR9-1237 T/C) and TLR9 mRNA expression in NPC severity and progression at diagnosis and after treatment. This study included 322 patients with NPC. RFLP-PCR and real-time PCR were used to assess, respectively, the genotypes and the mRNA expression of TLR9 gene. The genotyping analysis showed that the presence of mutated allele -1237C (TLR9-1237 TC+CC) was associated with large tumor size (p = 0.017; OR (CI 95%) = 1.888 (1.11-3.19)) at diagnosis. After treatment, the -1237C allele was associated with a better chance of complete remission (p = 0.031, OR (CI 95%) = 0.486 (0.25-0.95)), a lower risk of distant metastasis (p = 0.028, OR (CI 95%) = 0.435 (0.18-1.02)), and a lower risk of death by NPC (p = 0.003, OR (CI 95%) = 0.20 (0.06-0.67)). Kaplan-Meier analysis showed that patients with -1237CC and -1237TC genotypes had a better overall survival (OVS) (p < 0.01) and distant metastasis-free survival (DMFS) (p < 0.05). A multivariate analysis revealed that TLR9-1237 T/C polymorphism was an independent prognostic factor in OVS (p = 0.02; HR = 0.244) and DMFS (p = 0.048; HR = 0.388). The transcriptomic analysis showed that the mRNA expression was reduced in patients with larger tumor size (T4) (p = 0.013) and advanced clinical stage (SIII-SIV) (p = 0.037). The TLR9 mRNA expression was inversely correlated with tumor size (p = 0.014; r = −0.314) at diagnosis. Our results indicated for the first time that the functional -1237 T/C polymorphism and mRNA expression of TLR9 gene may be considered as protective factors for NPC severity and progression.

The amphibian (Xenopus laevis) colony-stimulating factor-1 and interleukin-34-derived macrophages possess disparate pathogen recognition capacities

Pathogens such as the Frog Virus 3 (FV3) ranavirus are contributing to the worldwide amphibian declines. While amphibian macrophages (Mϕs) are central to the immune defenses against these viruses, the pathogen recognition capacities of disparate amphibian Mϕ subsets remain unexplored. In turn, Mϕ differentiation and functionality are interdependent on the colony-stimulating factor-1 receptor (CSF-1R), which is ligated by colony-stimulating factor-1 (CSF-1) and the unrelated interleukin-34 (IL-34) cytokines. Notably, the Xenopus laevis frog CSF-1- and IL-34-derived Mϕs are functionally distinct, and while the CSF-1-Mϕs are more susceptible to FV3, the IL-34-Mϕs are highly resistant to this pathogen. Here, we elucidate the pathogen recognition capacities of CSF-1- and IL-34-differentiated Mϕs by evaluating their baseline transcript levels of key pathogen pattern recognition receptors (PRRs). Compared to the frog CSF-1-Mϕs, their IL-34-Mϕs exhibited greater expression of PRR genes associated with viral recognition as well as PRR genes known for recognizing bacterial pathogen-associated molecular patterns (PAMPs). By contrast, the CSF-1-Mϕs displayed greater expression of toll-like receptors (TLRs) that are absent in humans. Moreover, although the two Mϕ types possessed similar expression of most downstream PRR signaling components, they exhibited distinct outcomes upon stimulation with hallmark PAMPs, as measured by their tumor necrosis factor-alpha and interferon-7 gene expression. Remarkably, stimulation with a TLR2/6 agonist conferred FV3 resistance to the otherwise susceptible CSF-1-Mϕs while treatment with a TLR9 agonist significantly ablated the IL-34-Mϕ resistance to FV3. These changes in Mϕ-FV3 susceptibility and resistance appeared to be linked to changes in their expression of key immune genes. Greater understanding of the amphibian macrophage pathogen-recognition capacities will lend to further insights into the pathogen-associated causes of the amphibian declines.

PINK1 attenuates mtDNA release in alveolar epithelial cells and TLR9 mediated profibrotic responses

We have previously shown that endoplasmic reticulum stress (ER stress) represses the PTEN inducible kinase 1 (PINK1) in lung type II alveolar epithelial cells (AECII) reducing mitophagy and increasing the susceptibility to lung fibrosis. Although increased circulating mitochondrial DNA (mtDNA) has been reported in chronic lung diseases, the contribution of mitophagy in the modulation of mitochondrial DAMP release and activation of profibrotic responses is unknown. In this study, we show that ER stress and PINK1 deficiency in AECII led to mitochondrial stress with significant oxidation and damage of mtDNA and subsequent extracellular release. Extracellular mtDNA was recognized by TLR9 in AECII by an endocytic-dependent pathway. PINK1 deficiency-dependent mtDNA release promoted activation of TLR9 and triggered secretion of the profibrotic factor TGF-β which was rescued by PINK1 overexpression. Enhanced mtDNA oxidation and damage were found in aging and IPF human lungs and, in concordance, levels of circulating mtDNA were significantly elevated in plasma and bronchoalveolar lavage (BAL) from patients with IPF. Free mtDNA was found elevated in other ILDs with low expression of PINK1 including hypersensitivity pneumonitis and autoimmune interstitial lung diseases. These results support a role for PINK1 mediated mitophagy in the attenuation of mitochondrial damage associated molecular patterns (DAMP) release and control of TGF-β mediated profibrotic responses.

Role of invariant NKT cells in lipopolysaccharide-induced lethal shock during encephalomyocarditis virus infection

Viral infections can give rise to secondary bacterial infections. In the present study, we examined the role of invariant natural killer T (iNKT) cells in lipopolysaccharide (LPS)-induced lethal shock during encephalomyocarditis virus (EMCV) infection. Wild-type (WT) mice and Jα18 gene knockout (Jα18 KO) mice were inoculated with EMCV, 5days prior to challenging with LPS. The survival rate of Jα18 KO mice subjected to EMCV and LPS was significantly higher than that of WT mice. TNF-α and nitric oxide (NO) production were increased in WT mice, than that in Jα18 KO mice, after the administration of EMCV and LPS. EMCV infection increased the number of iNKT cells and IFN-γ production by iNKT cells in WT mice. Moreover, EMCV infection enhanced the expression of Toll-like receptor 4 (TLR4) in the lung and spleen. IFN-γ also increased the expression of TLR4 in splenocytes. These findings indicated that EMCV infection activated iNKT cells, and IFN-γ secreted from the iNKT cells up-regulated the expression of TLR4 in various tissues. As a result, EMCV-infected mice were susceptible to LPS and easily developed the lethal shock. In conclusion, iNKT cells were involved in the development of LPS-induced lethal shock during EMCV infection.