Intrinsic cellular defenses are non-specific antiviral activities by recognizing pathogen-associated molecular patterns (PAMPs). Toll-like receptors (TLRs), one of the pathogen recognize receptor (PRR), sense various microbial ligands. Especially, TLR2, TLR3, TLR4, TLR7, TLR8 and TLR9 recognize viral ligands such as glycoprotein, single- or double-stranded RNA and CpG nucleotides. The binding of viral ligands to TLRs transmits its signal to Toll/interleukin-1 receptor (TIR) to activate transcription factors via signal transduction pathway. Through activation of transcription factors, such as interferon regulatory factor-3, 5, and 7 (IRF-3, 5, 7) or nuclear factor-kappaB (NF-kappaB), type I interferons are induced, and antiviral proteins such as myxovirus-resistance protein (Mx) GTPase, RNA-dependent Protein Kinase (PKR), ribonuclease L (RNase L), Oligo-adenylate Synthetase (OAS) and Interferon Stimulated Gene (ISG) are further expressed. These antiviral proteins play an important role of antiviral resistancy against several viral pathogens in infected cells and further activate innate immune responses.
Animals ; GTP-Binding Proteins/metabolism ; Humans ; Interferon Regulatory Factors/metabolism ; Interferon Type I/*metabolism/physiology ; Models, Biological ; NF-kappa B/metabolism ; Toll-Like Receptors/metabolism ; Virus Diseases/*immunology/*metabolism/virology ; eIF-2 Kinase/metabolism

As the first line of immune defense for Mycobacterium tuberculosis (Mtb), macrophages also provide a major habitat for Mtb to reside in the host for years. The battles between Mtb and macrophages have been constant since ancient times. Triggered upon Mtb infection, multiple cellular pathways in macrophages are activated to initiate a tailored immune response toward the invading pathogen and regulate the cellular fates of the host as well. Toll-like receptors (TLRs) expressed on macrophages can recognize pathogen-associated-molecular patterns (PAMPs) on Mtb and mediate the production of immune-regulatory cytokines such as tumor necrosis factor (TNF) and type I Interferons (IFNs). In addition, Vitamin D receptor (VDR) and Vitamin D-1-hydroxylase are up-regulated in Mtb-infected macrophages, by which Vitamin D participates in innate immune responses. The signaling pathways that involve TNF, type I IFNs and Vitamin D are inter-connected, which play critical roles in the regulation of necroptosis, apoptosis, and autophagy of the infected macrophages. This review article summarizes current knowledge about the interactions between Mtb and macrophages, focusing on cellular fates of the Mtb-infected macrophages and the regulatory molecules and cellular pathways involved in those processes.
Animals ; Apoptosis ; Autophagy ; Humans ; Interferon Type I ; metabolism ; Macrophages ; immunology ; metabolism ; Mycobacterium tuberculosis ; physiology ; Receptors, Calcitriol ; metabolism ; Steroid Hydroxylases ; metabolism ; Toll-Like Receptors ; metabolism ; Tuberculosis ; immunology ; metabolism ; pathology ; Tumor Necrosis Factors ; metabolism

A soluble factor which augments the expression of major histocompatibility complex class I (MHC I) antigens on a number of murine tumor cell lines, has been isolated from the culture supernatants of mixed lymphocyte reaction of spleen cells derived from C57B1/6, Balb/c and Swiss mice. The factor, termed MHC-augmenting factor (MHC-AF) has been partially purified by Sephadex G-100 column chromatography and reverse phase HPLC. MHC-AF activity is associated with an 18 kDa molecule. MHC-AF activity was resistant to pH 2.0 treatment and partially purified MHC-AF preparations did not have any activity in L929 cell/vesicular stomatitis virus (VSV) interferon bioassay system. Antibodies to IFN-gamma did not block the activity of MHC-AF. These results indicate that a MHC-AF distinct from IFN-gamma, is produced by mouse spleen cells undergoing a mixed lymphocyte reaction.
Animal ; Antibodies/pharmacology ; Chymotrypsin/metabolism ; Chymotrypsin/chemistry ; Comparative Study ; Concanavalin A/pharmacology ; Heat ; Histocompatibility Antigens Class I/metabolism* ; Histocompatibility Antigens Class I/drug effects ; Interferon Type II/pharmacology ; Interferon Type II/metabolism ; Interferon Type II/immunology ; Lymphocytes/physiology ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Proteins/pharmacology* ; Proteins/metabolism ; Proteins/isolation & purification* ; Spleen/cytology ; Trypsin/metabolism ; Trypsin/chemistry ; Tumor Cells, Cultured/immunology ; Tumor Cells, Cultured/drug effects

OBJECTIVEThis study was designed to evaluate the role of interleukin (IL)-1β in the development of fibrosis in mice exposed to silica.

METHODSThe total of 96 Male C57BL/6 mice were divided into four groups. (1) blank control group, (2) PBS group in which mice were instilled with PBS only, (3) silica + IL-1β mAb group in which mice were instilled with 2.5 mg silica dust and 40 µg anti-IL-1β mAb, (4) silica group in which mice were instilled with 2.5 mg silica dust and 40 µg IgG. The final volume of suspension or PBS instilled into the mouse was 50 µl. At 7, 28 and 84 days after treatment, 8 mice were sacrificed in each group. Then BALF was collected for the count of inflammatory cells and cytokines determination. The lung tissues were collected for the detecting of mRNA levels of fibrogenic molecules.

RESULTSThe collagen deposition induced by silica in the lung tissues was partly inhibited by anti-IL-1β. A intensely pulmonary cytokines such as IL-1β, TNF-α, MCP-1 were induced by crystalline silica exposure, and partly inhibited by anti-IL-1β. The levels of TGF-β and fibronectin in silica exposed mice were significantly elevated than those in control mice at days 28 and 84 after treatment (P < 0.01). And the mRNA levels of TGF-β, collagen I and fibronectin were significantly decreased in silica+IL-1β mAb group when compared with those in silica group at days 7, 28 and 84 (P < 0.01). There was a significant decrease of the ratios of IFN-γ/IL-4 in both silica+anti-IL-1β mAb and silica groups when compared with those in control mice at the above three time points (P < 0.01). However, the IFN-γ/IL-4 ratios in silica+anti-IL-1β group were significantly higher than those in silica group at 7, 28 and 84 days (P < 0.05 or P < 0.01).

CONCLUSIONIL-1β may promote the pulmonary fibrosis in mice exposed to silica.

Animals ; Antibodies, Monoclonal ; pharmacology ; Bronchoalveolar Lavage Fluid ; chemistry ; Collagen Type I ; metabolism ; Disease Models, Animal ; Fibronectins ; metabolism ; Interferon-gamma ; metabolism ; Interleukin-1beta ; metabolism ; physiology ; Interleukin-4 ; metabolism ; Lung ; metabolism ; pathology ; Male ; Mice ; Mice, Inbred C57BL ; Pulmonary Fibrosis ; chemically induced ; metabolism ; pathology ; Silicon Dioxide ; toxicity ; Transforming Growth Factor beta ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism

In the last decade, substantial progress has been made in understanding the molecular mechanisms involved in the initial host responses to viral infections. Herpesviral infections can provoke an inflammatory cytokine response, however, the innate pathogen-sensing mechanisms that transduce the signal for this response are poorly understood. In recent years, it has become increasingly evident that the Toll-like receptors (TLRs), which are germline-encoded pattern recognition receptors (PRRs), function as potent sensors for infection. TLRs can induce the activation of the innate immunity by recruiting specific intracellular adaptor proteins to initiate signaling pathways, which then culminating in activation of the nuclear factor kappa B (NF-κB) and interferon-regulatory factors (IRFs) that control the transcription of genes encoding type I interferon (IFN I) and other inflammatory cytokines. Furthermore, activation of innate immunity is critical for mounting adaptive immune responses. In parallel, common mechanisms used by viruses to counteract TLR-mediated responses or to actively subvert these pathways that block recognition and signaling through TLRs for their own benefit are emerging. Recent findings have demonstrated that TLR2 plays a crucial role in initiating the inflammatory process, and surprisingly that the response TLR2 triggers might be overzealous in its attempt to counter the attack by the virus. In this review, we summarize and discuss the recent advances about the specific role of TLR2 in triggering inflammatory responses in herpesvirus infection and the consequences of the alarms raised in the host that they are assigned to protect.
Adaptive Immunity ; Gene Expression Regulation ; immunology ; Herpesviridae ; physiology ; Herpesviridae Infections ; genetics ; immunology ; virology ; Host-Pathogen Interactions ; Humans ; Immune Evasion ; Immunity, Innate ; Interferon Regulatory Factors ; genetics ; metabolism ; Interferon Type I ; biosynthesis ; immunology ; NF-kappa B ; genetics ; metabolism ; Signal Transduction ; genetics ; immunology ; Toll-Like Receptor 2 ; genetics ; immunology