Upregulation of microRNA-23a/b promotes tumor progression and confers poor prognosis in patients with gastric cancer

Background and purpose: To investigate the clinical significance of microRNA (miR)-23a and miR-23b expression in human gastric cancer (GC). Methods: Quantitative RT-PCR was performed to detect the expression changes of miR-23a and miR-23b in 160 human GC tissues and paired normal mucosa. The associations between miR-23a and miR-23b expression, and the selected clinicopathological characteristics and patients’ prognosis were also evaluated. Results: MiR-23a (GC vs. Normal: 3.98 ± 1.23 vs. 2.29 ± 1.12, P < 0.001) and miR-23b (GC vs. Normal: 3.70 ± 1.24 vs. 1.58 ± 1.18, P < 0.001) expression were both increased dramatically when compared with paired normal mucosa. Notably, the expression levels of miR-23a in GC tissues were positively correlated with those of miR-23b (Spearman correlation coefficient r = 0.77, P < 0.001). Then, the coexpression of miR-23a and miR-23b (miR-23a-high/miR-23b-high) in GC tissues was significantly associated with the advanced TNM stage (P < 0.001), the presence of lymph node metastasis (P = 0.008) and the great depth of invasion (P = 0.02). Furthermore, both univariate and multivariate analyses showed that miR-23a/miR-23b co-expression was an independent predictor for unfavorable overall survival. Conclusions: These results suggest that the dysregulation of miR-23a and miR-23b may be implicated in the progression of human GC. Combined expression of miR-23a and miR-23b appears to be a valuable marker for prognosis of this disease.     

Role of miR-155 in the Pathogenesis of Herpetic Stromal Keratitis

Ocular infection with herpes simplex virus 1 can result in a chronic immunoinflammatory stromal keratitis (SK) lesion that is a significant cause of human blindness. A key to controlling SK lesion severity is to identify cellular and molecular events responsible for tissue damage and to manipulate them therapeutically. Potential targets for therapy are miRNAs, but these are minimally explored especially in responses to infection. Here, we demonstrated that Mir155 expression was up-regulated after ocular herpes simplex virus 1 infection, with the increased Mir155 expression occurring mainly in macrophages and CD4⁺ T cells and to a lesser extent in neutrophils. In vivo studies indicated that Mir155 knockout mice were more resistant to herpes SK with marked suppression of T helper cells type 1 and 17 responses both in the ocular lesions and the lymphoid organs. The reduced SK lesion severity was reflected by increased phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase 1 and interferon-γ receptor α-chain levels in activated CD4⁺ T cells in the lymph nodes. Finally, in vivo silencing of miR-155 by the provision of antagomir-155 nanoparticles to herpes simplex virus 1–infected mice led to diminished SK lesions and corneal vascularization. In conclusion, our results indicate that miR-155 contributes to the pathogenesis of SK and represents a promising target to control SK severity.Ocular infection with herpes simplex virus 1 (HSV-1) can result in a chronic tissue-damaging response in the stroma, which is considered to be largely the consequence of a host inflammatory response to the infection.¹ This concept is strongly supported by animal model studies in which lesions were shown to be mainly orchestrated by CD4⁺ T cells with neutrophils and macrophage largely responsible for the tissue damage.^2–5 Several effective control measures for stromal keratitis (SK) are suggested.⁶ These include approaches that influence cellular infiltration and activation of the proinflammatory mediators of SK.⁶ One potential means of modulating SK lesions that so far has received minimal attention is to manipulate the expression of miRNA species that affect either virus or host events during SK.A prime miRNA candidate for consideration is miR-155 because this miRNA can influence the expression of several immune events that contribute to tissue damage.^7–10 For example, animals unable to produce miR-155 because of gene knockout may develop milder lesions in some models of autoimmunity,^8,11–13 and suppressing miR-155 expression, as can be achieved by treatment with antagomirs, holds promise as a means of therapy for autoimmunity.¹³ However, the absence of miR-155 can result in higher susceptibility to some virus infections and some tumors in part because protective CD8⁺ T-cell responses are diminished.^14–17 In fact, overexpression of miRNA can result in enhanced CD8⁺ T-cell–mediated immune protection with some tumors.¹⁷Few studies have focused on the role of miR-155 in situations in which the immune response to an infectious agent may be a principal cause of tissue damage. This is the situation in ocular lesions of the cornea after HSV-1 infection. Here, we have compared the disease outcome after HSV-1 infection in miRNA-155 knockout (Mir155^−/−) mice and in mice in which miR-155 was suppressed by antagomir therapy with controls. We show that HSV-1 infection resulted in up-regulation of miR-155, which was mainly produced by the inflammatory cells and T cells in the cornea. Suppression of miR-155 production resulted in milder lesions that were associated with diminished responses of T helper cells type 1 (Th1) and type 17 (Th17) and reduced inflammatory cytokine production. We also demonstrated that miR-155 suppression resulted in increased phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase 1 (Ship1) and IFN-γ receptor α-chain (IFN-γRα) levels, molecules known to be required for IFN-γ expression and Th1 differentiation.^17,18 These results indicate that miR-155 regulates differentiation and effector function of Th1 cells. Thus, our results suggest that miR-155 could be a promising therapeutic target to treat SK.     

The Adaptor CARD9 Is Required for Adaptive but Not Innate Immunity to Oral Mucosal Candida albicans Infections

Oropharyngeal candidiasis (OPC [thrush]) is an opportunistic infection caused by the commensal fungus Candida albicans. OPC is common in individuals with HIV/AIDS, infants, patients on chemotherapy, and individuals with congenital immune defects. Immunity to OPC is strongly dependent on the interleukin-23 (IL-23)/IL-17R axis, as mice and humans with defects in IL-17R signaling (IL17F, ACT1, IL-17RA) or in genes that direct Th17 differentiation (STAT3, STAT1, CARD9) are prone to mucocutaneous candidiasis. Conventional Th17 cells are induced in response to C. albicans infection via signals from C-type lectin receptors, which signal through the adaptor CARD9, leading to production of Th17-inducing cytokines such as IL-6, IL-1β, and IL-23. Recent data indicate that IL-17 can also be made by numerous innate cell subsets. These innate “type 17” cells resemble conventional Th17 cells, but they can be activated without need for prior antigen exposure. Because C. albicans is not a commensal organism in rodents and mice are thus naive to this fungus, we had the opportunity to assess the role of CARD9 in innate versus adaptive responses using an OPC infection model. As expected, CARD9^−/− mice failed to mount an adaptive Th17 response following oral Candida infection. Surprisingly, however, CARD9^−/− mice had preserved innate IL-17-dependent responses to Candida and were almost fully resistant to OPC. Thus, CARD9 is important primarily for adaptive immunity to C. albicans, whereas alternate recognition systems appear to be needed for effective innate responses.     

Porphyromonas gingivalis Exacerbates Ligature-Induced,RANKL-Dependent Alveolar Bone Resorption via Differential Regulation of Toll-Like Receptor 2 (TLR2) and TLR4

Toll-like receptors (TLRs) play a key role in the innate immune responses to periodontal pathogens in periodontal disease. The present study was performed to determine the roles of TLR2 and TLR4 signaling in alveolar bone resorption, using a Porphyromonas gingivalis-associated ligature-induced periodontitis model in mice. Wild-type (WT), Tlr2^−/−, and Tlr4^−/− mice (8 to 10 weeks old) in the C57/BL6 background were used. Silk ligatures were applied to the maxillary second molars in the presence or absence of live P. gingivalis infection. Ligatures were removed from the second molars on day 14, and mice were kept for another 2 weeks before sacrifice for final analysis (day 28). On day 14, there were no differences in alveolar bone resorption and gingival RANKL expression between mice treated with ligation plus P. gingivalis infection and mice treated with ligation alone. Gingival interleukin-1β (IL-1β) and tumor necrosis factor alpha (TNF-α) expression was increased, whereas IL-10 expression was decreased in WT and Tlr2^−/− mice but not in Tlr4^−/− mice. On day 28, WT and Tlr4^−/− mice treated with ligation plus P. gingivalis infection showed significantly increased bone loss and gingival RANKL expression compared to those treated with ligation alone, whereas such an increase was diminished in Tlr2^−/− mice. Gingival TNF-α upregulation and IL-10 downregulation were observed only in WT and Tlr4^−/− mice, not in Tlr2^−/− mice. In all mice, bone resorption induced by ligation plus P. gingivalis infection was antagonized by local anti-RANKL antibody administration. This study suggests that P. gingivalis exacerbates ligature-induced, RANKL-dependent periodontal bone resorption via differential regulation of TLR2 and TLR4 signaling.     

Defective Nitric Oxide Effector Functions Lead to Extreme Susceptibility of Trypanosoma cruzi-Infected Mice Deficient in Gamma Interferon Receptor or Inducible Nitric Oxide Synthase

Trypanosoma cruzi, the causative agent of Chagas’ disease, induces an innate and adaptive host immune response during the acute phase of infection. These responses were analyzed by comparing mouse lines deficient for the gamma interferon (IFN-γ) receptor (IFN-γR^−/−) or deficient for inducible nitric oxide synthase (iNOS^−/−). Both lines were highly susceptible, with similar and dramatically increased parasite burdens and severe histopathology and were incapable of surviving even very low doses, exhibiting similar mortality kinetics. This pathophysiological correlation has a common cause, since both mutant mouse strains were unable to respond to infection by producing nitric oxide (NO) with the consequence that mutant macrophages had impaired trypanocidal activities. These in vivo and subsequent in vitro studies further demonstrated that an IFN-γ-dependent pathway of iNOS induction is crucial for efficient NO production and mandatory for resisting acute infection with T. cruzi. Despite this defect, both mutant mouse strains had a rather normal proinflammatory cytokine response (interleukin-12 [IL-12], IFN-γ, IL-6), with the exception of an impaired tumor necrosis factor alpha and IL-1α response in IFN-γR^−/− mice, demonstrating that only the latter two cytokines are dependent on IFN-γ activation. Moreover, polarization of T cells in type 1 and type 2 T-helper (Th1/Th2) and cytotoxic T (Tc1/Tc2) cells as well as T. cruzi-specific antibody responses were normal in IFN-γR^−/− mice, demonstrating that IFN-γ is not necessary for the promotion of T-cell differentiation and T. cruzi-specific antibody responses.     

MicroRNA-140 plays dual roles in both cartilage development and homeostasis

Osteoarthritis (OA), the most prevalent aging-related joint disease, is characterized by insufficient extracellular matrix synthesis and articular cartilage degradation, mediated by several proteinases, including Adamts-5. miR-140 is one of a very limited number of noncoding microRNAs (miRNAs) specifically expressed in cartilage; however, its role in development and/or tissue maintenance is largely uncharacterized. To examine miR-140 function in tissue development and homeostasis, we generated a mouse line through a targeted deletion of miR-140. miR-140^−/− mice manifested a mild skeletal phenotype with a short stature, although the structure of the articular joint cartilage appeared grossly normal in 1-mo-old miR-140^−/− mice. Interestingly, miR-140^−/− mice showed age-related OA-like changes characterized by proteoglycan loss and fibrillation of articular cartilage. Conversely, transgenic (TG) mice overexpressing miR-140 in cartilage were resistant to antigen-induced arthritis. OA-like changes in miR-140-deficient mice can be attributed, in part, to elevated Adamts-5 expression, regulated directly by miR-140. We show that miR-140 regulates cartilage development and homeostasis, and its loss contributes to the development of age-related OA-like changes.     

Comparative study of IgA VH3 gene usage in healthy TST− and TST+ population exposed to tuberculosis: deep sequencing analysis

The acquired immune response against tuberculosis is commonly associated with T-cell responses with little known about the role of B cells or antibodies. There have been suggestions that B cells and humoral immunity can modulate the immune response to Mycobacterium tuberculosis. However, the mechanisms involving B-cell responses in M. tuberculosis are not fully understood, in particular the antibody gene preferences. We hypothesized that a preferential use of V genes can be seen associated with resistance to infection mainly in the IgA isotype, which is of prominent importance for infection by pathogens via the mucosal route. We studied healthy individuals with long-term exposure to tuberculosis, infected (TST⁺) and uninfected TST⁻) with M. tuberculosis. From a total of 22 V genes analysed, the TST⁻ population preferred the V_H3-23 and Vκ1 genes. The V_H3-23 genes were subsequently subjected to 454 amplicon sequencing. The TST⁻ population showed a higher frequency of the D3-10 segment compared with the D3-22 segment for the TST⁺ population. The J segment usage pattern was similar for both populations with J4 segment being used the most. A preferential pairing of J4 segments to D3-3 was seen for the TST⁻ population. The antibodyome difference between both populations suggests a preference for antibodies with V_H3-23, D3-3, J_H4 gene usage by the TST⁻ population that could be associated with resistance to infection with M. tuberculosis.     

Interleukin-17 Protects against the Francisella tularensis Live Vaccine Strain but Not against a Virulent F. tularensis Type A Strain

Francisella tularensis is a highly infectious intracellular bacterium that causes the zoonotic infection tularemia. While much literature exists on the host response to F. tularensis infection, the vast majority of work has been conducted using attenuated strains of Francisella that do not cause disease in humans. However, emerging data indicate that the protective immune response against attenuated F. tularensis versus F. tularensis type A differs. Several groups have recently reported that interleukin-17 (IL-17) confers protection against the live vaccine strain (LVS) of Francisella. While we too have found that IL-17Rα^−/− mice are more susceptible to F. tularensis LVS infection, our studies, using a virulent type A strain of F. tularensis (SchuS4), indicate that IL-17Rα^−/− mice display organ burdens and pulmonary gamma interferon (IFN-γ) responses similar to those of wild-type mice following infection. In addition, oral LVS vaccination conferred equivalent protection against pulmonary challenge with SchuS4 in both IL-17Rα^−/− and wild-type mice. While IFN-γ was found to be critically important for survival in a convalescent model of SchuS4 infection, IL-17 neutralization from either wild-type or IFN-γ^−/− mice had no effect on morbidity or mortality in this model. IL-17 protein levels were also higher in the lungs of mice infected with the LVS rather than F. tularensis type A, while IL-23p19 mRNA expression was found to be caspase-1 dependent in macrophages infected with LVS but not SchuS4. Collectively, these results demonstrate that IL-17 is dispensable for host immunity to type A F. tularensis infection, and that induced and protective immunity differs between attenuated and virulent strains of F. tularensis.     

Type 1 interferon-induced IL-7 maintains CD8+ T-cell responses and homeostasis by suppressing PD-1 expression in viral hepatitis

Type 1 interferon (IFN-I) promotes antigen-presenting cell maturation and was recently shown to induce hepatic IL-7 production during infection. Herein, we further explored the underlying mechanisms used by IFN-I to orchestrate antiviral immune responses in the liver. Acute viral hepatitis was induced by i.v. injection of adenovirus (Ad) in IFN-α receptor knockout (IFNAR^−/−) and control mice. To disrupt signaling, monoclonal antibodies (mAbs) against IL-7 receptor alpha (IL-7Rα) or PD-L1 were i.p. injected. We found that CD8⁺ T cells in IFNAR^−/− mice were less effective than those in control mice. The reduced T-cell function was accompanied by increased levels of PD-1 expression, apoptosis and decreased IFN-γ production. The lack of IFN-I signaling also impaired the expression of accessory molecules in both intrahepatic dendritic cell (DCs) and hepatocytes. PD-L1 was comparably and highly expressed on hepatocytes in both IFNAR^−/− and control mice. Injection of PD-L1-specific mAb in IFNAR^−/− mice reversed the compromised immune responses in the liver. Further investigation showed that hepatic IL-7 elevation was less pronounced in IFNAR^−/− mice compared to the controls. A treatment with recombinant IL-7 suppressed PD-1 expression on CD8⁺ T cells in vitro. Accordingly, blocking IL-7R signaling in vivo resulted in increased PD-1 expression on CD8⁺ T cells in Ad-infected mice. Collectively, the results suggest that IFN-I-induced hepatic IL-7 production maintains antiviral CD8⁺ T-cell responses and homeostasis by suppressing PD-1 expression in acute viral hepatitis.     

Defective erythroid differentiation in miR-451 mutant mice mediated by 14-3-3ζ

Erythrocyte formation occurs throughout life in response to cytokine signaling. We show that microRNA-451 (miR-451) regulates erythropoiesis in vivo. Mice lacking miR-451 display a reduction in hematrocrit, an erythroid differentiation defect, and ineffective erythropoiesis in response to oxidative stress. 14-3-3ζ, an intracellular regulator of cytokine signaling that is repressed by miR-451, is up-regulated in miR-451^−/− erythroblasts, and inhibition of 14-3-3ζ rescues their differentiation defect. These findings reveal an essential role of 14-3-3ζ as a mediator of the proerythroid differentiation actions of miR-451, and highlight the therapeutic potential of miR-451 inhibitors.     

Expression of MicroRNAs in the Urinary Sediment of Patients with IgA Nephropathy

Background: Micro-RNAs (miRNAs) regulate one-third of all protein-coding genes and are fundamental in the pathophysiology of a wide range of diseases. We studied the expression of several miRNA species (miR-200 family, miR-205 and miR-192) in the urinary sediment of patients with IgA nephropathy (IgAN). Methods: We studied 43 patients with biopsy-proven IgAN. Urinary expression of miRNAs was determined and compared to that from 13 healthy controls. Results: The levels of urinary miR-200a, miR-200b and miR-429, but not miR-200c, miR-141, miR-205, or miR-192, were down-regulated in patients with IgAN. Proteinuria significantly correlated with urinary expression of miR-200a (r = −0.483, P < 0.001), miR-200b (r = −0.448, P = 0.001) and miR-429 (r = −0.466, P = 0.001). Baseline renal function significantly correlated with urinary expression of miR-200b (r = 0.512, P < 0.001) and miR-429 (r = 0.425, P = 0.005). Urinary gene expression of ZEB2 inversely correlated with miR-200b (r = −0.321, P = 0.017); and vimentin expression inversely correlated with that of miR-200a (r = −0.360, P = 0.007), miR-200b (r = −0.416, P = 0.002) and miR-429 (r = −0.375, P = 0.005). After 33.4 ± 12.6 months, the rate of renal function decline significantly correlated with urinary expression of miR-200b (r = 0.316, P = 0.034). Conclusions: Urinary expression of miR-200a, miR-200b and miR-429 were down-regulated in patients with IgAN, and the degree of reduction correlated with disease severity and rate of progression. The results suggested that these miRNA species might play important roles in the pathophysiology of IgAN. Further studies are needed to clarify the role of urinary miRNA repression as a non-invasive marker of IgAN.     

MyD88-Dependent Signaling Drives Host Survival and Early Cytokine Production during Histoplasma capsulatum Infection

The ability of the innate immune system to trigger an adaptive T cell response is critical to resolution of infection with the fungal pathogen Histoplasma capsulatum. However, the signaling pathways and cell types involved in the recognition of and response to this respiratory pathogen remain poorly defined. Here, we show that MyD88, an adaptor protein vital to multiple innate immune pathways, is critically required for the host response to Histoplasma. MyD88-deficient (MyD88^−/−) mice are unable to control the fungal burden and are more sensitive to Histoplasma infection than wild-type, Dectin-1^−/−, or interleukin 1 receptor-deficient (IL-1R^−/−) mice. We found that MyD88 is necessary for the production of key early inflammatory cytokines and the subsequent recruitment of inflammatory monocytes to the lung. In both our in vitro and ex vivo analyses, MyD88 was intrinsically required in dendritic cells and alveolar macrophages for initial cytokine production. Additionally, MyD88-deficient bone marrow-derived dendritic cells fail to efficiently control fungal growth when cocultured with primed splenic T cells. Surprisingly, mice that lack MyD88 only in dendritic cells and alveolar macrophages are competent for early cytokine production and normal survival, indicating the presence of compensatory and redundant MyD88 signaling in other cell types during infection. Ultimately, global MyD88 deficiency prevents proper T cell activation and gamma interferon (IFN-γ) production, which are critical for infection resolution. Collectively, this work reveals a central role for MyD88 in coordinating the innate and adaptive immune responses to infection with this ubiquitous fungal pathogen of humans.     

Interleukin-13 Receptor α1-Dependent Responses in the Intestine Are Critical to Parasite Clearance

Nematode infection upregulates interleukin-4 (IL-4) and IL-13 and induces STAT6-dependent changes in gut function that promote worm clearance. IL-4 and IL-13 activate the type 2 IL-4 receptor (IL-4R), which contains the IL-13Rα1 and IL-4Rα chains. We used mice deficient in IL-13Rα1 (IL-13Rα1^−/−) to examine the contribution of IL-13 acting at the type 2 IL-4R to immune and functional responses to primary (Hb1) and secondary (Hb2) infections with the gastrointestinal nematode parasite Heligmosomoides bakeri. There were differences between strains in the IL-4 and IL-13 expression responses to Hb1 but not Hb2 infection. Following Hb2 infection, deficient mice had impaired worm expulsion and higher worm fecundity despite normal production of Th2-derived cytokines. The upregulation of IL-25 and IL-13Rα2 in Hb1- and Hb2-infected wild-type (WT) mice was absent in IL-13Rα1^−/− mice. Goblet cell numbers and resistin-like molecule beta (RELM-β) expression were attenuated significantly in IL-13Rα1^−/− mice following Hb2 infections. IL-13Rα1 contributes to the development of alternatively activated macrophages, but the type 1 IL-4R is also important. Hb1 infection had no effects on smooth muscle function or epithelial permeability in either strain, while the enhanced mucosal permeability and changes in smooth muscle function and morphology observed in response to Hb2 infection in WT mice were absent in IL-13Rα1^−/− mice. Notably, the contribution of claudin-2, which has been linked to IL-13, does not mediate the increased mucosal permeability following Hb2 infection. These results show that activation of IL-13Rα1 is critical for key aspects of the immune and functional responses to Hb2 infection that facilitate expulsion.     

MicroRNA-466l inhibits antiviral innate immune response by targeting interferon-alpha

Effective recognition of viral infections and subsequent triggering of antiviral innate immune responses are essential for the host antiviral defense, which is tightly regulated by multiple regulators, including microRNAs (miRNAs). A previous study showed that miR-466l upregulates IL-10 expression in macrophages by antagonizing RNA-binding protein tristetraprolin-mediated IL-10 mRNA degradation. However, the ability of miR-466l to regulate antiviral immune responses remains unknown. Here, we found that interferon-alpha (IFN-α) expression was repressed in Sendai virus (SeV)- and vesicular stomatitis virus (VSV)-infected macrophages and in dendritic cells transfected with miR-466l expression. Moreover, multiple IFN-α species can be directly targeted by miR-466l through their 3′ untranslated region (3′UTR). This study has demonstrated that miR-466l could directly target IFN-α expression to inhibit host antiviral innate immune response.