The response to tissue injury involves the coordination of inflammatory and repair processes. IL-6 expression correlates with the onset and severity of acute kidney injury (AKI), but its contribution to pathogenesis remains unclear. This study established a critical role for IL-6 in both the inflammatory response and the resolution of AKI. IL-6 -deficient mice were resistant to HgCl 2 -induced AKI compared with wild-type mice. The accumulation of peritubular neutrophils was lower in IL-6 -deficient mice than in wild-type mice, and neutrophil depletion before HgCl 2 administration in wild-type mice significantly reduced AKI; these results demonstrate the critical role of IL-6 signaling in the injurious inflammatory process in AKI. Renal IL-6 expression and STAT3 activation in renal tubular epithelial cells significantly increased during the development of injury, suggesting active IL-6 signaling. Although a lack of renal IL-6 receptors (IL-6R) precludes the activation of classical signaling pathways, IL-6 can stimulate target cells together with a soluble form of the IL-6R (sIL-6R) in a process termed trans-signaling. During injury, serum sIL-6R levels increased three-fold, suggesting a possible role for IL-6 trans-signaling in AKI. Stimulation of IL-6 trans-signaling with an IL-6/sIL-6R fusion protein activated STAT3 in renal tubular epithelium and prevented AKI. IL-6/sIL-6R reduced lipid peroxidation after injury, suggesting that its protective effect may be largely mediated through amelioration of oxidative stress. In summary, IL-6 simultaneously promotes an injurious inflammatory response and, through a mechanism of transsignaling, protects the kidney from further injury.

Toward the goal of gene therapy, we have been attempting to establish model somatic cell systems with the potential of talned expression of the foreign gene. We report here that long-term expression of foreign genes in mouse embryo fibroblast implants can be achieved If a housekeeping gene promoter is used to drive transcription. Speitfcally, we have shown that in implants conining a f-galactosidase gene linked to either an immediate early promoter of cytomegalovirus or a dihydrofolate reductase (DHIFR) gene promoter, only the DHFR promoter allows long-term expression. We propose that choice of the promoter manife sgificant influence on the long-term expression of genes introduced in fibroblast implants by retroviral vectors.Current models for gene therapy involve the retrovirusmediated transfer of genetic material into cells derived from a variety of somatic host tissues, including cells of the hematopoietic system, fibroblasts, hepatocytes, endothelial cells, and myoblasts (1, 2). We have previously described an approach for gene product delivery by retroviral infection of mouse skin fibroblasts (3). The transduced genes used in our previous studies in fibroblasts were the human and dog factor IX cDNAs (3, 4). Although high levels of sustained expression could be achieved in tissue culture, when transplanted as allografts in rodents, these fibroblasts produced substantial amounts of factor IX for only a short period of time (3,5). This short duration of expression in vivo could theoretically be attributed to different factors: (i) an immune response of the host against the exogenous factor IX; (ii) destruction of the foreign cells after transplantation; and (iiM) a specific decrease in transcription of the transferred gene once the transduced cells are grafted to the animal. It has been shown (3, 5) that antibodies to human factor IX are present after implantation of modified fibroblasts, which could explain, at least in part, the short period of detection of factor IX.In this work, using different promoters to control the expression of 8-galactosidase, we demonstrate that, whereas in tissue culture long-term expression can be easily obtained, the type of promoter directing transcription of the gene of interest can be one of the key factors determining long-term expression in vivo. MATERIALS AND METHODSAnimal and Cell Culture Conditions. Adult male C57BL/6J mice (6-8 weeks old) and Nu/Nu athymic mice were obtained from The Jackson Laboratory. The retroviral packaging cell lines fCRE and *CRIP (6) and the cell lines NIH 3T3 and rat 208 F were maintained in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% bovine calf serum. Primary fibroblasts were obtained from day 17 embryos of C57BL/6J mice and were grown in DMEM supplemented with 10% fetal calf serum. Infected cells were selected in medium containing 400 pkg of G418 per ml.Vector Construction. Retroviral vector LNCdF9L, which transduces canine factor IX, has been described (4). The vectors shown in Fig. 1

Head and neck cancer patients treated by radiation commonly suffer from a devastating side effect known as dry-mouth syndrome, which results from the irreversible loss of salivary gland function via mechanisms that are not completely understood. In this study, we used a mouse model of radiationinduced salivary hypofunction to investigate the outcomes of DNA damage in the head and neck region. We demonstrate that the loss of salivary function was closely accompanied by cellular senescence, as evidenced by a persistent DNA damage response (gH2AX and 53BP1) and the expression of senescence-associated markers (SA-bgal, p19ARF, and DcR2) and secretory phenotype (SASP) factors (PAI-1 and IL6). Notably, profound apoptosis or necrosis was not observed in irradiated regions. Signs of cellular senescence were also apparent in irradiated salivary glands surgically resected from human patients who underwent radiotherapy. Importantly, using IL6 knockout mice, we found that sustained expression of IL6 in the salivary gland long after initiation of radiation-induced DNA damage was required for both senescence and hypofunction. Additionally, we demonstrate that IL6 pretreatment prevented both senescence and salivary gland hypofunction via a mechanism involving enhanced DNA damage repair. Collectively, these results indicate that cellular senescence is a fundamental mechanism driving radiation-induced damage in the salivary gland and suggest that IL6 pretreatment may represent a promising therapeutic strategy to preserve salivary gland function in head and neck cancer patients undergoing radiotherapy. Cancer Res; 76(5); 1170-80. Ó2016 AACR.

No abstract

The liver is a unique organ, and first in line, the hepatocytes encounter the potential to proliferate during cell mass loss. This phenomenon is tightly controlled and resembles in some way the embryonal co-inhabitant cell lineage of the liver, the embryonic hematopoietic system. Interestingly, both the liver and hematopoietic cell proliferation and growth are controlled by various growth factors and cytokines. IL-6 and its signaling cascade inside the cells through STAT3 are both significantly important for liver regeneration as well as for hematopoietic cell proliferation. The process of liver regeneration is very complex and is dependent on the etiology and extent of liver damage and the genetic background. In this review we will initially describe the clinical relevant condition, portraying a number of available animal models with an emphasis on the relevance of each one to the human condition of fulminant hepatic failure (FHF). The discussion will then be focused on the role of cytokines in liver failure and regeneration, and suggest potential new therapeutic modalities for FHF. The recent findings on the role of IL-6 in liver regeneration and the activity of the designer IL-6/sIL-6R fusion protein, hyper-IL-6, in particular, suggest that this molecule could significantly enhance liver regeneration in humans, and as such could be a useful treatment for FHF in patients.

The gene transfer technique was used to examine the role of plasminogen activator (PA) Tumor cell invasion and metastasis are complex processes affected by a multiplicity of factors whose molecular nature is scarcely defined (13,24,44). Hydrolytic enzymes, including proteinases, were long ago implicated in tumor metastasis to account in part for the ability of tumor cells to detach from the primary lesion, to penetrate through basement membrane surrounding blood vessels, and finally to implant themselves into a remote organ (for reviews, see references 8 and 33). One of the enzymes whose role in metastasis is most controversial is plasminogen activator (PA), a serine proteinase that converts the ubiquitous extracellular zymogen plasminogen into the trypsinlike proteinase plasmin. Plasmin, in turn, dissolves the fibrin network of the blood clot, degrades interstitial glycoproteins such as fibronectin and laminin, and converts procollagenases into collagenases necessary for degradation of basement membrane collagen (8). Such a spectrum of activities renders the plasminogen activation system an ideal candidate to participate in tumor invasion and metastasis, since high levels of PA are closely associated with neoplasia-related phenomena (8, 41). The hypothesis concerning the role of the plasminogen activation system in tumor invasion has recently been supported by studies measuring cellular invasion in vitro in assay systems designed to simplify study of tumor cell invasion and metastasis (30,42). These studies have demonstrated that the passage of tumor cells through a barrier of basement membrane in vitro requires a proteolytic cascade of which the final proteinase collagenase is generated by PA-activated plasmin. That PA may also be involved in tumor invasion under physiological conditions is suggested by the immunocytochemical localization of urokinase-type PA (uPA) in areas of invasive growth of the Lewis lung carcinoma (47). Furthermore, the metastatic spread of the Hep-3 human carcinoma in an avian system was significantly inhibited by antibodies specifically blocking the activity of human uPA without affecting either the local growth of the tumor or the avian uPA activity (37,38). Similarly, inhibition by antibod-* Corresponding author.ies of surface-localized uPA on B16 melanoma cells reduced the capacity of the cells to generate experimental metastasis in mice (20). In contrast to the latter cases, in numerous other studies the role of PA in tumor metastasis was inferred from circumstantial rather than direct evidence (for reviews and detailed lists of references, see references 6, 8, 14, 22, 26, 34, 40, and 43). For example, in sublines derived from transplanted tumors, such as the B16 melanoma and the Lewis lung carcinoma, comparison was made between PA production and metastatic capacity (6,9,14,40,54). Comparison was also made between PA levels of spontaneously arising human tumors of the colon, breast, and prostate and PA produced by their invasive and metastatic derivatives (5,22,26,27,36

Acute liver injury can be secondary to a variety of causes, including infections, intoxication, and ischemia. All of these insults induce hepatocyte death and subsequent inflammation, which can make acute liver injury a life-threatening event. IL-22 is a dual natured cytokine which has context-dependent protective and pathogenic properties during tissue damage. Accordingly, IL-22 was shown to promote liver regeneration upon acute liver damage. However, other studies suggest pathogenic properties of IL-22 during chronic liver injury. IL-22 binding protein (IL-22BP, IL-22Ra2) is a soluble inhibitor of IL-22 that regulates IL-22 activity. However, the significance of endogenous IL-22BP in acute liver injury is unknown. We hypothesized that IL-22BP may play a role in acute liver injury. To test this hypothesis, we used -deficient mice and murine models of acute liver damage induced by ischemia reperfusion and-acetyl--aminophenol (acetaminophen) administration. We found that -deficient mice were more susceptible to acute liver damage in both models. We used × double-deficient mice to show that this effect is indeed due to uncontrolled IL-22 activity. We could demonstrate mechanistically increased expression of by hepatocytes, and consequently increased infiltration of inflammatory CD11bLy6C monocytes into the liver in -deficient mice upon liver damage. Accordingly, neutralization of CXCL10 reversed the increased disease susceptibility of-deficient mice. In conclusion, our data indicate that IL-22BP plays a protective role in acute liver damage, via controlling IL-22-induced expression.

The effective reduction in infarct size and apoptosis in the nondiabetic rat heart by postC was completely abrogated in diabetic rats. This inhibition is not relieved by insulin-induced normoglycemia. The PI3K pathway and mitochondrial adenosine triphosphate-dependent potassium channel activation are involved in the mechanism of postC. In diabetic rats, STAT3 activation was strongly reduced, as was postC cardioprotection, suggesting that the inability of insulin to restore postC may be attributed to diabetes-induced STAT3-mediated inhibition of PI3K signaling.