Interleukin-6 plays a protective role in development of cisplatin-induced acute renal failure through upregulation of anti-oxidative stress factors

AimsCisplatin, a major chemotherapeutic agent, accumulates in proximal tubules of the kidneys and causes acute renal failure dose-dependently. We previously reported that cisplatin induced more severe renal dysfunction in interleukin-6 (IL-6) knockout (IL-6^?/?) mice than in wild-type (WT) mice. Expression of a pro-apoptotic protein was significantly increased with cisplatin in IL-6^?/? mice compared to that in WT mice. IL-6, locally expressed in renal tubular cells after cisplatin administration, prevents the development of renal dysfunction at an early stage. In the present study, we focused on downstream signals of IL-6 and oxidative stress induced by cisplatin in order to evaluate the protective role of IL-6 in the development of acute renal failure.Main methodsWT and IL-6^?/? mice were given either cisplatin (30 mg/kg) or saline intraperitoneally. Blood and kidney samples were collected at 24 h and 72 h after cisplatin administration. The changes in expression of 4-hydroxy-2-nonenal protein (4-HNE, oxidative stress marker) and cyclooxygenase-2 (cox-2), activities of superoxide dismutases and caspase-3, and phosphorylation of extracellular signal-regulated kinase (ERK) were examined.Key findingsCisplatin increased the expression of 4-HNE and cox-2, and phosphorylation of ERK in IL-6^?/? mice than in WT mice. On the other hand, activity of superoxide dismutase, an anti-oxidative enzyme, was significantly decreased in the kidney obtained from IL-6^?/? mice after cisplatin administration.SignificanceOur findings suggest that IL-6 plays a protective role in the development of cisplatin-induced acute renal failure through upregulation of anti-oxidative stress factors.     

Sodium stibogluconate interacts with IL-2 in anti-Renca tumor action via a T cell-dependent mechanism in connection with induction of tumor-infiltrating macrophages

IL-2 therapy results in 10-20% response rates in advanced renal cell carcinoma (RCC) via activating immune cells, in which the protein tyrosine phosphatase Src homology 2 domain-containing phosphatase 1 (SHP-1) is a key negative regulator. Based on finding that sodium stibogluconate (SSG) inhibited SHP-1, the anti-RCC potential and action mechanism of SSG and SSG/IL-2 in combination were investigated in a murine renal cancer model (Renca). Despite its failure to inhibit Renca cell proliferation in cultures, SSG induced 61% growth inhibition of Renca tumors in BALB/c mice coincident with an increase (2-fold) in tumor-infiltrating macrophages (Mphi). A combination of SSG and IL-2 was more effective in inhibiting tumor growth (91%) and inducing tumor-infiltrating Mphi (4-fold), whereas IL-2 alone had little effect. Mphi increases were also detected in the spleens of mice treated with SSG (3-fold) or SSG/IL-2 in combination (6-fold), suggesting a systemic Mphi expansion similar to those in SHP-deficient mice. T cell involvement in the anti-Renca tumor action of the combination was suggested by the observations that the treatment induced spleen IFN-gamma T cells in BALB/c mice, but failed to inhibit Renca tumor growth in athymic nude mice and that SSG treatment of T cells in vitro increased production of IFN-gamma capable of activating tumoricidal Mphi. The SSG and SSG/IL-2 combination treatments were tolerated in the mice. These results together demonstrate an anti-Renca tumor activity of SSG that was enhanced in combination with IL-2 and functions via a T cell-dependent mechanism with increased IFN-gamma production and expansion/activation of Mphi. Our findings suggest that SSG might improve anti-RCC efficacy of IL-2 therapy by enhancing antitumor immunity.     

Targeting the superoxide/nitric oxide ratio by L-arginine and SOD mimic in diabetic rat skin

Abstract

Setting the correct ratio of superoxide anion (O₂^?-) and nitric oxide (^?NO) radicals seems to be crucial in restoring disrupted redox signaling in diabetic skin and improvement of ^?NO physiological action for prevention and treatment of skin injuries in diabetes. In this study we examined the effects of L-arginine and manganese(II)-pentaazamacrocyclic superoxide dismutase (SOD) mimic – M40403 in diabetic rat skin. Following induction of diabetes by alloxan (blood glucose level ≥12?mMol l?^?1) non-diabetic and diabetic male Mill Hill hybrid hooded rats were divided into three subgroups: (i) control, and receiving: (ii) L-arginine, (iii) M40403. Treatment of diabetic animals started after diabetes induction and lasted for 7 days. Compared to control, lower cutaneous immuno-expression of endothelial NO synthase (eNOS), heme oxygenase 1 (HO1), manganese SOD (MnSOD) and glutathione peroxidase (GSH-Px), in parallel with increased NFE2-related factor 2 (Nrf2) and nitrotyrosine levels characterized diabetic skin. L-arginine and M40403 treatments normalized alloxan-induced increase in nitrotyrosine. This was accompanied by the improvement/restitution of eNOS and HO1 or MnSOD and GSH-Px protein expression levels in diabetic skin following L-arginine, i.e. SOD mimic treatments, respectively. The results indicate that L-arginine and M40403 stabilize redox balance in diabetic skin and suggest the underlying molecular mechanisms. Restitution of skin redox balance by L-arginine and M40403 may represent an effective strategy to ameliorate therapy of diabetic skin.     

Absent in melanoma 2-mediating M1 macrophages facilitate tumor rejection in renal carcinoma

Absent in melanoma 2 (AIM2) as an immune regulator for the regulation of tumor-associated macrophages (TAMs) function is unclear in tumor development. Here, the AIM2 function was investigated in TAMs-mediated malignant behaviors of renal carcinoma. The correlation analysis result showed that the AIM2 expression in TAMs was negatively correlated with the percentages of M2-like polarization phenotype in human or murine renal cancer specimens. By the cocultured assay with bone marrow-derived macrophages (BMDMs) and Renca cells, overexpression of AIM2 in macrophages enhanced the inflammasome activation and reversed the phenotype from M2 to M1. Compared with BMDMs-Ctrl cocultured group, BMDMs-AIM2 cocultured group showed reduced tumor cell proliferation and migration. The blockade of inflammasome activation by the inhibitor Ac-YVAD-CMK abrogated AIM2-mediated M1 polarization and the inhibition of tumor cell growth. To evaluate the therapeutic efficacy of AIM2-mediated M1 macrophages in vivo, BMDMs-AIM2 were intravenously injected into subcutaneous Renca-tumor mice. The results showed that the infiltration of M1 TAMs was increased and tumor growth was suppressed in BMDMs-AIM2-treated mice when compared with BMDMs-Ctrl-treat mice. Accordingly, the blockade of inflammasome activation reduced the anti-tumor activities of BMDMs-AIM2. Moreover, the lung metastases of renal carcinoma were suppressed by the administration of BMDMs-AIM2 accompanied with the reduced tumor foci. These results demonstrated that AIM2 enhanced TAMs polarization switch from anti-inflammatory M2 phenotypy to pro-inflammatory M1 through inflammasome signaling activation, thus exerting therapeutic intervention in renal carcinoma models. Our results provide a possible molecular mechanism for the modulation of TAMs polarization in tumor microenvironment and open a new potential therapeutic approach for renal cancer.     

Reduction of antigen-induced respiratory abnormalities and airway inflammation in sensitized guinea pigs by a superoxide dismutase mimetic

Reactive oxygen species have been implicated in the pathogenesis of asthma and, in atopic asthmatics, endogenous superoxide dismutase (SOD) enzyme levels are known to decrease. This suggests that replacing a failed endogenous SOD enzyme system with a mimetic of the endogenous enzyme would be beneficial and protective. In this study we demonstrate that removal of superoxide by the SOD mimetic (SODm) M40403 reduces the respiratory and histopathological lung abnormalities due to ovalbumin (OA) aerosol in a model of allergic asthma-like reaction in sensitized guinea pigs. Both respiratory abnormalities and bronchoconstriction in response to OA challenge are nearly absent in na?ve animals, while they sharply became severe in sensitized animals. In addition, OA aerosol induced a reduction of MnSOD activity which was paralleled with bronchiolar lumen reduction, pulmonary air space hyperinflation, mast cell degranulation, eosinophil infiltration, bronchial epithelial cell apoptosis, increase in myeloperoxidase activity, malonyldialdehyde production and 8-hydroxy-2'-deoxyguanosine formation in the lung tissue, as well as elevation of PGD2 in the bronchoalveolar lavage fluid. Treatment with M40403 restored the levels of MnSOD activity and significantly reduced all the above parameters. In summary, our findings support the potential therapeutic use of SOD mimetics in asthma and anaphylactic reactions and account for a critical role for superoxide in acute allergic asthma-like reaction in actively sensitized guinea pig.     

Reactive oxygen species from NADPH oxidase contribute to altered pulmonary vascular responses in piglets with chronic hypoxia-induced pulmonary hypertension

Our main objective was to determine whether reactive oxygen species (ROS), such as superoxide (O(2)(-)) and hydrogen peroxide (H(2)O(2)), contribute to altered pulmonary vascular responses in piglets with chronic hypoxia-induced pulmonary hypertension. Piglets were raised in either room air (control) or hypoxia for 3 days. The effect of the cell-permeable superoxide dismutase mimetic (SOD; M40403) and/or PEG-catalase (PEG-CAT) on responses to acetylcholine (ACh) was measured in endothelium-intact and denuded pulmonary resistance arteries (PRAs; 90-to-300-microm diameter). To determine whether NADPH oxidase is an enzymatic source of ROS, PRA responses to ACh were measured in the presence and absence of a NADPH oxidase inhibitor, apocynin (APO). A Western blot technique was used to assess expression of the NADPH oxidase subunit, p67phox. A lucigenin-derived chemiluminescence technique was used to measure ROS production stimulated by the NADPH oxidase substrate, NADPH. ACh responses, which were dilation in intact control arteries but constriction in both intact and denuded hypoxic arteries, were diminished by M40403, PEG-CAT, the combination of M40403 plus PEG-CAT, as well as by APO. Although total amounts were not different, membrane-associated p67phox was greater in PRAs from hypoxic compared with control piglets. NADPH-stimulated lucigenin luminescence was nearly doubled in PRAs from hypoxic vs. control piglets. We conclude that ROS generated by NADPH oxidase contribute to the aberrant pulmonary arterial responses in piglets exposed to 3 days of hypoxia.     

A phase II study of interferon α and low-dose subcutaneous interleukin-2 in advanced renal cell carcinoma

 The activity of the drugs employed in the treatment of metastatic renal cell carcinoma, including biological response modifiers, is limited; one of the aims of clinical research in this area is to maintain the benefits of treatment whilst reducing its toxicity to a minimum level. We have evaluated toxicity and response of the combined administration of recombinant interferon α (IFNα) and low-dose subcutaneous (s.c.) recombinant interleukin-2 (IL-2) in patients with advanced renal cell carcinoma. A group of 20 previously untreated patients with advanced renal cell carcinoma were included in the study. Treatment consisted of 3 MU/m² recombinant IFNα daily i.m. continuously, and 0.5 MU/m² recombinant IL-2 twice a day s.c. on days 1–5 for the first week, followed by 1 MU/m² twice a day for 5 days in the following weeks. For IL-2, a 1-week rest was allowed after 4 weeks of treatment. Response was assessed after 3 months of therapy. Three objective responses were seen, one complete and two partial. Eight patients had stable disease. The median time to progression was 6 months; the median survival for all patients was 14 months. Side-effects were low, limited to grades 1 and 2 in the majority of patients, and included fever, anemia, leukopenia, dyspnea, and abnormalities of liver and renal function tests. Any flu-like syndrome was judged moderate in most patients; however, one-third of the patients refused treatment mostly because of the flu-like syndrome. One of these was the patient experiencing a complete response, who virtually received IFNα alone. This regimen, similar to others employed in the treatment of advanced renal cell carcinoma, produced a 15% response rate (95% confidence interval, 0–31%) with 14 months median survival, moderate toxicity and low cost, and required no hospitalization. These data seem to indicate an effectiveness comparable to, and a toxicity lower than, that of regimens employing higher doses of IL-2. Received: 25 March 1997 / Accepted: 22 May 1997     

Manganese superoxide dismutase is induced by IFN-gamma in multiple cell types. Synergistic induction by IFN-gamma and tumor necrosis factor or IL-1

We have previously characterized more than 20 proteins induced by the immunoregulatory lymphokine IFN-gamma in human fibroblasts by their m.w. and isoelectric points determined in two-dimensional gels. Some of these proteins are induced uniquely by IFN-gamma, whereas others are also induced by IFN-alpha, TNF, or IL-1. Recent technologic advances have allowed us to begin to rapidly identify proteins induced by IFN-gamma and other cytokines by sequencing the induced proteins from blots of preparative two-dimensional gels of total cell lysates. In this study, we show that the approximately 21 kDa, isoelectric point greater than 7 protein induced by IFN-gamma is manganese superoxide dismutase (Mn-SOD), a mitochondrial protective enzyme encoded by a nuclear gene. Mn-SOD is induced by IFN-gamma and also by TNF in all four human cell lines examined: HS153 fibroblasts, ACHN renal carcinoma, A549 lung carcinoma, and A375 melanoma. Induction of Mn-SOD mRNA is a primary, rapid, and dose-dependent response to IFN-gamma. In ACHN renal carcinoma cells, Mn-SOD mRNA and protein are induced synergistically by IFN-gamma in combination with either TNF or IL-1, and the induced protein is enzymatically active. IFN-gamma and TNF together induce Mn-SOD mRNA by more than 100-fold relative to its level in untreated ACHN cells. The induction of Mn-SOD by IFN-gamma and its synergistic induction by IFN-gamma in combination with TNF and IL-1 should protect healthy cells from the toxicity of O2- during an immune response, and may provide a mechanism for selective killing of infected cells.     

The presence of interleukin-2 receptor alpha in the serum of colorectal cancer patients is unlikely to result only from T cell up-regulation

It is unclear whether the presence of interleukin-2 soluble receptor alpha (IL-2 sRalpha) in the serum of colorectal cancer patients is solely due to T cell activation. In this study, we therefore investigated whether T cell activation, indicated by the up-regulation of the CD25 and HLA-DR markers, or cell-mediated immunity (CMI) were associated with increased serum levels of IL-2 sRalpha in patients with advanced colorectal carcinoma. The levels of serum IL-2 sRalpha and the proportion of T cells expressing HLA-DR (DR(+) T cells) were measured as markers for chronic activation. CMI was assessed by delayed-type hypersensitivity reaction (DTH) to intradermal injections of recall antigens. Eighty-seven colorectal liver metastases (CLM) patients and 23 'cancer-free' control subjects were studied. DR(+) T cells were found to be more prevalent ( P<0.0001) in CLM patients (median: 21.1%) than in controls (median: 3.4%), but DR(+) T cell up-regulation was not correlated with serum IL-2 sRalpha levels. CMI positivity was significantly reduced ( P=0.002) in CLM patients compared with controls, and this reduction was significantly associated ( P=0.05) with an increase in the number of DR(+) T cells. Although survival was significantly shorter ( P=0.0003) in patients with increased serum IL-2 sRalpha levels than in subjects with normal levels, no association was found between survival and DR(+) T cell up-regulation. These findings were consistent with the hypothesis of an additional source of serum IL-2 sRalpha other than T cell up-regulation in CLM patients -- either from other immune cells, or from tumour products.     

Prolonged renal allograft survival by donor interleukin-6 deficiency: association with decreased alloantibodies and increased intragraft T regulatory cells

Both humoral and cellular immune responses are involved in renal allograft rejection. Interleukin (IL)-6 is a regulatory cytokine for both B and Foxp3 (forkhead box P3)-expressing regulatory T (Treg) cells. This study was designed to investigate the impact of donor IL-6 production on renal allograft survival. Donor kidneys from IL-6 knockout (KO) vs. wild-type (WT) C57BL/6 mice (H-2(b)) were orthotopically transplanted to nephrotomized BALB/c mice (H-2(d)). Alloantibodies and Treg cells were examined by fluorescence-activated cell sorting analysis. Graft survival was determined by the time to graft failure. Here, we showed that a deficiency in IL-6 expression in donor kidneys significantly prolonged renal allograft survival compared with WT controls. IL-6 protein was upregulated in renal tubules and endothelium of renal allografts following rejection, which correlated with an increase in serum IL-6 compared with that in those receiving KO grafts or naive controls. The absence of graft-producing IL-6 or lower levels of serum IL-6 in the recipients receiving IL-6 KO allografts was associated with decreased circulating anti-graft alloantibodies and increased the percentage of intragraft CD4(+)CD25(+)Foxp3(+) Treg cells compared with those with WT allografts. In conclusion, the lack of graft-producing IL-6 significantly prolongs renal allograft survival, which is associated with reduced alloantibody production and/or increased intragraft Treg cell population, implying that targeting donor IL-6 may effectively prevent both humoral and cellular rejection of kidney transplants.     

Only one of a wide assortment of manganese-containing SOD mimicking compounds rescues the slow aerobic growth phenotypes of both Escherichia coli and Saccharomyces cerevisiae strains lacking superoxide dismutase enzymes

A variety of manganese-containing coordination compounds, frequently termed superoxide dismutase (SOD) mimics, have been reported to have SOD activity in vitro and to be effective at improving conditions related to increased oxidative stress in multicellular organisms. We tested the effectiveness of several of these compounds in substituting for authentic SOD enzymes in two simple systems--the prokaryote Escherichia coli and the single-celled eukaryote, Saccharomyces cerevisiae--where strains are available that completely lack cytoplasmic SOD activity and are thus significantly impaired in their ability to grow aerobically. Most of the compounds tested, including Euk-8 and Euk-134, manganese salen derivatives developed by Eukarion; M40403, a manganese complex of a bis(cyclohexylpyridine)-substituted macrocyclic ligand developed by Metaphore; and several manganese porphyrin derivatives, were ineffective in both systems. Only the manganese tetrapyridyl porphyrin complex MnTM-2-PyP and two close relatives were effective in rescuing aerobic growth of E. coli lacking SOD, and, in the case of sod1Delta yeast, only MnTM-2-PyP itself was fully effective. Surprisingly, several compounds reported to be beneficial in other in vivo model systems (Euk-8, Euk-134, M40403) were actually toxic to these organisms lacking SOD, although they had no effect on the wild-type parent strains. Our results suggest the possibility that the beneficial effects of some of the so-called "SOD mimic drugs" may be due to some property other than in vivo superoxide dismutase activity.     

New concepts of IL-10-induced lung fibrosis: fibrocyte recruitment and M2 activation in a CCL2/CCR2 axis

IL-10 is most commonly recognized as an anti-inflammatory cytokine possessing immunosuppressive effects necessary for regulated resolution of proinflammation. However, its role in the development of fibrosis during inflammatory resolution has not been clear. Few prior studies have linked IL-10 with the inhibition of fibrosis principally on the basis of regulating inflammation thought to be driving fibroproliferation. In contrast, in a model of long-term overexpression of IL-10, we observed marked induction of lung fibrosis in mice. The total cell number retrieved by bronchoalveolar lavage (BAL) increased 10-fold in the IL-10 overexpression (IL-10 OE) mice, with significant infiltration of T and B lymphocytes and collagen-producing cells. The presence of increased fibrocytes, isolated from collagenase-digested lungs, was identified by flow cytometry using dual staining of CD45 and collagen 1. Quantitative PCR analysis on an array of chemokine/chemokine receptor genes showed that receptor CCR2 and its ligand, CCL2, were highly upregulated in IL-10 OE mice, suggesting that IL-10-induced fibrocyte recruitment was CCL2/CCR2 specific. Given the prior association of alternatively activated (M(2)) macrophages with development of fibrosis in other disease states, we also examined the effect of IL-10 OE on the M(2) macrophage axis. We observed significantly increased numbers of M(2) macrophages in both BAL and whole lung tissue from the IL-10 OE mice. Administration of rabbit anti-CCL2 antiserum to IL-10 OE mice for three consecutive weeks significantly decreased fibrosis as evidenced by lung hydroxyproline content, compared with mice that received preimmune rabbit serum. These results indicate that overexpression of IL-10 induces fibrosis, in part, by fibrocyte recruitment and M(2) macrophage activation, and likely in a CCL2/CCR2 axis.     

Systemic treatment with interleukin-4 induces regression of pulmonary metastases in a murine renal cell carcinoma model

Advanced metastatic renal cell carcinoma has been shown to be responsive to immunotherapy but the response rate is still limited. We have investigated the therapeutic potential of systemic interleukin-4 (IL-4) administration for the treatment of pulmonary metastases in the murine Renca renal adenocarcinoma model. Renca cells were injected iv in Balb/c mice to induce multiple pulmonary tumor nodules. From Day 5, Renca-bearing mice were treated with two daily injections of recombinant murine IL-4 for 5 consecutive days. IL-4 treatment induced a significant reduction in the number of lung metastases in a dose-dependent manner and significantly augmented the survival of treated animals. Immunohistochemistry studies, performed on lung sections, showed macrophage and CD8⁺ T cell infiltration in the tumor nodules 1 day after the end of IL-4 treatment. The CD8 infiltration increased by Day 7 after IL-4 treatment. Granulocyte infiltration was not detectable. To clarify further the role of the immune system in IL-4 anti-tumor effect, mice were depleted of lymphocyte subpopulations by in vivo injections of specific antibodies prior to treatment with IL-4. Depletion of CD8⁺ T cells or AsGM1⁺ cells abrogated the effect of IL-4 on lung metastases, whereas depletion of CD4⁺ T cells had no impact. These data indicate that CD8⁺ T cells and AsGM1⁺ cells are involved in IL-4-induced regression of established renal cell carcinoma.     

Immunomodulatory effects of ultra-low-dose interleukin-2 in cancer patients: a phase-IB study

High-dose interleukin-(IL-2) has been broadly studied in tumour therapy, yet it may be inhibitory to T-cell-dependent immunity. Therefore immune and tumour responses mediated by low-dose IL-2 were studied systematically with respect to the feedback organisation of immune responses. IL-2 was administered once daily at three dose levels: 0.18, 0.9, 4.5 MIU/m² according to three different schedules requiring subcutaneous (s.c.) injection once weekly (four doses, stratum I), thrice weekly every other day (nine doses, stratum II), or five times weekly every other week (ten doses, stratum III). A total of 46 patients with advanced cancer were randomly assigned to one of the nine treatment groups. Systemic effects were induced at doses as low as 0.18 MIU/m² IL-2 s.c. as demonstrated from measurable IL-2 serum levels, induction of circulating IL-6, a transient lymphopenia, and stimulation of delayed-type hypersensitivity (DTH) responses of the skin. Analysis of the different IL-2 schedules demonstrated (a) prolonged effects of once-weekly injections on DTH responses, lymphocyte and eosinophil counts, and (b) maximum increase of eosinophil counts and preferential expansion of activated NK cells with repeated injections every 48 h or 72 h (stratum II), while sequential treatment according to stratum III was found to be more potent in increasing the number of activated T cells. A tumour response was observed in 1/15 patients with renal cell carcinoma who experienced more than 50% tumour regression for 8 months; 12 patients had stable disease for 4 months (median). These data demonstrate prolonged immunological effects of ultra-low doses of s. c. IL-2 despite its short half-life. Furthermore, scheduling of IL-2 was found to affect immune responsiveness specifically as demonstrated by the differential effects on natural killer and T cell populations.Supported by Bundesministerium für Forschung und Technologie, Förderkennzeichen 01GA8901/3 to R. M.     

Metabolites of cis,trans, and trans,cis isomers of linoleic acid in mice and incorporation into tissue lipids

Metabolism of octadecadienoic acid isomers in weanling mice was studied by feeding fat-free diets supplemented with 2% by weight of cis-9,trans-12-octadecadienoic acid (c,t-18:2-d0), tetradeuterated trans-9,cis-12-octadecadienoic acid (t,c-18:2-d4) or dideuterated cis-9,cis-12-octadecadienoic acid (c,c-18:2-d2). Rates for conversion of c,t-18:2-d0 and c,c-18:2-d2 to c,t-20:4-d0 and c,c-20:4-d2 were identical and both were 5-times higher than conversion of t,c-18:2-d4 to t,c-20:4-d4. Accumulation of t,c-18:2-d4 in liver lipids was 2-4-times higher than for c,t-18:2-d0 or c,c-18:2-d2. The t,c-18:2 diet significantly increased with the 20:3(n-9) and total lipid concentrations in liver but not in heart, plasma or brain. The 20:3(n-9)/20:4(n-6) ratio in the liver lipids was 2-4-times higher for t,c-18:2-d4 than c,c-18:2-d2 fed mice. The position of the trans bond had a marked influence on the distribution of the various intermediate desaturation and elongation products. Intermediate metabolite data for the liver lipids indicated t,c-18:2-d4 was preferentially converted to 5c,11c,14t-20:3 ('dead end' product) rather than to t,c-20:4. Concentration of the 18:3(n-6) metabolite of c,t-18:2-d0 was about 10-times greater than the 18:3(n-6) metabolite of c,c-18:2-d2. Conversely, the concentration of the normal 20:3(n-6) metabolite from c,c-18:2-d2 was 4-times higher than the 20:3(n-6) metabolite of c,t-18:2-d0. Compared to the c,c-18:2 diet, the t,c- and c,t-18:2 diets significantly increased the total n-3, but not the total n-6 fatty acid content of heart lipids. These results illustrate that the position of the trans double-bond influences a variety of enzyme activities and the isomers differ in their physiological effects.     

A regulatory T cell-dependent novel function of CD25 (IL-2Ralpha) controlling memory CD8(+) T cell homeostasis

A massive systemic expansion of CD8(+) memory T (T(M)) cells and a remarkable increase in circulating IL-2 were observed only in IL-2Ralpha (CD25) knockout (KO) mice but not in IL-2 KO and scurfy mice, although all three mutants lack regulatory T (Treg) cells. However, both phenotypes were suppressed by the transfer of Treg cells. The data presented indicate that Treg cell deficiency drives naive T cells to T(M) cells. The lack of high-affinity IL-2R in IL-2Ralpha KO mice increases circulating IL-2 that is then preferentially used by CD8(+) T(M) cells through its abundant low-affinity IL-2R, resulting in systemic CD8(+) T(M) cell dominance. Our study demonstrates the critical control of CD8(+) T(M) cell homeostasis by a Treg cell-dependent novel function of CD25 and resolves its mechanism of action.     

Interleukin-19 Mediates Tissue Damage in Murine Ischemic Acute Kidney Injury

Inflammation and renal tubular injury are major features of acute kidney injury (AKI). Many cytokines and chemokines are released from injured tubular cells and acts as proinflammatory mediators. However, the role of IL-19 in the pathogenesis of AKI is not defined yet. In bilateral renal ischemia/reperfusion injury (IRI)-induced and HgCl₂-induced AKI animal models, real-time quantitative (RTQ)-PCR showed that the kidneys, livers, and lungs of AKI mice expressed significantly higher IL-19 and its receptors than did sham control mice. Immunohistochemical staining showed that IL-19 and its receptors were strongly stained in the kidney, liver, and lung tissue of AKI mice. In vitro, IL-19 upregulated MCP-1, TGF-β1, and IL-19, and induced mitochondria-dependent apoptosis in murine renal tubular epithelial M-1 cells. IL-19 upregulated TNF-α and IL-10 in cultured HepG2 cells, and it increased IL-1β and TNF-α expression in cultured A549 cells. In vivo, after renal IRI or a nephrotoxic dose of HgCl₂ treatment, IL-20R1-deficient mice (the deficiency blocks IL-19 signaling) showed lower levels of blood urea nitrogen (BUN) in serum and less tubular damage than did wild-type mice. Therefore, we conclude that IL-19 mediates kidney, liver, and lung tissue damage in murine AKI and that blocking IL-19 signaling may provide a potent therapeutic strategy for treating AKI.     

Macrophage activation state determines the response to rhinovirus infection in a mouse model of allergic asthma

Background

The mechanisms by which viruses cause asthma exacerbations are not precisely known. Previously, we showed that, in ovalbumin (OVA)-sensitized and -challenged mice with allergic airway inflammation, rhinovirus (RV) infection increases type 2 cytokine production from alternatively-activated (M2) airway macrophages, enhancing eosinophilic inflammation and airways hyperresponsiveness. In this paper, we tested the hypothesis that IL-4 signaling determines the state of macrophage activation and pattern of RV-induced exacerbation in mice with allergic airways disease.

Methods

Eight week-old wild type or IL-4 receptor knockout (IL-4R KO) mice were sensitized and challenged with OVA and inoculated with RV1B or sham HeLa cell lysate.

Results

In contrast to OVA-treated wild-type mice with both neutrophilic and eosinophilic airway inflammation, OVA-treated IL-4R KO mice showed increased neutrophilic inflammation with few eosinophils in the airways. Like wild-type mice, IL-4R KO mice showed OVA-induced airway hyperreactivity which was further exacerbated by RV. There was a shift in lung cytokines from a type 2-predominant response to a type 1 response, including production of IL-12p40 and TNF-α. IL-17A was also increased. RV infection of OVA-treated IL-4R KO mice further increased neutrophilic inflammation. Bronchoalveolar macrophages showed an M1 polarization pattern and ex vivo RV infection increased macrophage production of TNF-α, IFN-γ and IL-12p40. Finally, lung cells from OVA-treated IL-4R KO mice showed reduced CD206+ CD301+ M2 macrophages, decreased IL-13 and increased TNF-α and IL-17A production by F4/80+, CD11b+ macrophages.

Conclusions

OVA-treated IL-4R KO mice show neutrophilic airway inflammation constituting a model of allergic, type 1 cytokine-driven neutrophilic asthma. In the absence of IL-4/IL-13 signaling, RV infection of OVA-treated mice increased type 1 cytokine and IL-17A production from conventionally-activated macrophages, augmenting neutrophilic rather than eosinophilic inflammation. In mice with allergic airways inflammation, IL-4R signaling determines macrophage activation state and the response to subsequent RV infection.