Aluminum-based adjuvants (aluminum salts or alum) are widely used in human vaccination, although their mechanisms of action are poorly understood. Here we report that, in mice, alum causes cell death ...and the subsequent release of host cell DNA, which acts as a potent endogenous immunostimulatory signal mediating alum adjuvant activity. Furthermore, we propose that host DNA signaling differentially regulates IgE and IgG1 production after alum-adjuvanted immunization. We suggest that, on the one hand, host DNA induces primary B cell responses, including IgG1 production, through interferon response factor 3 (Irf3)-independent mechanisms. On the other hand, we suggest that host DNA also stimulates 'canonical' T helper type 2 (T(H)2) responses, associated with IgE isotype switching and peripheral effector responses, through Irf3-dependent mechanisms. The finding that host DNA released from dying cells acts as a damage-associated molecular pattern that mediates alum adjuvant activity may increase our understanding of the mechanisms of action of current vaccines and help in the design of new adjuvants.
Background
The aim of this study is to investigate the renoprotective effect of the GLP-1 receptor agonist, liraglutide, in early-phase diabetic kidney disease (DKD) using an animal model of type 2 ...diabetes with several metabolic disorders.
Methods
Male 8-week-old spontaneously diabetic Torii (SDT) fatty rats (
n
= 19) were randomly assigned to three groups. The liraglutide group (
n
= 6) was injected subcutaneously with liraglutide. Another treatment group (
n
= 6) received subcutaneous insulin against hyperglycemia and hydralazine against hypertension for matching blood glucose levels and blood pressure with the liraglutide group. The control groups of SDT fatty (
n
= 7) and non-diabetic Sprague–Dawley rats (
n
= 7) were injected only with a vehicle.
Results
The control group of SDT fatty rats exhibited hyperglycemia, obesity, hypertension, hyperlipidemia, glomerular sclerosis, and tubulointerstitial injury with high urinary albumin and L-FABP levels. Liraglutide treatment reduced body weight, food intake, blood glucose and blood pressure levels, as well as ameliorated renal pathologic findings with lower urinary albumin and L-FABP levels. Liraglutide increased expressions of phosphorylated (p)-eNOS and p-AMPK in glomeruli, downregulated renal expression of p-mTOR, and increased renal expressions of LC3B-II, suggesting activation of autophagy. However, these effects were not caused by the treatments with insulin and hydralazine, despite comparable levels of hyperglycemia and hypertension to those achieved with liraglutide treatment.
Conclusions
Liraglutide may exert a renoprotective effect via prevention of glomerular endothelial abnormality and preservation of autophagy in early-phase DKD, independent of blood glucose, and blood pressure levels.
Agonists for TLR9 and Stimulator of IFN Gene (STING) act as vaccine adjuvants that induce type‐1 immune responses. However, currently available CpG oligodeoxynucleotide (ODN) (K‐type) induces IFNs ...only weakly and STING ligands rather induce type‐2 immune responses, limiting their potential therapeutic applications. Here, we show a potent synergism between TLR9 and STING agonists. Together, they make an effective type‐1 adjuvant and an anticancer agent. The synergistic effect between CpG ODN (K3) and STING‐ligand cyclic GMP–AMP (cGAMP), culminating in NK cell IFN‐γ (type‐II IFN) production, is due to the concurrent effects of IL‐12 and type‐I IFNs, which are differentially regulated by IRF3/7, STING, and MyD88. The combination of CpG ODN with cGAMP is a potent type‐1 adjuvant, capable of inducing strong Th1‐type responses, as demonstrated by enhanced antigen‐specific IgG2c and IFN‐γ production, as well as cytotoxic CD8+ T‐cell responses. In our murine tumor models, intratumoral injection of CpG ODN and cGAMP together reduced tumor size significantly compared with the singular treatments, acting as an antigen‐free anticancer agent. Thus, the combination of CpG ODN and a STING ligand may offer therapeutic application as a potent type‐II IFN inducer.
Particulates such as silica crystal (silica) and aluminum salts (alum) activate the inflammasome and induce the secretion of proinflammatory cytokines in macrophages. These particulates also induce ...the production of immunoglobulin E via a T helper 2 (Th2) cell-associated mechanism. However, the mechanism involved in the induction of type 2 immunity has not been elucidated. Here, we showed that silica and alum induced lipopolysaccharide-primed macrophages to produce the lipid mediator prostaglandin E
2 (PGE
2) and interleukin-1β (IL-1β). Macrophages deficient in the inflammasome components caspase 1, NALP3, and ASC revealed that PGE
2 production was independent of the NALP3 inflammasome. PGE
2 expression was markedly reduced in PGE synthase-deficient (
Ptges
−/−) macrophages, and
Ptges
−/−mice displayed reduced antigen-specific serum IgE concentrations after immunization with alum or silica. Our results indicate that silica and alum regulate the production of PGE
2 and that the induction of PGE
2 by particulates controls the immune response in vivo.
► Silica and alum induced Mϕs to produce PGE
2 ► The inflammasome was not involved in silica- and alum-induced PGE
2 production ► Silica- and alum-induced PGE
2 regulate IgE production in vivo ► Lysosomal damage triggered PGE
2 production via the activation of Syk and p38
We investigate whether suppressing the activation of the angiotensin II type 1a receptor (AT1a) can ameliorate severe chronic tubulointerstitial damage (TID) after renal ischemia reperfusion (IR) ...using AT1a knockout homozygous (AT1a
) male mice. To induce severe chronic TID after renal IR, unilateral renal ischemia was performed via clamping of the right renal pedicle in both AT1a
and wild-type (AT1a
) mice for 45 min. While marked renal atrophy and severe TID at 70 days postischemia was induced in the AT1a
mice, such a development was not provoked in the AT1a
mice. Although the AT1a
mice were administered hydralazine to maintain the same systolic blood pressure (SBP) levels as the AT1a
mice with lower SBP levels, hydralazine did not reproduce the renoprotective effects observed in the AT1a
mice. Acute tubular injury at 3 days postischemia was similar between the AT1a
mice and the AT1a
mice. From our investigations using IR kidneys at 3, 14, and 28 days postischemia, the multiple molecular mechanisms may be related to prevention of severe chronic TID postischemia in the AT1a
mice. In conclusion, inactivation of the AT1 receptor may be useful in preventing the transition of acute kidney injury to chronic kidney disease.
Liver-type fatty acid-binding protein (L-FABP) is a biomarker for the early detection of renal diseases in humans. L-FABP is a cytotoxic oxidation product secreted from the proximal tubules under ...ischemic and oxidative stress conditions. First, L-FABP gene expression in the kidney and liver was evaluated. Next, the urinary L-FABP concentrations in dogs with or without renal diseases were measured using a novel enzyme-linked immunosorbent assay kit. Urinary L-FABP was normalized relative to urinary creatinine (uCre) concentrations (µg/g uCre). Finally, the relationships between urinary L-FABP and renal biomarkers used in canine medicine or serum alanine transaminase (ALT) as an indicator of liver damage were examined. Serum and urine samples from 94 client-owned dogs including 23 dogs with renal diseases and 71 dogs without renal diseases were used for analysis. Relative L-FABP gene expression was confirmed both in the liver and kidney. Dogs with renal diseases had a significantly higher urinary L-FABP than those without, and its predictive cutoff value was 26 µg/g uCre. Urinary L-FABP was significantly correlated with serum creatinine (r=0.4674, P<0.01), urea nitrogen (r=0.4907, P<0.01), urine specific gravity (r=−0.5100, P<0.01), and urine protein/creatinine ratio (r=0.7216, P<0.01), but not with serum ALT. Hence, dogs with a high urinary L-FABP value were more likely to have renal diseases.
Type 2 diabetes mellitus represents an international health concern with its growing number of patients worldwide. At the same time, excessive salt consumption is also seen as a major cause of ...diseases such as hypertension and may expedite renal complications in diabetic patients. In this study, we investigated the effects of excessive sodium chloride supplementation on the kidney of the Spontaneously Diabetic Torii-Leprfa (SDT fatty) rat, an obese type 2 diabetes model. Male and female SDT fatty rats and normal Sprague-Dawley (SD) rats at 5 weeks of age were loaded with 0.3% sodium chloride (NaCl) in drinking water for 13 weeks. Blood serum and urinary parameters were observed throughout the experiment and kidney samples were examined in histopathological and genetical analyses. Significant changes on the body weight, blood pressure, urine volume, creatinine clearance, blood urea nitrogen (BUN), relative gene expressions of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), monocyte chemotactic protein-1 (MCP-1) and transforming growth factor-β (TGF-β) were observed in the salt-loaded male SDT fatty rats. Urinary L-type fatty acid-binding protein (L-FABP) and albumin levels were higher observed in the salt-loaded male SDT fatty rats throughout the period, but urinary albumin levels in the female SDT fatty rats remain unchanged. In the kidney, slight Armani-Ebstein changes, tubular degeneration, hyaline cast, and inflammatory cell infiltration were observed in female SDT fatty rats while the levels of some changes were higher in the salt-loaded group. The kidney of the salt-loaded male SDT fatty rats demonstrated a higher degree of lesions compared to the female group and the male unloaded group. Histopathological changes in salt-loaded SDT fatty rats show that excessive salt consumption may act as a diabetic pathology exacerbation factor, but the pathology may be influenced by gender difference. Urinary L-FABP levels may act as a useful biomarker to detect slight tubular damages in the kidney. Excessive salt loading was shown to exacerbate the renal injury in SDT fatty rats.
This study investigated the effect of liraglutide, a glucagon-like peptide-1 receptor agonist, on skeletal muscles in rats with type 2 diabetes. Male SDT fatty rats (8-week-old) were provided ...liraglutide, or insulin-hydralazine for 8 weeks; control SDT fatty rats and SD rats were administered a vehicle. At 16 weeks of age, muscle strength of limbs was significantly lower in all SDT fatty rats compared to SD rats. While cross-sectional areas of type IIb muscle fibers in extensor digitorum longus muscle were significantly lower in SDT fatty rats than in SD rats, those of type I muscle fibers in soleus were similar in all rats. In the soleus of SDT fatty rats, liraglutide led to greater citrate synthase activity and cytochrome c oxidase subunit 5 B protein expression, independently of blood glucose and blood pressure levels. Liraglutide may contribute to preservation of mitochondrial content on soleus muscle in type 2 diabetes.
•Liraglutide increased citrate synthase activity on soleus muscle in SDT fatty rats.•Liraglutide upregulated Cox5B protein expression on soleus muscle in SDT fatty rats.•Liraglutide did not provide beneficial effects on EDL muscle in SDT fatty rats.•Liraglutide may preserve mitochondrial content on soleus muscle in type 2 diabetes.
The study aim was to determine if suppressed activation of angiotensin II type 1 receptor (AT1) prevents severe muscle atrophy after denervation. The sciatic nerves in right and left inferior limbs ...were cut in AT1a knockout homo (AT1a
) male mice and wild-type (AT1a
) male mice. Muscle weight and cross-sectional areas of type IIb muscle fibers in gastrocnemius muscle decreased at 7 and 21 days postdenervation in both AT1a
mice and AT1a
mice, and the reduction was significantly attenuated in the denervated muscles of AT1a
mice compared to the AT1a
mice. Gene expressions in the protein degradation system two E3 ubiquitin ligases (muscle RING-finger protein-1 and Atrogin-1) upregulated at 7 days postdenervation in all denervated mice were significantly lower in AT1a
mice than in AT1a
mice. Activations of nuclear factor κB and Forkhead box subgroup O1, and protein expression of monocyte chemoattractant protein-1 were significantly suppressed in the AT1a
mice compared with those in the AT1a
mice. In addition, suppressed apoptosis, lower infiltration of M1 macrophages, and higher infiltration of M2 macrophages were significantly observed at 21 days postdenervation in the AT1a
mice compared with those in the AT1a
mice. In conclusion, the AT1 receptor deficiency retarded muscle atrophy after denervation.
Background
Liver‐type fatty acid‐binding protein (L‐FABP) is a biomarker for early detection of renal disease in humans. Liver‐type fatty acid‐binding protein is cytotoxic oxidation products secreted ...from proximal tubules under ischemia and oxidative stress.
Objective
To examine renal expression and quantify urinary excretion of L‐FABP in catswith renal disease.
Animals
One hundred and thirty‐four client‐owned cats including 34 cats with serum creatinine (sCre) values >1.6 mg/dL and 10 other cats that died in clinics.
Methods
Tissue expressions of L‐FABP were examined by reverse transcription polymerase chain reaction and Western blotting. Urinary L‐FABP (uL‐FABP) and serum L‐FABP (sL‐FABP) levels were determined by enzyme‐linked immunosorbent assay. Anti‐liver‐type fatty acid‐binding protein antibody immunostained renal sections.
Results
Feline kidneys express L‐FABP. Strong L‐FABP signals were observed in the lumens of proximal tubular cells in 5 cats with high uL‐FABP excretion, but not in 5 cats with low uL‐FABP excretion. In 9 normal cats, uL‐FABP index was <1.2 μg/g urinary creatinine (uCre). High uL‐FABP indexes (>10.0 μg/g uCre) were detected in 7 of 100 cats with low sCre (<1.6 mg/dL) and 18 of 44 cats with high sCre (>1.6 mg/dL). There was a weak correlation between L‐FABP index and sCre, serum symmetric dimethylarginine (SDMA), or blood urea nitrogen (BUN), and these correlation coefficients were increased by analyzing only data of cats with sCre >1.6 mg/dL. There was a weak correlation between u L‐FABP index and sL‐FABP in all tested cats, but not in cats with high sCre.
Conclusions and Clinical Importance
This study demonstrates correlations between L‐FABP and current renal biomarkers for chronic kidney disease in cats, such as sCre and SDMA. Liver‐type fatty acid‐binding protein may be a potential biomarker to predict early pathophysiological events in feline kidneys.
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