Upregulation of allograft inflammatory factor‑1 expression and secretion by macrophages stimulated with aldosterone promotes renal fibroblasts to a profibrotic phenotype

Macrophages have been identified as a key cell type in the pathogenesis of renal interstitial fibrosis (RIF). However, the mechanism through which macrophages drive fibrosis remains unclear. The current study focuses on the effects and possible underlying mechanism of allograft inflammatory factor-1 (AIF-1), an inflammation-responsive scaffold protein expressed and secreted by macrophages, in promoting fibroblasts to a profibrotic phenotype. In vivo experiments indicated that AIF-1, CD68 and α-smooth muscle actin (α-SMA) were upregulated in kidney tissues of mice subjected to unilateral ureteric obstruction, while their expressions were inhibited by an aldosterone receptor antagonist, spironolactone. Double immunofluorescence staining revealed that AIF-1 expression co-localized with CD68-positive macrophages in the renal interstitium, indicating that AIF-1 expression in macrophages was increased in the RIF animal model. Furthermore, to identify the role of AIF-1 in promoting fibrosis, its expression and secretion by the RAW264.7 macrophage cell line were detected in vitro. The expression levels of α-SMA, phosphorylated p38 (p-p38) and fibronectin (FN) in fibroblasts were examined subsequent to co-culture with macrophages. The increase in AIF-1 expression and secretion was confirmed in RAW264.7 cells in response to aldosterone. After 72 h of co-culture between fibroblasts and macrophages stimulated with aldosterone, the α-SMA expression was induced in fibroblasts, with significantly increased expression levels of FN and p-p38 observed. In addition, AIF-1 expression was reduced by stable transfection of RAW264.7 cells with AIF-1 small interfering RNA, resulting in significantly reduced expression levels of α-SMA, p-p38 and FN in fibroblasts co-cultured with macrophages as compared with normal macrophages. These findings indicate that the expression of AIF-1 in macrophages is critical for the activation of renal fibroblasts to a profibrotic phenotype. AIF-1 expression was upregulated in macrophages, and may be a novel mechanism linking macrophages to the promotion of RIF via the p38 signaling pathway.

Extract of Clinopodium bolivianum protects against E. coli invasion of uroepithelial cells

ETHNOPHARMACOLOGICAL RELEVANCE

Clinopodium bolivianum is a South American plant with anti-inflammatory and anti-infective activities. The increasing antibiotic resistance urges for alternative therapy. Based on its use in traditional medicine, we investigated the effect of C. bolivianum on the ability to defend bladder epithelial cells from E. coli infection.

MATERIALS AND METHODS

The extract was analyzed by LC-MS. Bladder epithelial cell lines T24 and 5637 and uropathogenic E. coli No. 12, its isogenic mutant WE16 csgBA bscA::Cm and CFT073 were used to investigate the effect of C. bolivianum on uroepithelial infection. Bacterial adherence and invasion to cells treated with C. bolivianum were analyzed. Expression of uroplakin 1a, β1 integrin, caveolin-1, IL-8 and antimicrobial peptides in response to C. bolivianum treatment was assessed using RT-PCR. Protein expression was confirmed by Western blot analysis or ELISA. The antimicrobial effects of C. bolivianum on bacteria and fungus were investigated using minimum inhibitory concentration. Furthermore, the formation of biofilm was investigated with crystal violet assay.

RESULTS

C. bolivianum extract consisted of more than 70 different types of phytochemicals including sugars and phenolic compounds. The extract decreased the uroplakin 1a expression and E. coli adhesion and invasion of uroepithelial cells while up-regulated caveolin-1. In uninfected C. bolivianum treated cells, IL-8 was lower than in non-treated cells. In infected cells, however, no difference was observed between treated and non-treated cells. Further, C. bolivianum treatment reduced uropathogenic E. coli (UPEC) biofilms but did not inhibit bacterial growth.

CONCLUSIONS

Our results show that C. bolivianum has a protective role on bladder epithelial cells against UPEC infection by decreasing the bacterial adhesion, invasion and biofilm formation.

allograft inflammatory factor 1 functions as a pro-inflammatory cytokine in the oyster, Crassostrea ariakensis

The oyster Crassostrea ariakensis is an economically important bivalve species in China, unfortunately it has suffered severe mortalities in recent years caused by rickettsia-like organism (RLO) infection. Prevention and control of this disease is a priority for the development of oyster aquaculture. Allograft inflammatory factor-1 (AIF-1) was identified as a modulator of the immune response during macrophage activation and a key gene in host immune defense reaction and inflammatory response. Therefore we investigated the functions of C. ariakensis AIF-1 (Ca-AIF1) and its antibody (anti-CaAIF1) in oyster RLO/LPS-induced disease and inflammation. Ca-AIF1 encodes a 149 amino acid protein containing two typical Ca2+ binding EF-hand motifs and shares a 48-95% amino acid sequence identity with other animal AIF-1s. Tissue-specific expression analysis indicates that Ca-AIF1 is highly expressed in hemocytes. Significant and continuous up-regulation of Ca-AIF1 is detected when hemocytes are stimulated with RLO/LPS (RLO or LPS). Treatment with recombinant Ca-AIF1 protein significantly up-regulates the expression levels of LITAF, MyD88 and TGFβ. When anti-CaAIF1 antibody is added to RLO/LPS-challenged hemocyte monolayers, a significant reduction of RLO/LPS-induced LITAF is observed at 1.5-12 h after treatment, suggesting that interference with Ca-AIF1 can suppress the inflammatory response. Furthermore, flow cytometric analysis indicated that anti-CaAIF1 administration reduces RLO/LPS-induced apoptosis and necrosis rates of hemocytes. Collectively these findings suggest that Ca-AIF1 functions as a pro-inflammatory cytokine in the oyster immune response and is a potential target for controlling RLO infection and LPS-induced inflammation.

Allograft inflammatory factor 1 (AIF-1) is a new human adipokine involved in adipose inflammation in obese women

BACKGROUND

Allograft inflammatory factor 1 (AIF-1) is a putative obesity gene. Our aim was to examine the expression of AIF-1 in human white adipose tissue (WAT) in relation to obesity and metabolic phenotypes in women.

METHODS

WAT secretion of AIF-1 was determined in subcutaneous adipose tissue pieces in vitro by ELISA from 5 subjects. mRNA expression of AIF-1 was determined by RT-qPCR in the isolated cell fractions of adipose tissue (n = 5-6 per group), in subcutaneous and visceral WAT pieces from non-obese (n = 12) and obese women (n = 23), and in some subcutaneous WAT also before and after weight reduction (n = 10). Finally, adipose AIF-1 mRNA was related to metabolic phenotypes in 96 subjects with a wide range of BMI.

RESULTS

AIF-1 was secreted in a time dependent fashion from WAT. The major source of AIF-1 was WAT resident macrophages. Expression of AIF-1 was similar in visceral and subcutaneous WAT and was two-fold increased in obese women (P < 0.01). AIF-1 mRNA expression levels were normalized after weight reduction (P < 0.01). Expression of AIF-1 was inversely correlated with insulin sensitivity as assessed by insulin tolerance test (KITT), and circulating levels of adiponectin (P = 0.02), and positively correlated with insulin resistance as estimated by HOMA (=0.0042).

CONCLUSIONS

AIF-1 is a novel adipokine produced mainly by macrophages within human WAT. Its expression is increased in obese women and associates with unfavourable metabolic phenotypes. AIF-1 may play a paracrine role in the regulation of WAT function through cross-talk between macrophages and other cell types within the adipose tissue.

Proteomic profiling for peritoneal dialysate: differential protein expression in diabetes mellitus

Peritoneal dialysis (PD) is an increasingly accepted modality of renal replacement therapy. It provides the advantages of having a flexible lifestyle, stable hemodynamics, and better preservation of residual renal function. To enhance our understanding of the peritoneal dialysate of diabetes mellitus (DM), peritoneal dialysate proteins were identified by two-dimensional gel electrophoresis (2DE) combined with reverse-phase nano-ultra performance liquid chromatography electrospray ionization tandem mass spectrometry (RP-nano-UPLC-ESI-MS/MS) followed by peptide fragmentation patterning. To validate the differential proteins, ELISA and Western blotting analyses were applied to detect candidate proteins that may be related to DM. We performed 2DE on the peritoneal dialysate samples, with detection of more than 300 spots. From this, 13 spots were excised, in-gel digested, and identified by RP-nano-UPLC-ESI-MS/MS. Ten of these showed significant differential expression between the DM and chronic glomerulonephritis (CGN) peritoneal dialysate samples. In this study, we conducted a comparative proteomic study on these two groups of dialysate that may provide evidence for understanding the different peritoneal protein changes. These proteins may not be new biomarkers; however, they may indicate a situation for possible drug treatment and can be the predictors of peritonitis for a validation study in the future.

Comparative proteomic analysis of peritoneal dialysate from chronic glomerulonephritis patients

Peritoneal dialysis (PD) frequently contributes to peritoneal damage which cannot be easily identified without invasive techniques, implying the urgent need for biomarkers and revealing mechanisms. Chronic glomerulonephritis (CGN) is one of the leading causes of receiving dialysis treatment. Here, we attempted to analyze the peritoneal dialysate collected from CGN patients when they receive continuous ambulatory peritoneal dialysis (CAPD) treatment for the first time and after a year to reveal the protein changes that resulted from PD. Proteins were displayed by two-dimensional gel electrophoresis (2DE). Altered gel spots were digested followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis for protein identification. Eight proteins were found to have differential expression levels between two groups. Their differential expressions were validated by Western blots in other sets of peritoneal dialysates. Proteins identified with higher levels in the first-time dialysate suggested their dominant appearance in CGN patients, while those that showed higher levels in peritoneal dialysate collected after one year may result from initial peritoneal inflammation or changes in the permeability of the peritoneum to middle-sized proteins. All the identified proteins may provide a perceptiveness of peritoneal changes caused by PD and may function as potential biomarkers or drug targets.

Differential proteomic characterization between normal peritoneal fluid and diabetic peritoneal dialysate

BACKGROUND

Since the mechanism of comorbidity and mortality in peritoneal dialysis is unclear, a comparison of peritoneal dialysate and normal peritoneal fluid may provide clues to the biological and pathological processes involved in peritoneal damage.

METHODS

Peritoneal dialysate and control samples were collected from five diabetes mellitus (DM) patients and two patients receiving laparoscopic cholecystectomy. Proteins were separated by two-dimensional gel electrophoresis (2D-GE). After image analysis, altered gel spots between these two sample groups were subjected to tryptic digestion and mass spectrometry analysis. The results were searched against the NCBI database.

RESULTS

A total of 26 protein spots were considered altered in 2D-GE between the two sample groups. After western blotting confirmation, vitamin D-binding protein, haptoglobin and alpha-2-microglobulin were at higher levels in the DM samples, while complement C4-A and IGK@ protein were at lower levels compared to the control samples.

CONCLUSION

The loss of vitamin D-binding protein, haptoglobin and alpha-2-microglobulin may be due to a change in the permeability of the peritoneal membrane to middle-sized proteins or leakage from peritoneal inflammation. Lower levels of complement C4-A in dialysate may shed light on the beginning of peritoneal membrane scleroses.

Preparation and Identification of Monoclonal Antibodies Against Daintain

Daintain is a 17-kDa polypeptide originally purified from porcine intestine. This polypeptide is associated with insulin secretion and inflammatory responses. Daintain is highly similar in amino acid sequence to allograft inflammatory factor-1 (AIF-1). Here we report the preparation and identification of monoclonal antibodies (MAbs) against daintain. To enhance its immunogenicity, daintain was coupled to carrier protein bovine serum albumin (BSA) by a two-step glutaraldehyde method. Using conventional procedures, we obtained four stable hybridoma cell lines that can produce and secret anti-daintain MAbs. We further analyzed their isotypes, titer, and affinity, and found that those MAbs belong to the G1 subclass with kappa light chains. The MAbs were capable of recognizing daintain as determined by Western blotting. The produced MAbs will be a useful tool for further investigation of daintain functions in organisms.