Allograft inflammatory factor-1 in the pathogenesis of bleomycin-induced acute lung injury

Type I/II Immune Balance Contributes to the Protective Effect of AIF-1 on Hepatic Immunopathology Induced by Schistosoma japonicum in a Transgenic Mouse Model

Schistosomiasis is the second most debilitating neglected tropical disease in the world. Liver egg granuloma and fibrosis are the main damage of schistosomiasis. In this study, the role of allograft inflammatory factor-1 (AIF-1) in liver pathology and its regulation in immune responses were investigated in a transgenic mouse infected with Schistosoma japonicum. We found that AIF-1 overexpression reduced worm burden and decreased egg granuloma sizes and serum alanine aminotransferase levels, along with inhibited hepatic collagen deposition and serum hydroxyproline levels during S. japonicum infection. Moreover, AIF-1 overexpression resulted in an increased ratio of Th1/Th2, increased levels of IFN-γ and T-bet, and lower levels of GATA-3 in the spleen, accompanied by increased M1 percentages, decreased M2 percentages, and thus a higher ratio of M1/M2 in the peritoneal cavity and liver. AIF-1 induced CD68 and iNOS mRNA expression and protein levels of cytoplasmic p-P38 and nuclear NF-κB, along with enhanced levels of TNF-α and TGF-β in macrophages in vitro. Moreover, the hepatic pathology had a negative correlation with Th1/Th2 and M1/M2 ratios in the infected mice. The findings reveal that the beneficial role of AIF-1 in alleviating hepatic damage is related to restoring type I/II immune balance in S. japonicum infection.

CG223, a novel BET inhibitor, exerts TGF-β1-mediated antifibrotic effects in a murine model of bleomycin-induced pulmonary fibrosis

Pulmonary fibrosis is a progressive disease with poor prognosis and limited therapeutic options. In this study, we evaluated the potential therapeutic effects of CG223, a novel inhibitor of bromodomain and extra-terminal motif (BET) proteins, on pulmonary fibrosis by focusing on the transforming growth factor-β1 (TGF-β1) pathway. In a murine model of bleomycin-induced pulmonary fibrosis, CG223 attenuated fibrosis while reducing the infiltration of inflammatory cells into the lungs. Fibroblasts expressing BRD4, a member of the BET protein family, were enriched in the tissue regions corresponding to bleomycin-induced fibrotic lesions. Additionally, pulmonary fibroblasts isolated from bleomycin-instilled mice showed a significantly increased association of BRD4 with the promoters of two pro-fibrotic genes linked to the entry into the TGF-β1 autocrine/paracrine loop, thrombospondin 1 (Thbs1) and integrin β3 (Itgb3), as well as with the promoter of a myofibroblast marker gene, actin alpha 2 (Acta2). Subsequent in vitro studies with murine primary lung fibroblasts showed that the mRNA induction of Thbs1, Itgb3, and Acta2 by TGF-β1 can be inhibited by CG223 in a dose-dependent manner. Taken together, CG223-induced BRD4 inhibition suppressed lung fibrogenesis by affecting multiple genes, including those involved in the triggering of the TGF-β1 autocrine/paracrine loop.

Acetylcholine Regulates Pulmonary Pathology During Viral Infection and Recovery

Introduction

This study was designed to explore the role of acetylcholine (ACh) in pulmonary viral infection and recovery. Inflammatory control is critical to recovery from respiratory viral infection. ACh secreted from non-neuronal sources, including lymphocytes, plays an important, albeit underappreciated, role in regulating immune-mediated inflammation.

Methods

ACh and lymphocyte cholinergic status in the lungs were measured over the course of influenza infection and recovery. The role of ACh was examined by inhibiting ACh synthesis in vivo. Pulmonary inflammation was monitored by Iba1 immunofluorescence, using a novel automated algorithm. Tissue repair was monitored histologically.

Results

Pulmonary ACh remained constant through the early stage of infection and increased during the peak of the acquired immune response. As the concentration of ACh increased, cholinergic lymphocytes appeared in the BAL and lungs. Cholinergic capacity was found primarily in CD4 T cells, but also in B cells and CD8 T cells. The cholinergic CD4⁺ T cells bound to influenza-specific tetramers and were retained in the resident memory regions of the lung up to 2 months after infection. Histologically, cholinergic lymphocytes were found in direct physical contact with activated macrophages throughout the lung. Inflammation was monitored by ionized calcium-binding adapter molecule 1 (Iba1) immunofluorescence, using a novel automated algorithm. When ACh production was inhibited, mice exhibited increased tissue inflammation and delayed recovery. Histologic examination revealed abnormal tissue repair when ACh was limited.

Conclusion

These findings point to a previously unrecognized role for ACh in the transition from active immunity to recovery and pulmonary repair following respiratory viral infection.

Studying the effects of sea cucumber ovum powder on nonalcoholic fatty liver disease by proteomics techniques in a rat model

Sea cucumber is a valuable marine food that has antioxidant, anti-diabetic, and anti-obesity functionalities. Sea cucumber ovum (SCO) may contain functional components, however, it is considered to be a waste product during industrial processing. In order to make good use of SCO, this work investigated the effects of freeze-dried SCO powder on NAFLD, using a rat model, through iBT labeling proteomics techniques, tracking changes in the hepatic protein profiles of rats whose diets were supplemented with SCO powder. Male rats were fed with standard food, a high fat diet (HFD), or a HFD supplemented with 150 mg per kg BW or 450 mg per kg BW SCO powder for 6 weeks. Compared with the HFD, low-dose SCO supplementation in the diet could significantly reduce body weight gain and liver weight. Furthermore, in total, 5922 proteins were identified, and 767 proteins were found to be significantly different proteins (p < 0.05) among all four groups. Most of the significantly different proteins were related to apoptosis and lipid metabolism. Fadd, Dci, and Aif1 have been identified as key proteins in the pathways related to apoptosis, lipid metabolism, and inflammation. The results in this study provide an overview of the SCO-induced changes in the liver proteome of NAFLD, which may help us to understand the molecular mechanism behind the effects of SCO on the alleviation of NAFLD.

Involvement of the myeloid cell compartment in fibrogenesis and systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune fibrotic disease of unknown aetiology that is characterized by vascular changes in the skin and visceral organs. Autologous haematopoietic stem cell transplantation can improve skin and organ fibrosis in patients with progressive disease and a high risk of organ failure, indicating that cells originating in the bone marrow are important contributors to the pathogenesis of SSc. Animal studies also indicate a pivotal function of myeloid cells in the development of fibrosis leading to changes in the tissue architecture and dysfunction in multiple organs such as the heart, lungs, liver and kidney. In this Review, we summarize current knowledge about the function of myeloid cells in fibrogenesis that occurs in patients with SSc. Targeted therapies currently in clinical studies for SSc might affect myeloid cell-related pathways. Therefore, myeloid cells might be used as cellular biomarkers of disease through the application of high-dimensional techniques such as mass cytometry and single-cell RNA sequencing.

AIF1 was identified as an up-regulated gene contributing to CSFV Shimen infection in porcine alveolar macrophage 3D4/21 cells

Classical swine fever (CSF) is a disease that is characterized by diffuse hemorrhaging, high fever, and high mortality rates. The pro-inflammatory characteristics of allograft inflammatory factor 1 (AIF1) have been well documented; however, insufficient attention has been given to porcine AIF1. In the present study, AIF1 was identified as a key player contributing to CSFV Shimen infection in porcine alveolar macrophage (PAM) 3D4/21 cell line. Our evaluation showed that AIF1 mRNA and protein are expressed at a time-dependent high level in CSFV Shimen-infected PAM 3D4/21 cells. The transcription and translation of IL6 were also significantly upregulated in infected PAM 3D4/21 cells. By utilizing overexpression RNAs approach, we showed that the cellular AIF1 induced an increased IL6 in PAM 3D4/21 cells. Furthermore, silencing of AIF1 suppressed CSFV Shimen-induced IL6 production in PAM 3D4/21 cells and also inhibited CSFV replication, whereas overexpression of recombinant AIF1 was beneficial for the replication of CSFV Shimen and promoting IL6 production in CSFV Shimen-infected PAM 3D4/21 cells. It is suggested CSFV Shimen induced IL6 in PAM 3D4/21 cells via AIF1 activation, which help clarify the AIF1-related inflammatory processes that occur on CSFV Shimen infected macrophages.

Stimulator of interferon genes (STING) activation exacerbates experimental colitis in mice

Detection of cytoplasmic DNA by the host’s innate immune system is essential for microbial and endogenous pathogen recognition. In mammalian cells, an important sensor is the stimulator of interferon genes (STING) protein, which upon activation by bacterially-derived cyclic dinucleotides (cDNs) or cytosolic dsDNA (dsDNA), triggers type I interferons and pro-inflammatory cytokine production. Given the abundance of bacterially-derived cDNs in the gut, we determined whether STING deletion, or stimulation, acts to modulate the severity of intestinal inflammation in the dextran sodium sulphate (DSS) model of colitis. DSS was administered to Tmem173^gt (STING-mutant) mice and to wild-type mice co-treated with DSS and a STING agonist. Colitis severity was markedly reduced in the DSS-treated Tmem173^gt mice and greatly exacerbated in wild-type mice co-treated with the STING agonist. STING expression levels were also assessed in colonic tissues, murine bone marrow derived macrophages (BMDMs), and human THP-1 cells. M1 and M2 polarized THP-1 and murine BMDMs were also stimulated with STING agonists and ligands to assess their responses. STING expression was increased in both murine and human M1 polarized macrophages and a STING agonist repolarized M2 macrophages towards an M1-like subtype. Our results suggest that STING is involved in the host’s response to acutely-induced colitis.

Functional Identification of Allograft Inflammatory Factor 1-Like Gene in Luning Chicken

Allograft inflammatory factor-1 (AIF-1) is an inflammation-related protein mainly produced by immune cells, such as monocyte/macrophages and activated T lymphocytes. It is essential for the survival and proinflammatory activity of immune cells. However, the function of AIF-1 in chicken still has not been defined. In the present study, AIF-1-like (AIF1L) gene was identified in Luning chicken. Bioinformatics analysis revealed that the molecular weight of the chicken AIF-1 protein was 16290.8 Da. AIF1L contained a Ca²⁺ binding EF hand and could interact with actin filament. Its transcript was found in all tested tissues including spleen, brain, heart, kidney, liver, thymus, bursa of Fabricius, lung, and a relative low-level expression was detected in leg muscle. Furthermore, AIF1L expression in peripheral blood lymphocyte was depressed in a dose-dependent manner with cadmium exposure and peripheral blood lymphocyte viability decrease displayed a similar pattern with AIF1L expression. The results indicated that newly identified chicken AIF1L might be associated with lymphocyte viability.

Increased AIF-1-mediated TNF-α expression during implantation phase in IVF cycles with GnRH antagonist protocol

STUDY QUESTION

Is allograft inflammatory factor-1 (AIF-1), a cytokine associated with inflammation and allograft rejection, aberrantly elevated in in vitro fertilization (IVF) cycles with gonadotropin-releasing hormone (GnRH) antagonist protocol with potential effects on endometrial receptivity?

SUMMARY ANSWER

Our findings indicated AIF-1 is increased in IVF cycles with GnRH antagonist protocol and mediates greater TNF-α expression during implantation phase, which may be unfavorable for embryo implantation.

WHAT IS KNOWN ALREADY

Studies have shown that GnRH antagonist protocol cycles have lower implantation and clinical pregnancy rates than GnRH agonist long protocol cycles. Endometrial receptivity but not embryo quality is a key factor contributing to this phenomenon; however, the mechanism is still unknown.

STUDY DESIGN, SIZE, DURATION

Implantation and pregnancy rates were studied in 238 patients undergoing their first cycle of IVF/ICSI between 2012 and 2014. Forty of these patients opted to have no fresh embryo replacement and were divided into two equal groups: (i) GnRH antagonist protocol and (ii) GnRH agonist long protocol, group 3 included 20 infertile women with a tubal factor in untreated cycles. During the same interval, endometrial tissues were taken from 18 infertile women with a tubal factor in the early proliferative phase, late proliferative phase, and mid-secretory phase of the menstrual cycle (n = 6/group).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Microarray analysis, RT-qPCR, Western blot analysis, immunohistochemistry were used to investigate the expression levels of AIF-1 and the related cytokines (TNF-α, IL1β, IL1RA, IL6, IL12, IL15 and IL18). The effect of AIF-1 on uterine receptivity was modeled using in vitro adhesion experiments (coculture of JAR cells and Ishikawa cells).

MAIN RESULTS AND THE ROLE OF CHANCE

The expression of AIF-1 was the highest in early proliferative phase, decreasing thereafter in the late proliferative phase, and almost disappearing in the mid-secretory phase, indicating that low AIF-1 expression might be important for embryo implantation during implantation phase. Microarray results revealed that AIF-1 was upregulated in the antagonist group compared with the control group (fold change [FC] = 3.75) and the agonist (FC = 2.20) group. The raw microarray data and complete gene expression table were uploaded to GEO under the accession number of GSE107914. Both the mRNA and protein expression levels of AIF-1 and TNF-α were the higher in the antagonist group than in the other two groups (P < 0.05) which did not differ significantly (P > 0.05). The protein levels of TNF-α in both Ishikawa cells and primary endometrial cells were significantly increased (P < 0.05) at 96 h after transfection with the AIF-1 expression vector, indicating that TNF-α was mediated by AIF-1 in endometrial cells. Overexpression of AIF-1 in Ishikawa cells inhibited adhesion of JAR cells to them. Thus, increased AIF-1 might inhibit adhesion during implantation via raised TNF-α.

LIMITATIONS REASONS FOR CAUTION

The sample size of the microarray was small, which might weaken the accuracy of our results; however, the sample size of RT-qPCR and the Western blotting assays were sufficient to compensate for this deficiency in our study. In addition, the aberrant AIF-1 and thus TNF-α expression is one of many factors that may contribute to limiting implantation success. Therefore, further extensive in vitro mechanistic and in vivo animal studies are needed to assess the actual functional impact of this pathway.

WIDER IMPLICATIONS OF THE FINDINGS

Anti-TNF-α therapy might mitigate the adverse effects of GnRH antagonist on endometrial receptivity and improve the implantation rate in GnRH antagonist protocols in IVF.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by grants from the National Natural Science Foundation of China, Grant numbers 81771656 and 81370763; Clinical research special fund of Chinese Medical Association, Grant number 16020480664; Shanghai Jiao Tong University Medicine-Engineering Fund, Grant number YG2017ZD11 and YG2017MS57; and the Merck-Serono China Research Fund for Fertility Agreement. P.C.K.L. is supported by a Canadian Institutes of Health Research Foundation Scheme Grant 143317. None of the authors has any competing interests.

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.

Role of allograft inflammatory factor-1 in bleomycin-induced lung fibrosis

Allograft inflammatory factor-1 (AIF-1) is a protein expressed by macrophages infiltrating the area around the coronary arteries in a rat ectopic cardiac allograft model. We previously reported that AIF-1 is associated with the pathogenesis of rheumatoid arthritis and skin fibrosis in sclerodermatous graft-versus-host disease mice. Here, we used an animal model of bleomycin-induced lung fibrosis to analyze the expression of AIF-1 and examine its function in lung fibrosis. The results showed that AIF-1 was expressed on lung tissues, specifically macrophages, from mice with bleomycin-induced lung fibrosis. Recombinant AIF-1 increased the production of TGF-β which plays crucial roles in the mechanism of fibrosis by mouse macrophage cell line RAW264.7. Recombinant AIF-1 also increased both the proliferation and migration of lung fibroblasts compared with control group. These results suggest that AIF-1 plays an important role in the mechanism underlying lung fibrosis, and may provide an attractive new therapeutic target.

Roles of high-mobility group box 1 and thrombin in murine pulmonary fibrosis and the therapeutic potential of thrombomodulin

Cross talk between inflammation and coagulation plays important roles in acute or subacute progressive pulmonary fibrosis characterized by diffuse alveolar damage. Thrombomodulin is a physiological inhibitor of high-mobility group box 1 (HMGB1), and thrombin and may be effective for this condition. This study investigated the roles of HMGB1 and thrombin in the pathophysiology of bleomycin-induced pulmonary fibrosis and the efficacy of recombinant human soluble thrombomodulin (rhTM). Pulmonary fibrosis was induced in wild-type C57BL/6 mice by intratracheal instillation of bleomycin. We first assessed HMGB1, thrombin, transforming growth factor (TGF)-β1, and α-smooth muscle actin (SMA) levels in bronchoalveolar lavage fluid and lung tissue sections over time. Expression of HMGB1 and thrombin was elevated before that of TGF-β1 and α-SMA and remained high during the fibrotic phase after bleomycin instillation. We next examined whether in vitro stimulation with HMGB1 and thrombin induced expression of TGF-β1 and α-SMA in cultured alveolar macrophages and lung fibroblasts, respectively, by performing quantitative PCR, enzyme-linked immunosorbent assay, Western blot, and immunofluorescence analyses. HMGB1 and thrombin stimulation induced TGF-β1 production by alveolar macrophages, and thrombin stimulation also induced α-SMA expression in lung fibroblasts. Finally, we evaluated the effect of rhTM on bleomycin-induced pulmonary fibrosis. Compared with the vehicle control, both early and late-phase administration of rhTM suppressed the fibrotic process. Our results suggest that HMGB1 and thrombin were involved in the pathophysiology of pulmonary fibrosis via production of profibrotic proteins and that rhTM attenuated bleomycin-induced pulmonary fibrosis. rhTM may be a therapeutic option for acute or subacute pulmonary fibrosis.