Indomethacin and retinoic acid modify mouse intestinal inflammation and fibrosis: a role for SPARC

Hypertrophic Ligamentum Flavum in Lumbar Spine Stenosis Is Associated With the Increased Expression of Secreted Protein Acidic and Rich in Cysteine

STUDY DESIGN

Basic research.

OBJECTIVES

Secreted protein acidic and rich in cysteine (SPARC) is a critical pro-fibrotic mediator. This study aims to characterize the role of SPARC in hypertrophic ligamentum flavum (LF) and fibrosis.

METHODS

Hypertrophic LF samples were obtained from 8 patients with L4/5 lumbar spinal stenosis (LSS) during the decompressive laminectomy. Non-hypertrophic LF from age- and sex-matched 8 patients with L4/5 lumbar disc herniation was selected as control. An in vitro model of fibrosis in human LF cells was established by interleukin 6 (IL-6) to assess SPARC expression.

RESULTS

Hypertrophic LF samples had higher fibrosis scores than control samples by Masson's trichrome staining (3.6 vs. 1.3, P < .001). Hypertrophic LF samples had significantly more positive staining for collagen and SPARC. Collagen III (Col3), α smooth muscle actin (α-SMA), and SPARC mRNA expression levels were significantly higher in hypertrophic LF samples than in control samples by qPCR. SPARC expression and fibrotic and inflammatory makers (collagen I, Col3, IL-6, interleukin 1β) were significantly upregulated in IL-6 stimulation of normal LF in vitro.

CONCLUSION

SPARC was detected in human LF and significantly upregulated in the clinical samples of hypertrophic LF compared to their normal counterparts. We also demonstrated an increased level of SPARC in an in vitro fibrosis model of LF. Thus, SPARC could be a crucial biomarker for the pathogenesis of hypertrophic LF and a therapeutic target for LSS.

Drug Repurposing in Crohn's Disease Using Danish Real-World Data

Aim

Drug repurposing, utilizing electronic healthcare records (EHRs), offers a promising alternative by repurposing existing drugs for new therapeutic indications, especially for patients lacking effective therapies. Intestinal fibrosis, a severe complication of Crohn's disease (CD), poses significant challenges, increasing morbidity and mortality without available pharmacological treatments. This article focuses on identifying medications associated with an elevated or reduced risk of fibrosis in CD patients through a population-wide real-world data and artificial intelligence (AI) approach.

Methods

Patients aged 65 or older with a diagnosis of CD from 1996 to 2019 in the Danish EHRs were followed for up to 24 years. The primary outcome was the need of specific surgical procedures, namely proctocolectomy with ileostomy and ileocecal resection as proxies of intestinal fibrosis. The study explored drugs linked to an increased or reduced risk of the study outcome through machine-learning driven survival analysis.

Results

Among the 9179 CD patients, 1029 (11.2%) underwent surgery, primarily men (58.5%), with a mean age of 76 years, 10 drugs were linked to an elevated risk of surgery for proctocolectomy with ileostomy and ileocecal resection. In contrast, 10 drugs were associated with a reduced risk of undergoing surgery for these conditions.

Conclusion

This study focuses on repurposing existing drugs to prevent surgery related to intestinal fibrosis in CD patients, using Danish EHRs and advanced statistical methods. The findings offer valuable insights into potential treatments for this condition, addressing a critical unmet medical need. Further research and clinical trials are warranted to validate the effectiveness of these repurposed drugs in preventing surgery related to intestinal fibrosis in CD patients.

Pathogenesis of Microscopic Colitis: A Systematic Review

BACKGROUND

Whereas the exact aetiology of microscopic colitis [MC] remains unknown, a dysregulated immune response to luminal factors or medications is the most accepted pathogenesis hypothesis.

METHODS

We conducted a systematic review of the pathogenesis of MC. We applied the Joanna Briggs Institute methodologies and the PRISMA statement for the reporting of systematic reviews [PROSPERO Trial Identifier: CRD42020145008]. Populations, Exposure of interest, and Outcome [PEO] questions were used to explore the following topics in MC: 1] intestinal luminal factors; 2] autoimmunity; 3] innate immunity; 4] adaptive immunity; 5] extracellular matrix; 6] genetic risk factors; and 7] mechanism of diarrhoea. A search was done in PubMed, Embase, and Web of Science up to February 2020. A narrative description was performed explaining the findings for each aspect of MC aetiopathogenesis.

RESULTS

Thirty-eight documents provided evidence for PEO1, 100 for PEO2, 72 for PEO3 and 4, 38 for PEO5, 20 for PEO6, and 23 for PEO7. The majority of documents were cohorts, case reports, and case series, with a few case-control and some experimental studies. Consistency among data provided by different studies was considered to support pathogenetic hypotheses. MC is a multifactorial disease believed to involve innate and adaptive immune responses to luminal factors, genetic risk, autoimmunity, and extracellular matrix alterations, all contributing by varied mechanisms to watery diarrhoea.

CONCLUSIONS

This is the first systematic review on the aetiology of MC supporting the notion that MC is a multifactorial disease. However, high-profile studies are lacking, and most evidence derives from small heterogeneous studies.

Secreted modular calcium-binding proteins in pathophysiological processes and embryonic development

Objective:

Secreted modular calcium-binding proteins (SMOCs) are extracellular glycoproteins of the secreted protein, acidic, and rich in cysteine-related modular calcium-binding protein family and include two isoforms, SMOC1 and SMOC2, in humans. Functionally, SMOCs bind to calcium for various cell functions. In this review, we provided a summary of the most recent advancements in and findings of SMOC1 and SMOC2 in development, homeostasis, and disease states.

Data sources:

All publications in the PubMed database were searched and retrieved (up to July 24, 2019) using various combinations of keywords searching, including SMOC1, SMOC2, and diseases.

Study selection:

All original studies and review articles of SMOCs in human diseases and embryo development written in English were retrieved and included.

Results:

SMOC1 and SMOC2 regulate embryonic development, cell homeostasis, and disease pathophysiology. They play an important role in the regulation of cell cycle progression, cell attachment to the extracellular matrix, tissue fibrosis, calcification, angiogenesis, birth defects, and cancer development.

Conclusions:

SMOC1 and SMOC2 are critical regulators of many cell biological processes and potential therapeutic targets for the control of human cancers and birth defects.

All-trans Retinoic Acid Counteracts Diarrhea and Inhibition of Downregulated in Adenoma Expression in Gut Inflammation

BACKGROUND

Intestinal epithelial apical membrane Cl-/HCO3- exchanger DRA (downregulated in adenoma, SLC26A3) has emerged as an important therapeutic target for diarrhea, emphasizing the potential therapeutic role of agents that upregulate DRA. All-trans retinoic acid (ATRA), a key vitamin A metabolite, was earlier shown by us to stimulate DRA expression in intestinal epithelial cells. However, its role in modulating DRA in gut inflammation has not been investigated.

AIMS

Our aim was to analyze the efficacy of ATRA in counteracting inflammation-induced decrease in DRA in vitro and in vivo.

METHODS

Interferon-γ (IFN-γ)-treated Caco-2 cells and dextran sulfate sodium (DSS)-treated C57BL/6J mice served as in vitro and in vivo models of gut inflammation, respectively. The effect of ATRA on IFN-γ-mediated inhibition of DRA function, expression, and promoter activity were elucidated. In the DSS colitis model, diarrheal phenotype, cytokine response, in vivo imaging, myeloperoxidase activity, and DRA expression were measured in the distal colon.

RESULTS

All-trans retinoic acid (10 μM, 24 h) abrogated IFN-γ (30 ng/mL, 24 h)-induced decrease in DRA function, expression, and promoter activity in Caco-2 cells. All-trans retinoic acid altered IFN-γ signaling via blocking IFN-γ-induced tyrosine phosphorylation of STAT-1. All-trans retinoic acid cotreatment (1 mg/kg BW, i.p. daily) of DSS-treated mice (3% in drinking water for 7 days) alleviated colitis-associated weight loss, diarrheal phenotype, and induction of IL-1β and CXCL1 and a decrease in DRA mRNA and protein levels in the colon.

CONCLUSION

Our data showing upregulation of DRA under normal and inflammatory conditions by ATRA demonstrate a novel role of this micronutrient in alleviating IBD-associated diarrhea.

Preclinical Study in Vivo for New Pharmacological Approaches in Inflammatory Bowel Disease: A Systematic Review of Chronic Model of TNBS-Induced Colitis

The preclinical studies in vivo provide means of characterizing physiologic interactions when our understanding of such processes is insufficient to allow replacement with in vitro systems and play a pivotal role in the development of a novel therapeutic drug cure. Chemically induced colitis models are relatively easy and rapid to develop. The 2,4,6-trinitrobenzenesulfonic acid (TNBS) colitis model is one of the main models in the experimental studies of inflammatory bowel disease (IBD) since inflammation induced by TNBS mimics several features of Crohn’s disease. This review aims to summarize the existing literature and discuss different protocols for the induction of chronic model of TNBS-induced colitis. We searched MEDLINE via Pubmed platform for studies published through December 2018, using MeSH terms (Crohn Disease.kw) OR (Inflammatory Bowel Diseases.kw) OR (Colitis, Ulcerative.kw) AND (trinitrobenzenesulfonic acid.kw) AND (disease models, animal.kw) AND (mice.all). The inclusion criteria were original articles, preclinical studies in vivo using mice, chronic model of colitis, and TNBS as the inducer of colitis and articles published in English. Chronic TNBS-induced colitis is made with multiple TNBS intrarectal administrations in an average dose of 1.2 mg using a volume lower than 150 μL in 50% ethanol. The strains mostly used are Balb/c and C57BL/6 with 5–6 weeks. To characterize the preclinical model the parameters more used include body weight, stool consistency and morbidity, inflammatory biomarkers like interferon (IFN)-γ, myeloperoxidase (MPO), tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10, presence of ulcers, thickness or hyperemia in the colon, and histological evaluation of the inflammation. Experimental chronic colitis is induced by multiple rectal instillations of TNBS increasing doses in ethanol using Balb/c and C57BL/6 mice.

Glucocorticoids Increase Renal Excretion of Urate in Mice by Downregulating Urate Transporter 1

Both nonsteroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids have been widely used for the treatment of gout, a disease promoted by an excess body burden of uric acid (UA); however, their effects on the homeostasis of UA remain poorly understood. The present study showed that 1-week treatments with three NSAIDs (ibuprofen, diclofenac, and indomethacin) had little effect on UA homeostasis in mice, whereas 1-week low doses (1 and 5 mg/kg) of dexamethasone (DEX) significantly decreased serum UA by about 15%. Additionally, low doses of DEX also resulted in increases in hepatic UA concentration and urinary UA excretion, which were associated with an induction of xanthine oxidoreductase (XOR) in the liver and a downregulation of urate transporter 1 (URAT1) in the kidney, respectively. Neither 75 mg/kg DEX nor 100 mg/kg pregnenolone-16α-carbonitrile altered UA concentrations in serum and livers of mice, suggesting that the effect of DEX on UA homeostasis was not due to the pregnane X receptor pathway. Further in vitro studies demonstrated that glucocorticoid receptor (GR) was involved in DEX-mediated downregulation of URAT1. Knockdown of both p65 and c-Jun completely blocked the effect of DEX on URAT1, suggesting that GR regulates URAT1 via its interaction with both nuclear factor κB and activator protein 1 signaling pathways. To conclude, the present study identifies, for the first time, a critical role of glucocorticoids in regulating UA homeostasis and elucidates the mechanism for GR-mediated regulation of URAT1 in mice. SIGNIFICANCE STATEMENT: This study demonstrates, for the first time, a critical role of glucocorticoid receptor in regulating urate transporter 1 in mouse kidney.

Mesenchymal stem cells in myeloproliferative disorders - focus on primary myelofibrosis

Primary myelofibrosis (PMF) is the most aggressive Philadelphia-negative (Ph-) myeloproliferative neoplasm (MPN), characterized by bone marrow (BM) insufficiency, myelofibrosis (MF), osteosclerosis, neoangiogenesis, and extramedullary hematopoiesis (EMH) in spleen and liver. Presently, there is no curative treatment for this disease and therapy consists primarily of symptom relief and, in selected cases, allogeneic hematopoietic stem cell transplant (alloHSCT). PMF's major defining characteristics, as well as several recently described aspects of its cellular and molecular pathophysiology all support a critical role for dysregulated cell-cell/cell-extracellular matrix interactions and cytokine/chemokine signaling within the BM niche in the natural history of this disease. This review will highlight current data concerning the involvement of the BM niche, particularly of mesenchymal stem cells (MSC), in PMF, and will then discuss the rationale for a stroma-directed treatment, and the advantages such an approach would offer over the current treatments focused on targeting the malignant clone.

Prostaglandin E₂ and polyenylphosphatidylcholine protect against intestinal fibrosis and regulate myofibroblast function

BACKGROUND

Intestinal fibrosis is a serious and often recurrent complication of inflammatory bowel disease despite surgical intervention. The anti-fibrotic potential of prostaglandin E2 (PGE2) and polyenylphosphatidylcholine (PC) was investigated using the murine model of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced chronic intestinal inflammation and fibrosis, and murine and human intestinal myofibroblasts.

METHODS

Mice were treated with TNBS enemas weekly for 2 or 6 weeks ± PGE2 (10 mg/kg/day orally) or PC (200 mg/kg/day orally). Inflammation and fibrosis were histologically assessed and scored. Pro-inflammatory cytokines, TLR4, and ECM-related gene expression from the colonic tissue and cultured myofibroblasts were assessed by RT-qPCR. The levels of α-SMA(+) staining and endogenous PGE2 in vivo were also assessed.

RESULTS

Both PGE2 and PC treatment significantly decreased TNBS-induced intestinal inflammation and excess collagen deposition in vivo. This was accompanied by decreased α-SMA(+) staining in the lamina propria and lower collagen type I (COL1α1) expression. Endogenous PGE2 levels demonstrated that PC was not being converted into PGE2, thus mediating its effects primarily via PGE2-independent pathways. Both PGE2 and the PC isoform, 1,2-dilinoleoylphosphatidylcholine (DLPC), regulated primary mouse myofibroblast and CCD-18co COL1α1 production, and induced lower collagen type I to III and TGF-β1 to TGF-β3 ratios, demonstrating their ability to induced normal healing in the presence of phorbol 12-myristate 13-acetate (protein kinase C-dependent inducer of collagen production).

CONCLUSION

PGE2 and PC both have potent anti-fibrogenic potentials in their ability to regulate inflammatory cell and myofibroblast accumulation within inflamed tissue, to decrease pro-inflammatory cytokine expression and to maintain normal healing in an inflammatory environment.

Results of the 4th scientific workshop of the ECCO (I): pathophysiology of intestinal fibrosis in IBD

The fourth scientific workshop of the European Crohn's and Colitis Organization (ECCO) focused on the relevance of intestinal fibrosis in the disease course of inflammatory bowel disease (IBD). The objective was to better understand the pathophysiological mechanisms of intestinal fibrosis, to identify useful markers and imaging modalities of fibrosis in order to assess its presence and progression, and, finally, to point out possible approaches for the prevention and the treatment of fibrosis. The results of this workshop are presented in three separate manuscripts. This first section describes the most important mechanisms that contribute to the initiation and progression of intestinal fibrosis in IBD including the cellular and molecular mediators, the extracellular matrix molecules and matrix metalloproteinases/tissue inhibitors of metalloproteinases-system, the microbiota products, the role of fat, genetic and epigenetic factors, as well as the currently available experimental models. Furthermore, it identifies unanswered questions in the field of intestinal fibrosis and provides a framework for future research.

The controversial role of retinoic acid in fibrotic diseases: analysis of involved signaling pathways

Fibrotic diseases, such as liver, pulmonary and renal fibrosis, are common end-stage conditions and represent a major global health problem. Furthermore, effective therapeutic measures are presently unavailable. Extracellular matrix accumulation is the most prominent characteristic in the pathogenesis of fibrotic disease. Retinoic acid, including all-trans retinoic acid, 9-cis and 13-cis retinoic acid, play important roles in various physiological processes, such as in embryonic development, reproduction, vision, cell growth, differentiation, apoptosis and inflammation. Present studies report that retinoic acid treatment may affect various processes involved in the onset and progression of fibrotic disease. However, the therapeutic effects of retinoic acid in such diseases remain controversial. Several reports indicate that retinoic acid positively affects the progression of fibrosis and alleviates the accumulation of the extracellular matrix, whereas other studies report the opposite; that retinoic acid exacerbates fibrosis and induces extracellular matrix accumulation. Signaling pathways might be an important influencing factor and differences in signaling events might be responsible for the contradictory role of retinoic acid in fibrotic diseases. Since there was no review available that investigated the role of retinoic acid and the signaling pathways involved, we retrospectively studied the literature and provide a comprehensive analysis of retinoic acid’s role in fibrotic diseases, and provide an overview of the signal transduction pathways involved in its pathogenesis.

Mucosal healing and fibrosis after acute or chronic inflammation in wild type FVB-N mice and C57BL6 procollagen α1(I)-promoter-GFP reporter mice

Background

Injury and intestinal inflammation trigger wound healing responses that can restore mucosal architecture but if chronic, can promote intestinal fibrosis. Intestinal fibrosis is a major complication of Crohn’s disease. The cellular and molecular basis of mucosal healing and intestinal fibrosis are not well defined and better understanding requires well characterized mouse models.

Methods

FVB-N wild type mice and C57BL6 procollagen α1(I)-GFP reporter mice were given one (DSS1) or two (DSS2) cycles of 3% DSS (5 days/cycle) followed by 7 days recovery. Histological scoring of inflammation and fibrosis were performed at DSS1, DSS1+3, DSS1+7, DSS2, DSS2+3, and DSS2+7. Procollagen α1(I)-GFP activation was assessed in DSS and also TNBS models by whole colon GFP imaging and fluorescence microscopy. Colocalization of GFP with α-smooth muscle actin (α-SMA) or vimentin was examined. GFP mRNA levels were tested for correlation with endogenous collagen α1(I) mRNA.

Results

Males were more susceptible to DSS-induced disease and mortality than females. In FVB-N mice one DSS cycle induced transient mucosal inflammation and fibrosis that resolved by 7 days of recovery. Two DSS cycles induced transmural inflammation and fibrosis in a subset of FVB-N mice but overall, did not yield more consistent, severe or sustained fibrosis. In C57BL6 mice, procollagen α1(I)-GFP reporter was activated at the end of DSS1 and through DSS+7 with more dramatic and transmural activation at DSS2 through DSS2+7, and in TNBS treated mice. In DSS and TNBS models GFP reporter expression localized to vimentin⁺ cells and much fewer α-SMA⁺ cells. GFP mRNA strongly correlated with collagen α1(I) mRNA.

Conclusions

One DSS cycle in FVB-N mice provides a model to study mucosal injury and subsequent mucosal healing. The procollagen α1(I)-GFP transgenic provides a useful model to study activation of a gene encoding a major extracellular matrix protein during acute or chronic experimental intestinal inflammation and fibrosis.

The Function of SPARC as a Mediator of Fibrosis

Fibrosis is a common end-point of a number of different diseases such as hypertension, diabetes, liver cirrhosis, and those associated with chronic inflammation. Fibrosis is characterized by excessive deposition of extracellular matrix that interferes with normal tissue architecture and function. Increased expression of secreted protein acidic and rich in cysteine (SPARC) in fibrotic tissues has been reported in numerous studies. SPARC is a 43 kDa collagen-binding protein secreted from several different cell types into the extracellular matrix and has been shown to be anti-proliferative and counter-adhesive in vitro. SPARC is a matricellular protein; meaning SPARC is secreted into the extracellular space but does not serve a structural function. Instead, SPARC modulates interactions between cells and the surrounding extracellular matrix. In animal models of fibrotic disease and in human fibrotic tissues, elevated expression of SPARC has been reported in many tissues including heart, lungs, kidneys, liver, dermis, intestine, and eyes. In this review, we will summarize current studies that have examined the expression and functional importance of SPARC in various animal models of fibrosis and in human tissues. Although cellular mechanisms of SPARC in fibrosis remain to be fully elucidated, the studies summarized here provide impetus to further explore the efficacy of SPARC as a potential target for reducing fibrosis.

Role of retinoic acid in immune regulation: implications in the treatment of inflammatory bowel disease

Retinoic acid, a derivative of vitamin A, can regulate cell proliferation, differentiation, maturation and plays important roles in the body's normal development and a variety of physiological activities. Retinoic acid is not only a differentiation inducer but also an immunomodulator. On one hand, retinoic acid can balance the Thl/Th2 ratio by reducing the secretion of INF-γ and promoting the secretion of IL-4; on the other hand, it can regulate Th17/Treg balance by promoting the differentiation of CD4+ CD25+ Treg cells. In this way, retinoic acid can regulate the body's disturbed immune system and help restore normal immune function. Thus, treatment with retinoic acid may affect the process of inflammatory bowel disease (IBD) and represent a new method for the therapy of IBD.

Mesenchymal cell proliferation and programmed cell death: key players in fibrogenesis and new targets for therapeutic intervention

An exquisite equilibrium between cell proliferation and programmed cell death is required to maintain physiological homeostasis. In inflammatory bowel disease, and especially in Crohn's disease, enhanced proliferation along with defective apoptosis of immune cells are considered key elements of pathogenesis. Despite the relatively limited attention that has been given to research efforts devoted to intestinal fibrosis to date, there is evidence suggesting that enhanced proliferation along with defective programmed cell death of mesenchymal cells can significantly contribute to the development of excessive fibrogenesis in many different tissues. Moreover, some therapies have demonstrated potential antifibrogenic efficacy through the regulation of mesenchymal cell proliferation and programmed cell death. Further understanding of the pathways involved in the regulation of mesenchymal cell proliferation and apoptosis is, however, required.

All-trans retinoic acid ameliorates trinitrobenzene sulfonic acid-induced colitis by shifting Th1 to Th2 profile

Inflammatory bowel disease is characterized with uncontrolled immune response in inflamed mucosa, with dominance of Th1 cells. Recently, all-trans retinoic acid has been shown that can lead T-cell response by suppressing Th17 development via retinoic acid receptor (RAR), but it is still unknown whether all-trans retinoic acid can modulate Th1 response of inflammatory bowel disease. In the experiment, we investigated the effect of all-trans retinoic acid on trinitrobenzene sulfonic acid (TNBS)-induced murine colitis, and the possible mechanism. Mice were intraperitoneally treated daily with all-trans retinoic acid (the agonist of RAR-alpha) or LE135 (the antagonist of RAR-alpha) or medium, and sacrificed 6 days later. Colon was collected for histological analysis and myeloperoxidase (MPO) activity measurement. Lamina propria mononuclear cells (LPMCs) were isolated, cultured, and assayed for the expressions of T-bet and GATA-3 by the use of Western blot and for cytokine levels by the use of ELISA. All-trans retinoic acid treatment inhibited inflammatory responses as shown by lower histological inflammatory scores and MPO activity, compared with LE135 and medium groups. Furthermore, in LPMCs culture supernatants, the levels of Th1 cytokines (INF-gamma, IL-12, and TNF-alpha) were decreased while those of Th2 cytokines (IL-4 and IL-10) were increased significantly in all-trans retinoic acid-treated mice. In addition, T-bet expression in LPMCs was inhibited and GATA-3 expression was up-regulated in all-trans retinoic acidtreated mice. On the contrary, LE135 showed the reverse effects in colon inflammation and cytokine profile. By shifting Th1 to Th2 profile in inflamed mucosa, all-trans retinoic acid down-regulates inflammatory response and ameliorates acute TNBS-induced colitis, which suggests the ligand of RAR-alpha-based pharmaceutical strategies for managing inflammatory bowel disease.

Retinoic acid in the immune system

On occasion, emerging scientific fields intersect and great discoveries result. In the last decade, the discovery of regulatory T cells (T(reg)) in immunity has revolutionized our understanding of how the immune system is controlled. Intersecting the rapidly emerging field of T(reg) function, has been the discovery that retinoic acid (RA) controls both the homing and differentiation of T(reg). Instantly, the wealth and breadth of knowledge of the molecular basis for RA action, its receptors, and how it controls cellular differentiation can and will be exploited to understand its profound effects on T(reg). Historically, vitamin A deprivation and repletion and RA agonists have been shown to profoundly affect immunity. Now these findings can be interpreted in light of the revelations that RA controls leukocyte homing and T(reg) function.