Stem cell-based therapy for fibrotic diseases: mechanisms and pathways.

Fibrosis is a pathological process, that could result in permanent scarring and impairment of the physiological function of the affected organ; this condition which is categorized under the term organ failure could affect various organs in different situations. The involvement of the major organs, such as the lungs, liver, kidney, heart, and skin, is associated with a high rate of morbidity and mortality across the world. Fibrotic disorders encompass a broad range of complications and could be traced to various illnesses and impairments; these could range from simple skin scars with beauty issues to severe rheumatologic or inflammatory disorders such as systemic sclerosis as well as idiopathic pulmonary fibrosis. Besides, the overactivation of immune responses during any inflammatory condition causing tissue damage could contribute to the pathogenic fibrotic events accompanying the healing response; for instance, the inflammation resulting from tissue engraftment could cause the formation of fibrotic scars in the grafted tissue, even in cases where the immune system deals with hard to clear infections, fibrotic scars could follow and cause severe adverse effects. A good example of such a complication is post-Covid19 lung fibrosis which could impair the life of the affected individuals with extensive lung involvement. However, effective therapies that halt or slow down the progression of fibrosis are missing in the current clinical settings. Considering the immunomodulatory and regenerative potential of distinct stem cell types, their application as an anti-fibrotic agent, capable of attenuating tissue fibrosis has been investigated by many researchers. Although the majority of the studies addressing the anti-fibrotic effects of stem cells indicated their potent capabilities, the underlying mechanisms, and pathways by which these cells could impact fibrotic processes remain poorly understood. Here, we first, review the properties of various stem cell types utilized so far as anti-fibrotic treatments and discuss the challenges and limitations associated with their applications in clinical settings; then, we will summarize the general and organ-specific mechanisms and pathways contributing to tissue fibrosis; finally, we will describe the mechanisms and pathways considered to be employed by distinct stem cell types for exerting anti-fibrotic events.

Induced pluripotent stem cells modulate the Wnt pathway in the bleomycin-induced model of idiopathic pulmonary fibrosis.

BACKGROUND: The Wnt signaling pathway has been implicated in the pathogenesis of fibrotic disorders and malignancies. Hence, we aimed to assess the potential of the induced pluripotent stem cells (IPS) in modulating the expression of the cardinal genes of the Wnt pathway in a mouse model of idiopathic pulmonary fibrosis (IPF). METHODS: C57Bl/6 mice were randomly divided into three groups of Control, Bleomycin (BLM), and BLM + IPS; the BLM mice received intratracheal instillation of bleomycin, BLM + IPS mice received tail vein injection of IPS cells 48 h post instillation of the BLM; The Control group received Phosphate-buffered saline instead. After 3 weeks, the mice were sacrificed and Histologic assessments including hydroxy proline assay, Hematoxylin and Eosin, and Masson-trichrome staining were performed. The expression of the genes for Wnt, ß-Catenin, Lef, Dkk1, and Bmp4 was assessed utilizing specific primers and SYBR green master mix. RESULTS: Histologic assessments revealed that the fibrotic lesions and inflammation were significantly alleviated in the BLM + IPS group. Besides, the gene expression analyses demonstrated the upregulation of Wnt, ß-Catenin, and LEF along with the significant downregulation of the Bmp4 and DKK1 in response to bleomycin treatment; subsequently, it was found that the treatment of the IPF mice with IPS cells results in the downregulation of the Wnt, ß-Catenin, and Lef, as well as upregulation of the Dkk1, but not the Bmp4 gene (P values < 0.05). CONCLUSION: The current study highlights the therapeutic potential of the IPS cells on the IPF mouse model in terms of regulating the aberrant expression of the factors contributing to the Wnt signaling pathway.

Insights into Overlappings of Fibrosis and Cancer: Exploring the Tumor-related Cardinal Genes in Idiopathic Pulmonary Fibrosis.

The pathogenesis of idiopathic pulmonary fibrosis (IPF) is quite similar to that of cancer pathogenesis, and several pathways appear to be involved in both disorders. The mammalian target of the rapamycin (mTOR) pathway harbors several established oncogenes and tumor suppressors. The same signaling molecules and growth factors, such as vascular endothelial growth factor (VEGF), contributing to cancer development and progression play a part in fibroblast proliferation, myofibroblast differentiation, and the production of extracellular matrix in IPF development as well. The expression of candidate genes acting upstream and downstream of mTORC1, as well as Vegf and low-density lipoprotein receptor related protein 1(Lrp1), was assessed using specific primers and quantitative polymerase chain reaction (qPCR) within the lung tissues of bleomycin (BLM)-induced IPF mouse models. Lung fibrosis was evaluated by histological examinations and hydroxyproline colorimetric assay. BLM-exposed mice developed lung injuries characterized by inflammatory manifestations and fibrotic features, along with higher levels of collagen and hydroxyproline. Gene expression analyses indicated a significant elevation of regulatory associated protein of mTOR (Raptor), Ras homolog enriched in brain (Rheb), S6 kinase 1, and Eukaryotic translation initiation factor 4E-binding protein 1 (4Ebp1), as well as a significant reduction of Vegfa, Tuberous sclerosis complex (Tsc2), and Lrp1; no changes were observed in the Tsc1 mRNA level. Our findings support the elevation of S6K1 and 4EBP1 in response to the TSC/RHEB/mTORC1 axis, which profoundly encourages the development and establishment of IPF and cancer. In addition, this study suggests a possible preventive role for VEGF-A and LRP1 in the development of IPF.

Plumbagin attenuates Bleomycin-induced lung fibrosis in mice.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disease with limited treatment options. Plumbagin (PL) is an herbal extract with diverse pharmacological effects that have been recently used to treat various types of cancer. This study aims to explore the anti-fibrotic effect of PL and possible underlying mechanisms in IPF. METHODS: We used a bleomycin-induced experimental mouse model of lung fibrosis to assess the potential anti-fibrotic effect of PL. Histological analysis of lung tissue samples by H&E and Masson's trichrome staining and hydroxyproline assay was performed to evaluate the fibrotic alterations. ELISA and real-time quantitative PCR were conducted to determine the amount of tumor necrosis factor-alpha (TNFα), tumor growth factor-beta (TGF-ß), connective tissue growth factor (CTGF), and endothelin-1 (ET-1). RESULTS: Bleomycin exposure induced lung fibrosis, which was indicated by inflammation, collagen deposition, and structural damage. PL remarkably prevented bleomycin-induced lung fibrosis. Furthermore, PL significantly inhibited TNF-α and TGF-ß production. PL also diminished the upregulated expression of CTGF and ET-1 induced by bleomycin. CONCLUSION: Overall, our findings suggest PL as an anti-fibrotic agent acting via down-regulation of TGF-ß/CTGF or ET-1 axis, as well as TNF-α, to improve lung fibrosis.

Evaluation of effective factors on IL-10 signaling in B cells in patients with selective IgA deficiency

Background: Selective IgA deficiency is the most prevalent form of primary immunodeficiencies. The pathogenesis of the disease is still unknown. Several studies have suggested a defect in B cell responses to IL-10; however, the main reason for this defect has not been reported. Elucidating IL-10 signaling defects and their correlation with clinical manifestations could be helpful for better understanding and treatment of the disease. Methods: In this study, 15 SIgAD patients and 15 age- and sex-matched healthy controls were included. Surface expression of transforming growth factor ß receptor II (TGF-ß RII), IL-10R and IgA was assessed by flow cytometry in human purified B cells before and after stimulation by IL-10. Protein expression of STAT3, p-STAT3 and SOCS3 was measured by Western blotting analysis. TGF-ß and IgA secretion was evaluated by ELISA. Finally, the measurement of B cell apoptosis was performed by flow cytometry. Results: The TGF-ßRII expression level was decreased after stimulation with IL-10 in patients compared with controls. Notably, the TGF-ß level were higher after stimulation with mCD40L and IL-10 in the control group as compared to stimulation with mCD40L alone. The IgA+ B cell percentage and IgA secretion levels were significantly increased in controls as compared with SIgAD patients. The relative concentration of the total STAT3 was decreased as compared with controls. Conclusion: The defect in IgA production in SIgAD patients could be due to inadequate B cell responses to IL-10 stimulation that probably originate from defective regulation of IL-10-mediated TGF-b 'symbol' production TGF-ß response by IL-10. Furthermore, it is suggested that the absence of STAT3 protein baseline expression could impair cytokine-mediated signaling such as thatinduced by IL-!0 and IL-21.

Induced Pluripotent Stem-cells Inhibit Experimental Bleomycin-induced Pulmonary Fibrosis through Regulation of the Insulin-like Growth Factor Signaling.

Idiopathic pulmonary fibrosis (IPF) is among the illnesses with a high mortality rate, yet no specific cause has been identified; as a result, successful treatment has not been achieved. Among the novel approaches for treating such hard-to-cure diseases are induced pluripotent stem cells (IPSCs). Some studies have shown these cells' potential in treating IPF. Therefore, we aimed to investigate the impact of IPSCs on insulin-like growth factor (Igf) signaling as a major contributor to IPF pathogenesis.  C57BL/6 mice were intratracheally instilled with Bleomycin (BLM) or phosphate-buffered saline; the next day, half of the bleomycin group received IPSCs through tail vein injection. Hydroxyproline assay and histologic examinations have been performed to assess lung fibrosis. The gene expression was evaluated using specific primers for Igf-1, Igf-2, and insulin receptor substrate 1 (Irs-1) genes and SYBR green qPCR master mix. The data have been analyzed using the 2-ΔΔCT method. The mice that received Bleomycin showed histological characteristics of the fibrotic lung injury, which was significantly ameliorated after treatment with IPSCs comparable to the control group. Furthermore, gene expression analyses revealed that in the BLM group, Igf1, Igf2, and Irs1 genes were significantly upregulated, which were returned to near-normal levels after treatment with IPSCs. IPSCs could modulate the bleomycin-induced upregulation of Igf1, Igf2, and Irs1 genes. This finding reveals a new aspect of the therapeutic impact of the IPSCs on IPF, which could be translated into other fibrotic disorders.

Circulating CTRP5 in rheumatoid arthritis: an exploratory biomarker study.

BACKGROUND: Rheumatoid arthritis (RA) is an inflammatory disease that is characterized by the overproduction of cytokines. Among the newly discovered cytokines are the adipokines which are primarily produced by and released from the adipose tissue and some immune cells, as well as synovial cells. they are involved in various immune responses and inflammatory processes. However, there are controversial data regarding the pro-inflammatory or anti-inflammatory effects of adipokines in different conditions. C1q/TNF-related protein 5 (CTRP5) is a newly identified adipokine and adiponectin paralogous protein, which has been shown to be correlated with inflammatory diseases. Accordingly, the present study was designed to investigate the serum levels of CTRP5 in RA patients and evaluate any possible alterations in comparison to healthy individuals. METHODS: Serum CTRP-5 levels were measured in 46 patients and 22 healthy controls by ELISA. The demographic, laboratory, and clinical features of the patients were also evaluated in order to find any correlations. RESULTS: Serum levels of CTRP-5 were significantly (p < 0.0001) higher in patients with RA (14.88 ± 25.55) compared to healthy controls (4.262 ± 2.374). There was a significant correlation between serum CTRP-5 levels and triglyceride (TG) (r: - 0.3010, p: 0.0498), as well as erythrocyte sedimentation rate (ESR) (r: 0.3139, p: 0.0457), C-reactive protein (CRP) (r: 0.5140, p: 0.0008), and the number of white blood cells (WBC) (r: 0.3380, p: 0.0307), which are considered as the markers indicating the extent of inflammation. Moreover, CTRP-5 was found to be correlated with interstitial lung disease (ILD) (r: 0.3416, p: 0.0385), a comorbidity associated with RA disease. CONCLUSION: This study demonstrated the increased level of circulating CTRP-5 in RA patients, which correlated with some inflammation-associated parameters and RA-associated comorbidities. Our observations suggest CTRP-5 as a putative inflammatory biomarker in RA, which may be useful besides the other disease-related markers.

The role of hypoxia in the tumor microenvironment and development of cancer stem cell: a novel approach to developing treatment.

Hypoxia is a common feature of solid tumors, and develops because of the rapid growth of the tumor that outstrips the oxygen supply, and impaired blood flow due to the formation of abnormal blood vessels supplying the tumor. It has been reported that tumor hypoxia can: activate angiogenesis, thereby enhancing invasiveness and risk of metastasis; increase survival of tumor, as well as suppress anti-tumor immunity and hamper the therapeutic response. Hypoxia mediates these effects by several potential mechanisms: altering gene expression, the activation of oncogenes, inactivation of suppressor genes, reducing genomic stability and clonal selection. We have reviewed the effects of hypoxia on tumor biology and the possible strategiesto manage the hypoxic tumor microenvironment (TME), highlighting the potential use of cancer stem cells in tumor treatment.

The role of interleukin-23 in stability of in vitro T helper-17 cells.

Interleukin (IL)-17-producing T helper (Th)-17 cells have recently been explained as a distinct population of CD4+ T cells which play an important role in immunity against infectious agents. Establishment of persistent phenotype of Th17 cells and recognition of lineage-deviating factors are of most attractive goals in modern researches in immunology. Although IL-6 and TGF-ß are frequently used to differentiate naive T cells to Th17 phenotype in mouse models, the application of IL-23 and its importance in preventing cells from plasticity needs to be more investigated. Our main objective was to evaluate the role of IL-23 in Th17 to Th1 plasticity. In this research project, we generated in vitro Myelin oligodendrocyte glycoprotein (MOG)-specific Th17 cells in the presence of TGF-ß, IL-6, IL-23 and peptide MOG35-55. Th17 development was confirmed by assessment of relevant transcription factors and secreted cytokines by flowcytometry and ELISA, respectively. Th17 to Th1 plasticity was monitored by consecutive samplings in different time points without any extra supplementation of IL-23. Cell culture supernatant was evaluated for Interferon (IFN)-γ secretion and cells were evaluated for intracellular expression of this cytokine. Our results showed that the employed method was relatively convenient in developing antigen-specific Th17 cells. We also showed that IL-23 deprivation which happens by prolongation of culture period, can convert IL-17 producing cells to IFN-γ secreting Th1 phenotype. IL-23 can be considered as a Th17 phenotype stabilizing factor for in-vitro developed lineages.