Upregulation of VEGF expression is associated with accumulation of HIF-1α in the skin of naïve scleroderma patients

Hypoxia-Inducible Factor-1α (HIF-1α) as a Biomarker for Changes in Microcirculation in Individuals with Systemic Sclerosis

INTRODUCTION

Systemic sclerosis is an autoimmune disease characterized by tissue fibrosis and microangiopathy. Vascular changes such as a decrease in capillary density diminish blood flow and impair tissue oxygenation. Reliable ways to monitor disease activity and predict disease progression are desired in the process of patient selection for clinical trials and to optimize individual patient outcomes. Hypoxia-inducible factor-1 (HIF-1) is a dimeric protein complex that plays an integral role in the body's response to hypoxia. Our study aimed to investigate the potential abnormalities of HIF-1α plasma concentration and its possible association with disease activity and vascular abnormalities in patients with systemic sclerosis.

METHODS

Blood plasma levels of HIF-1α were measured in patients with systemic sclerosis (n = 50) and in healthy individuals (n = 30) using commercially available ELISA test kits.

RESULTS

The results showed a marked increase in HIF-1α levels in patients with systemic sclerosis (3.042 ng/ml [2.295-7.749]) compared to the control group (1.969 ng/ml [1.531-2.903] p < 0.01). Patients with diffuse cutaneous SSc (2.803 ng/ml, IQR 2.221-8.799) and limited cutaneous SSc (3.231 ng/ml, IQR 2.566-5.502) exhibited elevated serum HIF-1α levels compared to the control group (p < 0.01). We found a notable increase in HIF-1α plasma concentration in patients with an "active" pattern (6.625 ng/ml, IQR 2.488-11.480) compared to those with either an "early" pattern (2.739, IQR 2.165-3.282, p < 0.05) or a "late" pattern (2.983 ng/ml, IQR 2.229-3.386, p < 0.05). Patients with no history of digital ulcers had significantly higher levels of HIF-1α (4.367 ng/ml, IQR 2.488-9.462) compared to patients with either active digital ulcers (2.832 ng/ml, IQR 2.630-3.094, p < 0.05) or healed digital ulcers (2.668 ng/ml, IQR 2.074-2.983, p < 0.05).

CONCLUSIONS

Our results indicate that HIF-1α may serve as a biomarker in assessing microcirculatory changes in individuals with systemic sclerosis.

Hypoxia-induced interstitial transformation of microvascular endothelial cells by mediating HIF-1α/VEGF signaling in systemic sclerosis

Objective

The aim of this research was to systematically investigate the effects of endothelial mesenchymal transition (EndMT) induced by hypoxia on the skin microvascular remodeling of systemic sclerosis (SSc) and the underlying mechanism.

Methods

Skin tissues from SSc patients and controls were collected for isobaric tags for the relative and absolute quantification (iTRAQ)-based proteomics and immunohistochemical test. Human microvascular endothelial cell line-1 (HMEC-1) cultured in hypoxic or normal conditions was treated by tamoxifen or bevacizumab.

Results

The iTRAQ-based proteomics indicated a significantly upregulated hypoxia-inducible factor-1 (HIF-1) signal in SSc samples. The immunohistochemical results demonstrated the significant downregulation of CD31, the positive staining of α-smooth muscle actin (α-SMA), HIF-1α, and vascular endothelial growth factor (VEGF-a) in SSc skin tissues, compared with control samples. Consistent with these observations, HMEC-1 cells cultured under hypoxic conditions exhibited a significant decrease in CD31 and VE-cadherin expression, alongside a marked increase in the expression of α-SMA and fibronectin, as well as a distinct upregulation of HIF-1α and VEGF-a, when compared with those under normal conditions. It is noteworthy that the inhibition of HIF-1α by tamoxifen effectively downregulated the hypoxic induction of VEGF-a and α-SMA while rescuing the hypoxic suppression of CD31. In addition, the VEGF-a inhibitor bevacizumab treatment had the same effect on the hypoxic expression of α-SMA and CD31, as a tamoxifen intervention, but did not reduce HIF-1α.

Conclusion

These results suggest that the HIF-1α/VEGF signaling pathway can have a critical role in mediating the effect of hypoxia-induced EndMT on the skin microvascular remodeling of SSc.

Natural Formulations: Novel Viewpoint for Scleroderma Adjunct Treatment

BACKGROUND

Scleroderma is a complex disease involving autoimmune, vascular, and connective tissues, with unknown etiology that can progress through any organ systems.

OBJECTIVE

Yet, no cure is available; the thorough treatment of scleroderma and current treatments are based on controlling inflammation. Nowadays, medicinal plants/natural-based formulations are emerging as important regulators of many diseases, including autoimmune diseases. Here, we provided an overview of scleroderma, also focused on recent studies on medicinal plants/natural-based formulations that are beneficial in scleroderma treatment/prevention.

METHODS

This study is the result of a search in PubMed, Scopus, and Cochrane Library with "scleroderma", "systemic sclerosis", "plant", "herb", and "phytochemical" keywords. Finally, 22 articles were selected from a total of 1513 results entered in this study.

RESULTS

Natural products can modulate the inflammatory and/or oxidative mediators, regulate the production or function of the immune cells, and control the collagen synthesis, thereby attenuating the experimental and clinical manifestation of the disease.

CONCLUSION

Natural compounds can be considered an adjunct treatment for scleroderma to improve the quality of life of patients suffering from this disease.

Hypoxia-inducible factor-1 drives divergent immunomodulatory functions in the pathogenesis of autoimmune diseases

Hypoxia-inducible factor-1 (HIF-1) is a heterodimeric (HIF-1α/ HIF-1β) transcription factor in which the oxygen-sensitive HIF-1α subunit regulates gene transcription to mediate adaptive tissue responses to hypoxia. HIF-1 is a key mediator in both regulatory and pathogenic immune responses, because ongoing inflammation in localized tissues causes increased oxygen consumption and consequent hypoxia within the inflammatory lesions. In autoimmune diseases, HIF-1 plays complex and divergent roles within localized inflammatory lesions by orchestrating a critical immune interplay sponsoring the pathogenesis of the disease. In this review, we have summarized the role of HIF-1 in lymphoid and myeloid immunomodulation in autoimmune diseases. HIF-1 drives inflammation by controlling the Th17/T_reg /Tr1 balance through the tipping of the differentiation of CD4⁺ T cells in favour of pro-inflammatory Th17 cells while suppressing the development of anti-inflammatory T_reg /Tr1 cells. On the other hand, HIF-1 plays a protective role by facilitating the expression of anti-inflammatory cytokine IL-10 in and expansion of CD1d^hi CD5⁺ B cells, known as regulatory B cells or B10 cells. Apart from lymphoid cells, HIF-1 also controls the activation of macrophages, neutrophils and dendritic cells, thus eventually further influences the activation and development of effector/regulatory T cells by facilitating the creation of a pro/anti-inflammatory microenvironment within the autoinflammatory lesions. Based on the critical immunomodulatory roles that HIF-1 plays, this master transcription factor seems to be a potent druggable target for the treatment of autoimmune diseases.

Abnormal Nailfold Capillaries in Patients after Hand Transplantation

BACKGROUND

The development of graft vasculopathy may play a role in the long-term deterioration of hand grafts. The aim of study was to examine the patterns of the nailfold capillaries in hand transplant recipients.

METHODS

the study was performed on six patients who received hand transplantation. To normalize for the effect of immunosuppression an age- and sex-matched group of 12 patients with active kidney transplant was selected. As an additional control group, 12 healthy volunteers were recruited. Nailfold videocapillaroscopy was performed in all participants. Additionally, serum concentrations of vascular endothelial growth factor (VEGF) were measured.

RESULTS

Videocapillaroscopic examination of the hand allografts revealed significant abnormalities: including capillary disorganization and microhaemorrhages. The number of capillaries was reduced, the vessels were enlarged and branched. Surprisingly, similar, albeit slightly less pronounced, changes were seen in the nailfolds of healthy hands of the limb transplant recipients. In kidney transplant recipients the capillaroscopic pattern was general normal and comparable to healthy individuals. Moreover, serum concentrations of VEGF in all participants correlated with average capillary diameter in capillaroscopy.

CONCLUSIONS

in hand transplant recipients advanced microvascular abnormalities are found in nailfold capillaroscopic pattern in both transplanted and own extremities connected with elevated levels of VEGF.

Hypoxia and HIF-1α Regulate Collagen Production in Keloids

Keloids are reactive or spontaneous fibroproliferative dermal tumors characterized by the exaggerated and uncontrolled accumulation of extracellular collagen. Current approaches to mitigate keloidogenesis are largely procedural in nature. However, a better understanding of its biological drivers may lead to novel targeted treatments for keloids. Through whole-genome expression analysis, we found that an HIF-1α transcriptional footprint is preferentially upregulated (activation score = 2.024; P = 1.05E-19) in keloid fibroblasts compared with normal dermal fibroblasts. We verified that HIF-1α protein is more strongly expressed in keloid specimens compared with normal skin (P = 0.035) and that hypoxia (1% O₂) leads to increased collagen, especially in the extracellular compartment. Collagen levels were reduced uniformly by selective HIF-1α inhibitor CAY10585. Our results indicate that collagen secretion may be intimately linked to a hypoxic microenvironment within keloid tumors and that HIF-1α blockade could be a novel avenue of treatment for these tumors.

2-Methoxyestradiol inhibits hypoxia-induced scleroderma fibroblast collagen synthesis by phosphatidylinositol 3-kinase/Akt/mTOR signalling

Objectives

To investigate the mechanism of 2-methoxyestradiol (2-ME) in inhibiting hypoxia-induced collagen synthesis of fibroblasts in SSc.

Methods

The expressions of hypoxia-inducible factor 1 alpha (HIF-1α) and connective tissue growth factor (CTGF) in skin specimens derived from SSc patients and healthy volunteers were examined by immunohistochemistry. HIF-1α was knocked down by lentiviral transduction, and SSc dermal fibroblasts cultured under normoxic (21% O2) or hypoxic (1% O2) condition were treated with PI3K inhibitor LY294002, rapamycin or 2-ME (25 μM). The protein levels of HIF-1α, CTGF, collagen I, p-Akt and p-mTOR were examined by western blotting or immunofluorescence. Apoptosis and cell cycle of fibroblasts were assessed by flow cytometry and by measuring caspase 3 activity, and cell proliferation was evaluated by Cell Counting Kit-8.

Results

The expressions of HIF-1α and CTGF were increased in skins of SSc patients compared with healthy controls. Hypoxia up-regulated the protein levels of HIF-1α, CTGF and collagen I in SSc fibroblasts. In contrast, 2-ME inhibited PI3K/Akt/mTOR pathway and down-regulated protein levels of HIF-1α, CTGF and collagen I. Knockdown of HIF-1α reduced expressions of CTGF and collagen I, which were further down-regulated by 2-ME intervention. Moreover, 2-ME promoted the apoptosis and inhibited the proliferation of SSc fibroblasts by arresting the cell cycle at the G2/M phase.

Conclusion

2-ME reduced the production of CTGF and collagen I in SSc fibroblasts induced by hypoxia through PI3K/Akt/mTOR/HIF-1α signalling and inhibited the proliferation of fibroblasts. These findings suggested that 2-ME could be employed as a promising antifibrotic therapy for SSc.

Reactive oxygen species and fibrosis: further evidence of a significant liaison

Age-related diseases such as obesity, diabetes, non-alcoholic fatty liver disease, chronic kidney disease and cardiomyopathy are frequently associated with fibrosis. Work within the last decade has improved our understanding of the pathophysiological mechanisms contributing to fibrosis development. In particular, oxidative stress and the antioxidant system appear to be crucial modulators of processes such as transforming growth factor-β1 (TGF-β1) signalling, metabolic homeostasis and chronic low-grade inflammation, all of which play important roles in fibrosis development and persistence. In the current review, we discuss the connections between reactive oxygen species, antioxidant enzymes and TGF-β1 signalling, together with functional consequences, reflecting a concept of redox-fibrosis that can be targeted in future therapies.

Graphical abstract

Redox-fibrosis: Impact of TGFβ1 on ROS generators, mediators and functional consequences

Fibrosis is one of the most prevalent features of age-related diseases like obesity, diabetes, non-alcoholic fatty liver disease, chronic kidney disease, or cardiomyopathy and affects millions of people in all countries. Although the understanding about the pathophysiology of fibrosis has improved a lot during the recent years, a number of mechanisms still remain unknown. Although TGF-β1 signaling, loss of metabolic homeostasis and chronic low-grade inflammation appear to play important roles in the pathogenesis of fibrosis, recent evidence indicates that oxidative stress and the antioxidant system may also be crucial for fibrosis development and persistence. These findings point to a concept of a redox-fibrosis where the cellular oxidant and antioxidant system could be potential therapeutic targets. The current review aims to summarize the existing links between TGF-β1 signaling, generation and action of reactive oxygen species, expression of antioxidative enzymes, and functional consequences including epigenetic redox-mediated responses during fibrosis.

Inhibition of angiogenesis by platelets in systemic sclerosis patients

INTRODUCTION

Systemic sclerosis (SSc) is a chronic autoimmune disease characterized by microvascular damage, inflammation, and fibrosis. It has become increasingly evident that platelets, beyond regulating hemostasis, are important in inflammation and innate immunity. Platelets may be an important source of proinflammatory and profibrotic cytokines in the vascular microenvironment. In this study, we sought to assess the contribution of platelet-derived factors in patients with SSc to the angiogenesis of human dermal microvascular endothelial cells (DMVECs) in a tubule formation assay and to characterize the secretion of profibrotic and proinflammatory cytokines in these platelets.

METHODS

We analyzed platelets obtained from 30 patients with SSc and 12 healthy control subjects. Angiogenesis was evaluated in vitro with a DMVEC tubule formation assay on Matrigel and platelet-derived angiogenic factors such as vascular endothelial growth factor (VEGF), 165b isoform (VEGF165b), and cytokine secretion was evaluated. Platelet serotonin content was also determined.

RESULTS

When DMVECs were incubated with SSc platelet releasates, tubule formation was significantly inhibited (p < 0.01, t test), and higher expression of endothelin-1 in these cells was observed compared with control subjects (p < 0.05, Mann-Whitney U test). In SSc platelet releasates, VEGF165b was significantly higher (p < 0.05, t test), and the VEGF165b/VEGF ratio was increased compared with that of control subjects. Higher secretion of transforming growth factor β (p < 0.01, t test) and CD40L (p < 0.01, t test) was observed compared with control subjects. Also, intraplatelet serotonin levels were lower in platelets obtained from patients with diffuse SSc compared with patients with limited SSc and control subjects (p < 0.05, t test).

CONCLUSIONS

Our findings suggest that antiangiogenic factors such as VEGF165b, together with proinflammatory and profibrotic factors secreted by platelets, can contribute to the progression of peripheral microvascular damage, defective vascular repair, and fibrosis in patients with SSc.

Endothelial dysfunction in systemic sclerosis

PURPOSE OF REVIEW

Microvascular endothelial cells (MVECs) injury is a critical early event in the pathogenesis of systemic sclerosis (SSc). We aim to provide the reader with an update regarding the role of MVECs in the pathogenesis of SSc and the mechanisms for MVECs dysfunction in the disease.

RECENT FINDINGS

Recent evidence confirms the central role for MVECs in the pathogenesis of SSc, and suggests further mechanisms for MVECs injury. The impact of MVECs perturbations in SSc goes beyond the initiation of the vascular disease to include activation of fibroblasts through the release of cytokines and growth factors like connective tissue growth factor that induce an active and aggressive form of fibroblasts. Moreover, recent studies highlighted a more prominent role for epigenetic factors in the pathogenesis of SSc, and suggested defects in the function of progenitor endothelial cells in SSc. Recent reports helped to shed light on the role of antiendothelial cell antibodies in the pathogenesis of SSc, especially purified subsets of these antibodies like anti-ICAM-1 antibodies, and also reported possible mechanisms for defective vascular endothelial growth factor signaling.

SUMMARY

It is clear that MVECs dysfunction is a key element in the pathogenesis of SSc, but the initial triggers for MVEC dysfunction remain uncharacterized.

Low-dose triptolide in combination with idarubicin induces apoptosis in AML leukemic stem-like KG1a cell line by modulation of the intrinsic and extrinsic factors

Leukemia stem cells (LSCs) are considered to be the main reason for relapse and are also regarded as a major hurdle for the success of acute myeloid leukemia chemotherapy. Thus, new drugs targeting LSCs are urgently needed. Triptolide (TPL) is cytotoxic to LSCs. Low dose of TPL enhances the cytotoxicity of idarubicin (IDA) in LSCs. In this study, the ability of TPL to induce apoptosis in leukemic stem cell (LSC)-like cells derived from acute myeloid leukemia cell line KG1a was investigated. LSC-like cells sorted from KG1a were subjected to cell cycle analysis and different treatments, and then followed by in vitro methyl thiazole tetrazolium bromide cytotoxicity assay. The effects of different drug combinations on cell viability, intracellular reactive-oxygen species (ROS) activity, colony-forming ability and apoptotic status were also examined. Combination index-isobologram analysis indicates a synergistic effect between TPL and IDA, which inhibits the colony-forming ability of LSC-like cells and induces their apoptosis. We further investigated the expression of Nrf2, HIF-1α and their downstream target genes. LSC-like cells treated with both TPL and IDA have increased levels of ROS, decreased expression of Nrf2 and HIF-1α pathways. Our findings indicate that the synergistic cytotoxicity of TPL and IDA in LSCs-like cells may attribute to both induction of ROS and inhibition of the Nrf2 and HIF-1α pathways.

Breast cancer in systemic sclerosis: results of a cross-linkage of an Italian Rheumatologic Center and a population-based Cancer Registry and review of the literature

OBJECTIVE

Increased frequency of few types of cancer in systemic sclerosis (SSc) has been reported in the literature; in particular, breast carcinoma has been proposed as one of the most frequent malignancy in SSc patients, even though data are not univocal. The aim of the present study was to retrospectively evaluate the prevalence of breast cancer in our SSc series, compared with sex-/age-matched general population of the same geographical area, and the possible correlations with SSc features, including X-ray exposure for clinical investigations. A review of the world literature about this topic was also done.

METHODS

Clinical records of 318 consecutive SSc patients, 31 M and 287 F, age 51.5±14.5 SD years, disease duration 10±6.5 SD years, referred to our Rheumatology Unit between January 2002 and December 2012 were evaluated.

RESULTS

Twelve (3.8%) cases of breast cancer were recorded, including 11/287 females (3.8%) and 1/31 (3.2%) male patients. Considering the subgroup of 202 SSc patients resident in the Province of Modena compared with data of the local Tumor Registry, the incidence of breast cancer observed in our SSc series is significantly higher than expected (SIR 2.1; 95% interval of confidence: 1.13-3.90; p<0.01). On the whole, the comparison between SSc patients with cancer and those without did not show any significant differences with regard to SSc clinical features, including the X-ray exposure. Of note is the relatively shorter disease duration at the time of breast cancer detection (median 2.5years, range 1-21; disease duration of mean 10±6.5 SD years in the entire cohort). The review of the literature revealed that the observed incidence of breast cancer in our case series is comparable to the few studies reporting the highest percentages of this malignancy.

CONCLUSIONS

A significant increase of breast cancer incidence compared to sex-age-matched general population from the same geographic area was observed. Moreover, a close temporal relationship between SSc and breast cancer onset was found, independently from clinical, serological, and instrumental features of SSc. The possible pathogenetic link between this systemic autoimmune disease and complicating breast cancer, as well as the results of previous studies, are discussed.