Hypoxia-sensitive pathways in inflammation-driven fibrosis

Hydrogel crosslinking modulates macrophages, fibroblasts, and their communication, during wound healing

Biomaterial wound dressings, such as hydrogels, interact with host cells to regulate tissue repair. This study investigates how crosslinking of gelatin-based hydrogels influences immune and stromal cell behavior and wound healing in female mice. We observe that softer, lightly crosslinked hydrogels promote greater cellular infiltration and result in smaller scars compared to stiffer, heavily crosslinked hydrogels. Using single-cell RNA sequencing, we further show that heavily crosslinked hydrogels increase inflammation and lead to the formation of a distinct macrophage subpopulation exhibiting signs of oxidative activity and cell fusion. Conversely, lightly crosslinked hydrogels are more readily taken up by macrophages and integrated within the tissue. The physical properties differentially affect macrophage and fibroblast interactions, with heavily crosslinked hydrogels promoting pro-fibrotic fibroblast activity that drives macrophage fusion through RANKL signaling. These findings suggest that tuning the physical properties of hydrogels can guide cellular responses and improve healing, offering insights for designing better biomaterials for wound treatment.

Radiation-induced fibrosis: Mechanisms and therapeutic strategies from an immune microenvironment perspective

Radiation-induced fibrosis (RIF) is a severe chronic complication of radiotherapy (RT) manifested by excessive extracellular matrix (ECM) components deposition within the irradiated area. The lung, heart, skin, jaw, pelvic organs and so on may be affected by RIF, which hampers body functions and quality of life. There is accumulating evidence suggesting that the immune microenvironment may play a key regulatory role in RIF. This article discussed the synergetic or antagonistic effects of immune cells and mediators in regulating RIF's development. Several potential preventative and therapeutic strategies for RIF were proposed based on the immunological mechanisms to provide clinicians with improved cognition and clinical treatment guidance.

Effect of apigetrin in pseudo-SARS-CoV-2-induced inflammatory and pulmonary fibrosis in vitro model

SARS-CoV-2 has become a global public health problem. Acute respiratory distress syndrome (ARDS) is the leading cause of death due to the SARS-CoV-2 infection. Pulmonary fibrosis (PF) is a severe and frequently reported COVID-19 sequela. In this study, an in vitro model of ARDS and PF caused by SARS-CoV-2 was established in MH-S, THP-1, and MRC-5 cells using pseudo-SARS-CoV-2 (PSCV). Expression of proinflammatory cytokines (IL-6, IL-1β, and TNF-α) and HIF-1α was increased in PSCV-infected MH-S and THP-1 cells, ARDS model, consistent with other profiling data in SARS-CoV-2-infected patients have been reported. Hypoxia-inducible factor-1 alpha (HIF-1α) siRNA and cobalt chloride were tested using this in vitro model. HIF-1α knockdown reduces inflammation caused by PSCV infection in MH-S and THP-1 cells and lowers elevated levels of CTGF, COLA1, and α-SMA in MRC-5 cells exposed to CPMSCV. Furthermore, apigetrin, a glycoside bioactive dietary flavonoid derived from several plants, including Crataegus pinnatifida, which is reported to be a HIF-1α inhibitor, was tested in this in vitro model. Apigetrin significantly reduced the increased inflammatory cytokine (IL-6, IL-1β, and TNF-α) expression and secretion by PSCV in MH-S and THP-1 cells. Apigetrin inhibited the binding of the SARS-CoV-2 spike protein RBD to the ACE2 protein. An in vitro model of PF induced by SARS-CoV-2 was produced using a conditioned medium of THP-1 and MH-S cells that were PSCV-infected (CMPSCV) into MRC-5 cells. In a PF model, CMPSCV treatment of THP-1 and MH-S cells increased cell growth, migration, and collagen synthesis in MRC-5 cells. In contrast, apigetrin suppressed the increase in cell growth, migration, and collagen synthesis induced by CMPSCV in THP-1 and MH-S MRC-5 cells. Also, compared to control, fibrosis-related proteins (CTGF, COLA1, α-SMA, and HIF-1α) levels were over two-fold higher in CMPSV-treated MRC-5 cells. Apigetrin decreased protein levels in CMPSCV-treated MRC-5 cells. Thus, our data suggest that hypoxia-inducible factor-1 alpha (HIF-1α) might be a novel target for SARS-CoV-2 sequela therapies and apigetrin, representative of HIF-1alpha inhibitor, exerts anti-inflammatory and PF effects in PSCV-treated MH-S, THP-1, and CMPVSC-treated MRC-5 cells. These findings indicate that HIF-1α inhibition and apigetrin would have a potential value in controlling SARS-CoV-2-related diseases.

Resveratrol promotes the differentiation of human umbilical cord mesenchymal stem cells into esophageal fibroblasts via AKT signaling pathway

Objectives: Resveratrol has been implicated in the differentiation and development of human umbilical cord mesenchymal stem cells. The differentiation of into esophageal fibroblasts is a promising strategy for esophageal tissue engineering. However, the pharmacological effect and underlying mechanism of resveratrol on human umbilical cord mesenchymal stem cells differentiation are unknown. Here, we investigated the effects and mechanism of resveratrol on the differentiation of human umbilical cord mesenchymal stem cells. Methods: Using a transwell-membrane coculture system to culture human umbilical cord mesenchymal stem cells and esophageal fibroblasts, we examined how resveratrol act on the differentiation of human umbilical cord mesenchymal stem cells. Immunocytochemistry, Sirius red staining, quantitative real-time PCR, and Western blotting were performed to examine collagen synthesis and possible signaling pathways in human umbilical cord mesenchymal stem cells. Results: We found that resveratrol promoted collagen synthesis and AKT phosphorylation. However, co-treatment of cells with resveratrol and the PI3K inhibitor LY294002 inhibited collagen synthesis and AKT phosphorylation. We demonstrated that resveratrol down-regulated the expression of IL-6, TGF-β, caspase-9, and Bax by activating the AKT pathway in human umbilical cord mesenchymal stem cell. Furthermore, resveratrol inhibited phosphorylated NF-ĸB in human umbilical cord mesenchymal stem cells. Conclusion: Our data suggest that resveratrol promotes the differentiation of human umbilical cord mesenchymal stem cells into fibroblasts. The underlying mechanism is associated with the downregulation of IL-6 and TGF-β via the AKT pathway and by inhibiting the NF-ĸB pathway. Resveratrol may be useful for esophageal tissue engineering.

Post-COVID Interstitial Lung Disease and Other Lung Sequelae

As the world emerges from the COVID-19 pandemic, clinicians and researchers across the world are trying to understand the sequelae in patients recovered from COVID-19 infection. In this article, the authors review post-acute sequelae of SARS-COV-2, interstitial lung disease, and other lung sequelae in patients recovering from COVID-19 infection.

Role of HIF-1α in pathogenic mechanisms of keloids

BACKGROUDS AND OBJECTIVE

Keloids are defined as overrepairing products that develop after skin lesions. Keloids are characterized by the proliferation of fibroblasts and the overaccumulation of extracellular matrix components (mainly collagen), leading to a locally hypoxic microenvironment. Hence, this article was aimed to review hypoxia in pathogenesis of keloids.

METHODS

We reviewed and summarized the relevant published studies.

RESULTS

Hypoxia results in the accumulation of hypoxia-inducible factor 1α (HIF-1α) in keloids, contributing to overactivation of the fibrotic signaling pathway, epithelial-mesenchymal transition, and changes in metabolism, eventually leading to aggravated fibrosis, infiltrative growth, and radiotherapy resistance.

CONCLUSION

It is, therefore, essential to understand the role of HIF-1α in the pathogenic mechanisms of keloids in order to develop new therapeutic approaches.

Hypoxia-Inducible Factor 1-Alpha Stabilizers in the Treatment of Inflammatory Bowel Diseases: Oxygen as a Novel IBD Therapy?

Despite the significant advances in the medical armamentarium for inflammatory bowel diseases [IBD], current treatment options have notable limitations. Durable remission rates remain low, loss of response is common, administration routes are largely parenteral for novel biologics, and medication safety remains a concern. This explains an ongoing unmet need for safe medications with novel mechanisms of action that are administered orally. In line with these criteria, hypoxia-inducible factor [HIF]-1α stabilizers, acting via inhibition of prolyl hydroxylase enzymes, are emerging as an innovative therapeutic strategy. We herein review the mechanism of action and available clinical data for HIF-1α stabilizers and their potential place in the future IBD treatment algorithm.

Hypoxia-inducible factor as a bridge between healthy barrier function, wound healing, and fibrosis

The healthy mammalian intestine is lined by a single layer of epithelial cells. These cells provide a selectively permeable barrier to luminal contents and normally do so in an efficient and effective manner. Barrier function in the healthy mucosa is provided via several mechanisms including epithelial junctional complexes, mucus production, as well as mucosal-derived antimicrobial proteins. As tissue metabolism is central to the maintenance of homeostasis in the mucosa, intestinal [Formula: see text] levels are uniquely low due to counter-current blood flow and the presence of the microbiota, resulting in the stabilization of the transcription factor hypoxia-inducible factor (HIF). Ongoing studies have revealed that HIF molds normal intestinal metabolism and is central to the coordination of barrier regulation during both homeostasis and active disease. During acute inflammation, HIF is central to controlling the rapid restitution of the epithelium consistent with normal wound healing responses. In contrast, HIF may also contribute to the fibrostenotic response associated with chronic, nonresolving inflammation. As such, HIF may function as a double-edged sword in the overall course of the inflammatory response. Here, we review recent literature on the contribution of HIF to mucosal barrier function, wound healing, and fibrosis.

Nrf2 driven macrophage responses in diverse pathophysiological contexts: Disparate pieces from a shared molecular puzzle

The wide anatomical distribution of macrophages and their vast array of functions match various polarization states and their involvement in homeostasis and disease. The confluence of different cellular signaling networks, including direct involvement in inflammation, at the doorstep of the transcription factor Nuclear Factor- erythroid (NF-E2) p45-related factor 2 (Nrf2) activation raises the importance of deciphering the molecular circuitry at the background of multiple-discrete and antagonistic yet flexible and contextual pathways. While we primarily focus on wound healing and repair mechanisms that are affected in diabetic foot ulcers (DFUs), we strive to explore the striking similarities and differences in molecular events including inflammation, angiogenesis, and fibrosis during tissue injury and wound persistence that accumulates pro-inflammatory senescent macrophages, as a means to identify possible targets or cellular mediators to lessen DFU disease burden. In addition, the role of iron in the modulation of Nrf2 response in macrophages is crucial and reviewed here. Targeted approaches, unlike conventional treatments, in DFU management will require the review and re-assessment of mediators with relevance to other pathological conditions.

Hypoxia and Hypoxia-Inducible Factors in Lymphedema

Lymphedema is a chronic inflammatory disorder characterized by edema, fat deposition, and fibrotic tissue remodeling. Despite significant advances in lymphatic biology research, our knowledge of lymphedema pathology is incomplete. Currently, there is no approved pharmacological therapy for this debilitating disease. Hypoxia is a recognized feature of inflammation, obesity, and fibrosis. Understanding hypoxia-regulated pathways in lymphedema may provide new insights into the pathobiology of this chronic disorder and help develop new medicinal treatments.

Endometriosis and adverse pregnancy outcome

INTRODUCTION

Endometriosis is a gynecologic disease affecting approximately 10% of reproductive age women, around 21-47% of women presenting subfertility and 71-87% of women with chronic pelvic pain. Main symptoms are chronic pelvic pain, dysmenorrhea, dyspareunia and infertility that seem to be well controlled by oral contraceptive pill, progestogens, GnRh antagonists. The aim of this review was to illustrate the modern diagnosis of endometriosis during pregnancy, to evaluate the evolution of endometriotic lesions during pregnancy and the incidence of adverse outcomes.

EVIDENCE ACQUISITION

Published literature was retrieved through searches of the database PubMed (National Center for Biotechnology Information, US National Library of Medicine, Bethesda, MD, USA). We searched for all original articles published in English through April 2020 and decided to extract every notable information for potential inclusion in this review. The search included the following MeSH search terms, alone or in combination: "endometriosis" combined with "endometrioma," "biomarkers," "complications," "bowel," "urinary tract," "uterine rupture," "spontaneous hemoperitoneum in pregnancy" and more "adverse pregnancy outcome," "preterm birth," "miscarriage," "abruption placentae," "placenta previa," "hypertensive disorder," "preeclampsia," "fetal grow restriction," "small for gestation age," "cesarean delivery."

EVIDENCE SYNTHESIS

Pregnancy in women with endometriosis does not always lead to disappearance of symptoms and decrease in the size of endometriotic lesions, but it may be possible to observe a malignant transformation of ovarian endometriotic lesions. Onset of complications may be caused by many factors: chronic inflammation, adhesions, progesterone resistance and a dysregulation of genes involved in the embryo implantation. As results, the pregnancy can be more difficult because of endometriosis related complications (spontaneous hemoperitoneum [SH], bowel complications, etc.) or adverse outcomes like preterm birth, FGR, hypertensive disorders, obstetrics hemorrhages (placenta previa, abruptio placenta), miscarriage or cesarean section. Due to insufficient knowledge about its pathogenesis, currently literature data are contradictory and do not show a strong correlation between endometriosis and these complications except for miscarriage and cesarean delivery.

CONCLUSIONS

Future research should focus on the potential biological pathways underlying these relationships in order to inform patients planning a birth about possible complications during pregnancy.

Post-COVID-19 Pulmonary Fibrosis: Novel Sequelae of the Current Pandemic

Since the initial identification of the novel coronavirus SARS-CoV-2 in December 2019, the COVID-19 pandemic has become a leading cause of morbidity and mortality worldwide. As effective vaccines and treatments begin to emerge, it will become increasingly important to identify and proactively manage the long-term respiratory complications of severe disease. The patterns of imaging abnormalities coupled with data from prior coronavirus outbreaks suggest that patients with severe COVID-19 pneumonia are likely at an increased risk of progression to interstitial lung disease (ILD) and chronic pulmonary vascular disease. In this paper, we briefly review the definition, classification, and underlying pathophysiology of interstitial lung disease (ILD). We then review the current literature on the proposed mechanisms of lung injury in severe COVID-19 infection, and outline potential viral- and immune-mediated processes implicated in the development of post-COVID-19 pulmonary fibrosis (PCPF). Finally, we address patient-specific and iatrogenic risk factors that could lead to PCPF and discuss strategies for reducing risk of pulmonary complications/sequelae.

Deciduosis of the Appendix During Pregnancy

Acute appendicitis is an important differential diagnosis in patients with right lower quadrant pain during pregnancy. Endometriosis, a hormone-related pathology, is another possibility. Patients with endometriosis are typically symptomatic before pregnancy. Stromal endometriosis is a variant of endometriosis that presents no symptoms before pregnancy but which occasionally presents with the new onset of symptoms during pregnancy. We report the case of a 35-year-old woman in her 8th month of pregnancy who presented with impending appendiceal rupture due to deciduosis of the appendix, a progesterone-related condition, during pregnancy. This case suggests that deciduosis/stromal endometriosis should be considered as a differential diagnosis of acute abdomen during pregnancy, even if the patient is asymptomatic before pregnancy.

Uterine pseudoaneurysm on the basis of deep infiltrating endometriosis during pregnancy-a case report

Background

Pseudoaneurysm of the uterine artery (UPA) is a rare cause of potentially life-threatening hemorrhage during pregnancy and puerperium. It is an uncommon condition that mainly occurs after traumatic injury to a vessel following pelvic surgical intervention, but also has been reported based on underlying endometriosis. There is an increased risk of developing UPA during pregnancy. Diagnosis includes clinical symptoms, with severe abdominal pain and is confirmed by sonographic or magnetic resonance imaging (MRI). Due to its potential risk of rupture, with a subsequent hypovolemic maternal shock and high fetal mortality, an interdisciplinary treatment should be considered expeditiously.

Case presentation

We present the case of a 34-year old pregnant symptomatic patient, where a large UPA was detected at 26 weeks, based on deep infiltrating endometriosis (DIE). The UPA was successfully treated by selective arterial embolization. After embolization, the pain decreased but the woman still required intravenous analgesics during follow-up. At 37 weeks she developed a sepsis from the intravenous catheter which led to a cesarean section and delivery of a healthy boy. She was discharged 10 days postpartum.

Conclusions

UPA should be considered in pregnant women with severe abdominal and pelvic pain, once other obstetrical factors have been excluded. DIE might be the underlying diagnosis. It is a rare but potentially life-threatening condition for mother and fetus.

Hypoxia Reduces the Transcription of Fibrotic Markers in the Intestinal Mucosa

Introduction

Intestinal fibrosis, characterized by excessive deposition of extracellular matrix proteins, is a common and severe clinical complication of inflammatory bowel disease (IBD). However, the mechanisms underlying fibrosis remain elusive, and currently, there are limited effective pharmacologic treatments that target the development of fibrosis. Hypoxia is one of the key microenvironmental factors influencing intestinal inflammation and has been linked to fibrosis.

Objective

In the present study, we sought to elucidate the impact of hypoxia on fibrotic gene expression in the intestinal mucosa.

Methods

Human volunteers, IBD patients, and dextran sulphate sodium-treated mice were exposed to hypoxia, and colonic biopsies were collected. The human intestinal epithelial cell line Caco-2, human THP-1 macrophages, and primary human gut fibroblasts were subjected to hypoxia, and changes in fibrotic gene expression were assessed.

Results

Human volunteers subjected to hypoxia presented reduced transcriptional levels of fibrotic and epithelial-mesenchymal transition markers in the intestinal mucosa. IBD patients showed a trend towards a decrease in tissue inhibitor of metalloproteinase 1 protein expression. In mice, hypoxic conditions reduced the colonic expression of several collagens and matrix metalloproteinases. Hypoxic Caco-2 cells, THP-1 cells, and primary gut fibroblasts showed a significant downregulation in the expression of fibrotic and tissue remodelling factors.

Conclusions

Stabilization of hypoxia-inducible factors might represent a novel therapeutic approach for the treatment of IBD-associated fibrosis.

Increased Production of LIGHT by T Cells in Eosinophilic Esophagitis Promotes Differentiation of Esophageal Fibroblasts Toward an Inflammatory Phenotype

BACKGROUND & AIMS

Eosinophilic esophagitis (EoE) is an antigen-mediated eosinophilic disease of the esophagus that involves fibroblast activation and progression to fibrostenosis. Cytokines produced by T-helper type 2 cells and transforming growth factor beta 1 (TGFβ1) contribute to the development of EoE, but other cytokines involved in pathogenesis are unknown. We investigate the effects of tumor necrosis factor superfamily member 14 (TNFSF14, also called LIGHT) on fibroblasts in EoE.

METHODS

We analyzed publicly available esophageal CD3+ T-cell single-cell sequencing data for expression of LIGHT. Esophageal tissues were obtained from pediatric patients with EoE or control individuals and analyzed by immunostaining. Human primary esophageal fibroblasts were isolated from esophageal biopsy samples of healthy donors or patients with active EoE. Fibroblasts were cultured; incubated with TGFβ1 and/or LIGHT; and analyzed by RNA sequencing, flow cytometry, immunoblots, immunofluorescence, or reverse transcription polymerase chain reaction. Eosinophils were purified from peripheral blood of healthy donors, incubated with interleukin 5, cocultured with fibroblasts, and analyzed by immunohistochemistry.

RESULTS

LIGHT was up-regulated in the esophageal tissues from patients with EoE, compared with control individuals, and expressed by several T-cell populations, including T-helper type 2 cells. TNF receptor superfamily member 14 (TNFRSF14, also called HVEM) and lymphotoxin beta receptor are receptors for LIGHT that were expressed by fibroblasts from healthy donors or patients with active EoE. Stimulation of esophageal fibroblasts with LIGHT induced inflammatory gene transcription, whereas stimulation with TGFβ1 induced transcription of genes associated with a myofibroblast phenotype. Stimulation of fibroblasts with TGFβ1 increased expression of HVEM; subsequent stimulation with LIGHT resulted in their differentiation into cells that express markers of myofibroblasts and inflammatory chemokines and cytokines. Eosinophils tethered to esophageal fibroblasts after LIGHT stimulation via intercellular adhesion molecule-1.

CONCLUSIONS

T cells in esophageal tissues from patients with EoE express increased levels of LIGHT compared with control individuals, which induces differentiation of fibroblasts into cells with inflammatory characteristics. TGFβ1 increases fibroblast expression of HVEM, a receptor for LIGHT. LIGHT mediates interactions between esophageal fibroblasts and eosinophils via ICAM1. This pathway might be targeted for the treatment of EoE.

Hypoxia and HIF Signaling: One Axis with Divergent Effects

The correct concentration of oxygen in all tissues is a hallmark of cellular wellness, and the negative regulation of oxygen homeostasis is able to affect the cells and tissues of the whole organism. The cellular response to hypoxia is characterized by the activation of multiple genes involved in many biological processes. Among them, hypoxia-inducible factor (HIF) represents the master regulator of the hypoxia response. The active heterodimeric complex HIF α/β, binding to hypoxia-responsive elements (HREs), determines the induction of at least 100 target genes to restore tissue homeostasis. A growing body of evidence demonstrates that hypoxia signaling can act by generating contrasting responses in cells and tissues. Here, this dual and controversial role of hypoxia and the HIF signaling pathway is discussed, with particular reference to the effects induced on the complex activities of the immune system and on mechanisms determining cell and tissue responses after an injury in both acute and chronic human diseases related to the heart, lung, liver, and kidney.

M2 Macrophages and Phenotypic Modulation of Intestinal Smooth Muscle Cells Characterize Inflammatory Stricture Formation in Rats

The progression of Crohn disease to intestinal stricture formation is poorly controlled, and the pathogenesis is unclear, although increased smooth muscle mass is present. A previously described rat model of trinitrobenzenesulfonic acid-induced colitis is re-examined here. Although inflammation of the mid-descending colon typically resolved, a subset showed characteristic stricturing by day 16, with an inflammatory infiltrate in the neuromuscular layers including eosinophils, CD3-positive T cells, and CD68-positive macrophages. Closer study identified CD163-positive, CD206-positive, and arginase-positive cells, indicating a M2 macrophage phenotype. Stricturing involved ongoing proliferation of intestinal smooth muscle cells (ISMC) with expression of platelet-derived growth factor receptor beta and progressive loss of phenotypic markers, and stable expression of hypoxia inducible factor 1 subunit alpha. In parallel, collagen I and III showed a selective and progressive increase over time. A culture model of the stricture phenotype of ISMC showed stable hypoxia inducible factor 1 subunit alpha expression that promoted growth and improved both survival and growth in models of experimental ischemia. This phenotype was hyperproliferative to serum and platelet-derived growth factor BB, and unresponsive to transforming growth factor beta, a prominent cytokine of M2 macrophages, compared with control ISMC. We identified a hyperplastic phenotype of ISMC, uniquely adapted to an ischemic environment to drive smooth muscle layer expansion, which may reveal new targets for treating intestinal fibrosis.

Impaired function of aorta and perivascular adipose tissue in IL-18-deficient mice

IL-18 is ubiquitously produced by both hematopoietic and non-hematopoietic cells. The present study examined the thoracic aorta, including the surrounding perivascular adipose tissue (PVAT), of IL-18KO mice from functional and histological perspectives. IL-18KO mice exhibited raised blood pressure compared with wild-type mice. Echocardiographic examination showed a thickened vascular wall and narrowed vascular diameter of the aorta. Examination by the Magnus test demonstrated dysfunction of endothelial cells (ECs) in the IL-18KO thoracic aorta and impairment of the anticontractile function of IL-18KO PVAT. Histological examination showed no inflammatory lesions in the aorta but indicated progressive fibrosis in the vessel and conversion of PVAT from brown adipose tissue-like features to white adipose tissue-like features. Electron microscopic observation suggested several deformed mitochondria in the aorta and vacuole-like structures in ECs from IL-18KO mice. In addition, activity of complex IV was lower and production of reactive oxygen species was augmented in the mitochondria of IL-18KO aorta. Although expression of LC3 B was higher, rapamycin-induced autophagy flux was impaired in the IL-18KO PVAT. Moreover, Western blot analysis revealed that LAMP 1/2 was increased in IL-18KO PVAT, and measurement of cathepsin-D activity indicated decreased levels in IL-18KO PVAT. The IL-18KO thoracic aorta thus showed defects in physiological functions related to histological alterations, and the inflammasome/IL-18 system was suggested to play a protective role in cardiovascular cells, probably through quality control of mitochondria via promotion of autophagosome/autophagolysosome formation.NEW & NOTEWORTHY IL-18 deficiency caused aortic abnormalities in terms of morphology and functions in parallel with an accumulation of damaged mitochondria and anomalous turnover of protein complexes, such as PGC-1 and LAMP1 and -2 in PVAT. These findings suggested that IL-18 plays roles in maintaining the homeostasis of vessels and PVAT around the aorta, possibly by promoting autophagy.

Laser fluorescence spectroscopy and optical tissue oximetry in the diagnosis of skin fibrosis

There are currently no effective measures to combat fibrosis in modern medical practice. One of the reasons for that is the late diagnosis associated with the lack of available clinical biomarkers and effective methods of non-invasive detection of the process. Fibrosis of the skin is characterized by fibrosis of the dermis, underlying tissues and is represented by a wide range of nosologies. Scleroderma and scars are of the greatest interest for the study. Skin changes in the development of bleomycin-induced fibrosis was studied in the experimental model using laser fluorescence spectroscopy and optical tissue oximetry. A significant increase in the rates of endogenous fluorescence of porphyrins, caused by inflammation and hypoxia, was detected at 7 and 21 days. An increased intensity of endogenous collagen fluorescence and a decreased specific oxygen uptake due to excess accumulation of the extracellular matrix were recorded on the 21st day after bleomycin treatment. Synchronous measurements of the collagen fluorescence and the specific oxygen uptake allowed to correlate the obtained data and the phases of the fibrogenic response described morphologically. The results allow to judge the severity of inflammation and hypoxia in the process of the fibrosis development. The objective and quantitative nature of the recorded parameters makes it possible to develop criteria for diagnosing the phases of fibrosis development.

Hyperbaric oxygen therapy improves the effect of keloid surgery and radiotherapy by reducing the recurrence rate

OBJECTIVE

Keloids are exuberant cutaneous scars that form due to abnormal growth of fibrous tissue following an injury. The primary aim of this study was to assess the efficacy and mechanism of hyperbaric oxygen therapy (HBOT) to reduce the keloid recurrence rate after surgical excision and radiotherapy.

METHODS

(1) A total of 240 patients were randomly divided into two groups. Patients in the HBOT group (O group) received HBOT after surgical excision and radiotherapy. Patients in the other group were treated with only surgical excision and radiotherapy (K group). (2) Scar tissue from recurrent patients was collected after a second operation. Hematoxylin and eosin (H&E) staining was used to observe keloid morphology. Certain inflammatory factors (interleukin-6 (IL-6), hypoxia-inducible factor-1α (HIF-1α), tumor necrosis factor-α (TNF-α), nuclear factor κB (NF-κB), and vascular endothelial growth factor (VEGF)) were measured using immunohistochemical staining.

RESULTS

(1) The recurrence rate of the O group (5.97%) was significantly lower than that of the K group (14.15%), P<0.05. Moreover, patients in the O group reported greater satisfaction than those in the K group (P<0.05). (2) Compared with the recurrent scar tissue of the K group, the expression levels of the inflammatory factors were lower in the recurrent scar tissue of the O group.

CONCLUSIONS

Adjunctive HBOT effectively reduces the keloid recurrence rate after surgical excision and radiotherapy by improving the oxygen level of the tissue and alleviating the inflammatory process.

Mechanisms and context underlying the role of autophagy in cancer metastasis

Macroautophagy/autophagy is a fundamental cellular degradation mechanism that maintains cell homeostasis, regulates cell signaling, and promotes cell survival. Its role in promoting tumor cell survival in stress conditions is well characterized, and makes autophagy an attractive target for cancer therapy. Emerging research indicates that autophagy also influences cancer metastasis, which is the primary cause of cancer-associated mortality. However, data demonstrate that the regulatory role of autophagy in metastasis is multifaceted, and includes both metastasis-suppressing and -promoting functions. The metastasis-suppressing functions of autophagy, in particular, have important implications for autophagy-based treatments, as inhibition of autophagy may increase the risk of metastasis. In this review, we discuss the mechanisms and context underlying the role of autophagy in metastasis, which include autophagy-mediated regulation of focal adhesion dynamics, integrin signaling and trafficking, Rho GTPase-mediated cytoskeleton remodeling, anoikis resistance, extracellular matrix remodeling, epithelial-to-mesenchymal transition signaling, and tumor-stromal cell interactions. Through this, we aim to clarify the context-dependent nature of autophagy-mediated metastasis and provide direction for further research investigating the role of autophagy in cancer metastasis.

Anti-inflammatory effects of Lefty-1 in renal tubulointerstitial inflammation via regulation of the NF-κB pathway

Renal tubulointerstitial inflammation has an important role in fibrosis, which is the main pathogenetic alteration associated with chronic kidney disease (CKD). The left-right determination factor 1 (Lefty-1) gene pleiotropically and biologically regulates transforming growth factor, mitogen-activated protein kinase and other signaling pathways, and is considered to have a potential anti-inflammatory function. However, its role in renal tubulointerstitial inflammation, which is often a long-term consequence of renal fibrosis, is currently unknown. In the present study, the effects of adenovirus-mediated overexpression of Lefty-1 (Ad-Lefty-1-flag) on renal tubulointerstitial inflammation were determined using a mouse model of unilateral ureteral obstruction (UUO) and a rat renal tubular duct epithelial cell line (NRK-52E), which was treated with lipopolysaccharide (LPS). In vivo results indicated that the inflammatory response was increased in UUO mice, as evidenced by the increase in inflammatory cytokines and chemokines. Conversely, Lefty-1 significantly reversed the effects of UUO. Furthermore, the results of the in vitro study demonstrated that Lefty-1 significantly inhibited LPS-induced inflammatory marker expression in cultured NRK-52E cells via the nuclear factor (NF)-κB signaling pathway. These results suggested that Lefty-1 may ameliorate renal tubulointerstitial inflammation by suppressing NF-κB signaling. In conclusion, the findings of the present study indicated that Lefty-1 may be considered a potential novel therapeutic agent for inhibiting renal tubulointerstitial inflammation or even reversing the CKD process.

Regulation of immunity and inflammation by hypoxia in immunological niches

Immunological niches are focal sites of immune activity that can have varying microenvironmental features. Hypoxia is a feature of physiological and pathological immunological niches. The impact of hypoxia on immunity and inflammation can vary depending on the microenvironment and immune processes occurring in a given niche. In physiological immunological niches, such as the bone marrow, lymphoid tissue, placenta and intestinal mucosa, physiological hypoxia controls innate and adaptive immunity by modulating immune cell proliferation, development and effector function, largely via transcriptional changes driven by hypoxia-inducible factor (HIF). By contrast, in pathological immunological niches, such as tumours and chronically inflamed, infected or ischaemic tissues, pathological hypoxia can drive tissue dysfunction and disease development through immune cell dysregulation. Here, we differentiate between the effects of physiological and pathological hypoxia on immune cells and the consequences for immunity and inflammation in different immunological niches. Furthermore, we discuss the possibility of targeting hypoxia-sensitive pathways in immune cells for the treatment of inflammatory disease.

From Endometriosis to Pregnancy: Which is the “Road-Map”?

In the last decade, pregnancy was considered as a therapeutic period for patients affected by endometriosis and painful symptoms. However, several studies have taken into consideration how endometriosis affects pregnancy achievement and pregnancy development, including obstetric complications. The adverse effects of endometriosis on the development of pregnancy include miscarriage, hypertensive disorders and pre-eclampsia, placenta previa, obstetric hemorrhages, preterm birth, small for gestational age, and adverse neonatal outcomes. The aim of this review is to analyze the current literature regarding the relationship between different forms of endometriosis (endometrioma, peritoneal endometriosis, deep endometriosis) and infertility, and the impact of endometriosis on pregnancy outcomes.

Specialized pro-resolving mediators in renal fibrosis

Inflammation and its timely resolution play a critical role in effective host defence and wound healing. Unresolved inflammatory responses underlie the pathology of many prevalent diseases resulting in tissue fibrosis and eventual organ failure as typified by kidney, lung and liver fibrosis. The role of autocrine and paracrine mediators including cytokines, prostaglandins and leukotrienes in initiating and sustaining inflammation is well established. More recently a physiological role for specialized pro-resolving lipid mediators [SPMs] in modulating inflammatory responses and promoting the resolution of inflammation has been appreciated. As will be discussed in this review, SPMs not only attenuate the development of fibrosis through promoting the resolution of inflammation but may also directly suppress fibrotic responses. These findings suggest novel therapeutic paradigms to treat intractable life-limiting diseases such as renal fibrosis.

Hypoxia Inducible Factor (HIF) Hydroxylases as Regulators of Intestinal Epithelial Barrier Function

Human health is dependent on the ability of the body to extract nutrients, fluids, and oxygen from the external environment while at the same time maintaining a state of internal sterility. Therefore, the cell layers that cover the surface areas of the body such as the lung, skin, and gastrointestinal mucosa provide vital semipermeable barriers that allow the transport of essential nutrients, fluid, and waste products, while at the same time keeping the internal compartments free of microbial organisms. These epithelial surfaces are highly specialized and differ in their anatomic structure depending on their location to provide appropriate and effective site-specific barrier function. Given this important role, it is not surprising that significant disease often is associated with alterations in epithelial barrier function. Examples of such diseases include inflammatory bowel disease, chronic obstructive pulmonary disease, and atopic dermatitis. These chronic inflammatory disorders often are characterized by diminished tissue oxygen levels (hypoxia). Hypoxia triggers an adaptive transcriptional response governed by hypoxia-inducible factors (HIFs), which are repressed by a family of oxygen-sensing HIF hydroxylases. Here, we review recent evidence suggesting that pharmacologic hydroxylase inhibition may be of therapeutic benefit in inflammatory bowel disease through the promotion of intestinal epithelial barrier function through both HIF-dependent and HIF-independent mechanisms.

Hypometabolism as the ultimate defence in stress response: how the comparative approach helps understanding of medically relevant questions

First conceptualized from breath-hold diving mammals, later recognized as the ultimate cell autonomous survival strategy in anoxia-tolerant vertebrates and burrowing or hibernating rodents, hypometabolism is typically recruited by resilient organisms to withstand and recover from otherwise life-threatening hazards. Through the coordinated down-regulation of biosynthetic, proliferative and electrogenic expenditures at times when little ATP can be generated, a metabolism turned 'down to the pilot light' allows the re-balancing of energy demand with supply at a greatly suppressed level in response to noxious exogenous stimuli or seasonal endogenous cues. A unifying hallmark of stress-tolerant organisms, the adaptation effectively prevents lethal depletion of ATP, thus delineating a marked contrast with susceptible species. Along with disengaged macromolecular syntheses, attenuated transmembrane ion shuttling and PO₂ -conforming respiration rates, the metabolic slowdown in tolerant species usually culminates in a non-cycling, quiescent phenotype. However, such a reprogramming also occurs in leading human pathophysiologies. Ranging from microbial infections through ischaemia-driven infarcts to solid malignancies, cells involved in these disorders may again invoke hypometabolism to endure conditions non-permissive for growth. At the same time, their reduced activities underlie the frequent development of a general resistance to therapeutic interventions. On the other hand, a controlled induction of hypometabolic and/or hypothermic states by pharmacological means has recently stimulated intense research aimed at improved organ preservation and patient survival in situations requiring acutely administered critical care. The current review article therefore presents an up-to-date survey of concepts and applications of a coordinated and reversibly down-regulated metabolic rate as the ultimate defence in stress responses.

Hydroxylase inhibition regulates inflammation-induced intestinal fibrosis through the suppression of ERK-mediated TGF-β1 signaling. [corrected]

Fibrosis is a complication of chronic inflammatory disorders such as inflammatory bowel disease, a condition which has limited therapeutic options and often requires surgical intervention. Pharmacologic inhibition of oxygen-sensing prolyl hydroxylases, which confer oxygen sensitivity upon the hypoxia-inducible factor pathway, has recently been shown to have therapeutic potential in colitis, although the mechanisms involved remain unclear. Here, we investigated the impact of hydroxylase inhibition on inflammation-driven fibrosis in a murine colitis model. Mice exposed to dextran sodium sulfate, followed by a period of recovery, developed intestinal fibrosis characterized by alterations in the pattern of collagen deposition and infiltration of activated fibroblasts. Treatment with the hydroxylase inhibitor dimethyloxalylglycine ameliorated fibrosis. TGF-β1 is a key regulator of fibrosis that acts through the activation of fibroblasts. Hydroxylase inhibition reduced TGF-β1-induced expression of fibrotic markers in cultured fibroblasts, suggesting a direct role for hydroxylases in TGF-β1 signaling. This was at least in part due to inhibition of noncanonical activation of extracellular signal-regulated kinase (ERK) signaling. In summary, pharmacologic hydroxylase inhibition ameliorates intestinal fibrosis through suppression of TGF-β1-dependent ERK activation in fibroblasts. We hypothesize that in addition to previously reported immunosupressive effects, hydroxylase inhibitors independently suppress profibrotic pathways.

[Morphometric and molecular biological features of femoral head tissue in different nosological entities of coxarthrosis]

AIM

to comparatively analyze the morphometric and molecular biological characteristics of femoral head tissue in different nosological entities of coxarthrosis.

MATERIAL AND METHODS

A total of 95 samples of femoral head tissue extirpated during hip endoprosthesis in patients with coxarthrosis were investigated. Clinical findings were used to identify the following nosological entities of coxarthrosis: dysplastic, postischemic and posttraumatic. Histological, immunohistochemical and morphometric studies were used. Osteoclast resorptive activity was assessed by determining the cytoplasmic expression of TRAcP (9C5, «Cell Marque»). Vasculogenesis was evaluated by estimating the mean area of vessels with CD34 (QBEnd/10, «Ventana») from the positive stained endothelium and by determining the cytoplasmic expression level of VEGF (SP28, «Spring Bio») in osteoblasts and osteoclasts.

RESULTS

Specific histopathological signs were described for each nosological entity of coxarthrosis. Morphometric analysis could reveal a number of additional characteristics of the magnitude of fibrous changes and the thickness of the articular surface and bone rods. Immunohistochemical assessment of molecular biological parameters, such as the expression level of VEGF and TRAcP, also pointed to the characteristic features of bony tissue in the above-mentioned nosological entities of coxarthrosis. In dysplastic coxarthrosis, the maximal expression level of VEGF was recorded in osteoblasts and the expression of VEGF and TRAcP in osteoclasts remained at the minimum level. The lowest expression of VEGF in osteoblasts was found in posttraumatic coxarthrosis. In postischemic coxarthrosis, the highest expression of VEGF and TRAcP was recorded in osteoclasts.

CONCLUSION

The comparative analysis of the morphometric and molecular biological characteristics of femoral head tissue in different nosological entities of coxarthrosis indicated a number of peculiar features. The most specific manifestations of certain morphological and molecular biological signs were identified for each nosological entity of coxarthrosis.

Exploring the HIFs, buts and maybes of hypoxia signalling in disease: lessons from zebrafish models

A low level of tissue oxygen (hypoxia) is a physiological feature of a wide range of diseases, from cancer to infection. Cellular hypoxia is sensed by oxygen-sensitive hydroxylase enzymes, which regulate the protein stability of hypoxia-inducible factor α (HIF-α) transcription factors. When stabilised, HIF-α binds with its cofactors to HIF-responsive elements (HREs) in the promoters of target genes to coordinate a wide-ranging transcriptional programme in response to the hypoxic environment. This year marks the 20th anniversary of the discovery of the HIF-1α transcription factor, and in recent years the HIF-mediated hypoxia response is being increasingly recognised as an important process in determining the outcome of diseases such as cancer, inflammatory disease and bacterial infections. Animal models have shed light on the roles of HIF in disease and have uncovered intricate control mechanisms that involve multiple cell types, observations that might have been missed in simpler in vitro systems. These findings highlight the need for new whole-organism models of disease to elucidate these complex regulatory mechanisms. In this Review, we discuss recent advances in our understanding of hypoxia and HIFs in disease that have emerged from studies of zebrafish disease models. Findings from such models identify HIF as an integral player in the disease processes. They also highlight HIF pathway components and their targets as potential therapeutic targets against conditions that range from cancers to infectious disease.

Summary: Hypoxia signalling, mediated by HIF, is a crucial pathway in many disease processes. Here, we review current knowledge of HIF signalling and disease, focusing on recent findings from zebrafish models.

Quantitating intracellular oxygen tension in vivo by phosphorescence lifetime measurement

Hypoxia appears to have an important role in pathological conditions in many organs such as kidney; however, a method to quantify intracellular oxygen tension in vivo has not been well established. In this study, we established an optical method to quantify oxygen tension in mice kidneys using a cationic lipophilic phosphorescence probe, BTPDM1, which has an intracellular oxygen concentration-sensitive phosphorescence lifetime. Since this probe is distributed inside the tubular cells of the mice kidney, we succeeded in detecting acute renal hypoxic conditions and chronic kidney disease. This technique enabled us to estimate intracellular partial pressures of oxygen in vivo by extrapolating the calibration curve generated from cultured tubular cells. Since intracellular oxygen tension is directly related to cellular hypoxic reactions, such as the activation of hypoxia-inducible factors, our method will shed new light on hypoxia research in vivo.

A systematic review on endometriosis during pregnancy: diagnosis, misdiagnosis, complications and outcomes

BACKGROUND

Traditionally, pregnancy was considered to have a positive effect on endometriosis and its painful symptoms due not only to blockage of ovulation preventing bleeding of endometriotic tissue but also to different metabolic, hormonal, immune and angiogenesis changes related to pregnancy. However, a growing literature is emerging on the role of endometriosis in affecting the development of pregnancy and its outcomes and also on the impact of pregnancy on endometriosis. The present article aims to underline the difficulty in diagnosing endometriotic lesions during pregnancy and discuss the options for the treatment of decidualized endometriosis in relation to imaging and symptomatology; to describe all the possible acute complications of pregnancy caused by pre-existing endometriosis and evaluate potential treatments of these complications; to assess whether endometriosis affects pregnancy outcome and hypothesize mechanisms to explain the underlying relationships.

METHODS

This systematic review is based on material searched and obtained via Pubmed and Medline between January 1950 and March 2015. Peer-reviewed, English-language journal articles examining the impact of endometriosis on pregnancy and vice versa were included in this article.

RESULTS

Changes of the endometriotic lesions may occur during pregnancy caused by the modifications of the hormonal milieu, posing a clinical dilemma due to their atypical appearance. The management of these events is actually challenging as only few cases have been described and the review of available literature evidenced a lack of formal estimates of their incidence. Acute complications of endometriosis during pregnancy, such as spontaneous hemoperitoneum, bowel and ovarian complications, represent rare but life-threatening conditions that require, in most of the cases, surgical operations to be managed. Due to the unpredictability of these complications, no specific recommendation for additional interventions to the routinely monitoring of pregnancy of women with known history of endometriosis is advisable. Even if the results of the published studies are controversial, some evidence is suggestive of an association of endometriosis with spontaneous miscarriage, preterm birth and small for gestational age babies. A correlation of endometriosis with placenta previa (odds ratio from 1.67 to 15.1 according to various studies) has been demonstrated, possibly linked to the abnormal frequency and amplitude of uterine contractions observed in women affected. Finally, there is no evidence that prophylactic surgery would prevent the negative impact of endometriosis itself on pregnancy outcome.

CONCLUSIONS

Complications of endometriosis during pregnancy are rare and there is no evidence that the disease has a major detrimental effect on pregnancy outcome. Therefore, pregnant women with endometriosis can be reassured on the course of their pregnancies although the physicians should be aware of the potential increased risk of placenta previa. Current evidence does not support any modification of conventional monitoring of pregnancy in patients with endometriosis.

Contribution of metabolic reprogramming to macrophage plasticity and function

Macrophages display a spectrum of functional activation phenotypes depending on the composition of the microenvironment they reside in, including type of tissue/organ and character of injurious challenge they are exposed to. Our understanding of how macrophage plasticity is regulated by the local microenvironment is still limited. Here we review and discuss the recent literature regarding the contribution of cellular metabolic pathways to the ability of the macrophage to sense the microenvironment and to alter its function. We propose that distinct alterations in the microenvironment induce a spectrum of inducible and reversible metabolic programs that might form the basis of the inducible and reversible spectrum of functional macrophage activation/polarization phenotypes. We highlight that metabolic pathways in the bidirectional communication between macrophages and stromals cells are an important component of chronic inflammatory conditions. Recent work demonstrates that inflammatory macrophage activation is tightly associated with metabolic reprogramming to aerobic glycolysis, an altered TCA cycle, and reduced mitochondrial respiration. We review cytosolic and mitochondrial mechanisms that promote initiation and maintenance of macrophage activation as they relate to increased aerobic glycolysis and highlight potential pathways through which anti-inflammatory IL-10 could promote macrophage deactivation. Finally, we propose that in addition to their role in energy generation and regulation of apoptosis, mitochondria reprogram their metabolism to also participate in regulating macrophage activation and plasticity.

Histamine inhibits differentiation of skin fibroblasts into myofibroblasts

Histamine and TGF-β, major mediators secreted by mast cells, are involved in skin inflammation and play critical roles in the pathogenesis of systemic sclerosis. However, the roles of signaling mechanisms in the development of skin fibrosis remain largely unclear. Here we show that histamine suppressed the expression of α smooth muscle actin (αSMA), a marker of myofibroblasts, induced by TGF-β1 in skin fibroblasts. Histamine H1-receptor (H1R), but not H2-receptor (H2R) or H4-receptor (H4R), was expressed on skin fibroblasts at both mRNA and protein levels. Interestingly, an H1R antagonist, but not H2R or H4R antagonists, antagonized the histamine-mediated suppression of αSMA expression by TGF-β1. Correspondingly, phosphorylated Smad2 was detected after treatment with TGF-β1, whereas the addition of histamine inhibited this phosphorylation. Taken together, histamine-H1R decreased TGF-β1-mediated Smad2 phosphorylation and inhibited differentiation of skin fibroblasts into myofibroblasts.