Regulation of keratinocyte growth factor gene expression by interleukin 1

Neural and Inflammatory Interactions in Wound Healing

ABSTRACT

The skin is an intricate network of both neurons and immunocytes, where emerging evidence has indicated that the regulation of neural-inflammatory processes may play a crucial role in mediating wound healing. Disease associated abnormal immunological dysfunction and peripheral neuropathy are implicated in the pathogenesis of wound healing impairment. However, the mechanisms through which neural-inflammatory interactions modulate wound healing remain ambiguous. Understanding the underlying mechanisms may provide novel insights to develop therapeutic devices, which could manipulate neural-inflammatory crosstalk to aid wound healing. This review aims to comprehensively illustrate the neural-inflammatory interactions during different stages of the repair process. Numerous mediators including neuropeptides secreted by the sensory and autonomic nerve fibers and cytokines produced by immunocytes play an essential part during the distinct phases of wound healing.

Transcriptional responses consistent with perturbation in dermo-epidermal homeostasis in septic sole ulceration

The aim of this study was to evaluate transcriptional changes in sole epidermis and dermis of bovine claws with septic sole ulceration of the lateral claw. Assessment included changes in transcripts orchestrating epidermal homeostatic processes including epidermal proliferation, differentiation, inflammation, and cell signaling. Sole epidermis and dermis was removed from region 4 of lesion-bearing lateral and lesion-free medial claws of pelvic limbs in multiparous, lactating Holstein cows. Control sole epidermis and dermis was obtained from region 4 of lateral claws of normal pelvic limbs. Transcript abundances were evaluated by real-time QPCR and relative expression analyzed by ANOVA. Relative to normal lateral claws, sole epidermis and dermis in ulcer-bearing claws exhibited downregulation of genes associated with growth factors, growth factor receptors, activator protein 1 (AP-1) and proto-oncogene (CMYC) transcription components, cell cycle elements, lateral cell-to-cell signaling elements and structures of early and late keratinocyte differentiation. These changes were accompanied by upregulation of pro-inflammatory transcripts interleukin 1 α (IL1A), interleukin1 β (IL1B), interleukin 1 receptor 1 (IL1R1), inducible nitric oxide synthase (NOS2), the inflammasome components NOD like receptor protein 3 (NLRP3), pyrin and caspase recruitment domain (PYCARD), and caspase-1 interleukin converting enzyme (CASPASE), the matrix metalloproteinases (MMP2 and MMP9), and anti-inflammatory genes interleukin 1 receptor antagonist (IL1RN) and interleukin1 receptor 2 (IL1R2). Transcript abundance varied across epidermis and dermis from the ulcer center, margin and epidermis and dermis adjacent to the lesion. Sole epidermis and dermis of lesion-free medial claws exhibited changes paralleling those in the adjacent lateral claws in an environment lacking inflammatory transcripts and downregulated IL1A, interleukin 18 (IL18), tumor necrosis factor α (TNFA) and NOS2. These data imply perturbations in signal pathways driving epidermal proliferation and differentiation are associated with, but not inevitably linked to epidermis and dermis inflammation. Further work is warranted to better define the role of crushing tissue injury, sepsis, metalloproteinase activity, and inflammation in sole ulceration.

Cytokines and Regulating Epithelial Cell Division

Physiologically, cytokines play an extremely important role in maintaining cellular and subcellular homeostasis, as they interact almost with every cell in the organism. Therefore, cytokines play a significantly critical role in the field of pathogenic pharmacological therapy of different types of pathologies. Cytokine is a large family containing many subfamilies and can be evaluated into groups according to their action on epithelial cell proliferation; stimulatory include transforming growth factor-α (TGF-α), Interlukine-22 (IL-22), IL-13, IL-6, IL-1RA and IL-17 and inhibitory include IL-1α, interferon type I (IFN type I), and TGF-β. The balance between stimulatory and inhibitory cytokines is essential for maintaining normal epithelial cell turnover and tissue homeostasis. Dysregulation of cytokine production can contribute to various pathological conditions, including inflammatory disorders, tissue damage, and cancer. Several cytokines have shown the ability to affect programmed cell death (apoptosis) and the capability to suppress non-purpose cell proliferation. Clinically, understanding the role of cytokines' role in epithelial tissue is crucial for evaluating a novel therapeutic target that can be of use as a new tactic in the management of carcinomas and tissue healing capacity. The review provides a comprehensive and up-to-date synthesis of current knowledge regarding the multifaceted effects of cytokines on epithelial cell proliferation, with a particular emphasis on the intestinal epithelium. Also, the paper will highlight the diverse signaling pathways activated by cytokines and their downstream consequences on epithelial cell division. It will also explore the potential therapeutic implications of targeting cytokine- epithelial cell interactions in the context of various diseases.

Effect of topical naringenin and its combination with minoxidil on enhancing hair growth in a mouse model

This study aimed to investigate the efficacy of naringenin (NAR) in reducing hair loss. Twenty-four adult Wistar Albino mice, weighing between 25-35 g and aged 6-7 weeks, were used in this research. The dorsal hair of these mice was meticulously clipped and stained subsequently. The mice were randomly divided into four groups (n=6 for each group): (1) negative control group, treated with absolute ethanol alcohol as the vehicle (2) minoxidil (5%) treated group; (3) 0.5% naringenin treated group, and (4) naringenin plus minoxidil treated group. The treatment groups had significantly higher total antioxidant capacity in tissue levels and increased serum levels of vascular endothelial growth factor compared to the control group. No significant differences were observed in keratinocyte growth factor tissue levels between the treatment and control groups. However, the medication significantly increased hair growth, hair follicle diameter expansion, and hair follicle quantity compared to the control group. The finding suggests that the antioxidant and anti-inflammatory properties of NAR significantly reduced hair loss in adult male mice.

Transcriptomic Analysis Reveals Candidate Ligand-Receptor Pairs and Signaling Networks Mediating Intercellular Communication between Hair Matrix Cells and Dermal Papilla Cells from Cashmere Goats

Hair fiber growth is determined by the spatiotemporally controlled proliferation, differentiation, and apoptosis of hair matrix cells (HMCs) inside the hair follicle (HF); however, dermal papilla cells (DPCs), the cell population surrounded by HMCs, manipulate the above processes via intercellular crosstalk with HMCs. Therefore, exploring how the mutual commutations between the cells are molecularly achieved is vital to understanding the mechanisms underlying hair growth. Here, based on our previous successes in cultivating HMCs and DPCs from cashmere goats, we combined a series of techniques, including in vitro cell coculture, transcriptome sequencing, and bioinformatic analysis, to uncover ligand-receptor pairs and signaling networks mediating intercellular crosstalk. Firstly, we found that direct cellular interaction significantly alters cell cycle distribution patterns and changes the gene expression profiles of both cells at the global level. Next, we constructed the networks of ligand-receptor pairs mediating intercellular autocrine or paracrine crosstalk between the cells. A few pairs, such as LEP-LEPR, IL6-EGFR, RSPO1-LRP6, and ADM-CALCRL, are found to have known or potential roles in hair growth by acting as bridges linking cells. Further, we inferred the signaling axis connecting the cells from transcriptomic data with the advantage of CCCExplorer. Certain pathways, including INHBA-ACVR2A/ACVR2B-ACVR1/ACVR1B-SMAD3, were predicted as the axis mediating the promotive effect of INHBA on hair growth via paracrine crosstalk between DPCs and HMCs. Finally, we verified that LEP-LEPR and IL1A-IL1R1 are pivotal ligand-receptor pairs involved in autocrine and paracrine communication of DPCs and HMCs to DPCs, respectively. Our study provides a comprehensive landscape of intercellular crosstalk between key cell types inside HF at the molecular level, which is helpful for an in-depth understanding of the mechanisms related to hair growth.

Scarless wound healing: Current insights from the perspectives of TGF-β, KGF-1, and KGF-2

The process of wound healing involves a complex and vast interplay of growth factors and cytokines that coordinate the recruitment and interaction of various cell types. A series of events involving inflammation, proliferation, and remodeling eventually leads to the restoration of the damaged tissue. Abrogation in the regulation of these events has been shown to result in excessive scarring or non-healing wounds. While the process of wound healing is not fully elucidated, it has been documented that the early events of wound healing play a key role in the outcome of the wound. Furthermore, high levels of inflammation have been shown to lead to scarring. The regulation of these events may result in scarless wound healing, especially in adults. The inhibition of transforming growth factor-β (TGF-β) and the administration of keratinocyte growth factors (KGF), KGF-1 and KGF-2, has in recent years yielded positive results in the acceleration of wound closure and reduced scarring. Here, we encapsulate recent knowledge on the roles of TGF-β, KGF1, and KGF2 in wound healing and scar formation and highlight the areas that need further investigation. We also discuss potential future directions for the use of growth factors in wound management.

The Immunological Impact of IL-1 Family Cytokines on the Epidermal Barrier

The skin barrier would not function without IL-1 family members, but their physiological role in the immunological aspects of skin barrier function are often overlooked. This review summarises the role of IL-1 family cytokines (IL-1α, IL-1β, IL-1Ra, IL-18, IL-33, IL-36α, IL-36β, IL-36γ, IL-36Ra, IL-37 and IL-38) in the skin. We focus on novel aspects of their interaction with commensals and pathogens, the important impact of proteases on cytokine activity, on healing responses and inflammation limiting mechanisms. We discuss IL-1 family cytokines in the context of IL-4/IL-13 and IL-23/IL-17 axis-driven diseases and highlight consequences of human loss/gain of function mutations in activating or inhibitory pathway molecules. This review highlights recent findings that emphasize the importance of IL-1 family cytokines in both physiological and pathological cutaneous inflammation and emergent translational therapeutics that are helping further elucidate these cytokines.

Plasma Levels of Keratinocyte Growth Factor Are Significantly Elevated for 5 Weeks After Minimally Invasive Colorectal Resection Which May Promote Cancer Recurrence and Metastasis

Background: Human Keratinocyte Growth Factor (KGF) is an FGF family protein produced by mesenchymal cells. KGF promotes epithelial cell proliferation, plays a role in wound healing and may also support tumor growth. It is expressed by some colorectal cancers (CRC). Surgery's impact on KGF levels is unknown. This study's purpose was to assess plasma KGF levels before and after minimally invasive colorectal resection (MICR) for CRC. Aim: To determine plasma KGF levels before and after minimally invasive colorectal resection surgery for cancer pathology. Method: CRC MICR patients (pts) in an IRB approved data/plasma bank were studied. Pre-operative (pre-op) and post-operative (post-op) plasma samples were taken/stored. Late samples were bundled into 7 day blocks and considered as single time points. KGF levels (pg/ml) were measured via ELISA (mean ± SD). The Wilcoxon paired t-test was used for statistical analysis. Results: Eighty MICR CRC patients (colon 61%; rectal 39%; mean age 65.8 ± 13.3) were studied. The mean incision length was 8.37 ± 3.9 and mean LOS 6.5 ± 2.6 days. The cancer stage breakdown was; I (23), II (26), III (27), and IV (4). The median pre-op KGF level was 17.1 (95 %CI: 14.6-19.4; n = 80); significantly elevated (p < 0.05) median levels (pg/ml) were noted on post-op day (POD) 1 (23.4 pg/ml; 95% CI: 21.4-25.9; n = 80), POD 3 (22.5 pg/ml; 95% CI: 20.7-25.9; n = 76), POD 7-13 (21.8 pg/ml; 95% CI: 17.7-25.4; n = 50), POD 14-20 (20.1 pg/ml; 95% CI: 17.1-23.9; n = 33), POD 21-27 (19.6 pg/ml; 95% CI: 15.2-24.9; n = 15) and on POD 28-34 (16.7 pg/ml; 95% CI: 14.0-25.8; n = 12). Conclusion: Plasma KGF levels were significantly elevated for 5 weeks after MICR for CRC. The etiology of these changes is unclear, surgical trauma related acute inflammatory response and wound healing process may play a role. These changes, may stimulate angiogenesis in residual tumor deposits after surgery.

Keratinocyte growth factor signaling promotes stem/progenitor cell proliferation under p63 expression during middle ear cholesteatoma formation

PURPOSE OF REVIEW

Middle ear cholesteatoma is an epithelial lesion that expands into the middle ear, resulting in bone destruction. However, the pathogenesis of this has been unknown. The purpose of this review is to understand the role of keratinocyte growth factor (KGF) during epithelial stem and/or progenitor cell proliferation in middle ear cholesteatoma.

RECENT FINDINGS

Many researchers have investigated the molecular mechanism of middle ear cholesteatoma to establish a conservative treatment. Recently, some studies have focused on the stem cells of middle ear cholesteatoma and their detection, but the key molecules for stem cell formation were not shown.

SUMMARY

We established an animal model for middle ear cholesteatoma and are showing the results of our studies. KGF expression accelerates the proliferation of stem/progenitor cells through the induction of transcription factor p63 expression in the epithelium of the tympanic membrane and mucosal epithelium overlying the promontory of the cochlea and within the attic. This is typical in middle ear cholesteatoma. Moreover, the partial epithelial-mesenchymal transition under the p63 signaling pathway plays an essential role in epithelial cell growth in middle ear cholesteatoma formation. Understanding p63 expression following KGF expression and associated signaling events can improve therapeutic outcomes in patients with middle ear cholesteatoma.

Cellular Mechanisms of FGF-Stimulated Tissue Repair

Growth factors belonging to the FGF family play important roles in tissue and organ repair after trauma. In this review, I discuss the regulation by FGFs of the aspects of cellular behavior important for reparative processes. In particular, I focus on the FGF-dependent regulation of cell proliferation, cell stemness, de-differentiation, inflammation, angiogenesis, cell senescence, cell death, and the production of proteases. In addition, I review the available literature on the enhancement of FGF expression and secretion in damaged tissues resulting in the increased FGF supply required for tissue repair.

Could basement membrane alterations, resembling micro-wounds at the dermo-epidermal junction in psoriatic non-lesional skin, make the skin susceptible to lesion formation?

Current data suggest that tissue microenvironment control immune functions. Therefore, understanding the tissue environment in which immune activation occurs will enhance our capability to interfere with abnormal immune pathology. Here, we argue that studying the constitutively abnormal functions of clinically uninvolved psoriatic skin in patients with plaque type psoriasis is very important to better understand psoriasis pathobiology, because non-lesional skin provides the tissue environment in which the psoriatic lesion develops. A key question in psoriasis is what initiates the abnormal, uncontrolled immune activation in the first place and the answer may lie in the skin. In light of this concept, we summarize abnormalities at the dermal-epidermal junction region which shows a special "non-healing-like" micro-wound phenotype in the psoriatic non-lesional skin that may act as a crucial susceptibility factor in the development of the disease.

Matrix metalloproteinases in keratinocyte carcinomas

The incidence of cutaneous keratinocyte-derived cancers is increasing globally. Basal cell carcinoma (BCC) is the most common malignancy worldwide, and cutaneous squamous cell carcinoma (cSCC) is the most common metastatic skin cancer. BCC can be classified into subtypes based on the histology, and these subtypes are classified further into low- and high-risk tumors. There is an increasing need to identify new therapeutic strategies for the treatment of unresectable and metastatic cSCC, and for aggressive BCC variants such as infiltrating, basosquamous or morpheaform BCCs. The most important risk factor for BCC and cSCC is solar UV radiation, which causes genetic and epigenetic alterations in keratinocytes. Similar gene mutations are noted already in sun-exposed normal skin emphasizing the role of the alterations in the tumor microenvironment in the progression of cSCC. Early events in cSCC progression are alterations in the composition of basement membrane and dermal extracellular matrix induced by influx of microbes, inflammatory cells and activated stromal fibroblasts. Activated fibroblasts promote inflammation and produce growth factors and proteolytic enzymes, including matrix metalloproteinases (MMPs). Transforming growth factor-β produced by tumor cells and fibroblasts induces the expression of MMPs by cSCC cells and promotes their invasion. Fibroblast-derived keratinocyte growth factor suppresses the malignant phenotype of cSCC cells by inhibiting the expression of several MMPs. These findings emphasize the importance of interplay of tumor and stromal cells in the progression of cSCC and BCC and suggest tumor microenvironment as a therapeutic target in cSCC and aggressive subtypes of BCC.

miR124-3p/FGFR2 axis inhibits human keratinocyte proliferation and migration and improve the inflammatory microenvironment in psoriasis

Keratinocyte hyperproliferation has been regarded as a central event in psoriasis pathogenesis. Investigating the mechanisms of keratinocyte hyperproliferation might provide novel strategies for psoriasis treatment. we demonstrated that fibroblast growth factor receptor 2 (FGFR2) expression was abnormally upregulated within psoriatic lesion tissues and HaCaT cells under rIL-22 stimulation. FGFR2 silence within HaCaT cells under rIL-22 stimulation significantly inhibited the capacity of cells to proliferate and to migrate, reduced IL-17A and TNFα mRNA expression, and decreased the protein levels of FGFR2, keratin 6, keratin 16, MMP1, MMP9, p-PI3K, p-AKT and p-ERK. In contrast to FGFR2, the expression of miR-124-3p showed to be remarkably downregulated within psoriasis lesion tissue samples and rIL-22-stimulated HaCaT cells. miR-124-3p inhibited the expression of FGFR2 via direct binding to its 3'UTR. Within HaCaT cells under rIL-22 stimulation, the overexpression of miR-124-3p also suppressed the capacity of cells to proliferate and to migrate, reduced IL-17A and TNFα mRNA expression, and decreased the protein levels of FGFR2, keratin 6, keratin 16, MMP1, MMP9 and p-PI3K, p-AKT and p-ERK. More importantly, when co-transfected to HaCaT cells, FGFR2-overexpressing vector significantly attenuated the effects of miR-124-3p mimics on HaCaT cells. In conclusion, we demonstrated an miR124-3p/FGFR2 axis that might inhibit human keratinocyte proliferation, migration, and improve the inflammatory microenvironment in psoriasis. miR124-3p/FGFR2 axis could be an underlying target for psoriasis therapy, which requires further in vivo and clinical investigation.

Keratinocyte growth factor (KGF) induces stem/progenitor cell growth in middle ear mucosa

OBJECTIVE

The middle ear epithelium is derived from the neural crest and endoderm, which line distinct regions of the middle ear cavity. In this study, we investigated the localization of stem/progenitor cells in the middle ear mucosa of adult mice and the effects of keratinocyte growth factor (KGF) on the cell kinetics of stem/progenitor cells in vivo.

METHODS

In this study, after KGF-expression vector was transfected in the ear, two kinds of thymidine analogues, BrdU and EdU, were transferred at different time points. BrdU was detected by immunohistochemistry and EdU was detected by click chemistry. We also performed immunohistochemistry using anti-Keratin14 (K14) antibody (an undifferentiated epithelial cell marker), anti-p63 antibody (a stem/progenitor cell marker) and anti-acetylated α-tubulin antibody (a ciliated epithelial cell marker).

RESULTS

A large number of EdU-positive cells were detected in the thickened mucosal epithelium of the pars flaccida and attic region at Day 1 after KGF transfection. Interestingly, in the mucosal epithelium overlying the promontory of the cochlea, many EdU-positive cells were detected. These cells were also positive for K14 and p63. The acetylated α-tubulin positive cells were reduced in the attic region at Day 1 after KGF transfection.

CONCLUSION

These findings indicate that KGF over-expression may increase stem/progenitor cell proliferation in the mucosal epithelium not only within the attic which is typical in middle ear cholesteatoma, but also overlying the promontory of the cochlea.

The RNA-binding protein ESRP1 promotes human colorectal cancer progression

Epithelial splicing regulatory protein 1 (ESRP1) is an epithelial cell-specific RNA binding protein that controls several key cellular processes, like alternative splicing and translation. Previous studies have demonstrated a tumor suppressor role for this protein. Recently, however, a pro-metastatic function of ESRP1 has been reported. We thus aimed at clarifying the role of ESRP1 in Colorectal Cancer (CRC) by performing loss- and gain-of-function studies, and evaluating tumorigenesis and malignancy with in vitro and in vivo approaches. We found that ESRP1 plays a role in anchorage-independent growth of CRC cells. ESRP1-overexpressing cells grown in suspension showed enhanced fibroblast growth factor receptor (FGFR1/2) signalling, Akt activation, and Snail upregulation. Moreover, ESRP1 promoted the ability of CRC cells to generate macrometastases in mice livers. High ESRP1 expression may thus stimulate growth of cancer epithelial cells and promote colorectal cancer progression. Our findings provide mechanistic insights into a previously unreported, pro-oncogenic role for ESRP1 in CRC, and suggest that fine-tuning the level of this RNA-binding protein could be relevant in modulating tumor growth in a subset of CRC patients.

Keratinocyte growth factor supports pulmonary innate immune defense through maintenance of alveolar antimicrobial protein levels and macrophage function

Keratinocyte growth factor (KGF) is an epithelial mitogen that has been reported to protect the lungs from a variety of toxic and infectious insults. In prior studies we found that recombinant human KGF accelerates clearance of bacteria from the murine lung by augmenting the function of alveolar macrophages (AM). In this study we tested the hypothesis that endogenous KGF plays a role in the maintenance of innate pulmonary defense against gram-negative bacterial infections. KGF-deficient mice exhibited delayed clearance of Escherichia coli from the lungs, attenuated phagocytosis by AM, and decreased antimicrobial activity in bronchoalveolar lavage (BAL) fluid, due in part to reductions in levels of surfactant protein A, surfactant protein D, and lysozyme. These immune deficits were accompanied by lower alveolar type II epithelial cell counts and reduced alveolar type II epithelial cell expression of collectin and lysozyme genes on a per cell basis. No significant between-group differences were detected in selected inflammatory cytokines or BAL inflammatory cell populations at baseline or after bacterial challenge in the wild-type and KGF-deficient mice. A single intranasal dose of recombinant human KGF reversed defects in bacterial clearance, AM function, and BAL fluid antimicrobial activity. We conclude that KGF supports alveolar innate immune defense through maintenance of alveolar antimicrobial protein levels and functions of AM. Together these data demonstrate a role for endogenous KGF in maintenance of normal pulmonary innate immune function.

Clinical implication of perioperative inflammatory cytokine alteration

Cytokines are key modulators of inflammatory responses, and play an important role in the defense and repair mechanisms following trauma. After traumatic injury, an immuno-inflammatory response is initiated immediately, and cytokines rapidly appear and function as a regulator of immunity. In pathologic conditions, imbalanced cytokines may provide systemic inflammatory responses or immunosuppression. Expression of perioperative cytokines vary by different intensities of surgical trauma and types of anesthesia and anesthetic agents. Inflammatory cytokines play important roles in postoperative organ dysfunction including central nervous system, cardiovascular, lung, liver, and kidney injury. Inhibition of cytokines could protect against traumatic injury in some circumstances, therefore cytokine inhibitors or antagonists might have the potential for reducing postoperative tissue/organ dysfunction. Cytokines are also involved in wound healing and post-traumatic pain. Application of cytokines for the improvement of surgical wound healing has been reported. Anesthesia-related immune response adjustment might reduce perioperative morbidity because it reduces proinflammatory cytokine expression; however, the overall effects of anesthetics on postoperative immune-inflammatory responses needs to be further investigated.

In vivo over-expression of KGF mimic human middle ear cholesteatoma

We reported previously that keratinocyte growth factor (KGF), a mesenchymal cell-derived paracrine growth factor, plays an important role in middle ear cholesteatoma formation, which is characterized by marked proliferation of epithelial cells. Here, we investigated whether KGF, the main factor that induces cholesteatoma, overexpression in vivo results in the formation of cholesteatoma. Flag-hKGF cDNA driven by CMV14 promoter was transfected through electroporation into the external auditory canal (EAC) of rats once (short-term model) or five times on every fourth day (long-term model). Ears transfected with empty vector were used as controls. Successful transfection of plasmids into epithelial and stromal cells was confirmed by Flag immunohistochemistry. In the short-term model, the intensity of KGF protein was the strongest in hKGF transfected ear at day 4. KGF expression induced epithelial cell proliferation, reaching a peak level at day 4 and then decreased later, while in the long-term model, KGF expression in the EAC led to middle ear cholesteatoma formation. In conclusion, we described here a new experimental model of human middle ear cholesteatoma, and demonstrated that KGF and KGF receptor paracrine action play an essential role in middle ear cholesteatoma formation in an in vivo model.

Growth factors and cytokines in acute lung injury

Cytokines and growth factors play an integral role in the maintenance of immune homeostasis, the generation of protective immunity, and lung reparative processes. However, the dysregulated expression of cytokines and growth factors in response to infectious or noxious insults can initiate and perpetuate deleterious lung inflammation and fibroproliferation. In this article, we will comprehensively review the contribution of individual cytokines and growth factors and cytokine networks to key pathophysiological events in human and experimental acute lung injury (ALI), including inflammatory cell recruitment and activation, alveolar epithelial injury and repair, angiogenesis, and matrix deposition and remodeling. The application of cytokines/growth factors as prognostic indicators and therapeutic targets in human ALI is explored.

Sestrin-2, a repressor of PDGFRβ signalling, promotes cigarette-smoke-induced pulmonary emphysema in mice and is upregulated in individuals with COPD

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. COPD is caused by chronic exposure to cigarette smoke and/or other environmental pollutants that are believed to induce reactive oxygen species (ROS) that gradually disrupt signalling pathways responsible for maintaining lung integrity. Here we identify the antioxidant protein sestrin-2 (SESN2) as a repressor of PDGFRβ signalling, and PDGFRβ signalling as an upstream regulator of alveolar maintenance programmes. In mice, the mutational inactivation of Sesn2 prevents the development of cigarette-smoke-induced pulmonary emphysema by upregulating PDGFRβ expression via a selective accumulation of intracellular superoxide anions (O₂⁻). We also show that SESN2 is overexpressed and PDGFRβ downregulated in the emphysematous lungs of individuals with COPD and to a lesser extent in human lungs of habitual smokers without COPD, implicating a negative SESN2-PDGFRβ interrelationship in the pathogenesis of COPD. Taken together, our results imply that SESN2 could serve as both a biomarker and as a drug target in the clinical management of COPD.

Myofibroblasts and their relationship with oral squamous cell carcinoma

Myofibroblasts are hybrid-phenotype differentiated cells in between fibroblasts and smooth muscle cells. Due to their contractile features and ability to synthesize extracellular matrix components, cytokines, proteases, and proangiogenic factors, myofibroblasts have been implicated in the pathogenesis of fibrocontractive diseases and in the progression of many tumors, including oral squamous cell carcinoma (SCC).

Objective

To perform a literature review on the origin of myofibroblasts, their main morpho-physiological and immunohistochemical aspects, and to discuss the correlations with oral SCC.

Method

A search was made on the PUBMED database to select the main papers in the literature in English related to the subject, published between January 1991 and December 2011.

Conclusion

Myofibroblasts are an important component of the stroma of oral SCCs, although they are not present in all tumors. Abundant presence of myofibroblasts may be associated with local disease recurrence and decreased patient survival. However, given the relatively limited number of studies on the subject, further research is needed to clarify the molecular mechanisms by which myofibroblasts influence the biological behavior of oral SCC.

Upregulation of IL-6, IL-8 and CXCL-1 production in dermal fibroblasts by normal/malignant epithelial cells in vitro: Immunohistochemical and transcriptomic analyses

BACKGROUND INFORMATION

Considering an analogy between wound healing and tumour progression, we studied chemokine and cytokine transcription and expression in normal fibroblasts by co-culture and in situ.

RESULTS

Whole-genome transcriptome profiling revealed strong upregulation for the interleukin (IL)-6, IL-8 and the chemokine CXCL-1 in in vitro co-cultures of normal fibroblasts with either normal or malignant epithelial cells compared to fibroblast cultures. The same ILs/chemokines were distinctly upregulated in clinical samples of squamous cell carcinoma when compared with paired normal mucosae. Analysis of culture supernatants showed that during the course of co-culture of the fibroblasts with the epithelial cells, IL-6, IL-8 and CXCL-1 were secreted to the culture medium. Experiments with addition of any of the proteins to the culture medium supported the notion that these ILs/chemokines strongly contributed to maintenance of a low-differentiation phenotype of epithelial cells, evaluated by the detection of keratin-8. Simultaneous addition of all factors increased the extent of the effect. These studies were extended by experiments with epithelial cells, either cultured in medium conditioned by preceding use for malignant keratinocytes without and in the presence of normal or cancer-associated fibroblasts or medium containing antibodies against IL-6, IL-8 and CXCL-1.

CONCLUSIONS

Our results indicate an analogy between wound healing and tumour growth, support the importance of epithelial-mesenchymal interaction in this model system and establish a potential bio-inspired anticancer therapy.

TNFα modulates Fibroblast Growth Factor Receptor 2 gene expression through the pRB/E2F1 pathway: identification of a non-canonical E2F binding motif

Interactions between epithelium and mesenchyme during wound healing are not fully understood, but Fibroblast Growth Factors (FGFs) and their receptors FGFRs are recognized as key elements. FGFR2 gene encodes for two splicing transcript variants, FGFR2-IIIb or Keratinocyte Growth Factor Receptor (KGFR) and FGFR2-IIIc, which differ for tissue localization and ligand specificity. Proinflammatory cytokines play an essential role in the regulation of epithelial-mesenchymal interactions, and have been indicated to stimulate FGFs production. Here we demonstrated that upregulation of FGFR2 mRNA and protein expression is induced by the proinflammatory cytokines Tumor Necrosis Factor-α, Interleukin-1β and Interleukin 2. Furthermore, we found that TNFα determines FGFR2 transcriptional induction through activation of pRb, mediated by Raf and/or p38 pathways, and subsequent release of the transcription factor E2F1. Experiments based on FGFR2 promoter serial deletions and site-directed mutagenesis allowed us to identify a minimal responsive element that retains the capacity to be activated by E2F1. Computational analysis indicated that this element is a non-canonical E2F responsive motif. Thus far, the molecular mechanisms of FGFR2 upregulation during wound healing or in pathological events are not known. Our data suggest that FGFR2 expression can be modulated by local recruitment of inflammatory cytokines. Furthermore, since alterations in FGFR2 expression have been linked to the pathogenesis of certain human cancers, these findings could also provide elements for diagnosis and potential targets for novel therapeutic approaches.

Interleukin (IL)-19 promoted skin wound healing by increasing fibroblast keratinocyte growth factor expression

BACKGROUND

Interleukin (IL)-19, a member of the IL-10 cytokine family, is involved in keratinocyte proliferation in psoriasis.

OBJECTIVES

We investigated the role of IL-19 in the wound-healing process in vivo and in vitro.

METHODS

Two full-thickness circular wounds (4mm in diameter) were punched into the skin of BALB/C mice. IL-19 and keratinocyte growth factor (KGF) mRNA in wounded skin were determined using real-time PCR. The wounds were treated with PBS, vehicle, IL-19 (400ng/mL), or IL-20 (400ng/mL) (n=6 in each group) twice daily and the percentage of wound healing was measured daily for 7days. In vitro, human skin fibroblast CCD966-SK cells and keratinocyte HaCaT cells were treated with IL-19 or KGF. Cell proliferation and migration were determined using bromodeoxyuridine (BrdU) and transwell assays, respectively. The expression of IL-19 and KGF mRNA was also analyzed.

RESULTS

In wounded mouse skin, IL-19 mRNA was upregulated at 12h, and KGF at 24h after the injury. Both increases in gene expression declined 72h after the skin had been wounded. The percentage of wound healing in IL-19-treated mice was higher than in control mice. In vitro, IL-19 upregulated KGF expression in the CCD966-SK cells; IL-19 was upregulated in KGF-treated HaCaT cells. KGF but not IL-19 promoted HaCaT cell proliferation. However, IL-19 significantly increased the migration of HaCaT cells. HaCaT cells treated with the cultured supernatants of IL-19-stimulated CCD966-SK cells showed significantly more proliferation than in controls.

CONCLUSIONS

IL-19 is important for cutaneous wound healing because it upregulates KGF expression.

Myofibroblast keratinocyte growth factor reduces tight junctional integrity and increases claudin-2 levels in polarized Caco-2 cells

The colonic epithelium is composed of a polarized monolayer sheathed by a layer of pericryptal myofibroblasts (PCMFs). We mimicked these cellular compartments in vitro to assess the effects of paracrine-acting PCMF-derived factors on tight junction (TJ) integrity, as measured by transepithelial electrical resistance (TER). Coculture with 18Co PCMFs, or basolateral administration of 18Co conditioned medium, significantly reduced TER of polarized Caco-2 cells. Among candidate paracrine factors, only keratinocyte growth factor (KGF) reduced Caco-2 TER; basolateral KGF treatment led to time- and concentration-dependent increases in claudin-2 levels. We also demonstrate that amphiregulin (AREG), produced largely by Caco-2 cells, increased claudin-2 levels, leading to epidermal growth factor receptor-mediated TER reduction. We propose that colonic epithelial TJ integrity can be modulated by paracrine KGF and autocrine AREG through increased claudin-2 levels. KGF-regulated claudin-2 induction may have implications for inflammatory bowel disease, where both KGF and claudin-2 are upregulated.

Modelling the interaction of keratinocytes and fibroblasts during normal and abnormal wound healing processes

The crosstalk between fibroblasts and keratinocytes is a vital component of the wound healing process, and involves the activity of a number of growth factors and cytokines. In this work, we develop a mathematical model of this crosstalk in order to elucidate the effects of these interactions on the regeneration of collagen in a wound that heals by second intention. We consider the role of four components that strongly affect this process: transforming growth factor-β, platelet-derived growth factor, interleukin-1 and keratinocyte growth factor. The impact of this network of interactions on the degradation of an initial fibrin clot, as well as its subsequent replacement by a matrix that is mainly composed of collagen, is described through an eight-component system of nonlinear partial differential equations. Numerical results, obtained in a two-dimensional domain, highlight key aspects of this multifarious process, such as re-epithelialization. The model is shown to reproduce many of the important features of normal wound healing. In addition, we use the model to simulate the treatment of two pathological cases: chronic hypoxia, which can lead to chronic wounds; and prolonged inflammation, which has been shown to lead to hypertrophic scarring. We find that our model predictions are qualitatively in agreement with previously reported observations and provide an alternative pathway for gaining insight into this complex biological process.

Regulation of epithelial differentiation and proliferation by the stroma: a role for the retinoblastoma protein

Signaling between the epithelium and stromal cells is crucial for growth, differentiation, and repair of the epithelium. Although the retinoblastoma protein (Rb) is known to regulate the growth of keratinocytes in a cell-autonomous manner, here we describe a function of Rb in the stromal compartment. We find that Rb depletion in fibroblasts leads to inhibition of differentiation and enhanced proliferation of the epithelium. Analysis of conditioned medium identified that keratinocyte growth factor (KGF) levels were elevated following Rb depletion. These findings were also observed with organotypic co-cultures. Treatment of keratinocytes with KGF inhibited differentiation and enhanced keratinocyte proliferation, whereas reduction of KGF levels in Rb-depleted fibroblasts was able to restore expression of differentiation markers. Our findings suggest a crucial role for dermal fibroblasts in regulating the differentiation and proliferation of keratinocytes, and we demonstrate a role for stromal Rb in this cross-talk.

Inactivation of Rb in stromal fibroblasts promotes epithelial cell invasion

Stromal-derived growth factors are required for normal epithelial growth but are also implicated in tumour progression. We have observed inactivation of the retinoblastoma protein (Rb), through phosphorylation, in cancer-associated fibroblasts in oro-pharyngeal cancer specimens. Rb is well known for its cell-autonomous effects on cancer initiation and progression; however, cell non-autonomous functions of Rb are not well described. We have identified a cell non-autonomous role of Rb, using three-dimensional cultures, where depletion of Rb in stromal fibroblasts enhances invasive potential of transformed epithelia. In part, this is mediated by upregulation of keratinocyte growth factor (KGF), which is produced by the depleted fibroblasts. KGF drives invasion of epithelial cells through induction of MMP1 expression in an AKT- and Ets2-dependent manner. Our data identify that stromal fibroblasts can alter the invasive behaviour of the epithelium, and we show that altered expression of KGF can mediate these functions.

Keratinocyte growth factor induces gene expression signature associated with suppression of malignant phenotype of cutaneous squamous carcinoma cells

Keratinocyte growth factor (KGF, fibroblast growth factor-7) is a fibroblast-derived mitogen, which stimulates proliferation of epithelial cells. The expression of KGF by dermal fibroblasts is induced following injury and it promotes wound repair. However, the role of KGF in cutaneous carcinogenesis and cancer progression is not known. We have examined the role of KGF in progression of squamous cell carcinoma (SCC) of the skin. The expression of KGF receptor (KGFR) mRNA was lower in cutaneous SCCs (n = 6) than in normal skin samples (n = 6). Expression of KGFR mRNA was detected in 6 out of 8 cutaneous SCC cell lines and the levels were downregulated by 24-h treatment with KGF. KGF did not stimulate SCC cell proliferation, but it reduced invasion of SCC cells through collagen. Gene expression profiling of three cutaneous SCC cell lines treated with KGF for 24 h revealed a specific gene expression signature characterized by upregulation of a set of genes specifically downregulated in SCC cells compared to normal epidermal keratinocytes, including genes with tumor suppressing properties (SPRY4, DUSP4, DUSP6, LRIG1, PHLDA1). KGF also induced downregulation of a set of genes specifically upregulated in SCC cells compared to normal keratinocytes, including genes associated with tumor progression (MMP13, MATN2, CXCL10, and IGFBP3). Downregulation of MMP-13 and KGFR expression in SCC cells and HaCaT cells was mediated via ERK1/2. Activation of ERK1/2 in HaCaT cells and tumorigenic Ha-ras-transformed HaCaT cells resulted in downregulation of MMP-13 and KGFR expression. These results provide evidence, that KGF does not promote progression of cutaneous SCC, but rather suppresses the malignant phenotype of cutaneous SCC cells by regulating the expression of several genes differentially expressed in SCC cells, as compared to normal keratinocytes.

Keratinocyte growth factor augments pulmonary innate immunity through epithelium-driven, GM-CSF-dependent paracrine activation of alveolar macrophages

Keratinocyte growth factor (KGF) is an epithelial mitogen that has been reported to protect the lungs from a variety of insults. In this study, we tested the hypothesis that KGF augments pulmonary host defense. We found that a single dose of intrapulmonary KGF enhanced the clearance of Escherichia coli or Pseudomonas aeruginosa instilled into the lungs 24 h later. KGF augmented the recruitment, phagocytic activity, and oxidant responses of alveolar macrophages, including lipopolysaccharide-stimulated nitric oxide release and zymosan-induced superoxide production. Less robust alveolar macrophage recruitment and activation was observed in mice treated with intraperitoneal KGF. KGF treatment was associated with increased levels of MIP1γ, LIX, VCAM, IGFBP-6, and GM-CSF in the bronchoalveolar lavage fluid. Of these, only GM-CSF recapitulated in vitro the macrophage activation phenotype seen in the KGF-treated animals. The KGF-stimulated increase in GM-CSF levels in lung tissue and alveolar lining fluid arose from the epithelium, peaked within 1 h, and was associated with STAT5 phosphorylation in alveolar macrophages, consistent with epithelium-driven paracrine activation of macrophage signaling through the KGF receptor/GM-CSF/GM-CSF receptor/JAK-STAT axis. Enhanced bacterial clearance did not occur in response to KGF administration in GM-CSF(-/-) mice, or in mice treated with a neutralizing antibody to GM-CSF. We conclude that KGF enhances alveolar host defense through GM-CSF-stimulated macrophage activation. KGF administration may constitute a promising therapeutic strategy to augment innate immune defenses in refractory pulmonary infections.

Asian dust storm particles induce a broad toxicological transcriptional program in human epidermal keratinocytes

Exposure to airborne dust particles originated from seasonal Asian dust storms in Chinese and Mongolian deserts results in increased incidence of a range of diseases including asthma, contact dermatitis and conjunctivitis. The areas affected by Asian dust particles extend from East China to the west coast of North America. In order to study toxicological mechanisms in human skin, we evaluated the effects of dust particles collected during Asian dust storms (Asian dust particles) on gene expression in human epidermal keratinocytes (HEK). In HEK, exposure to Asian dust particles significantly increased gene expressions of cytochrome P450 1A1 (CYP1A1), CYP1A2, and CYP1B1, which is an indication of aryl hydrocarbon receptor (AHR) activation. In addition, Asian dust particles increased gene transcription of the cytokines IL-6, IL-8, and GM-CSF, which have broad pro-inflammatory and immunomodulatory properties. Asian dust particles significantly up-regulated expression of caspase 14 in HEK, suggesting that Asian dust particles directly affect keratinocyte differentiation. We also demonstrated that protein extract of pollen, a material frequently adsorbed onto Asian dust particles, potentially contributes to the increased transcription of IL-6, CYP1A1, CYP1A2, and CYP1B1. Taken together, these studies suggest that Asian dust particles can exert toxicological effects on human skin through the activation of the cellular detoxification system, the production of pro-inflammatory and immunomodulatory cytokines, and changes in the expression of proteins essential in normal epidermal differentiation.

Prostaglandin E2receptor subtype EP2- and EP4-regulated gene expression profiling in human ciliary smooth muscle cells

Prostanoids are an important class of intraocular pressure (IOP)-lowering antiglaucoma agents that act primarily via increased uveo-scleral aqueous humor outflow through the ciliary body. We have developed two novel PGE2analogs that are specific agonists for the PGE2receptor subtypes EP2 and EP4, respectively. To identify gene regulatory networks and key players that mediate the physiological effects observed in vivo, we performed genomewide expression studies using human ciliary smooth muscle cells. Quantitative real-time RT-PCR confirmed a largely overlapping gene expression profile subsequent to EP2 and EP4 agonist treatment, with 65 significantly regulated genes identified overall, 5 being specific for the EP2 agonist and 6 specific for the EP4 agonist. We found predicted functional cAMP-response elements in promoter regions of a large fraction of the predominantly upregulated genes, which suggests that the cAMP signaling pathway is the most important intracellular signaling pathway for these agonists in these cells. Several target genes were identified that, as part of complex regulatory networks, are implicated in tissue remodeling processes and osmoregulation (e.g., AREG, LOXL3, BMP2, AQP3) and thus may help elucidate the mechanism of action of these IOP-lowering drugs involving the uveo-scleral outflow path.

Epithelial Repair and Regeneration

Contact with the environment positions the respiratory epithelium at risk for acute and chronic injury from infectious pathogens, noxious agents, and inflammatory processes. Thus, to protect gas transfer within the lung the epithelium is programmed for routine maintenance and repair. Programs for repair are directed by epithelial, mesenchymal, and inflammatory signals that collectively constitute highly regulated networks. Principal components of the repair network are developmental morphogens, integrin and growth factor signaling molecules, and transcription factors. The epithelium responds to these signals with a remarkable plasticity and is bulwarked by a population of lung progenitor cells to ensure maintenance and repair for fluid balance and host defense functions.

The effects of TGF-alpha, IL-1beta and PDGF on fibroblast adhesion to ECM-derived matrix and KGF gene expression

The goal of this study was to elucidate the control mechanisms by which exogenous proteins regulate keratinocyte growth factor (KGF) expression in fibroblasts adhered to differing substrates and thereby provide insights into both fundamental in vitro cell signaling and cell-biomaterial interaction research. A serum-free culture system in which cells maintained their proliferative capacity was established and employed. The addition of transforming growth factor- alpha (TGF-alpha), interleukin-1beta (IL-1beta) and platelet-derived growth factor-BB (PDGF-BB) individually showed no effect on KGF protein release, however, IL-1beta addition led to increased KGF mRNA transcription, intracellular KGF protein synthesis, and granulocyte-macrophage colony-stimulating factor (GM-CSF) release. Intracellular KGF protein synthesis and extracellular release were enhanced when fibroblasts were treated with a combination of IL-1beta and PDGF-BB which suggests KGF synthesis and release are largely regulated by synergistic mechanisms. Surface-bound fibronectin-derived ligands and individual exogenous proteins promoted fibroblast adhesion to semi-interpenetrating polymer networks (sIPNs) but did not stimulate KGF release despite enhancement of KGF mRNA transcription. Additionally, serum conditioning was found to have a significant impact on KGF synthesis and the subsequent mechanisms controlling KGF release. This study demonstrates that KGF release from fibroblasts is likely regulated by multiple mechanisms involving post-transcriptional and exocytic controls which may be impacted by the presence of serum and how serum is removed from the in vitro cell environment.

FGFR2 abnormalities underlie a spectrum of bone, skin, and cancer pathologies

Fibroblast growth factor receptor (FGFR)2 is regulated on the basis of the balance of FGFs, heparan-sulfate proteoglycans, FGFR2 isoforms, endogenous inhibitors, and microRNAs. FGFR2 signals cross-talk with hedgehog, bone morphogenetic protein, and other regulatory networks. Some cases of congenital skeletal disorders with an FGFR2 mutation show skin phenotypes, including acne, cutis gyrata, and acanthosis nigricans. Gain-of-function mutations or variations of human FGFR2 occur in estrogen receptor-positive breast cancer, diffuse-type gastric cancer, and endometrial uterine cancer. Oral administration of AZD2171 or Ki23057 inhibits in vivo proliferation of cancer cells with aberrant FGFR2 activation in rodent therapeutic models. However, loss-of-function mutations of FGFR2 are reported in human melanoma. Conditional Fgfr2b knockout in the rodent epidermis leads to increased macrophage infiltration to the dermis and adipose tissue, epidermal thickening accompanied by basal-layer dysplasia and parakeratosis, and the promotion of chemically induced squamous-cell carcinoma. Dysregulation of FGFR2 results in a spectrum of bone and skin pathologies and several types of cancer.

Interleukin-1 regulates keratinocyte expression of T cell targeting chemokines through interleukin-1 receptor associated kinase-1 (IRAK1) dependent and independent pathways

IL-1 is a potent pro-inflammatory cytokine that activates intracellular signaling cascades some of which may involve IL-1 receptor associated kinase-1 (IRAK1). Psoriasis is a T cell dependent chronic inflammatory condition of the skin of unknown cause. IL-1 has been implicated in psoriasis pathology, but the mechanism has not been elucidated. Interestingly, expression of IRAK1 is elevated in psoriatic skin. To identify a potential link between IL-1, keratinocytes and T cells in skin inflammation we employed pathway-focused microarrays to evaluate IL-1 dependent gene expression in keratinocytes. Several candidate mRNAs encoding known T cell chemoattractants were identified in primary keratinocytes and the stable keratinocyte cell line HaCaT. CCL5 and CCL20 mRNA and protein levels were confirmed up-regulated by IL-1 in concentration and time-dependent manners. Furthermore IL-1 synergized with IFN-gamma and TNF-alpha. Expression of CXCL9, CXCL10 and CXCL11 mRNAs was also increased in response to IL-1, but protein could only be detected in medium from cells treated with IFN-gamma alone or in combination with IL-1. Over-expression of IRAK1 led to increased constitutive and cytokine induced production of CCL5 and CCL20. Inhibition of IRAK1 activity through RNAi or expression of a dominant negative mutant blocked production of CCL5 and CCL20 but had no effect upon the IL-1 enhancement of IFN-gamma induced CXCL9, CXCL10 and CXCL11 production. In conclusion IL-1 regulates T cell targeting chemokine production in keratinocytes through IRAK1 dependent and independent pathways. These pathways may contribute to acute and chronic skin inflammation.

Modulation of the keratinocyte-fibroblast paracrine relationship with gelatin-based semi-interpenetrating networks containing bioactive factors for wound repair

Gelatin-based semi-interpenetrating networks (sIPNs) containing soluble and covalently-linked bioactive factors have been shown to aid in wound healing; however, the biological responses elicited by the introduction of sIPN biomaterials remain unclear. In the current study, modulation of the re-epithelialization phase of wound healing by sIPNs grafted with PEGylated fibronectin-derived peptides and utilized as platforms for the delivery of exogenous keratinocyte growth factor (KGF) was evaluated. Following wounding, keratinocyte migration, proliferation and protein secretion is largely controlled by diffusible factors, such as KGF, released by the underlying fibroblasts. The impact of sIPNs and exogenous KGF upon the latter keratinocyte-fibroblast paracrine relationship and keratinocyte behavior was explored by monitoring keratinocyte adhesion and cytokine (IL-1alpha, IL-1beta, IL-6, KGF, GM-CSF and TGF-alpha) release. Results were generally similar for keratinocyte monoculture and keratinocyte-fibroblast co-culture systems. Although keratinocyte adhesion increased over time for positive control surfaces, adhesion to the sIPNs remained low throughout the course of the study. Release of IL-1alpha and GM-CSF was increased by exogenous KGF. The effects were more noticeable on the positive control surfaces relative to the sIPN surfaces. Regulation of the release of TGF-alpha was surface dependent, while IL-6 release was dependent upon surface type, the inclusion of exogenous KGF and the presence of fibroblasts. The findings indicate that during re-epithelialization, sIPNs containing soluble bioactive factors aid in wound healing primarily by serving as conduits for KGF, which induces the release of other key cytokines involved in tissue repair.

Differential regulated expression of keratinocyte growth factor and its receptor in experimental and human liver fibrosis

BACKGROUND AND AIM

Immunomodulatory and protective properties have been identified for the keratinocyte growth factor (KGF). For hepatocytes, pro-proliferative and anti-apoptotic effects of this growth factor have been reported in vitro. This study was designed to characterize a putative role of KGF in observed histomorphological changes in both, human and experimental liver fibrosis.

METHODS

Liver fibrosis and cirrhosis was induced in rats by repetitive exposure to phenobarbitone and increasing doses of carbon tetrachloride. Human samples were obtained from patients undergoing surgery for partial hepatectomy or transplantation. Organ samples were scored for inflammation and morphological changes. Expression of KGF and its receptor (KGFR) mRNA was quantified by real-time RT-PCR. Protein expression and receptor phosphorylation was determined by Western blot analysis. In-situ hybridization and immunohistochemistry were utilized to determine distribution of KGF and KGFR in the liver.

RESULTS

Expression of KGF was significantly increased in damaged liver tissue in correlation to the degree of fibrosis, whereas expression of the receptor was up-regulated in early stages of liver fibrosis and down-regulated in cirrhotic organs. Protein expression of this growth factor and its receptor correlated with the alterations in mRNA. KGF expression was restricted to mesenchymal cells, whereas expression of KGFR was detected on hepatocytes only.

CONCLUSION

The expression of KGF and KGFR is differentially and significantly regulated in damaged liver tissue. This growth factor might therefore not only contribute to morphological alterations but also regeneration of liver parenchyma most likely mediated by indirect mechanisms of action.

Regulation of Expression of Fibroblast Growth Factor 7 in the Pig Uterus by Progesterone and Estradiol1

Fibroblast growth factor 7 (FGF7) stimulates cell proliferation, differentiation, migration and angiogenesis. The consensus is that FGF7, expressed by mesenchymal cells, binds FGF receptor 2IIIb (FGFR2) on epithelia, thereby mediating epithelial-mesenchymal interactions. The pig uterus is unique in that FGF7 is expressed by the luminal epithelium (LE) and FGFR2 is expressed by the LE, glandular epithelium (GE), and trophectoderm to effect proliferation and differentiated cell functions during conceptus development and implantation. FGF7 expression by the uterine LE of pigs increases between Days 9 and 12 of the estrus cycle and pregnancy, as circulating concentrations of progesterone increase, progesterone receptors (PGR) in the uterine epithelia decrease, and the conceptuses secrete estradiol-17beta (E(2)), for pregnancy recognition. Furthermore, E(2) increases the expression of FGF7 in pig uterine explants. The present study investigates the relationships between progesterone, E(2), and their receptors and the expression of FGF7 in the pig uterus in vivo. Pigs were ovariectomized on Day 4 of the estrus cycle and injected i.m. daily from Day 4 to Day 12 with either corn oil (CO), progesterone (P4), P4 and ZK317,316 (PZK), E(2), P4 and E(2) (PE), or P4 and ZK and E(2) (PZKE). All gilts (n = 5/treatment) were hysterectomized on Day 12. The results suggest that: 1) P4 is permissive to FGF7 expression by down-regulating PGR in LE; 2) P4 stimulates PGR-positive uterine stromal cells to release an unidentified progestamedin that induces FGF7 expression by LE; 3) E(2) and P4 can induce FGF7 when PGR are rendered nonfunctional by ZK; and 4) E(2) from conceptuses interacts via estrogen receptor alpha, but not estrogen receptor beta in LE to induce maximal expression of FGF7 in LE on Day 12 of pregnancy in pigs.

Keratinocyte-fibroblast interactions in wound healing

Cutaneous tissue repair aims at restoring the barrier function of the skin. To achieve this, defects need to be replaced by granulation tissue to form new connective tissue, and epithelial wound closure is required to restore the physical barrier. Different wound-healing phases are recognized, starting with an inflammation-dominated early phase giving way to granulation tissue build-up and scar remodeling after epithelial wound closure has been achieved. In the granulation tissue, mesenchymal cells are maximally activated, cells proliferate, and synthesize huge amounts of extracellular matrix. Epithelial cells also proliferate and migrate over the provisional matrix of the underlying granulation tissue, eventually closing the defect. This review focuses on the role of keratinocyte-fibroblast interactions in the wound-healing process. There is ample evidence that keratinocytes stimulate fibroblasts to synthesize growth factors, which in turn will stimulate keratinocyte proliferation in a double paracrine manner. Moreover, fibroblasts can acquire a myofibroblast phenotype under the control of keratinocytes. This depends on a finely tuned balance between a proinflammatory or a transforming growth factor (TGF)-beta-dominated environment. As the phenotype of fibroblasts from different tissues or body sites becomes better defined, we may understand their individual contribution in wound healing in more detail and possibly explain different clinical outcomes.

Keratinocyte growth factor/fibroblast growth factor-7-regulated cell migration and invasion through activation of NF-kappaB transcription factors

Keratinocyte growth factor (KGF)/fibroblast growth factor-7 (FGF-7) is a paracrine- and epithelium-specific growth factor produced by cells of mesenchymal origin. It acts exclusively through FGF-7 receptor (FGFR2/IIIb), which is expressed predominantly by epithelial cells, but not by fibroblasts, suggesting that it might function as a paracrine mediator of mesenchymal-epithelial interactions. KGF/FGF-7 plays an essential role in the growth of epithelial cells and is frequently overexpressed in cancers of epithelial origin such as pancreatic cancer, switching paracrine stimulation of KGF/FGF-7 to an autocrine loop. Less is known, however, about the signaling pathways by which KGF/FGF-7 regulates the response of epithelial cells. To delineate the signaling pathways activated by KGF/FGF-7 and examine cellular response to KGF/FGF-7 stimulation, we performed functional analysis of KGF/FGF-7 action. In this report, we show that KGF/FGF-7 activated nuclear factor kappaB (NF-kappaB), which in turn induced expression of VEGF, MMP-9, and urokinase-type plasminogen activator and increased migration and invasion of KGF/FGF-7-stimulated human pancreatic ductal epithelial cells. Expression of phosphorylation-defective IkappaBalpha (IkappaBalphaS32A,S36A), which blocked NF-kappaB activation, inhibited KGF/FGF-7-induced gene expression and cell migration and invasion. Our results demonstrate for the first time that KGF/FGF-7 induces NF-kappaB activation and that NF-kappaB plays an essential role in regulation of KGF/FGF-7-inducible gene expression and KGF/FGF-7-initiated cellular responses. Thus, these findings identify one signaling pathway for KGF/FGF-7-regulated cell migration and invasion and suggest that paracrine sources of KGF/FGF-7 are one of the malignancy-contributing factors from tumor stroma.

Elevated expression of FGF7 protein is common in human gastric diseases

Growth alterations within the gastric mucosa during chronic gastric inflammation are key steps in gastric cancer development. FGF7, a specific mitogen for epithelial cells, is implicated in epithelial tissue repair and cancer. We investigated FGF7 expression in normal human stomach, and in 35 cases from various gastric pathologies including 23 gastritis and 8 adenocarcinoma cases. Modest FGF7 protein levels were detected in the normal mucosal gland epithelium and in stromal fibroblasts. FGF7 protein levels, however, were markedly increased in the mucosal epithelium of all gastric inflammation cases. A similar elevated expression was also observed in gastric adenocarcinoma. Upregulation of FGF7 protein was associated with a modest increase in FGF7 mRNA expression. Interestingly, high levels of FGF7 anti-sense (AS) RNA were observed in the gastric pathologies, at the same sites where FGF7 protein was upregulated. Altogether, these findings suggest a role for FGF7 in maintaining gastric mucosa integrity, and that FGF7 protein levels are regulated mainly by posttranscriptional mechanisms. The elevated FGF7 protein levels in gastric inflammation and gastric cancer, together with the known oncogenic potential of FGF7, implicate excessive FGF7 signaling in gastric tumorigenesis, and point to FGF7 as an attractive target for gastric cancer prevention and treatment.