Selection of iPSCs without mtDNA deletion for autologous cell therapy in a patient with Pearson syndrome.

Screening for genetic defects in the cells should be examined for clinical application. The Pearson syndrome (PS) patient harbored nuclear mutations in the POLG and SSBP1 genes, which could induce systemic large-scale mitochondrial genome (mtDNA) deletion. We investigated iPSCs with mtDNA deletions in PS patient and whether deletion levels could be maintained during differentiation. The iPSC clones derived from skin fibroblasts (9% deletion) and blood mononuclear cells (24% deletion) were measured for mtDNA deletion levels. Of the 13 skin-derived iPSC clones, only 3 were found to be free of mtDNA deletions, whereas all blood-derived iPSC clones were found to be free of deletions. The iPSC clones with (27%) and without mtDNA deletion (0%) were selected and performed in vitro and in vivo differentiation, such as embryonic body (EB) and teratoma formation. After differentiation, the level of deletion was retained or increased in EBs (24%) or teratoma (45%) from deletion iPSC clone, while, the absence of deletions showed in all EBs and teratomas from deletion-free iPSC clones. These results demonstrated that non-deletion in iPSCs was maintained during in vitro and in vivo differentiation, even in the presence of nuclear mutations, suggesting that deletion-free iPSC clones could be candidates for autologous cell therapy in patients. [BMB Reports 2023; 56(8): 463-468].

Dysfunctional pancreatic cells differentiated from induced pluripotent stem cells with mitochondrial DNA mutations.

Diabetes mellitus (DM) is a serious disease in which blood sugar levels rise abnormally because of failed insulin production or decreased insulin sensitivity. Although many studies are being conducted for the treatment or early diagnosis of DM, it is not fully understood how mitochondrial genome (mtDNA) abnormalities appear in patients with DM. Here, we induced iPSCs from fibroblasts, PBMCs, or pancreatic cells of three patients with type 2 DM (T2D) and three patients with non-diabetes counterpart. The mtDNA mutations were detected randomly without any tendency among tissues or patients. In T2D patients, 62% (21/34) of iPSC clones harbored multiple mtDNA mutations, of which 37% were homoplasmy at the 100% mutation level compared to only 8% in non-diabetes. We next selected iPSC clones that were a wild type or carried mutations and differentiated into pancreatic cells. Oxygen consumption rates were significantly lower in cells carrying mutant mtDNA. Additionally, the mutant cells exhibited decreased production of insulin and reduced secretion of insulin in response to glucose. Overall, the results suggest that screening mtDNA mutations in iPSCs from patients with T2D is an essential step before pancreatic cell differentiation for disease modeling or autologous cell therapy. [BMB Reports 2022; 55(9): 453-458].

Mitochondrial genome mutations and neuronal dysfunction of induced pluripotent stem cells derived from patients with Alzheimer's disease.

OBJECTIVES: Patient-derived induced pluripotent stem cells (iPSCs) are materials that can be used for autologous stem cell therapy. We screened mtDNA mutations in iPSCs and iPSC-derived neuronal cells from patients with Alzheimer's disease (AD). Also, we investigated whether the mutations could affect mitochondrial function and deposition of ß-amyloid (Aß) in differentiated neuronal cells. MATERIALS AND METHODS: mtDNA mutations were measured and compared among iPSCs and iPSC-derived neuronal cells. The selected iPSCs carrying mtDNA mutations were subcloned, and then their growth rate and neuronal differentiation pattern were analyzed. The differentiated cells were measured for mitochondrial respiration and membrane potential, as well as deposition of Aß. RESULTS: Most iPSCs from subjects with AD harbored ≥1 mtDNA mutations, and the number of mutations was significantly higher than that from umbilical cord blood. About 35% and 40% of mutations in iPSCs were shared with isogenic iPSCs and their differentiated neuronal precursor cells, respectively, with similar or different heteroplasmy. Furthermore, the mutations in clonal iPSCs were stable during extended culture and neuronal differentiation. Finally, mtDNA mutations could induce a growth advantage with higher viability and proliferation, lower mitochondrial respiration and membrane potential, as well as increased Aß deposition. CONCLUSION: This study demonstrates that mtDNA mutations in patients with AD could lead to mitochondrial dysfunction and accelerated Aß deposition. Therefore, early screening for mtDNA mutations in iPSC lines would be essential for developing autologous cell therapy or drug screening for patients with AD.

Anti-inflammatory and anti-apoptotic effects of N-acetylcysteine in diabetic rat corneal epithelium.

AIM: To characterize the anti-inflammatory and anti-apoptotic effects of N-acetylcysteine (NAC) in streptozotocin (STZ)-induced diabetic rat corneal epithelium and human corneal epithelial cells (HCECs) exposed to a high-glucose environment. METHODS: HCECs were incubated in 0, 5, 50 mmol/L glucose medium, or 50 mmol/L glucose medium with NAC for 24h. Diabetes was induced in rats by intraperitoneal injection of 65 mg/kg STZ and some of these rats were topically administered NAC to corneas with 3 mice per group. We characterized receptor for advanced glycation end-products (RAGE) expression using immunofluorescence, and interleukin (IL)-1ß and cleaved caspase-3 (CCAP-3) expression using immunohistochemistry. Circulating tumor necrosis factor (TNF)-α concentration was measured by ELISA and cleaved poly-ADP ribose polymerase (PARP) concentration was quantified by Western blotting. Apoptotic cells were detected using TUNEL assay and annexin V and propidium iodide staining. RESULTS: Diabetic rats had higher expression of RAGE (2.46±0.13 fold), IL-1ß, and CCAP-3 in apoptotic cells of their corneas than control rats. The expression of RAGE (1.83±0.11 fold), IL-1ß, and CCAP-3, and the number of apoptotic cells, were reduced by topical NAC treatment. HCECs incubated in 50 mmol/L glucose medium showed high concentrations of TNF-α (310±2.00 pg/mL) and cleaved PARP (7.43±0.56 fold), and more extensive apoptosis than cells in 50 mmol/L glucose medium. However, the addition of NAC reduced the concentrations of TNF-α (153.67±2.31 pg/mL) and cleaved PARP (5.55±0.31 fold) and the number of apoptotic cells. CONCLUSION: NAC inhibits inflammation and apoptosis in the corneas of diabetic rats and HCECs maintained in a high-glucose environment.

Corneal Epithelial Removal with a Newly Designed Epithelial Brush.

This study aimed to evaluate and compare the effectiveness of a newly developed epithelial removal brush with conventional methods in a rabbit model of corneal epithelial defects. The corneal epithelia of thirty-seven rabbits were removed by three different methods including blades (blade group), newly developed epithelial brushes (Ocu group), and conventional rotating brushes (Amo group). The defect area was measured with light microscopy immediately and at 4, 18, 24, and 50 hours after removal. Corneas were obtained immediately and at 24 and 50 hours and subjected to hematoxylin and eosin (H&E) and immunofluorescence staining using proliferating cell nuclear antigen (PCNA) and phosphorylated heat shock protein 27 (pHSP27) antibodies. The residual stromal surface was observed by scanning electron microscopy (SEM). In the Ocu group, epithelia were significantly recovered at 18, 24, and 50 hours compared with immediately after removal, and in the blade and Amo groups, epithelia were significantly recovered only at 50 hours after epithelial removal. The expression levels of PCNA and pHSP27 did not differ among three groups. There was significantly more inflammatory cell infiltration in the blade group than in the other groups. SEM showed a more regular and uniform residual stromal surface in the Ocu group than in the other groups. The newly developed epithelial brush showed better polishing ability and led to earlier significant epithelial recovery and a more regular and uniform stromal surface than conventional methods in this rabbit model of epithelial defects. Accumulation of clinical data is expected to expand the scope of application of new brushes for laser surface ablation.

Topical nerve growth factor attenuates streptozotocin-induced diabetic cataracts via polyol pathway inhibition and Na+/K+-ATPase upregulation.

The purpose of this study was to investigate whether and how topical nerve growth factor (NGF) attenuates streptozotocin (STZ)-induced diabetic cataracts in vivo. Rats were randomly divided into three groups, including the normal control rat group, STZ-induced diabetic cataract rat group (DM group), and STZ-induced diabetic cataract rat group treated with 200 µg/mL recombinant rat ß-NGF (DM + NGF group). Cataract formation was evaluated by portable slit lamp biomicroscopy following pupil dilation at 8 weeks. The expression levels of NGF, aldose reductase (AR), and Na+/K+-ATPase in the lens epithelial cells (LECs) of the three groups were measured in the presence or absence of topical NGF. TUNEL-positive LECs were quantified to determine if hyperglycemia caused LEC apoptosis. At 8 weeks, the mean cataract score in the control group was significantly lower than that in DM and DM + NGF groups, and the score in the DM + NGF group was significantly lower than that in the DM group. At the equatorial zone and anterior central zone of lens, NGF and Na+/K+-ATPase expression levels were significantly decreased in the DM group; however, they were partially restored in the DM + NGF group. At the equatorial zone and anterior central zone of lens, AR expression and TUNEL-positive apoptotic LECs were significantly increased in the DM group compared with the control group, however, they were significantly decreased in the DM + NGF group. In conclusion, topical NGF could delay the progression of diabetic cataracts by attenuating polyol pathway activation and increasing Na+/K+-ATPase protein levels.

Protective Effects of Cyclosporine A Emulsion Versus Cyclosporine A Cationic Emulsion Against Desiccation Stress in Human Corneal Epithelial Cells.

PURPOSE: To compare the protective effects of cyclosporine A emulsion (Restasis: 0.05% cyclosporine A) (CsAE) and cyclosporine A cationic emulsion (Ikervis: 0.1% cyclosporine A) (CsACE) on cellular inflammation, apoptosis, proliferation, and survival in an in vitro dry eye model. METHODS: The concentration of CsA in CsAE and CsACE was verified using a liquid chromatography tandem mass spectrometry system. Human corneal epithelial cells were subjected to desiccation stress. Human corneal epithelial cells were incubated with or without 3 groups of cyclosporine A medium (CsAE 1:50, CsACE 1:50, and CsACE 1:100). p-NF-κB p65, p-IκBα, Bax, Bcl-xL, p-Erk1/2, and p-Akt levels were determined using Western blots, and TNF-α levels were quantified using an enzyme-linked immunosorbent assay. RESULTS: The CsA concentration of CsACE 1:100 was nearly the same as that of CsAE 1:50. Compared with CsAE 1:50 (0.78 ± 0.19 fold), the p-NF-κB p65 level was further reduced in CsACE 1:50 (0.38 ± 1.20 fold) and 1:100 (0.29 ± 0.11 fold) as well as p-IκBα. Levels of TNF-α were also lower in CsACE 1:50 and 1:100 than in CsAE 1:50. Induction of the apoptotic protein Bax was significantly decreased in CsACE 1:50 and 1:100 compared with CsAE 1:50, whereas that of the antiapoptotic protein Bcl-xL was increased in CsACE 1:50 and 1:100. p-ERK1/2 and p-Akt levels were higher in CsACE 1:50 and 1:100 than in CsAE 1:50. CONCLUSIONS: CsACE had more potent anti-inflammatory and antiapoptotic effects than CsAE in a transwell desiccation stress model. CsACE also enhanced proliferation and survival factors under desiccation stress compared with CsAE in this in vitro dry eye model.

Diquafosol Sodium Inhibits Apoptosis and Inflammation of Corneal Epithelial Cells Via Activation of Erk1/2 and RSK: In Vitro and In Vivo Dry Eye Model.

Purpose: To evaluate the effect of diquafosol on corneal epithelium in a dry eye model using Transwell culture and a scopolamine-induced dry eye rat model. Methods: Desiccation stress induced in an in vitro dry eye model using human corneal epithelial cells was used, and the cells were incubated with or without diquafosol media diluted at 1:100. Reactive oxygen species (ROS) generation was measured using 2',7'-dichlorofluorescein diacetate (DCFH-DA). Apoptosis was analyzed, and levels of phosphorylated Erk1/2, phosphorylated p90RSK, phosphorylated Akt, IκB-α, and NF-κB-p65 were determined. Levels of IL-1ß, TNF-α, IL-6, IL-8, and GM-CSF were quantified. To investigate the in vivo effects of diquafosol, we induced dry eye in Wistar rats using scopolamine hydrobromide. The rats were divided into three groups: control, dry eye, and dry eye diquafosol; topical DIQUAS was applied four times daily for 28 days. We used immunohistochemistry to detect the levels of phosphorylated Erk1/2, phosphorylated p90RSK, and IL-1ß, and used the TUNEL assay in corneal tissue. Results: The distribution of highly fluorescent dichlorofluorescein and the proportion of annexin V- and PI-positive cells decreased in the diquafosol medium. Diquafosol increased the levels of phospho-Erk1/2, phospho-90RSK, phospho-Akt, and IκB-α, whereas it significantly decreased the levels of NF-κB-p65, IL-1ß, and TNF-α. In vivo, apoptosis was enhanced in dry eye group. This response was markedly reduced and the level of phosphorylated p90RSK and phosphorylated ERK1/2 were upregulated and IL-1ß was downregulated by DIQUAS. Conclusions: Diquafosol treatment reduced intracellular ROS levels, apoptosis, and inflammation, all of which were increased in the dry eye model through desiccation.

Nerve Growth Factor Attenuates Apoptosis and Inflammation in the Diabetic Cornea.

Purpose: To examine the effects of nerve growth factor (NGF) on apoptosis and inflammation in the diabetic cornea. Methods: To investigate the effects of NGF on glucose-induced apoptosis, we stained human corneal epithelial cells (HCECs) for annexin-V and propidium iodide (PI), and measured expression of cleaved caspase-3 and the Bcl-2-associated X protein (BAX). Moreover, to examine the effects of NGF on inflammation, we quantified the expression of interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α) using multiplex cytokine analysis, and analyzed nuclear factor-κB (NF-κB) activation and NF-κ-B inhibitor α (IκBα) degradation using Western blot analysis. To investigate the effects in vivo, we induced diabetes in male Sprague-Dawley rats using streptozotocin. The rats were divided into three groups: control, diabetic control, and diabetic NGF; topical NGF was applied three times daily for 3 weeks. We used the TUNEL assay to detect apoptosis in corneal tissue, and immunohistochemistry to identify cleaved caspase-3 and IL-1ß. Results: In HCECs, high glucose concentration (≥25 mM) led to reactive oxygen species (ROS) generation, apoptosis, and the release of inflammatory cytokines. Nerve growth factor markedly reduced ROS activation, annexin-PI-positive cells, and levels of cleaved caspase-3, BAX, IL-1ß, and TNF-α. In the diabetic rat cornea, apoptosis and inflammation were enhanced, as were levels of cleaved caspase-3 and IL-1ß. These responses were markedly reduced by NGF. Conclusions: Apoptosis and inflammation are enhanced in the diabetic cornea; NGF attenuates these responses-both in vivo and in vitro. Therefore, NGF therapy may represent a novel approach for the management of diabetic keratopathy.

RNA Interference-based Investigation of the Function of Heat Shock Protein 27 during Corneal Epithelial Wound Healing.

Small interfering RNA (siRNA) is among the most widely used RNA interference methods for the short-term silencing of protein-coding genes. siRNA is a synthetic RNA duplex created to specifically target a mRNA transcript to induce its degradation and it has been used to identify novel pathways in various cellular processes. Few reports exist regarding the role of phosphorylated heat shock protein 27 (HSP27) in corneal epithelial wound healing. Herein, cultured human corneal epithelial cells were divided into a scrambled control-siRNA transfected group and a HSP27-specific siRNA-transfected group. Scratch-induced directional wounding assays, and western blotting, and flow cytometry were then performed. We conclude that HSP27 has roles in corneal epithelial wound healing that may involve epithelial cell apoptosis and migration. Here, step-by-step descriptions of sample preparation and the study protocol are provided.

In vitro Effects of Prostaglandin Analogs on Cultured Astrocytes Obtained from the Lamina Cribrosa.

PURPOSE: To evaluate the effects of prostaglandin analogs (PGAs) on cell viability and apoptosis in cultured astrocytes obtained from the lamina cribrosa (LC) of the human optic nerve head (ONH). METHODS: Astrocytes were cultured from LC samples obtained from human donor ONH and treated with three kinds of acid form of PGAs: latanoprost (LAT-A), tafluprost (TAF-A), and bimatoprost (BIM-A) (0.1, 1, 10, 50 and 100 ug/mL). Cell viability was assessed using the WST-1 assay. Cell apoptosis was measured using the deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL) assay. Apoptotic protein expression was evaluated using western blot analysis. RESULTS: ONH astrocytes expressed FP receptor in western blot analysis. In the presence of 0.1 ug/mL of LAT-A, BIM-A, and TAF-A, the cell viability was 85%, 85% and 82%, respectively. WST-1 assay revealed about 50% of cell viability following treatment with 50 ug/mL of all PGAs. After exposing astrocytes to 10 ug/mL of each PGA for 24 hours, apoptotic cells were stained in TUNEL assay. Western blot analysis revealed that the PGAs up-regulated Bax (pro-apoptotic protein) and down-regulated Bcl-xL (anti-apoptotic protein) in the astrocytes. CONCLUSIONS: PGAs affected cell viability in cultured astrocytes obtained from human ONH LC. PGA treatment may induce apoptosis in ONH astrocytes.

The Antioxidant N-Acetylcysteine Inhibits Inflammatory and Apoptotic Processes in Human Conjunctival Epithelial Cells in a High-Glucose Environment.

PURPOSE: We evaluated the effects of N-acetylcysteine (NAC), which is known to inhibit reactive oxygen species (ROS)-dependent apoptosis, on high glucose-induced ROS, apoptosis, inflammation, and delayed-wounding closure in primary cultured human conjunctival epithelial cells (pHCECs), and the regulatory effects of cleaved caspase-3, BAX, nuclear factor κB (NF-κB), IL-6, and TNF-α on these processes. METHODS: High glucose-induced ROS generation was measured using 2',7'-dichlorofluorescein diacetate (DCFH-DA). The effects of NAC on high glucose-induced apoptosis were investigated in pHCECs using Annexin-V and PI staining, and cleaved caspase-3 and BAX expression levels using immunoblotting. To evaluate the inflammatory response, IL-6 and TNF-α expression levels were quantified by multiplex cytokine analysis, and NF-κB activation and IkB-α degradation were assessed by Western blot analysis. The effects of NAC on high glucose-delayed conjunctival epithelial wound healing were assessed by a scratch-induced directional wounding assay. RESULTS: Compared to the untreated control and normal glucose (5 mM), high glucose at 25 mM stimulated ROS generation, apoptosis, and release of inflammatory cytokines, and delayed wound healing in pHCECs. The addition of NAC markedly reduced the high glucose-induced ROS activation, Annexin-PI-positive cells, and levels of cleaved caspase-3, BAX, IL-6, and TNF-α. N-acetylcysteine also prevented high glucose-delayed wound healing. CONCLUSIONS: High glucose levels promote apoptosis by affecting mitochondria-dependent caspase activity through elevation of ROS production, a process that can be reversed by the antioxidant NAC. These findings demonstrate that NAC has a beneficial effect on conjunctival epithelial cell wound healing, antiapoptosis, and anti-inflammation in the conjunctival epithelial cell.

Secretory clusterin inhibits osteoclastogenesis by attenuating M-CSF-dependent osteoclast precursor cell proliferation.

Secretory clusterin (sCLU)/apolipoprotein J is a multifunctional glycoprotein that is ubiquitously expressed in various tissues. Reduced sCLU in the joints of patients with bone erosive disease is associated with disease activity; however, its exact role has yet to be elucidated. Here, we report that CLU is expressed and secreted during osteoclastogenesis in mouse bone marrow-derived macrophages (BMMs) that are treated with receptor activator of nuclear factor kappa-B ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). CLU-deficient BMMs obtained from CLU(-/-) mice exhibited no significant alterations in OC differentiation in comparison with BMMs obtained from wild-type mice. In contrast, exogenous sCLU treatment significantly inhibited OC formation in both BMMs and OC precursor cultures. The inhibitory effect of sCLU was more prominent in BMMs than OC precursor cultures. Interestingly, treating BMMs with sCLU decreased the proliferative effects elicited by M-CSF and suppressed M-CSF-induced ERK activation of OC precursor cells without causing apoptotic cell death. This study provides the first evidence that sCLU reduces OC formation by inhibiting the actions of M-CSF, thereby suggesting its protective role in bone erosion.

Effect of nerve growth factor on the in vitro induction of apoptosis of human conjunctival epithelial cells by hyperosmolar stress.

PURPOSE: To evaluate the effects of nerve growth factor (NGF), which is activated during inflammatory episodes of ocular diseases, on the apoptotic response in cultured human primary conjunctival epithelial cells (pHCECs). METHODS: Levels of NGF transcripts and NGF protein in pHCEC grown in medium with normal osmolarity (307 mOsm/L) or hyperosmolar medium (350, 400, and 450 mOsm/L) were determined using RT-PCR or ELISA, respectively. To assess apoptosis, pHCEC were cultured in normal or 400 mOsm/L hyperosmolar medium with neutralizing anti-NGF antibody or recombinant human NGF for 6 hours before analysis by flow cytometry. Levels of Bcl-xL, Bax, phosphorylated JNK, and cleaved caspase-3 were detected using Western blotting. Levels of the inflammatory cytokine IL-6 was analyzed using ELISA. RESULTS: Hyperosmolar conditions increased NGF levels in cultured pHCECs. Hyperosmolarity and exposure to neutralizing anti-NGF antibody significantly increased the number of apoptotic cells. Addition of recombinant human NGF to 400 mOsm/L medium decreased the number of apoptotic cells, reduced the expression of phosphorylated JNK, Bax, and cleaved caspase-3 and increased the expression of Bcl-xL. Levels of IL-6 were increased by hyperosmotic stress but decreased by exposure to recombinant human NGF. CONCLUSIONS: Hyperosmolarity induces apoptosis of pHCECs by activating JNK signaling. Increased levels of NGF under hyperosmolar conditions may contribute, at least in part, to the reduced apoptosis of pHCECs and may be beneficial in recovering conjunctival damage due to chronic hyperosmolar stress.

Heat shock protein 27 phosphorylation is involved in epithelial cell apoptosis as well as epithelial migration during corneal epithelial wound healing.

We reported the expression of phosphorylated HSP27 during epithelial wound healing in murine corneas (Jain et al., 2012) in July of 2012. This in vivo investigation demonstrated that the expression levels of phosphorylated HSP27 were greater in wounded corneal epithelial cells than in unwounded controls and that the localization of phosphorylated HSP27 was in the basal and superficial epithelia three days following corneal epithelial wounding. We suggested that phosphorylated HSP27 had a role in the early phase of corneal epithelial wound healing. The purpose of this study was to investigate the exact role of heat shock protein 27 (HSP27) phosphorylation for the wound healing of cultured human corneal epithelial cells (HCECs). HSP27-specific siRNAs and control-siRNAs, with no known homologous targets in HCECs, were created. The cultured HCECs were divided into two groups: Scrambled control-siRNA-transfected group vs. HSP27-specific siRNA-transfected group. The scratch-induced directional wounding assay, Western blotting, using antibodies against non-phosphorylated and phosphorylated HSP27, non-phosphorylated and phosphorylated Akt, and Bcl-2-associated X protein (Bax), immunofluorescence staining to determine the filament actin, flow cytometry to measure apoptosis, and proliferation assay were performed to determine the role of HSP27. Western blot assay showed that the expression of phosphorylated HSP27 significantly increased at 5, 10, and 30 min after scratch wounding, compared with those in unwounded HCECs (all p < 0.05). Western blot assay also showed HSP27-specific siRNAs effectively blocked the expression of non-phosphorylated HSP27. The HSP27-specific siRNA-transfected group had more Bax expression, less phosphorylated Akt expression, and less non-phosphorylated and phosphorylated HSP27 expression (all p < 0.05). The scratch-induced directional wounding assay showed the HSP27-specific siRNA-transfected group with a less migrating cell number than the control-siRNA-transfected group (p < 0.05). Immunofluorescence staining showed that reorganization of actin cytoskeleton prominently decreased in the HSP27-specific siRNA-transfected group, compared with the control siRNA-tranfected group. Flow cytometry revealed that the HSP27-specific siRNA-transfected group had more HCEC apoptosis. Proliferation assay showed no difference between the two groups. In conclusion, the role of HSP27 in corneal epithelial wound healing can be epithelial cell apoptosis, as well as epithelial migration. HSP27 is involved in HCEC migration by the reorganization of actin cytoskeleton.

Osmoprotective effects of supplemental epidermal growth factor in an ex vivo multilayered human conjunctival model under hyperosmotic stress.

BACKGROUND: To analyze the effects of supplemental epidermal growth factor (EGF) and the roles of inflammatory cytokines (interleukin [IL]-6) in an ex vivo dry-eye model under hyperosmotic stress using a multilayered culture of human conjunctival epithelial cells (HCECs). METHODS: Multilayered cultures of HCECs were exposed to hyperosmotic stress (400 mOsm/L) for 24 h in addition to 0.5 ng/mL EGF (low-EGF group) or 25 ng/mL EGF (high-EGF group). Apoptosis was analyzed using the TUNEL assay. Cell proliferation was measured using the [3H]-thymidine incorporation assay. The expression of IL-6, EGF, EGF receptor (EGFR), and phosphorylated extracellular signal-regulated kinase (p-ERK) was measured by western blot analysis. The secretion of IL-6 was measured using ELISA. Western blot analysis was also performed using antibodies against cleaved caspase-3. RESULTS: The percentage of apoptotic cells was lower in the high-EGF group (6.7%) than in the low-EGF group (10.3%). The high-EGF group demonstrated increased proliferation (323.7 counts/min in the low-EGF group vs 649.1 counts/min in the high-EGF group). EGF induced higher phosphor-EGFR expression and upregulated p-ERK in HCECs. In addition, EGF significantly decreased the secretion of IL-6 and cleaved caspase-3 in HCECs. CONCLUSIONS: The level of IL-6 was increased in the ex vivo HCEC dry-eye model that was under hyperosmotic stress. Supplemental EGF reduces the level of IL-6, decreases apoptosis, and increases proliferation. These findings indicate that EGF has potential as a therapeutic agent for the treatment of dry eyes.

Interleukin-34 produced by human fibroblast-like synovial cells in rheumatoid arthritis supports osteoclastogenesis.

INTRODUCTION: Interleukin-34 (IL-34) is a recently defined cytokine, showing a functional overlap with macrophage colony stimulating factor (M-CSF). This study was undertaken to address the expression of IL-34 in rheumatoid arthritis (RA) patients and to investigate its regulation and pathogenic role in RA. METHODS: IL-34 levels were determined in the RA synovium, synovial fluid (SF) and fibroblast-like synovial cells (FLS) by immunohistochemistry, real-time PCR, enzyme-linked immunosorbent assay and immunoblotting. RA activity was assessed using Disease Activity Score 28 (DAS28) activity in the plasma collected at baseline and one year after treatment. Conditioned media (CM) were prepared from RA FLS culture with tumor necrosis factor alpha (TNFα) for 24 hours and used for functional assay. RESULTS: IL-34 was expressed in the synovium, SF, and FLS from RA patients. The production of IL-34 in FLS was up-regulated by TNFα in RA samples compared with osteoarthritis (OA) patients. Importantly, the preferential induction of IL-34 rather than M-CSF by TNFα in RAFLS was mediated by the transcription factor nuclear factor kappa B (NF-κB) and activation of c-Jun N-terminal kinase (JNK). IL-34 elevation in plasma from RA patients was decreased after the administration of disease-modifying anti-rheumatic drugs (DMARDs) in accordance with a decrease in DAS28. CM from RAFLS cultured with TNFα promoted chemotactic migration of human peripheral blood mononuclear cells (PBMCs) and subsequent osteoclast (OC) formation, effects that were attenuated by an anti-IL-34 antibody. CONCLUSIONS: These data provide novel information about the production of IL-34 in RA FLS and indicate that IL-34 is an additional osteoclastogenic factor regulated by TNFα in RA, suggesting a discrete role of IL-34 in inflammatory RA diseases.

AWP1 binds to tumor necrosis factor receptor-associated factor 2 (TRAF2) and is involved in TRAF2-mediated nuclear factor-kappaB signaling.

Tumor necrosis factor receptor-associated factor 2 (TRAF2) is an adaptor protein which involves in the activation of the transcription factor, nuclear factor kappaB (NF-κB), in the tumor necrosis factor (TNF) receptor pathway. This signaling is modulated by proteins that interact with tumor necrosis factor receptor-associated factor 2. In this study, we identified the zinc-finger protein AWP1 as a tumor necrosis factor receptor-associated factor 2-interacting protein through yeast two-hybrid screening. We found that AWP1 directly interacted with the C-terminal tumor necrosis factor receptor-associated factor (TRAF) domain of tumor necrosis factor receptor-associated factor 2. Knockdown of AWP1 using small hairpin RNA significantly decreased nuclear factor kappaB activity but increased tumor necrosis factor alpha (TNFα)-induced apoptosis, presumably by decreasing the induction of nuclear factor kappaB-responsive anti-apoptotic molecules, including FICE-like inhibitory protein (FLIP), X-linked inhibitor of apoptosis protein (XIAP), Bcl-2, and Bcl-xL. In contrast, overexpression of wild-type AWP1 inhibited nuclear factor kappaB activation. Detailed domain mapping experiments showed that the AN1 domain of AWP1 mediated the functional interaction with tumor necrosis factor receptor-associated factor 2, and the A20 domain was responsible for the negative regulation of nuclear factor kappaB activation. Importantly, ectopic AWP1 overexpression led to an A20 domain-dependent increase in K-48 ubiquitination of tumor necrosis factor receptor-associated factor 2. These data indicate that AWP1 binds to tumor necrosis factor receptor-associated factor 2 and that regulates tumor necrosis factor alpha-induced nuclear factor kappaB activation through two distinct domains.

CB1 and CB2 cannabinoid receptors differentially regulate the production of reactive oxygen species by macrophages.

AIMS: We investigated the mechanism by which cannabinoid receptors-1 (CB1) and -2 (CB2) modulate inflammatory activities of macrophages. METHODS AND RESULTS: Real-time polymerase chain reaction showed the predominant CB2 expression in freshly isolated human monocytes. PMA, a potent inducer of differentiation, upregulated CB1 and increased CB1:CB2 transcript ratio from 1:17.5 to 1:3 in 5 days of culture. Immunohistochemistry showed that CB1 protein was colocalized in CD68- and CD36-positive macrophages in human atheroma. Through selective expression of CB1 or CB2 to thioglycollate-elicited peritoneal macrophages, we proved that CB1 and CB2 mediate opposing influences on the production of reactive oxygen species (ROS). Flow cytometry showed that cannabinoid-induced ROS production by macrophages was CB1-dependent. Immunoblotting assays confirmed that macrophage CB1, not CB2, induced phosphorylation of p38-mitogen-activated protein kinase, which modulated ROS production and the subsequent synthesis of tumour necrosis factor-alpha and monocyte chemoattractant protein-1. Pull-down assays showed that the Ras family small G protein, Rap1 was activated by CB2. Dominant-negative Rap1 profoundly enhanced CB1-dependent ROS production by macrophages, suggesting CB2 Rap1-dependently inhibits CB1-stimulated ROS production. CONCLUSION: CB1 promotes pro-inflammatory responses of macrophages through ROS production, which is negatively regulated by CB2 through Rap1 activation. Blocking CB1 together with selective activation of CB2 may suppress pro-inflammatory responses of macrophages.