Anti-inflammatory effect of 635 nm irradiations on in vitro direct/indirect irradiation model.

Low-level laser therapy (LLLT) has been promoted for its beneficial effects on tissue healing and pain relief. As during laser treatment it is possible to irradiate only a small area of the surface body or wound and, correspondingly, of a very small volume of the circulating blood, it is necessary to explain how its photomodification can lead to a wide spectrum of therapeutic effects. To establish the experimental model for indirect irradiation, irradiation with 635 nm was performed on immortalized human gingival fibroblasts (IGFs) in the presence of Porphyromonas gingivalis lipopolysaccharides (LPS). The irradiated medium was transferred to non-irradiated IGFs which were compared with direct irradiated IGFs. The protein expressions were assessed by Western blot, and prostaglandin E2 (PGE2 ) was measured using an enzyme-linked immunoassay. Reactive oxygen species (ROS) were measured by DCF-DA; cytokine profiles were assessed using a human inflammation antibody array. Cyclooxygenase-2 (COX-2) protein expression and PGE2 production were significantly increased in the LPS-treated group and decreased in both direct and indirect irradiated IGFs. Unlike direct irradiated IGFs, ROS level in indirect irradiated IGFs was decreased by time-dependent manners. There were significant differences of released granulocyte colony-stimulating factor (G-CSF), regulated on activated normal T-cell expressed and secreted (RANTES), and I-TAC level observed compared with direct and indirect irradiated IGFs. In addition, in the indirect irradiation group, phosphorylations of C-Raf and Erk1/2 increased significantly compared with the direct irradiation group. Thus, we suggest that not only direct exposure with 635 nm light, but also indirect exposure with 635 nm light can inhibit activation of pro-inflammatory mediators and may be clinically useful as an anti-inflammatory tool.

[Impact of laser therapy on PGE2 level, 24-hour pH-metry changes, and quality of life in patients with gastroesophageal reflux disease].

AIM: To study the impact of low-intensity laser irradiation on 24-hour pH-metry parameters and prostaglandin E2 (PGE2) levels in patients with gastroesophageal reflux disease (GERD). SUBJECTS AND METHODS: One hundred and twelve patients aged 19 to 79 years with GERD were examined. Seventy-eight patients received a 10-day course of continuous intravenous laser therapy using a Matrix VLOK laser therapy apparatus (Matrix, Russia) with a wavelength of 0.405 pm, radiation power at the exit of a main light guide 1-1.5 mW, pulse rate 80 Hz. The indicators under study were determined before and after treatment. RESULTS: After treatment, the intravenous laser therapy group showed a significant increase in PGE2 (1376 +/- 93 pg/ml) to the levels typical of those in healthy individuals and a significant decrease in all esophageal pH-metry parameters; the DeMeester score achieved normal values, and all quality of life (QL) indicators, except for physical function index, significantly improved (10.2 +/- 5.7; p < 0.05). CONCLUSION: The findings are suggestive of elevated PGE2 levels and improved QL during laser therapy.

Squalene as a target molecule in skin hyperpigmentation caused by singlet oxygen.

Based on our previous finding (Biochem. Biophys. Res. Commun., 223, 578-582, 1996) of singlet oxygen generation from coproporphyrin excreted on the skin surface from Propionibacterium acnes, we hypothesized that singlet oxygen formed in this way under UV exposure would promote peroxidation of skin surface lipids. We found that squalene was oxidized efficiently by singlet oxygen derived from coproporphyrin under UV exposure, and that the rate constant of squalene peroxidation by singlet oxygen was ten-fold higher than that of other skin surface lipids examined. The reaction was promoted more efficiently by UVA than by UVB. Furthermore, we found that topical application of squalene peroxide induced skin hyperpigmentation through increasing prostaglandin E(2) release from keratinocytes in guinea pigs. These results suggest that squalene peroxide formation by singlet oxygen plays a key role in photo-induced skin damage.

The Antinociceptive Effect of Light-Emitting Diode Irradiation on Incised Wounds Is Correlated with Changes in Cyclooxygenase 2 Activity, Prostaglandin E2, and Proinflammatory Cytokines.

Background. Light-emitting diode (LED) phototherapy has been reported to relieve pain and enhance tissue repair through several mechanisms. However, the analgesic effect of LED on incised wounds has never been examined. Objectives. We examined the analgesic effect of LED therapy on incision pain and the changes in cyclooxygenase 2 (COX-2), prostaglandin E2 (PGE2), and the proinflammatory cytokines interleukin 6 (IL-6), IL-1ß, and tumor necrosis factor α (TNF-α). Methods. Rats received LED therapy on incised skin 6 days before incision (L-I group) or 6 days after incision (I-L group) or from 3 days before incision to 3 days after incision (L-I-L group). Behavioral tests and analysis of skin tissue were performed after LED therapy. Results. LED therapy attenuated the decrease in thermal withdrawal latency in all the irradiated groups and the decrease in the mechanical withdrawal threshold in the L-I group only. The expression levels of COX-2, PGE2, and IL-6 were significantly decreased in the three LED-treated groups, whereas IL-1ß and TNF-α were significantly decreased only in the L-I group compared with their levels in the I groups (p < 0.05). Conclusions. LED therapy provides an analgesic effect and modifies the expression of COX-2, PGE2, and proinflammatory cytokines in incised skin.

A growth factor for hepatocytes is inactivated by sub-lethal gamma-irradiation in vivo or in vitro.

Serum from partially hepatectomized rats promoted DNA synthesis in primary adult rat hepatocyte cultures. If the rats had been exposed to sub-lethal gamma-irradiation immediately following operation or if their serum, collected at 3 h, was exposed to irradiation in vitro, the growth-promoting activity was destroyed. Prostaglandin E2 also stimulated DNA synthesis in the cultures; if PGE2 was irradiated in serum from intact or partially hepatectomized rats its growth-promoting activity was markedly diminished.

Enhanced prostaglandin synthesis after ultraviolet-B exposure modulates DNA synthesis of lens epithelial cells and lowers intraocular pressure in vivo.

PURPOSE: To study the functional significance of prostaglandin synthesis after ultraviolet-B (UVB) exposure of cultured human lens epithelial cells and rabbit eyes in vivo. METHODS: Prostaglandin E2 (PGE2) was assayed using a radioimmunoassay (RIA) and mass spectroscopy. An immortalized human lens epithelial cell line (HLE-B3) was exposed to UV irradiation, and the synthesis of PGE2 was compared with the rabbit lens epithelial cell line N/N1003A. Intact human lenses were exposed to UVB in organ culture. [3H]Thymidine incorporation was measured in cultured lens epithelial cells by incubation with the radiolabel. The effects of isobutyl methyl xanthine (IBMX), an inhibitor of phosphodiesterase and of dibutyryl cyclic adenosine monophosphate (cAMP), an analog of cAMP, on PGE2 synthesis and DNA synthesis, were determined. Rabbit eyes were exposed to UVB radiation in vivo. Intraocular pressure was measured at specific times after exposure. Aqueous humor was remove from rabbit eyes, and its PGE2 content was measured by RIA. RESULTS: Cultured human lens epithelial cells (HLE), like rabbit lens epithelial cells (RLE), showed a dose-dependent increase in basal PGE2 synthesis 24 hours after UVB exposure. However, the amount of PGE2 synthesis was 2000-fold higher in the rabbit cells. Ultraviolet-B radiation enhanced the incorporation of [3H]thymidine in lens epithelial cells. Pretreatment of cells with indomethacin reduce PGE2 synthesis and [3H]thymidine incorporation. The human and rabbit cells responded in a similar manner to changes in DNA synthesis after UVB exposure. The addition of IBMX or dbcAMP to indomethacin-treated, UVB-exposed cells restored DNA synthesis toward the levels observed in the UVB-exposed cells. An increase in the concentration of cAMP was observed in lens epithelial cells exposed to exogenous PGE2. PGE2 synthesis in intact human lenses also increased twofold 24 hours after UVB exposure. Exposure of the rabbit eye in vivo to an optimal dose of UVB produced an increase in the PGE2 levels of the lens and the aqueous humor. Measurements of the intraocular pressure (IOP) of the animals showed a decrease in IOP by 2.21 +/- 0.66 and 6.45 +/- 0.79 mm Hg (mean +/- SEM, P = 0.004, t-test) at 6 and 24 hours after UVB exposure, respectively. The decrease in IOP was prevented by pretreatment with indomethacin. Exposure of the rabbit lens to UVB radiation in vivo enhanced [3H]thymidine incorporation twofold into the lens. Pretreatment of rabbits with indomethacin before exposure reduced this response. CONCLUSIONS: Results indicate that UVB exposure enhances PGE2 synthesis in HLE cultures as well as in rabbit lenses irradiated in vivo. This increased PGE2 synthesis is related to the increase in DNA synthesis observed after UVB treatment. The modulation of DNA synthesis in cultured lens epithelial cells after UVB exposure may be mediated by a cAMP-dependent mechanism.

Fructose-1,6-diphosphate attenuates prostaglandin E2 production and cyclo-oxygenase-2 expression in UVB-irradiated HaCaT keratinocytes.

1. Fructose-1,6-diphosphate (FDP), a glycolytic metabolite, is reported to ameliorate inflammation and inhibit the nitric oxide production in murine macrophages stimulated with endotoxin. It is also reported that FDP has cytoprotective effects against hypoxia or ischaemia/reperfusion injury in brain and heart. However, underlying mechanisms of its various biological activities are not completely understood. 2. In this study, we examined the effects of FDP on UVB-induced prostaglandin production in HaCaT keratinocytes. 3. Ultraviolet B (UVB, 280-320 nm) irradiation (30 mJ cm(-2)) increased prostaglandin E(2)(PGE(2)) production, which was significantly decreased by FDP in a concentration dependent manner. NS-398, a cyclo-oxygenase-2 (COX-2) selective inhibitor completely inhibited UVB-induced PGE(2) production showing that COX-2 activity is responsible for the increase in PGE(2) production under our experimental conditions. 4. UVB irradiation increased total COX activity and COX-2 mRNA in HaCaT keratinocytes, which were significantly blocked by FDP in a concentration dependent manner. 5. N-acetylcysteine (NAC) significantly attenuated UVB-induced PGE(2) production, COX activity and COX-2 mRNA expression indicating oxidative components might contribute to these events. 6. FDP reduced UVB-induced increase in cellular reactive oxygen species (ROS) level although it did not show direct radical scavenging effect in the experiment using 1,1-diphenyl-2picrylhydrazil (DPPH). FDP preserved the cellular antioxidant capacity including catalase activity and GSH content after irradiation. 7. Our data obtained hitherto suggest that FDP may have a protective role in UVB-injured keratinocyte by attenuating PGE(2) production and COX-2 expression, which are possibly through blocking intracellular ROS accumulation.

Inhibition of prostaglandin E2 and interleukin 1-beta production by low-power laser irradiation in stretched human periodontal ligament cells.

It is well-known that orthodontic treatment usually causes some discomfort and pain to the patients. Recently, it has been reported that low-power laser irradiation is effective in reducing the pain accompanying tooth movement. However, the mechanism of such pain relief cannot be elucidated. Since high levels of prostaglandin (PG) E2 and interleukin (IL)-1 beta are found in the periodontal ligament (PDL) during tooth movement, and both factors are involved in the induction of pain, the effects of low-power laser irradiation on PGE2 and IL-1 beta production in stretched human PDL cells were studied in vitro. The PDL cells, derived from healthy premolars extracted for orthodontic treatment, were utilized for experiments. Cells were seeded in flexible-bottomed culture plates, and the bottom of each plate was elongated (18% increase) under vacuum at 6 cycles per min for 1, 3, or 5 days. The stretched cells were irradiated with a Ga-Al-As low-power diode laser (60 mW) once a day for 3, 6, or 10 min (from 10.8 to 36.0 J) for 1, 3, or 5 days. PGE2 and IL-1 beta levels in the medium were measured by radioimmunoassay. In response to mechanical stretching, human PDL cells showed a marked elevation in PGE2 production in a time-dependent manner. IL-1 beta production was also elevated, but this remained constant. The increase in PGE2 production was significantly inhibited by laser irradiation in a dose-dependent manner. The increase in IL-1 beta production was also significantly inhibited by laser irradiation, although the inhibition was only partial.(ABSTRACT TRUNCATED AT 250 WORDS)

[The effect of laser therapy on the mechanisms for generating healing in long-term nonhealing stomach ulcers]. / Vliianie lazeroterapii na nekotorye mekhanizmy sanogeneza dlitel'no nezazhivaiushchikh iazv zheludka.

A study was made of the effect of copper laser therapy on the content of PGE and PGF2 alpha and on the adenylate cyclase system (cAMP, cGMP and adenylate cyclase content) in patients with gastric ulcer. Seventy patients with indolent (from 3 months to 2 years) gastric ulcers were examined. The patients were assigned into 2 groups: group I received drug therapy combined with the influence of laser on copper vapours on the ulcerous surface (a single radiation dose 10 to 15 J). As compared to group I, the patients of group II manifested a considerable rise of the content of cAMP and prostaglandins, as well as adenylate cyclase activation in the gastric mucosa. Nonspecific biostimulating action of laser radiation exercised via the influence on the dysregenerative processes in the epitheliocytes of long nonhealing ulcer edges is under discussion.

Anti-ulcerogenic effect of aqueous propolis extract and the influence of radiation exposure.

PURPOSE: To study the effect of aqueous propolis extract (AEP) against indomethacin (Indo)-induced gastric ulcers in irradiated and non-irradiated rats. MATERIALS AND METHODS: Animals were irradiated at different radiation dose levels before the induction of ulcers. AEP was injected orally 1 hour before induction of gastric ulcers and the effects compared with those of lansoprazole (Lanso), which was used as a reference anti-ulcerogenic drug. RESULTS: Pretreatment of rats, either irradiated or non-irradiated, with AEP effectively protected against Indo-induced gastric ulceration. This was associated with a reduction in acid output and peptic activity and an increase in the secretion of mucin. The mucosal prostaglandin E(2) (PGE(2)) level was also increased. The levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1ß) were suppressed to the same extent after treatment. Both propolis and Lanso were effective in reducing the number of gastric lesions as well as the plasma level of malondialdehyde (MDA). CONCLUSIONS: These findings indicate that the gastroprotective effect of AEP could be of value in the management of excessive gastric damage induced by radiation exposure.

Conjugated linoleic acids modulate UVR-induced IL-8 and PGE2 in human skin cells: potential of CLA isomers in nutritional photoprotection.

Conjugated linoleic acids (CLA), derivatives of linoleic acid found in food products, inhibit chemically induced skin cancers in mice. However, their potential photoprotective properties remain unexplored. We examined whether CLA may modulate ultraviolet radiation (UVR)-induced secretion of interleukin (IL)-8 and prostaglandin E2 (PGE(2)), mediators implicated in UVR-induced inflammation and carcinogenesis, in human skin cells. Since tumour necrosis factor (TNF)-alpha is an early mediator of UVR effects, we also examined influence of CLA on TNF-alpha-induced mediator release. HaCaT keratinocytes were supplemented with CLA isomers cis-9-trans-11 (c9,t11-CLA; > or =90%), trans-10-cis-12 (t10,c12-CLA; > or =90%) or all trans-trans isomers (tt-CLA; 23.7%) in tetrahydrofuran/fetal calf serum (THF/FCS) or THF/FCS control. Supplementation of keratinocytes with c9,t11-CLA reduced Ultraviolet B(UVB)-induced IL-8 from 37 113 +/- 2903 pg/ng protein in control cells to 14 167 +/- 2063 pg/ng protein (P < 0.001). Similarly, t10,c12-CLA reduced UVB-induced IL-8 to 9786 +/- 1291.5 pg/ng protein (P < 0.001). Additionally, t10,c12-CLA and tt-CLA inhibited TNF-alpha-induced IL-8 from 11 669 +/- 1692 pg/ng protein in control cells to 5540 +/- 191 (P < 0.001) and 8082 +/- 1298 pg/ng (P < 0.01) protein, respectively. UVB-induced PGE(2) release was reduced by tt-CLA supplementation, from 4.8 +/- 1.2 to 1.6 +/- 0.8 pg/mg protein (P < 0.01), but increased by t10,c12-CLA to 8.8 +/- 1 pg/mg protein (P < 0.001). Influence of CLA on UVB-induced PGE(2) release was further explored in CCD922SK dermal fibroblasts. CLA isomers reduced UVB-induced PGE(2) in fibroblasts, reaching significance with c9,t11-CLA (98 +/- 5 falling to 0 pg/mg protein, P < 0.05). Hence, CLA isomers differentially modulate UVB effects on skin cells in vitro. CLA-containing foods have potential in photoprotection; the cutaneous effects of individual isomers warrant clinical study.

Ionizing radiation induces astrocyte gliosis through microglia activation.

The aim of this study was to investigate the role of microglia in radiation-induced astrocyte gliosis. We found that a single dose of 15 Gy radiation to a whole rat brain increased immunostaining of glial fibrillary acidic protein in astrocytes 6 h later, and even more so 24 h later, indicating the initiation of gliosis. While irradiation of cultured rat astrocytes had little effect, irradiation of microglia-astrocyte mixed-cultures displayed altered astrocyte phenotype into more processed, which is another characteristic of gliosis. Experiments using microglia-conditioned media indicated this astrocyte change was due to factors released from irradiated microglia. Irradiation of cultured mouse microglial cells induced a dose-dependent increase in mRNA levels for cyclooxygenase-2 (COX-2), interleukin (IL)-1beta, IL-6, IL-18, tumor necrosis factor-alpha and interferon-gamma-inducible protein-10, which are usually associated with microglia activation. Consistent with these findings, irradiation of microglia activated NF-kappaB, a transcription factor that regulates microglial activation. Addition of prostaglandin E2 (PGE2: a metabolic product of the COX-2 enzyme) to primary cultured rat astrocytes resulted in phenotypic changes similar to those observed in mixed-culture experiments. Therefore, it appears that PGE(2) released from irradiated microglia is a key mediator of irradiation-induced gliosis or astrocyte phenotype change. These data suggest that radiation-induced microglial activation and resultant production of PGE2 seems to be associated with an underlying cause of inflammatory complications associated with radiation therapy for malignant gliomas.

Primary defect in UVB-induced systemic immunomodulation does not relate to immature or functionally impaired APCs in regional lymph nodes.

UVB irradiation of the shaved dorsal skin of mice can cause both local and systemic suppression of contact hypersensitivity responses; the former demonstrated by administration of the sensitizing Ag/hapten to the irradiated site and the latter by its administration at least 72 h later to distal unirradiated sites. The immunological basis of systemic immunomodulation is not clear. When haptens (trinitrochlorobenzene, FITC) were administered to the shaved ventral skin 4 days after irradiation (8 kJ/m(2)) to the shaved dorsum of BALB/c mice, CD11c(+)/FITC(+) cells in the skin-draining lymph nodes from control and irradiated mice produced on a per cell basis similar levels of IL-12 and PGE(2) were phenotypically mature and efficient at presenting FITC to lymphocytes from FITC-sensitized mice. Ag presentation by FACS-sorted CD11c(+) lymph node cells isolated 4 days after UVB irradiation was as efficient as were cells from unirradiated mice at presentation in vitro of an OVA peptide (OVA(323-339)) to CD4(+) cells from OVA-TCR-transgenic DO11.10 mice. Further, IFN-gamma levels were increased in the cultures containing CD11c(+) cells from UVB-irradiated mice, suggesting that inflammation may precede downstream immunosuppression. These results suggest that the primary cause of reduced contact hypersensitivity responses in mice in which UV irradiation and the sensitizing Ag are applied to different sites several days apart must originate from cells other than CD11c(+) APCs that directly or by production of soluble mediators (IL-12, PGE(2)) affect cellular responses in the nodes of UVB-irradiated mice.

Argon laser irradiation of rabbits' eyes-changes in prostaglandin E2 levels.

Laser irradiation of the eye is a widely used therapeutic measure in various ocular disorders. We investigated in laser-treated rabbits' eyes the changes in prostaglandin E2 (PGE2) levels of the tissue affected by the laser (the retina/choroid) and of its adjacent vitreous over a two-week period. The parameters studied were; PGE2 in vitro production by the retina/choroid, as well as PGE2 and protein levels in the vitreous, the latter indicative of a break in the blood retinal barrier (BRB). The effect of noncoherent light exposure used for illumination, and that of the mechanical manipulation involved (sham exposure) were also studied. Following laser exposure vitreal PGE2 levels were increased two-fold above baseline (days three and 14), whereas light exposure resulted in a single peak. PGE2 in vitro production by the retina/choroid in the laser-exposed group was elevated throughout the observation period, peaking twice (days 3 and 14), in the light-exposed group the enhanced production was evident during a shorter period, whereas in the sham group it remained unchanged from baseline. An elevation in vitreal protein levels to above baseline levels occurred in both the laser- and, to a lesser degree, in the noncoherent light-exposed groups, but not in the sham group. Our study demonstrated an enhanced PGE2 in vitro production by retina/choroid of laser-exposed eyes, which might be attributable to the additive effect of the laser induced trauma, and the noncoherent light photochemical changes; the clinical significance of the recurrent increase in vitreal PGE2 levels in laser-treated eyes might be related to its anti-inflammatory properties.

Inhibitory effect of low-level laser irradiation on LPS-stimulated prostaglandin E2 production and cyclooxygenase-2 in human gingival fibroblasts.

It has been reported that lipopolysaccharide (LPS) from periodontal pathogens can penetrate gingival tissues and stimulate the production of prostaglandin E2 (PGE2), which is known as a potent stimulator of inflammation and bone resorption. Although biostimulatory effects of low-level laser irradiation such as anti-inflammatory results have been reported, the physiological mechanism is not yet clarified. The purpose of the present study was to determine the effect of laser irradiation on PGE2 production and cyclooxygenase (COX)-1 and COX-2 gene expression in LPS-challenged human gingival fibroblast (hGF) cells in vitro. hGF cells were prepared from healthy gingival tissues and challenged with LPS, and Ga-Al-As diode laser was irradiated to the hGF cells. The amount of PGE2 released in the culture medium was measured by radioimmunoassay, and mRNA levels were analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR). Irradiation with Ga-Al-As diode low-level laser significantly inhibited PGE2 production in a dose-dependent manner, which led to a reduction of COX-2 mRNA levels. In conclusion, low-level laser irradiation inhibited PGE2 by LPS in hGF cells through a reduction of COX-2 mRNA level. The findings suggest that low-level laser irradiation may be of therapeutic benefit against the aggravation of gingivitis and periodontitis by bacterial infection.