Radon Therapy Is Very Promising as a Primary or an Adjuvant Treatment for Different Types of Cancers: 4 Case Reports.

We report on the application of radon inhalation therapy to patients with 4 types of cancer: colon, uterine, lung, and liver cell. The radon treatments were given to improve the efficacy of chemotherapy and were potent in all 4 cases. Marker values decreased and disease symptoms were alleviated. We include a lengthy discussion on the mechanism that may be responsible for the observed results. While employing the radon generator to treat the patient with hepatocellular carcinoma, we discovered that a concentration of 6 MBq/m3 was very effective, while 1 MBq/m3 was marginal. This implies different, and rather high, radon concentration thresholds for the treatment of different types of cancer. The evidence from these 4 cases suggests that radon inhalation may be beneficial against various cancer types as an important adjuvant therapy to conventional chemotherapy and for local high-dose radiotherapy, which would address the problem of distant metastasis. A previous case report on 2 patients with advanced breast cancer, who refused chemotherapy or radiotherapy, indicates that radon may be effective as a primary therapy for cancer. Clinical trials should be carried out to determine the best radon concentrations for treatment of other types of cancer, at different stages of progression.

Radon Therapy for Autoimmune Diseases Pemphigus and Diabetes: 2 Case Reports.

We report on the application of radon therapy to relieve the suffering of 2 patients with autoimmune diseases, one with pemphigus with an old myocardial infarction and diabetes mellitus and the other with type I diabetes. We include a lengthy discussion of the biological mechanisms that we believe produced the observed benefits. During the 6 to 9 months of the treatments, the marker values decreased to the upper limit of their normal ranges and the symptoms of the diseases were alleviated. Disorders of Th1/Th2 balance are implicated in the onset of many diseases, including autoimmune diseases. Our decision to give radon (222Rn) therapy to these patients was based on the results of 2 similar case reports and our earlier mouse experiments, which indicated that low doses of radiation induce regulatory T cells. Regulatory T cells regulate the T helper 1 cell and the T helper 2 cell balance. There are more than 80 different autoimmune diseases that are treated with anti-inflammatory agents or immune-suppressing drugs because the exact causes of these diseases and the cures are unknown. These and other case reports indicate that proper radon therapy is an effective treatment. We urge physicians to consider radon as a standard therapy for refractory autoimmune diseases.

The Lowest Radiation Dose Having Molecular Changes in the Living Body.

We herein attempted to identify the lowest radiation dose causing molecular changes in the living body. We investigated the effects of radiation in human cells, animals, and humans. DNA double-strand breaks (DSBs) formed in cells at γ- or X-ray irradiation doses between 1 mGy and 0.5 Gy; however, the extent of DSB formation differed depending on the cell species. The formation of micronuclei (MNs) and nucleoplasmic bridges (NPBs) was noted at radiation doses between 0.1 and 0.2 Gy. Stress-responsive genes were upregulated by lower radiation doses than those that induced DNA DSBs or MN and NPBs. These γ- or X-ray radiation doses ranged between approximately 10 and 50 mGy. In animals, chromosomal aberrations were detected between 50 mGy and 0.1 Gy of low linear energy transfer radiation, 0.1 Gy of metal ion beams, and 9 mGy of fast neutrons. In humans, DNA damage has been observed in children who underwent computed tomography scans with an estimated blood radiation dose as low as 0.15 mGy shortly after examination. The frequencies of chromosomal translocations were lower in residents of high background areas than in those of control areas. In humans, systemic adaptive responses may have been prominently expressed at these radiation doses.

Recovery From Rheumatoid Arthritis Following 15 Months of Therapy With Low Doses of Ionizing Radiation: A Case Report.

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease that occurs commonly in old people. Hot spring radon therapy is widely practiced in Central Europe and Japan for relief from the painful symptoms. The usual duration of a spa treatment is a week or two, and the relief is temporary. This article reports on the near-complete recovery of a patient who had been suffering from RA for 10 years. The patient received 15 months of low-dose radon and γ-radiation therapy in a room that reproduced the conditions of a radon spa. The daily 40-minute exposure in the therapy room was supplemented by ten 6-minute radio-nebulizer treatments. The inflammation markers C-reactive protein and matrix metalloproteinase 3 declined strongly to the normal level of 0.07 mg/dL and the near-normal level of 48.9 ng/mL, respectively. After the patient's return to good health, the frequency of the visits was reduced to twice each month. The patient's protection systems appear to have adapted to stimulated conditions, sufficiently to sustain the recovery from RA. Such a long-term course of treatments and follow-up maintenance could be carried out in any hospital that has these low-dose radiation therapy rooms. The therapy could be scheduled to suit patient availability.

A Novel Mechanism of γ-Irradiation-Induced IL-6 Production Mediated by P2Y11 Receptor in Epidermal Keratinocytes.

Skin inflammation is caused by excessive production of cytokines and chemokines in response to an external stimulus, such as radiation, but the mechanisms involved are not completely understood. Here, we report a novel mechanism of γ-irradiation-induced interleukin-6 (IL-6) production mediated by P2Y11 receptors in epidermal cells. After irradiation of HaCaT cells derived from human epidermal keratinocytes with 5 Gy of γ-rays (137Cs: 0.78 Gy/min), IL-6 production was unchanged at 24 h after γ-irradiation, but was increased at 48 h. IL-6 mRNA was increased at 30 h, and IL-6 production was increased at 33 h after irradiation. The production of IL-6 was sustained at least for 4 d after irradiation. P2Y11 receptor antagonist NF157 inhibited IL-6 production in irradiated cells. Treatment with ATP, a ligand of P2Y11 receptor caused IL-6 production within 24 h. ATP-induced IL-6 production was also suppressed by NF157. Extracellular ATP level was increased after irradiation. The p38 mitogen-activated protein kinase (MAPK) and nuclear factor-kappaB (NF-κB) signaling was involved in the production of IL-6 at the downstream of P2Y11 receptor activation. In addition, the cell cycle was arrested at the G2/M phase, and DNA repair foci were not disappeared at 48 h after γ-irradiation. The protein level of histone methylation enzyme G9a, which inhibits IL-6 production, was decreased after γ-irradiation. In conclusion, we suggest that γ-irradiation induces sustained IL-6 production in HaCaT cells from 33 h after irradiation, which is mediated through P2Y11 receptor-p38 MAPK-NF-κB signaling pathway and G9a degradation. This is a novel mechanism of cytokine production in γ-irradiated cells.

Present and Future Prospects of Radiation Therapy Using α-Emitting Nuclides.

Therapy with α-radiation has issues associated with internal exposure; its clinical use has been avoided. However, phase III clinical tests of the α-emitting nuclide 223Ra on patients with cancer have been conducted, and results were reported in 2011 to 2012. Since then, research has being carried out on targeted internal therapy by introducing α-emitting nuclides directly into the cancers. For many decades, nontargeted radon therapy has been carried out and is controversial because its mechanism of action is stimulation. The low-level radiation sends powerful signals to upregulate many biological protection systems, which protect against the effects of radiogenic and nonradiogenic toxins. These vital systems prevent, repair, and remove DNA and other biomolecular damage being produced endogenously at a very high rate by the very abundant reactive oxygen species associated with aerobic metabolism. Stimulation of protection systems results in beneficial effects, including a lower risk of cancer. This article reports the results of treatments on 4 patients with cancer and reviews the clinical use of α-radiation from 223Ra and radon. It discusses the prospect of using the novel 225Ac-prostate-specific membrane antigen ligand-617 ligand as a therapeutic agent for prostate cancer. It presents a new treatment system that we developed, α-Radiorespiro-Rn, which seems to be extremely effective in treating cancer.

Treatment of Cancer and Inflammation With Low-Dose Ionizing Radiation: Three Case Reports.

There is considerable evidence from experimental studies in animals, as well as from clinical reports, that low-dose radiation hormesis is effective for the treatment of cancer and ulcerative colitis. In this study, we present 3 case reports that support the clinical efficacy of low-dose radiation hormesis in patients with these diseases. First, a patient with prostate cancer who had undergone surgical resection showed a subsequent increase in prostate-specific antigen (PSA). His PSA value started decreasing immediately after the start of repeated low-dose X-ray irradiation treatment and remained low thereafter. Second, a patient with prostate cancer with bone metastasis was treated with repeated low-dose X-ray irradiation. His PSA level decreased to nearly normal within 3 months after starting the treatment and remained at the low level after the end of hormesis treatment. His bone metastasis almost completely disappeared. Third, a patient with ulcerative colitis showed a slow initial response to repeated low-dose irradiation treatment using various modalities, including drinking radon-containing water, but within 8 months, his swelling and bleeding had completely disappeared. After 1 year, the number of bowel movements had become normal. Interest in the use of radiation hormesis in clinical practice is increasing, and we hope that these case reports will encourage further clinical investigations.

Role of ATP as a Key Signaling Molecule Mediating Radiation-Induced Biological Effects.

Adenosine triphosphate (ATP) serves as a signaling molecule for adaptive responses to a variety of cytotoxic agents and plays an important role in mediating the radiation stress-induced responses that serve to mitigate or repair the injurious effects of γ radiation on the body. Indeed, low doses of radiation may have a net beneficial effect by activating a variety of protective mechanisms, including antitumor immune responses. On the other hand, ATP signaling may be involved in the radiation resistance of cancer cells. Here, focusing on our previous work, we review the evidence that low-dose γ irradiation (0.25-0.5 Gy) induces release of extracellular ATP, and that the released ATP mediates multiple radiation-induced responses, including increased intracellular antioxidant synthesis, cell-mediated immune responses, induction of DNA damage repair systems, and differentiation of regulatory T cells.

Silica nanoparticles activate purinergic signaling via P2X7 receptor in dendritic cells, leading to production of pro-inflammatory cytokines.

We examined the mechanism of SNP-mediated stimulation of IL-1ß and IL-18 production via P2R-mediated pathways in mouse bone marrow dendritic cells (mBMDCs). Examination of uptake of SNPs with diameters of 30, 70, and 300nm (SNP30, SNP70, and SNP300, respectively) by lipopolysaccharide-matured mBMDCs revealed that significant uptake of SNP30 occurred within as short a time as 1h. Production of IL-1ß and IL-18 by cells exposed to SNPs increased dose-dependently, and was highest in cells exposed to SNP30. The SNP30-induced cytokine production was significantly inhibited by ATPase (apyrase) and by P2X7 receptor antagonist (A438079). ATP release was also highest in SNP30-exposed cells. Treatment of mBMDCs with exogenous ATP induced release of high levels of IL-1ß and IL-18, and this release was also significantly inhibited by apyrase and A438079. The order of effectiveness of the three SNPs for inducing intracellular reactive oxygen species (ROS) production accorded well with those of cytokine production and ATP release. ROS production was inhibited by diphenyleneiodonium chloride (DPI). SNPs, especially SNP30, activate purinergic signaling in matured mBMDCs by inducing ATP release via P2X7 receptor. ATP induces ROS production via NADPH oxidase, and ROS activate inflammasomes, leading to caspase-1-dependent processing of pro-cytokines and release of IL-1ß and IL-18.

Radiosensitizing Effect of TRPV1 Channel Inhibitors in Cancer Cells.

Radiosensitizers are used in cancer therapy to increase the γ-irradiation susceptibility of cancer cells, including radioresistant hypoxic cancer cells within solid tumors, so that radiotherapy can be applied at doses sufficiently low to minimize damage to adjacent normal tissues. Radiation-induced DNA damage is repaired by multiple repair systems, and therefore these systems are potential targets for radiosensitizers. We recently reported that the transient receptor potential vanilloid type 1 (TRPV1) channel is involved in early responses to DNA damage after γ-irradiation of human lung adenocarcinoma A549 cells. Therefore, we hypothesized that TRPV1 channel inhibitors would have a radiosensitizing effect by blocking repair of radiation-induced cell damage. Here, we show that pretreatment of A549 cells with the TRPV1 channel inhibitors capsazepine, AMG9810, SB366791 and BCTC suppressed the γ-ray-induced activation of early DNA damage responses, i.e., activation of the protein kinase ataxia-telangiectasia mutated (ATM) and accumulation of p53-binding protein 1 (53BP1). Further, the decrease of survival fraction at one week after γ-irradiation (2.0 Gy) was enhanced by pretreatment of cells with these inhibitors. On the other hand, inhibitor pretreatment did not affect cell viability, the number of apoptotic or necrotic cells, or DNA synthesis at 24 h after irradiation. These results suggest that inhibition of DNA repair by TRPV1 channel inhibitors in irradiated A549 cells caused gradual loss of proliferative ability, rather than acute facilitation of apoptosis or necrosis. TRPV1 channel inhibitors could be novel candidates for radiosensitizers to improve the efficacy of radiation therapy, either alone or in combination with other types of radiosensitizers.

Brain-Specific Superoxide Dismutase 2 Deficiency Causes Perinatal Death with Spongiform Encephalopathy in Mice.

Oxidative stress is believed to greatly contribute to the pathogenesis of various diseases, including neurodegeneration. Impairment of mitochondrial energy production and increased mitochondrial oxidative damage are considered early pathological events that lead to neurodegeneration. Manganese superoxide dismutase (Mn-SOD, SOD2) is a mitochondrial antioxidant enzyme that converts toxic superoxide to hydrogen peroxide. To investigate the pathological role of mitochondrial oxidative stress in the central nervous system, we generated brain-specific SOD2-deficient mice (B-Sod2(-/-)) using nestin-Cre-loxp system. B-Sod2(-/-) showed perinatal death, along with severe growth retardation. Interestingly, these mice exhibited spongiform neurodegeneration in motor cortex, hippocampus, and brainstem, accompanied by gliosis. In addition, the mutant mice had markedly decreased mitochondrial complex II activity, but not complex I or IV, in the brain based on enzyme histochemistry. Furthermore, brain lipid peroxidation was significantly increased in the B-Sod2(-/-), without any compensatory alterations of the activities of other antioxidative enzymes, such as catalase or glutathione peroxidase. These results suggest that SOD2 protects the neural system from oxidative stress in the perinatal stage and is essential for infant survival and central neural function in mice.

Extracellular ATP induces unconventional release of glyceraldehyde-3-phosphate dehydrogenase from microglial cells.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key glycolytic enzyme that is predominantly localized in the cytoplasm. However, recent studies have suggested that GAPDH is released by various cells and that extracellular GAPDH is involved in the regulation of neuritogenesis in neuronal cells. It has also been reported that GAPDH is expressed on the surfaces of macrophages and functions as a transferrin receptor. However, since GAPDH is a leaderless protein the mechanisms by which it reaches the extracellular environment remain unclear. Here, we examined the role of P2X7 receptor (P2X7R), an ATP-gated cation channel, in the unconventional release of GAPDH from microglial cells, the resident macrophages in the brain. The activation of P2X7R by ATP triggered GAPDH release from lipopolysaccharide (LPS)-primed microglial cells. ATP-induced microvesicle formation, exosome release, and K(+) efflux followed by caspase-1 activation are likely involved in the GAPDH release, but ATP-induced dilatation of membrane pores and lysosome exocytosis are not. It was also demonstrated that exogenous GAPDH facilitated LPS-induced phosphorylation of p38 MAP kinase in microglial cells. These findings suggest that P2X7R plays an important role in the unconventional release of GAPDH from microglial cells, and the GAPDH released into the extracellular space might be involved in the regulation of the neuroinflammatory response in the brain.

Autocrine Regulation of UVA-Induced IL-6 Production via Release of ATP and Activation of P2Y Receptors.

Extracellular nucleotides, such as ATP, are released from cells in response to various stimuli and act as intercellular signaling molecules through activation of P2 receptors. Exposure to the ultraviolet radiation A (UVA) component of sunlight causes molecular and cellular damage, and in this study, we investigated the involvement of extracellular nucleotides and P2 receptors in the UVA-induced cellular response. Human keratinocyte-derived HaCaT cells were irradiated with a single dose of UVA (2.5 J/cm2), and ATP release and interleukin (IL)-6 production were measured. ATP was released from cells in response to UVA irradiation, and the release was blocked by pretreatment with inhibitors of gap junction hemichannels or P2X7 receptor antagonist. IL-6 production was increased after UVA irradiation, and this increase was inhibited by ecto-nucleotidase or by antagonists of P2Y11 or P2Y13 receptor. These results suggest that UVA-induced IL-6 production is mediated by release of ATP through hemichannels and P2X7 receptor, followed by activation of P2Y11 and P2Y13 receptors. Interestingly, P2Y11 and P2Y13 were associated with the same pattern of IL-6 production, though they trigger different intracellular signaling cascades: Ca2+-dependent and PI3K-dependent, respectively. Thus, IL-6 production in response to UVA-induced ATP release involves at least two distinct pathways, mediated by activation of P2Y11 and P2Y13 receptors.

Extracellular ATP induces P2X7 receptor activation in mouse Kupffer cells, leading to release of IL-1ß, HMGB1, and PGE2, decreased MHC class I expression and necrotic cell death.

Kupffer cells, which are resident macrophages in liver, can produce various cytokines and chemokines that induce hepatitis and liver fibrosis. It is suggested that extracellular ATP-induced activation of macrophage P2X7 receptor plays an important role in inflammation via release of pro-inflammatory mediators, but the role of P2X7 receptor in Kupffer cells remains unclear. Here, we show that activation of P2X7 receptor in Kupffer cells causes multiple inflammatory responses, using the clonal mouse Kupffer cell line (KUP5) that we previously established. Treatment of LPS-primed Kupffer cells with 3 mM ATP induced Ca(2+) influx, non-selective large pore formation, activation of MAPK, cell lysis, IL-1ß release, prostaglandin E2 (PGE2) release, high mobility group box1 (HMGB1) release, and major histocompatibility complex (MHC) class I shedding. These events were significantly suppressed by pretreatment with P2X7 antagonist A438079, indicating involvement of P2X7 receptor activation in these inflammatory responses. Our results suggest that extracellular ATP-induced activation of P2X7 receptor of Kupffer cells plays multiple roles in the inflammatory response in liver. P2X7 receptor might be a new therapeutic target for treatment of liver diseases.

Purinergic signaling mediates oxidative stress in UVA-exposed THP-1 cells.

Ultraviolet A (UVA) radiation, the major UV component of solar radiation, can penetrate easily to the dermis, where it causes significant damage to cellular components by inducing formation of reactive oxygen species (ROS). On the other hand, extracellular ATP is released in response to various stimuli, and activates purinergic P2X7 receptor, triggering ROS production and cell death. Here, we examined the hypothesis that ATP release followed by activation of P2X7 receptor plays a role in UVA-induced oxidative cell damage, using human acute monocytic leukemia cell line THP-1. Indeed, UVA irradiation of THP-1 cells induced ATP release and activation of P2X7 receptor. Irradiated cells showed a rapid increase of both p67 phox in membrane fraction and intracellular ROS. Pretreatment with ecto-nucleotidase or P2X7 receptor antagonist blocked the UVA-initiated membrane translocation of p67 phox and ROS production. Furthermore, pretreatment with antioxidant or P2X7 receptor antagonist efficiently protected UVA-irradiated cells from caspase-dependent cell death. These findings show that autocrine signaling through release of ATP and activation of P2X7 receptor is required for UVA-induced stimulation of oxidative stress in monocytes.

Effects of low-dose-gamma rays on the immune system of different animal models of disease.

We reviewed the beneficial or harmful effects of low-dose ionizing radiation on several diseases based on a search of the literature. The attenuation of autoimmune manifestations in animal disease models irradiated with low-dose γ-rays was previously reported by several research groups, whereas the exacerbation of allergic manifestations was described by others. Based on a detailed examination of the literature, we divided animal disease models into two groups: one group consisting of collagen-induced arthritis (CIA), experimental encephalomyelitis (EAE), and systemic lupus erythematosus, the pathologies of which were attenuated by low-dose irradiation, and another group consisting of atopic dermatitis, asthma, and Hashimoto's thyroiditis, the pathologies of which were exacerbated by low-dose irradiation. The same biological indicators, such as cytokine levels and T-cell subpopulations, were examined in these studies. Low-dose irradiation reduced inter-feron (IFN)-gamma (γ) and interleukin (IL)-6 levels and increased IL-5 levels and the percentage of CD4(+)CD25(+)Foxp3(+)Treg cells in almost all immunological disease cases examined. Variations in these biological indicators were attributed to the attenuation or exacerbation of the disease's manifestation. We concluded that autoimmune diseases caused by autoantibodies were attenuated by low-dose irradiation, whereas diseases caused by antibodies against external antigens, such as atopic dermatitis, were exacerbated.

[Involvement of ATP in radiation-induced bystander effect as a signaling molecule].

We previously reported that low doses (0.25-0.5 Gy) of γ-rays induce intracellular antioxidant, radioresistant, DNA damage repair, and so on. Meanwhile, we have recently reported that ATP is released from the cells exposed to low-dose γ-rays. Here, it was investigated whether or not γ-radiation-induced release of extracellular ATP contributes to various radiation effects, in paricular, focusing on the inductions of intracellular antioxidant and DNA damage repair. Irradiation with γ-rays or exogenously added ATP increased expression of intracellular antioxidants such as thioredoxin and the increases were blocked by pretreatment with an ecto-nucleotidase in both cases. Moreover, release of ATP and autocrine/paracrine positive feedback through P2Y receptors serve to amplify the cellular repair response to radiation-induced DNA damage. To sum up, it would be suggested that ATP signaling is important for the effective induction of radiation stress response, such as protection of the body from the radiation and DNA damage repair. In addition, the possibility that this signaling is involved in the radiation resistance of cancer cells and beneficial effect on the organism of low-dose radiation and radiation adaptive response, would be further suggested.

Purinergic signaling via P2Y receptors up-mediates IL-6 production by liver macrophages/Kupffer cells.

Resident macrophages in the liver (Kupffer cells) produce various cytokines and chemokines, and have important roles in hepatitis and liver fibrosis. The cells are activated by various factors, for example lipopolysaccharide (LPS), which is an endotoxin and is high in the blood of patients with liver cirrhosis. Involvement of P2 receptors in the release of pro-inflammatory cytokines from Kupffer cells is little. In this study, we investigated purinergic signaling in the release of pro-inflammatory cytokines, such as IL-6 and TNF-α, from liver Kupffer cells of C57BL/6 mice (KUP5 cells). KUP5cells were isolated from C57BL/6 mice and cultivated with Dulbecco's modified Eagle's medium. The cells were stimulated with LPS. LPS-induced IL-6 production by KUP5 cells was suppressed significantly by pretreatments with non-selective P2 antagonist suramin, P2Y13antagonist MRS2211, and ecto-nucleotidase, whereas P2Y receptor agonists, significantly increased the IL-6 production. P2Y13knockdown reduced LPS-induced IL-6 production, but by less than 50%. These results would suggest that P2Y receptors including P2Y13and others, may involves in LPS-induced IL-6 production in Kupffer cells, leading to the liver inflammation. Therefore, we first showed the importance of purinergic signaling via P2Y receptors in the activation of Kupffer cells and liver injury, which is worthwhile in drug development for liver diseases.

Antibody-dependent cellular cytotoxicity and cytokine/chemokine secretion by KHYG-1 cells stably expressing FcγRIIIA.

Antibody-dependent cellular cytotoxicity (ADCC) mediated by natural killer (NK) cells is a major mechanism of tumor therapy with antibodies. NK cells not only manifest cytotoxicity but also secrete a variety of cytokines/chemokines that regulate immune responses. Using a retroviral vector, in this study we established a KHYG-1 cell line that stably expresses FcγRIIIA (CD16A). The KHYG-1/FcγRIIIA cells exerted potent antibody concentration-dependent ADCC, whereas parental KHYG-1 cells did not. In contrast, without antibody, the natural killer activity of KHYG-1/FcγRIIIA cells was less potent than that of parental KHYG-1 cells. During the course of ADCC, KHYG-1/FcγRIIIA cells secreted IFN-γ and MIP-1α dependent upon antibody concentration, but parental KHYG-1 cells did not. These results suggest that KHYG-1/FcγRIIIA cells would be useful in studies to elucidate the function of NK cells and the mechanism of ADCC.

Involvement of P2Y11 receptor in silica nanoparticles 30-induced IL-6 production by human keratinocytes.

We have previously reported that P2Y11 receptor mediates IFN-γ-induced IL-6 production in human keratinocytes, suggesting the importance of purinergic signaling in skin inflammatory diseases. In this study, the involvement of various P2 receptors in IL-6 production induced by silica nanoparticle 30 (SNP30) was examined in a human keratinocyte cell line, HaCaT. Exposure to SNP30 increased IL-6 production in the cells. Ecto-nucleotidase (apyrase), a non-selective antagonist of P2Y receptors (suramin), and a selective P2Y11 receptor antagonist (NF157) all inhibited IL-6 production. Nucleotides such as ATP and UTP themselves also significantly increased IL-6 production in the cells. It was further confirmed that ATP was released from HaCaT cells exposed to SNP30. These results support the possible role of ATP in SNP30-induced IL-6 production by HaCaT cells. In conclusion, these data demonstrate that P2Y11 receptor also mediates SNP30-induced IL-6 production in human keratinocytes, confirming that the ATP-P2Y11 purinergic signaling is a common pathway of IL-6 production leading to induction of skin inflammatory diseases.