Red light as a 12-oxo-leukotriene B₄ antagonist: an explanation for the efficacy of intensive red light in the therapy of peripheral inflammatory diseases

To explain the successful treatment of various inflammatory diseases by using intensive red light, a non-linear theory is presented for the interaction of electric dipoles with light involving frequency doubling. It is applied to analyze the influence of light on organic molecules with permanent electric dipoles. The molecule 5-hydroxy-12-oxo-(5S,6Z,8E,10E,14Z)-6,8,10,14-eicosatetraenoic acid, 12-oxo-leukotriene B4 (12-Oxo-LTB4, an intermediate in the lipoxygenase-catalyzed path of arachidonic acid metabolism), is suspected to play a major role in the healing process, as, first, it plays a key role in the metabolism of leukotriene B4 (LTB4), which in many diseases acts as a source of inflammatory reactions; second, its dipole resonance is located at a wavelength of 316 nm, which can be excited by a 632 nm source through frequency doubling. From the structure of 12-Oxo-LTB4 and the knowledge of the partial charges of its 54 atoms, the equivalent values for dipole charges and dipole moment are derived. The power balance demonstrates that intensive red light with a power density of 0.4 W/cm2 transfers sufficient energy to 12-Oxo-LTB4 to render it biologically inactive. Hence, by generating a reactive high-energy leukotriene pathway intermediate, the law of mass action steers the chemical equilibrium to interrupt the inflammatory cascade.

[The antioxidant system of patients with chronic inflammatory liver diseases after exposure to ionizing radiation]

Commonly seen in liquidators of the effects of the Chernobyl accident are affections of the liver (chronic hepatitis) and bile tract (chronic calculous cholecystitis) accompanied by IHD. The above patients demonstrate enhancement of the antioxidant defence in the blood with the values for free-radical peroxidation remaining unchanged. Absolute values for blood content of LTV4 in chronic active hepatitis were found out to be low, which fact suggests that such patients need to be kept under periodic oncological surveillance.

Transformation and degradation of leukotriene B4, 12-hydroxyeicosatetraenoic acid and 5-hydroxyeicosatetraenoic acid induced by ultraviolet radiation

To reveal the underlying mechanisms in the therapeutic effectiveness of ultraviolet (UBV)- and psoralen plus UVA phototherapy, the photostability of leukotriene B4 (LTB4), 12-hydroxyeicosatetraenoic acid (12-HETE) and 5-HETE was investigated in the presence and absence of photosensitizers (8-methoxypsoralen and 5-methoxypsoralen). Arachidonic lipoxygenase products were irradiated with doses of narrow-band UVB (311 nm) ranging from 0.5-3.2 J/cm2, UVB and UVA (305-400 nm) ranging from 0.6-6.3 J/cm2 and UVA ranging from 5.0-60.0 J/cm2, respectively. High-performance liquid chromatography demonstrated a dose-dependent decrease of LTB4, 12-HETE, and 5-HETE. The photostability of 12-HETE was much higher than that of LTB4 and 5-HETE. Two products of transformation of LTB4 were identified as 5(S), 12(R)-dihydroxy-(6E, 8E, 10E, 14Z)-eicosatetraenoic acid [6-trans-LTB4] and 5(S), 12(R)-dihydroxy-(6E, 8Z, 10E, 14Z)-eicosatetraenoic acid [5(S), 12(R)-DiHETE]. There was no significant increase in photodegradation after addition of photosensitizing psoralens.

A study of the photodegradation of leukotriene B4 by ultraviolet irradiation (UVB, UVA)

In view of the presence of the polymorphonuclear leukocyte (PMN) chemoattractant Leukotriene B4 (LTB4) in the surface scale of the psoriatic lesion and the known therapeutic effect of phototherapy in psoriasis, the photostability of LTB4 was investigated. LTB4 was irradiated with dosages of UVB (290-320 nm) ranging from 100-1500 mJ cm-2 and with dosages of UVA (320-400 nm) ranging from 5-40 J cm-2. Topical application of UVB irradiated LTB4 to the forearm skin of normal volunteers showed a marked reduction in cutaneous erythema, paralleled histologically by reduced transepidermal PMN migration when compared with sites of application of unirradiated and UVA irradiated LTB4. High performance liquid chromatography (HPLC) demonstrated a dose-dependent photodegradation of LTB4 by UVB irradiation. UVA irradiation produced no such effect. The wavelengths responsible lie within the absorption spectrum of LTB4. In vitro chemotaxis studies, using an under agarose technique, showed a statistically significant reduction in the migration of PMN from both psoriatic and non-psoriatic subjects to the UVB irradiated LTB4 compared with the unirradiated LTB4, whilst UVA irradiated LTB4 produced a normal PMN chemotactic response.

Eicosanoid release in polymorphous light eruption: selective UV-A-induced LTB4 generation by peripheral blood leukocytes

The biochemical basis of ultraviolet-induced cutaneous inflammation in polymorphous light eruption (PLE) is not known. We investigated the potential role of eicosanoids--derivatives of arachidonic acid--as mediators of inflammation in this common disorder. 13 patients were investigated, in whom skin lesions could be experimentally reproduced by repeated UV-A but not UV-B irradiation. Peripheral blood leukocytes of these patients were irradiated with UV-A or UV-B, and the release of leukotriene B4 (LTB4), LTC4 and prostaglandin E2 (PGE2) was measured. Cells from PLE patients, but not healthy controls, released selectively high amounts of LTB4 in response to UV-A. The UV-A-induced LTB4 release was light-dose-dependent. This phenomenon was not observed with UV-B. The selective UV-A-induced release of LTB4 could play a major role in the pathophysiology of cutaneous inflammation in PLE.

[Mediator function of molecular factors--lipoxygenase enzyme systems during exposure to ionizing radiation]

This paper, which is a review of the national literature on the mediatory function of lipoxygenase systems affected by ionizing radiation, reports data on the functional role of lipoxygenases, their regulator--mediate contribution to radiation response of plants and animals. The latest data are submitted concerning the biological regulatory systems, eicosanoids--leukotrienes, formed under the effect of lipoxygenases which catalyse oxidation of polyunsaturated arachidonic acid (20:4). The structure and function of leukotrienes are described for these are necessary in studying the biochemical functions of lipoxygenases after ionizing irradiation. Emphasis is made on biologically active leukotrienes which take part in biological processes involved in inflammatory and hypersensitive reactions under the effect of radiation. Possible involvement of the lipoxygenase systems in metabolism regulation, its resistance and activation in a living body during development of radiopathological processes are discussed. The modelling concepts are considered for perspective radiation research aimed at biotechnological utilisation of lipoxygenases. Some regularities of mediatory function of lipoxygenase systems have been found. An assumption has been made that lipoxygenases and leukotrienes play an important role in the life of irradiated cells and tissues.