Effects of water-filtered infrared A and visible light (wIRA/VIS) radiation on heat- and stress-responsive proteins in the retina and cornea of guinea pigs

Refinement of water-filtered infrared A (wIRA) irradiations of in vitro acute and persistent chlamydial infections

“…Interestingly, this and previous investigations did not confirm consistent detrimental effects of wIRA (and VIS) on host cells and/or host tissues, even at high irradiances and/or long irradiation durations [21,26,28]. While biological effects of infrared A in mammalian cells are likely induced upon absorption of light energy by photoacceptor molecules like the cytochrome c oxidase, such photoacceptor homologues, to our knowledge, are not reported in Chlamydia.…”

“…In contrast, for developing chlamydial inclusions, irradiances at 150 or 200 mW/cm 2 provide similar anti-chlamydial effects as levels >200 mW/cm 2 . Even though previously no harmful effects have been reported even at higher irradiances (210 mW/cm 2 in vivo [21], 370 mW/cm 2 in vitro [26]) an irradiance of 150-200 mW/cm 2 is recommended for use in future safety studies in vivo as increased heat is correlated with increased irradiances [28]. Other applications of low-level light sources for medical use are referred to by the terms "photobiomodulation" or "low-level light therapy (LLLT)" [52].…”

“…Anti-chlamydial effects of wIRA (and VIS) have been reported for various cell culture models (reviewed in [18,19]) and in vivo in a guineapig inclusion conjunctivitis infection model [20]. Though no detrimental effects of this irradiation on host cells or induction of heatresponsive proteins have been reported so far [21,26,28], investigation of potential refinement of wIRA irradiation protocols is useful to 1) assess the efficacy of adapted treatment regimens and 2) gain information about the nature and mechanisms of anti-chlamydial wIRA and VIS effects.…”

“…However, the effect of wavelength on anti-chlamydial efficacy was not further commented on by the authors [50]. In our previous investigations, we evaluated either the efficacy of combined visible light and wIRA spectrum (termed wIRA/VIS, [26,29]) or more targeted wavelengths combinations using different filters and reducing the spectrum to 595-1400 nm (BTE595 orange filter) or 780-1400 nm (wIRA only, RG780 black filter) [20,21,27,28]. We observed similar anti-chlamydial efficacy for the filtered spectra excluding wavelengths below 595 nm as in the full spectrum, which partially contradicts the data of Wasson et al [50].…”

“…We have demonstrated in previous studies that wIRA (and VIS) has antichlamydial effects in acute chlamydial infections in vitro. In vivo wIRA and VIS (595-1400 nm) treatment also reduces Chlamydia-induced inflammatory parameters in a guinea pig infection model without causing negative effects on ocular structures [18,20,21]. Therefore, wIRA radiation shows promise as a non-antibiotic treatment option for ocular chlamydial infections in humans [19], including trachoma and/or inclusion conjunctivitis caused by genital strains of CT [7,[22][23][24][25].…”