Magnetic Stimulation Drives Macrophage Polarization in Cell to-Cell Communication with IL-1ß Primed Tendon Cells.

Inflammation is part of the natural healing response, but it has been simultaneously associated with tendon disorders, as persistent inflammatory events contribute to physiological changes that compromise tendon functions. The cellular interactions within a niche are extremely important for healing. While human tendon cells (hTDCs) are responsible for the maintenance of tendon matrix and turnover, macrophages regulate healing switching their functional phenotype to environmental stimuli. Thus, insights on the hTDCs and macrophages interactions can provide fundamental contributions on tendon repair mechanisms and on the inflammatory inputs in tendon disorders. We explored the crosstalk between macrophages and hTDCs using co-culture approaches in which hTDCs were previously stimulated with IL-1ß. The potential modulatory effect of the pulsed electromagnetic field (PEMF) in macrophage-hTDCs communication was also investigated using the magnetic parameters identified in a previous work. The PEMF influences a macrophage pro-regenerative phenotype and favors the synthesis of anti-inflammatory mediators. These outcomes observed in cell contact co-cultures may be mediated by FAK signaling. The impact of the PEMF overcomes the effect of IL-1ß-treated-hTDCs, supporting PEMF immunomodulatory actions on macrophages. This work highlights the relevance of intercellular communication in tendon healing and the beneficial role of the PEMF in guiding inflammatory responses toward regenerative strategies.

Revisiting the Photon/Cell Interaction Mechanism in Low-Level Light Therapy.

Objective: Several reports claim that the enzyme cytochrome c oxidase (CCO) is the primary absorber for red-to-near-infrared (R-NIR) light in cells and causal for mitochondrial adenosine triphosphate (ATP) upregulation, and that pulsed R-NIR light has frequent therapeutic effects, which are superior to those of the continuous wave (CW) mode used in low-level light therapy (LLLT). Background data: Convincing evidence that the absorption of R-NIR photons by CCO is involved in mitochondrial ATP upregulations as well as a coherent explanation for the superiority of the pulsed irradiation mode is presently lacking in the literature. Methods: A comprehensive literature search and rigorous analysis of the data published on the idea that CCO is the primary absorber for R-NIR light, and of the claim that the effectivity of the pulsed irradiation mode can be derived from the absorption of R-NIR photons by CCO, reveal a number of severe inconsistencies. Results: A systematical analysis covering both the theory that CCO is the primary acceptor for R-NIR light and of its use to interpret differences between the biological effect of pulsed light and CW casts doubt on the general validity of the CCO-based hypothesis. Instead, we are offered a simple and conflict-free model accounting for both ATP upregulation and superiority of the pulsed mode in LLLT, which is in agreement with the results of recent laboratory experiments. Conclusions: CCO is not the primary acceptor for R-NIR light.

Q-switched 1064 nm Nd-Yag nanosecond laser effects on skin barrier function and on molecular rejuvenation markers in keratinocyte-fibroblasts interaction.

Skin represents an interface between internal and external environment; it protects human body by regulating the water loss and the maintenance of body temperature, defending against irritant and pathogen agents, and against physical, chemical, and UV damage. It provides to essential physiological functions, such as the important antioxidant defense capacity; its protective/defensive function is performed by a high number of proteins, and shows important functions in maintenance of skin barrier homeostasis. Keratinocytes and fibroblasts play a pivotal role to determine or prevent skin aging in response to intrinsic or extrinsic stimuli, modulating cytokines and several biochemical factors. Non-ablative technologies are playing an increasing role in the management of skin aging, inducing a dermal remodeling without a visible epidermal damage. The objective of this study was to evaluate the effect of Q-switched 1064 Nd-YAG laser (Medlite Conbio C6 Nd-YAG laser, Cynosure USA) in skin barrier function, analyzing the constituents which are strongly altered in aging skin. Particularly, we evaluated the expression of filaggrin, TGase, HSP70, and aquaporins, on HaCaT cells. The expression of proinflammatory cytokines has been investigated too.As a second step of the study, we analyzed the modulation of the rejuvenation molecular markers on human skin fibroblasts (HDFs) stimulated with keratinocytes conditioned medium (KCM).Our results demonstrated that Q-switched 1064 nm Nd:YAG laser acts on the skin barrier function, increasing the expression of aquaporins, filaggrin, TGase, and HSP70, modulating the proinflammatory cytokines. In fibroblasts stimulated with keratinocytes conditioned medium (KCM) and irradiated with Q-switched 1064 nm Nd:YAG laser, we can observe a reduction of MMP-1 and an increase in procollagen, collagen type I, and elastin. Our results highlight that Q-switched 1064 nm Nd:YAG laser treatment could represent an effective weapon to fight skin aging.

Effects of low-dose radiation on the immune system of mice after total-body irradiation.

The effects of acute exposure to low- and high-dose radiation on the quantitative and functional parameters of the immune system were analyzed. C57BL/6 mice were irradiated with different doses of γ radiation (0.01, 0.05, 0.1, 0.5 and 2 Gy) and splenocytes were isolated at various times. Alterations in the distribution and surviving fraction of splenocyte subsets such as CD4(+) and CD8(+) T lymphocytes, regulatory T cells (Treg), natural killer (NK) cells, dendritic cells (DCs) and B lymphocytes were analyzed by flow cytometry. Apoptosis frequency was quantified by the TdT-mediated dUTP-biotin nick end labeling (TUNEL) method 4 h after irradiation. Cytokine expression was investigated by real-time reverse transcription-polymerase chain reaction (RT-PCR). Low doses decreased apoptosis in the splenocyte subpopulations studied most prominently in NK cells and DCs. Exposure to 2 Gy increased apoptosis in all splenocyte subpopulations; B cells were the most sensitive and NK cells and DCs the least sensitive. The lowest cell numbers were measured 3 days after irradiation, with minor changes by day 7. CD8(+) and B cells were rather resistant to low doses but were very sensitive to 2 Gy, while NK cells, DCs and Treg cells were much more resistant to high doses. Expression of the T-helper 1 (Th1)- and helper 2 (Th2)-type cytokines decreased after low doses and increased after high doses. Interleukin 6 (IL-6) reacted at early times and IL-10 at later times. IL-5 levels were consistently elevated. These data highlight the differences in the responses of different splenocyte subpopulations to low- and high-dose radiation.

Expression of CONNEXIN43 is highly sensitive to ionizing radiation and other environmental stresses.

To gain a greater understanding of the mechanisms underlying the cellular responses to low-dose ionizing radiation, gene expression profiles were examined by microarray analysis of cDNA from confluent human diploid fibroblast cultures exposed to very low fluences of alpha-particles. The data, supported by Northern and Western analyses, indicate that radiation induces a significant up-regulation of CONNEXIN43 expression. This phenomenon was observed in a variety of irradiated cell types. These findings are consistent with our previous observations that connexin43 (cx43)-mediated gap-junction intercellular communication is involved in the bystander response observed in cell cultures exposed to fluences of alpha-particles by which only a very small fraction of the cell nuclei is traversed by a particle track (E. I. Azzam et al., Proc. Natl. Acad. Sci. USA, 98: 473-478, 2001). Increased mRNA levels in cells from irradiated cultures correlated with increased cx43 protein levels by approximately 4 h after irradiation. The induction of cx43 was observed by mean alpha-particle doses as low as 0.16 cGy, and also in cells exposed to gamma-rays, t-butyl hydroperoxide, and hyperthermia. Exposure to these stresses also resulted in post-translational modification of cx43; increased phosphorylation and hyperphosphorylation of the protein was observed. Up-regulation of cx43 expression in ionizing radiation exposed cells correlated with functional communication through gap junctions, as evidenced by dye transfer from irradiated to nonirradiated cells. In contrast, the response after UV radiation varied and was cell type-dependent. Overall, these data suggest a critical role for genes involved in intercellular communication in mediating the cellular responses to a variety of stresses.

Participation of gap-junctional cell communication on the adaptive response in human cells induced by low dose of X-rays.

To investigate the radioadaptive response of normal cells to low-dose radiation, we irradiated human embryonic (HE) cells and HeLa cells with low-dose X-rays and examined the changes in sensitivity to subsequent high-dose X-irradiation using the trypan blue dye-exclusion test. When HE cells were irradiated by 200 cGy, the growth ratio of the living cells 5 days after the irradiation decreased to 37% of that of the cells which received no X-irradiation. When the cells received a conditioning irradiation of 10-20 cGy 4 h before the irradiation of 200 cGy, the relative growth ratios increased significantly to 45-53%, and a peak was reached at a conditioning dose of 13 cGy to the cells. This conditioning effect was not observed in LeLa cells. When the HE cells were suspended in a Ca2+ ion-free medium or TPA added to the medium while receiving the conditioning irradiation of 13 cGy, the effect of the conditioning dose was not observed. This indicates that normal cells show an adaptive response to low-dose radiation and become more radioresistant. These results suggest that gap junctional intercellular communication may play a role in radioadaptive responses in human cells.

[Effect of low-intensity monochromatic electromagnetic fields of the millimeter range on biological processes]. / Vliianie monokhromaticheskikh élektromagnitnykh izluchenii millimetrovogo diapazona maloi moshchnosti na biologicheskie protsessy.

A short systematized analysis of Soviet and foreign published materials is presented dealing with biological and physical factors responsible for the effects of monochromatic electromagnetic radiations of low power on the living activity.