Purpose The present investigation demonstrates a convenient laser-based approach to enhance DC migration resulting in improved DC-based immunotherapy in murine models. Experimental design Influence of laser illumination on dermal tissue microenvironment and migration of DCs following intradermal injection were determined by whole-mount immunohistochemistry, transmission electron microscope, and flow cytometry. We also investigated in vivo expansion of cytotoxic T lymphocytes (CTLs) by flow cytometry, CTL activity by in vitro CTL assay, and anti-tumor efficacy of DC immunization following cutaneous laser illumination in both preventive and therapeutic tumor models. Results Laser illumination was found to significantly enlarge perforations in the peri-lymphatic basement membrane, disarray collagen fibers and disrupt cell-matrix interactions in the dermis. The altered dermal tissue microenvironment permitted more efficient migration of intradermally injected DCs from the dermis to the draining lymph nodes (dLNs). Laser illumination also slightly but significantly enhanced the expression of costimulatory molecule CD80 and MHC I on DCs injected into the skin, when compared to those DCs administered into sham-treated skin. As a result, more vigorous expansion of tumor-specific IFN-γ+CD8+ T lymphocytes and enhanced CTL activity against 4T1 but not irrelevant tumor cells were obtained in the laser-treated group over the control group. Laser-augmented DC immunization also completely abrogated early growth of 4T1 tumor and B16F10 melanoma in preventive tumor models and significantly extended the survival of 4T1-resected mice in a therapeutic tumor model. Conclusion These data suggest a simple, safe, laser-based approach to significantly enhance DC-based immunotherapy.

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Although the inflammatory response triggered by damage-associated molecular patterns (DAMPs) in the infarcted cardiac tissues after acute myocardial infarction (MI) contributes to cardiac repair, the unrestrained inflammation induces excessive matrix degradation and myocardial fibrosis, leading to the development of adverse remodeling and cardiac dysfunction, although the molecular mechanisms that fine tune inflammation post-MI need to be fully elucidated. Protein phosphatase Mg 2+ /Mn 2+-dependent 1L (PPM1L) is a member of the serine/threonine phosphatase family. It is originally identified as a negative regulator of stress-activated protein kinase signaling and involved in the regulation of ceramide trafficking from the endoplasmic reticulum to Golgi apparatus. However, the role of PPM1L in MI remains unknown. In this study, we found that PPM1L transgenic mice exhibited reduced infarct size, attenuated myocardial fibrosis, and improved cardiac function. PPM1L transgenic mice showed significantly lower levels of inflammatory cytokines, including IL-1b, IL-6, TNF-a, and IL-12, in myocardial tissue. In response to DAMPs, such as HMGB1 or HSP60, released in myocardial tissue after MI, macrophages from PPM1L transgenic mice consistently produced fewer inflammatory cytokines. PPM1L-silenced macrophages showed higher levels of inflammatory cytokine production induced by DAMPs. Mechanically, PPM1L overexpression selectively inhibited the activation of NF-kB signaling in myocardial tissue post-MI and DAMP-triggered macrophages. PPM1L directly bound IKKb and then inhibited its phosphorylation and activation, leading to impaired NF-kB signaling activation and suppressed inflammatory cytokine production. Thus, our data demonstrate that PPM1L prevents excessive inflammation and cardiac dysfunction after MI, which sheds new light on the protective regulatory mechanism underlying MI.