Leonid Izikson

Activation of CD25+CD4+ Regulatory T Cells by Oral Antigen Administration

CD25+CD4+ T cells are naturally occurring regulatory T cells that are anergic and have suppressive properties. Although they can be isolated from the spleens of normal mice, there are limited studies on how they can be activated or expanded in vivo. We found that oral administration of OVA to OVA TCR transgenic mice resulted in a modification of the ratio of CD25+CD4+ to CD25−CD4+ cells with an increase of CD25+CD4+ T cells accompanied by a decrease of CD25−CD4+ T cells. The relative increase in CD25+CD4+ T cells persisted for as long as 4 wk post feeding. We also found that CTLA-4 was dominantly expressed in CD25+CD4+ T cells and there was an increase in the percentage of CD25+CD4+ T cells expressing CTLA-4 in OVA-fed mice. In contrast to CD25−CD4+ cells, CD25+CD4+ cells from fed mice proliferated only minimally to OVA or anti-CD3 and secreted IL-10 and elevated levels of TGF-β1 following anti-CD3 stimulation. CD25+CD4+ cells from fed mice suppressed the proliferation of CD25−CD4+ T cells in vitro more potently than CD25+CD4+ T cells isolated from unfed mice, and this suppression was partially reversible by IL-10 soluble receptor or TGF-β soluble receptor and high concentration of anti-CTLA-4. With anti-CD3 stimulation, CD25+CD4+ cells from unfed mice secreted IFN-γ, whereas CD25+CD4+ cells from fed mice did not. Adoptive transfer of CD25+CD4+ T cells from fed mice suppressed in vivo delayed-type hypersensitivity responses in BALB/c mice. These results demonstrate an Ag-specific in vivo method to activate CD25+CD4+ regulatory T cells and suggest that they may be involved in oral tolerance.

Targeting Dipeptidyl Peptidase IV (CD26) Suppresses Autoimmune Encephalomyelitis and Up-Regulates TGF-β1 Secretion In Vivo

CD26 or dipeptidyl peptidase IV (DP IV) is expressed on various cell types, including T cells. Although T cells can receive activating signals via CD26, the physiological role of CD26/DP IV is largely unknown. We used the reversible DP IV inhibitor Lys[Z(NO2)]-pyrrolidide (I40) to dissect the role of DP IV in experimental autoimmune encephalomyelitis (EAE) and to explore the therapeutic potential of DP IV inhibition for autoimmunity. I40 administration in vivo decreased and delayed clinical and neuropathological signs of adoptive transfer EAE. I40 blocked DP IV activity in vivo and increased the secretion of the immunosuppressive cytokine TGF-β1 in spinal cord tissue and plasma during acute EAE. In vitro, while suppressing autoreactive T cell proliferation and TNF-α production, I40 consistently up-regulated TGF-β1 secretion. A neutralizing anti-TGF-β1 Ab blocked the inhibitory effect of I40 on T cell proliferation to myelin Ag. DP IV inhibition in vivo was not generally immunosuppressive, neither eliminating encephalitogenic T cells nor inhibiting T cell priming. These data suggest that DP IV inhibition represents a novel and specific therapeutic approach protecting from autoimmune disease by a mechanism that includes an active TGF-β1-mediated antiinflammatory effect at the site of pathology.

All you need is light: antimicrobial photoinactivation as an evolving and emerging discovery strategy against infectious disease.

The story of prevention and control of infectious diseases remains open and a series of highly virulent pathogens are emerging both in and beyond the hospital setting. Antibiotics were an absolute success story for a previous era. The academic and industrial biomedical communities have now come together to formulate consensus beliefs regarding the pursuit of novel and effective alternative anti-infective countermeasures. Photodynamic therapy was established and remains a successful modality for malignancies but photodynamic inactivation has been transformed recently to an antimicrobial discovery and development platform. The concept of photodynamic inactivation is quite straightforward and requires microbial exposure to visible light energy, typically wavelengths in the visible region, that causes the excitation of photosensitizer molecules (either exogenous or endogenous), which results in the production of singlet oxygen and other reactive oxygen species that react with intracellular components, and consequently produce cell inactivation. It is an area of increasing interest, as research is advancing i) to identify the photochemical and photophysical mechanisms involved in inactivation; ii) to develop potent and clinically compatible photosensitizer; iii) to understand how photoinactivation is affected by key microbial phenotypic elements (multidrug resistance and efflux, virulence and pathogenesis determinants, biofilms); iv) to explore novel delivery platforms inspired by current trends in pharmacology and nanotechnology; and v) to identify photoinactivation applications beyond the clinical setting such as environmental disinfectants.

IFN-Inducible Protein 10/CXC Chemokine Ligand 10-Independent Induction of Experimental Autoimmune Encephalomyelitis

In multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), autoaggressive T cells traffic into the CNS and induce disease. Infiltration of these pathogenic T cells into the CNS has been correlated with the expression of the chemokine IFN-inducible protein (IP)10/CXC chemokine ligand (CXCL)10, a chemoattractant for activated T cells, and its receptor CXCR3, in the CNS of both MS patients and mice with EAE. In the present study, we report that targeted deletion of IP-10 did not diminish the expression, severity, or histopathology of EAE induced by active immunization with 100 μg of myelin oligodendrocyte glycoprotein peptide (MOG)p35–55. However, we found that IP-10-deficient mice had a lower threshold for expression of disease compared with wild-type littermates. EAE induced by immunization with 5 μg of MOGp35–55 resulted in more severe disease characterized by a greater number of CNS lesions and infiltrating mononuclear cells in IP-10-deficient mice compared with wild-type controls. IP-10-deficient mice immunized with MOGp35–55 demonstrated increased levels of IFN-inducible T cell α-chemokine/CXCL11 mRNA in the CNS and decreased levels of monokine induced by IFN-γ/CXCL9 mRNA in draining lymph nodes, suggesting differential compensation for loss of IP-10 in lymphoid vs parenchymal tissue compartments. EAE in IP-10-deficient mice induced by low-dose immunization was associated with enhanced Ag-specific Th1 responses in the draining lymph node, which corresponded with diminished lymph node TGF-β1 expression. Our data demonstrated that IP-10 was not required for the trafficking of pathogenic T cells into the CNS in EAE but played an unexpected role in determining the threshold of disease susceptibility in the periphery.

Treatment of hypertrophic and resistant port wine stains with a 755 nm laser: A case series of 20 patients

Port wine stains (PWS) are heterogeneous vascular malformations that can be treated with vascular‐selective pulsed dye lasers (PDL). Hypertrophic PWS, especially in adults, are consistently less responsive to PDL. Furthermore, many PWS that respond well initially to PDL treatment may reach a response plateau, becoming unresponsive to further PDL treatments, a phenomenon termed “treatment resistance.” Based on the theory of selective photothermolysis, vessels in such lesions may also be specifically targeted with a 755 nm laser that has selectivity for deoxyhemoglobin as well as oxyhemoglobin and increased depth of skin penetration.

The ICOS Molecule Plays a Crucial Role in the Development of Mucosal Tolerance

The ICOS molecule stimulates production of the immunoregulatory cytokine IL-10, suggesting an important role for ICOS in controlling IL-10-producing regulatory T cells and peripheral T cell tolerance. In this study we investigate whether ICOS is required for development of oral, nasal, and high dose i.v. tolerance. Oral administration of encephalitogenic myelin oligodendrocyte glycoprotein (MOG) 35–55 peptide to ICOS-deficient (ICOS−/−) mice did not inhibit experimental autoimmune encephalomyelitis (EAE), T cell proliferation, or IFN-γ production, in striking contrast to wild-type mice. Similarly, intranasal administration of MOG35–55 before EAE induction suppressed EAE and T cell responses in wild-type, but not in ICOS−/−, mice. In contrast, ICOS−/− mice were as susceptible as wild-type mice to high dose tolerance. These results indicate that ICOS plays an essential and specific role in mucosal tolerance and that distinct costimulatory pathways differentially regulate different forms of peripheral tolerance. Surprisingly, CD4+ cells from MOG-fed wild-type and ICOS−/− mice could transfer suppression to wild-type recipients, indicating that functional regulatory CD4+ cells can develop in the absence of ICOS. However, CD4+ T cells from MOG-fed wild-type mice could not transfer suppression to ICOS−/− recipients, suggesting that ICOS may have a key role in controlling the effector functions of regulatory T cells. These results suggest that stimulating ICOS may provide an effective therapeutic approach for promoting mucosal tolerance.

Androgen receptor expression helps to differentiate basal cell carcinoma from benign trichoblastic tumors.

Histologic differentiation between basal cell carcinoma and benign trichoblastic neoplasms such as trichoepithelioma and trichoblastoma can be difficult on small biopsies. Therefore, several attempts have been made to identify immunohistochemical differences between these entities. Recent studies have shown androgen receptor expression in a number of mature epithelial structures in the skin and in epithelial neoplasms including basal cell carcinoma. In contrast, androgen receptor expression was absent in mature hair follicles or the few trichogenic neoplasms studied to date. These findings suggested that androgen receptor expression might be a useful adjunct in the histologic differential diagnosis between basal cell carcinoma and benign trichoblastic neoplasms. Therefore, we performed immunohistochemical analysis of androgen receptor expression in 32 basal cell carcinomas and 10 benign trichoblastic tumors (6 trichoepitheliomas and 4 trichoblastomas). In our study, at least focal expression of androgen receptor was detected in 78% of basal cell carcinomas. None of the trichoblastic tumors showed any androgen receptor immunoreactivity. These results confirm the lack of expression of androgen receptor in benign trichoblastic neoplasms and indicate that androgen receptor expression by tumor cells points to basal cell carcinoma as the most likely diagnosis.

Safety and effectiveness of black tattoo clearance in a pig model after a single treatment with a novel 758 nm 500 picosecond laser: a pilot study.

Optimal selective photothermolysis of a pigment particle requires pulse durations equal to or less than the particles thermal relaxation time (t½). Since tattoo particles in skin range in diameter from 40 to 300 nm, picosecond pulses would approximate t½ more closely and, therefore, might be more effective at tattoo particle fragmentation.

Treatment endpoints for resistant port wine stains with a 755 nm laser

Laser therapy of port wine stains (PWS) resistant to pulsed dye laser is challenging and controversial. Based on the theory of selective photothermolysis, vessels in such lesions may be specifically targeted with the laser wavelength of 755 nm. There is much deeper penetration of the near‐infrared light and it is difficult to visualize laser‐induced changes within the deeper dermis. The recognition of an appropriate immediate endpoint response with this wavelength would be helpful. This is a clinical observations report. We present examples of an appropriate PWS tissue response endpoint based on our clinical observations in resistant PWS treated with a 755 nm laser at high fluences (40–100 J/cm2), 1.5‐ms pulse duration, with dynamic cooling device (DCD) cooling. Mild‐to‐moderate PWS lightening was associated with the immediate endpoint of a transient gray color that gradually evolved into persistent deep purpura within several minutes. We also discuss the clinical endpoints that represent undertreatment and overtreatment of PWS. It is important to attain, and maintain, the correct endpoint when treating PWS with this deeply penetrating near‐infrared laser at high fluences in order to (a) induce lesional lightening, and (b) avoid deep dermal burns that may produce scarring. Judicious use of the 755 nm laser can be beneficial for resistant PWS.

A prospective, randomized controlled trial on the efficacy of fractional photothermolysis on scar remodeling

Non‐ablative fractional resurfacing (NAFR) has been reported in case studies as an effective treatment for surgical and burn scars [Behroozan et al., J Cosmet Laser Ther 2006; 8(1):35–38; Haedersdal et al., Lasers Surg Med 2009; 41(3):189–195; Waibel and Beer, J Drugs Dermatol 2008; 7(1):59–61; Niwa et al., Dermatol Surg 2009; 35(5):773–777; discussion 777–778; and Tierney et al., Dermatol Surg 2009; 35(8):1172–1180]. We have performed a prospective, randomized controlled study with two different treatment arms to better characterize the response of hypertrophic scars to NAFR.