Human keratinocyte-derived IL-12 affects LC-induced allogeneic T-cell responses

Down selecting adjuvanted vaccine formulations: a comparative method for harmonized evaluation

Background

The need for rapid and accurate comparison of panels of adjuvanted vaccine formulations and subsequent rational down selection, presents several challenges for modern vaccine development. Here we describe a method which may enable vaccine and adjuvant developers to compare antigen/adjuvant combinations in a harmonized fashion. Three reference antigens: Plasmodium falciparum apical membrane antigen 1 (AMA1), hepatitis B virus surface antigen (HBsAg), and Mycobacterium tuberculosis antigen 85A (Ag85A), were selected as model antigens and were each formulated with three adjuvants: aluminium oxyhydroxide, squalene-in-water emulsion, and a liposome formulation mixed with the purified saponin fraction QS21.

Results

The nine antigen/adjuvant formulations were assessed for stability and immunogenicity in mice in order to provide benchmarks against which other formulations could be compared, in order to assist subsequent down selection of adjuvanted vaccines. Furthermore, mouse cellular immune responses were analyzed by measuring IFN-γ and IL-5 production in splenocytes by ELISPOT, and humoral responses were determined by antigen-specific ELISA, where levels of total IgG, IgG1, IgG2b and IgG2c in serum samples were determined.

Conclusions

The reference antigens and adjuvants described in this study, which span a spectrum of immune responses, are of potential use as tools to act as points of reference in vaccine development studies. The harmonized methodology described herein may be used as a tool for adjuvant/antigen comparison studies.

Skin immune systems and inflammation: protector of the skin or promoter of aging?

The immune system may either have a protective role against sunburn and skin cancer or, conversely, promote solar damage. The skin is poised to react to infections and injury, such as sunburn, with rapidly acting mechanisms (innate immunity) that precede the development of acquired immunity and serve as an immediate defense system. Some of these mechanisms, including activation of defensins and complement, modify subsequent acquired immunity. An array of induced immune-regulatory and pro-inflammatory mediators is evident, at the gene expression level, from the microarray analysis of both intrinsically aged and photoaged skin. Thus, inflammatory mechanisms may accentuate the effect of UV radiation to amplify direct damaging effects on molecules and cells, including DNA, proteins, and lipids, which cause immunosuppression, cancer, and photoaging. A greater understanding of the cutaneous immune system's response to photo-skin interactions is essential to comprehensively protect the skin from adverse solar effects. Sunscreen product protection measured only as reduction in redness (current "sun" protection factor) may no longer be sufficient, as it is becoming clear that protection against UV-induced immune changes is of equal if not of greater importance. Greater knowledge of these processes will also enable the development of improved strategies to repair photodamaged skin.

IL-23 production by cosecretion of endogenous p19 and transgenic p40 in keratin 14/p40 transgenic mice: evidence for enhanced cutaneous immunity

p40, the common subunit of the proinflammatory cytokines IL-12 and IL-23, is produced by resident skin cells. Whereas the in vivo effects of IL-12 are well established, little is known about the role of IL-23 in cutaneous immune responses. In this study we show that p40 transgenic (TG) mice constitutively produce IL-23 (p19/p40), but not IL-12 (p35/p40), in basal keratinocytes by cosecretion of TG p40 with endogenous p19. Repeated injections of rIL-23 in littermate (LM) mice result in an inflammatory skin disease similar to that of p40 TG mice, confirming the proinflammatory activity of IL-23. Furthermore, IL-23 secretion by p40 TG keratinocytes induces elevated numbers of Langerhans cells (LC) with a marked up-regulation of costimulatory molecules, indicating advanced maturation of keratin 14 (K14)/p40 LC when compared with LM LC. At the functional level, freshly isolated K14/p40 LC greatly exceeded LC from LM animals in their capacity to stimulate allogeneic T cell proliferation. To assess whether IL-23 regulates cutaneous immune responses in vivo, we used an allogeneic skin transplantation model. Full thickness skin grafts from K14/p40 donors (H-2(q)) transplanted across a MHC class I and class II barrier onto BALB/c (H-2(d)) recipients were rejected in a significantly accelerated fashion (mean survival time: 8.8 days) when compared with skin grafts from non-TG LM (H-2(q)) (mean survival time: 10.7 days, p < 0.01). Based on these results we propose that IL-23-induced changes of LC may be an important mechanism in directing the outcome of cutaneous immune responses.

Inflammatory skin disease in K14/p40 transgenic mice: evidence for interleukin-12-like activities of p40

The proinflammatory cytokine interleukin-12, a p35/p40 heterodimer, is produced by resident cells in skin and has been implicated as a pathogenetic factor in T-cell-mediated skin diseases. Secretion of heterodimeric interleukin-12 is always accompanied by production of p40 monomer and p40/p40 homodimer. To investigate the possible in vivo role of p40 per se, we generated mice that constitutively express monomeric and homodimeric p40 in basal keratinocytes. These mice spontaneously developed an eczematous skin disease that was characterized by hyperkeratosis, focal epidermal spongiosis, and a mixed inflammatory infiltrate composed of T cells (CD4+), macrophages, eosinophils, mast cells, and few neutrophils. Fluorescence-activated cell sorter analysis of transgenic epidermal cell suspensions revealed induction of major histocompatibility complex class II molecules on keratinocytes and a 2-3-fold increase in the content of Langerhans cells. Cytokines produced by these activated epidermal cells include interleukin-1alpha and tumor necrosis factor alpha. The skin disease in K14/p40 mice was similar to that of littermate mice that received injections of interleukin-12, suggesting overlapping in vivo functional properties. As induction of interferon-gamma is a major function of interleukin-12, we tested the in vitro ability of transgenic p40 to induce interferon-gamma. In contrast to interleukin-12, transgenic p40 did not stimulate interferon-gamma secretion by cultured splenocytes. We conclude that transgenic p40 and interleukin-12 are equally capable of initiating cutaneous inflammation. Despite these in vivo similarities, there is a clear functional difference between interleukin-12 and transgenic p40 in vitro, suggesting that interferon-gamma is not a major factor contributing to interleukin-12-like activities of transgenic p40.

Proinflammatory and immunoregulatory functions of interleukin-12

Interleukin-12 (IL-12) is a cytokine composed of two chains, a heavy chain or p40, and a light chain or p35, forming a disulfite-linked heterodimer, or p70. IL-12 was originally discovered as a product of human B lymphoblastoid cell lines; however, the most important physiological producers of IL-12 in vitro are phagocytic cells and antigen-presenting cells rather than B cells. The major target cells of IL-12 action are natural killer and T cells, on which IL-12 induce: (1) production of cytokine, particularly interferon-gamma (IFN-gamma); (2) proliferation, in synergy with other mitogenic or costimulatory signals; (3) enhancement of cytotoxic activity. In addition, IL-12 has been described to have stimulatory effects on hematopoietic precursor cells and on B lymphocytes. In vivo, IL-12 is produced very early during infections or immune response, and exerts important proinflammatory functions and enhancement of innate resistance by activating natural killer cells and, through IFN-gamma induction, phagocytic cells. The IL-12 produced during this inflammatory phase, both by direct action and, indirectly, by determining the composition of the cytokine milieu at the site of the murine response, induces differentiation of T helper type 1 (Th1) cells while inhibiting the generation of Th2 cells. Thus, because of its double function of a proinflammatory cytokine and an immunoregulatory factor, IL-12 plays a key role in the resistance to infections, particularly those mediated by bacteria or intracellular parasites, against which phagocytic cell activation and Th1-mediated responses are particularly effective. However, because of the same activities, IL-12 also plays a role in pathological situations, such as septic shock, tissue damage during inflammation and organ-specific autoimmune diseases.

Immunopathogenesis of oral lichen planus and recurrent aphthous stomatitis

Oral mucosal bullous/desquamative/ulcerative diseases involve immunopathological mechanisms that account for loss of adhesion between contiguous keratinocytes or to structures within the basal lamina. Some are antibody mediated, in which specific adhesion molecules of the desmosome, hemidesmosome, and basement membrane become antigenic targets. Oral lichen planus and recurrent apthous ulcers, although manifesting disparate clinical appearances and natural history, share immunopathological features that involve T cell-mediated immunity. Although the antigens, haptens, or autoantigens are not usually apparent, current research poses the hypothesis that both of these common oral mucosal diseases are a delayed-type hypersensitivity or cell-mediated response to an antigenic stimulus residing within the epithelium. This article reviews the research evidence for this hypothesis.

Oral keratinocyte immune responses in HIV-associated candidiasis

INTRODUCTION

Candidiasis is the most commonly encountered opportunistic infection among HIV-positive subjects. The purpose of this study was to assess specific keratinocyte immune parameters in the pseudomembranous and erythematous forms of HIV-associated oral candidiasis.

MATERIAL/METHODS

This collaborative study from three centers analyzed 25 HIV-positive and 10 HIV-negative subjects with either pseudomembranous or erythematous candidiasis. Oral biopsy specimens from lesional tissues were procured, and histopathologic features were correlated with immunohistochemical and in situ hybridization investigations for the expression of interleukin 1 alpha, interleukin 8, antimicrobial calprotectin, lymphocyte populations, and Candida antigen.

RESULTS

Both pseudomembranous and erythematous candidiasis among HIV-infected subjects showed a mild interface lymphocytic mucositis with the presence of neutrophilic subcorneal abscesses in the latter. Erythematous candidiasis cases that failed to show surface mycelia, did yield positive results for Candida antigens in the parakeratinized layer. The expression of inflammatory chemokines were positive in all groups and calprotectin appeared to serve as a keratinocyte barrier to hyphal penetration.

CONCLUSIONS

The erythematous form of candidiasis is often devoid of hyphae yet the presence of Candida antigens in the surface epithelium implicates an immune or allergic process. The intactness of chemokines and antimicrobial calprotectin in keratinocytes may explain why disseminated candidiasis is rarely encountered in HIV-infected patients.