Dendritic cells as stimulator cells of MHC class I-restricted immune responses

Cutaneous adaptive immunity and uraemia: a narrative review

Chronic kidney disease affects 1 in 10 people globally, with a prevalence twenty times that of cancer. A subset of individuals will progress to end-stage renal disease (ESRD) where renal replacement therapy is required to maintain health. Cutaneous disease, including xerosis and pruritus, are endemic amongst patients with ESRD. In the uraemia-associated immune deficiency of ESRD, impaired circulating immune responses contribute to increased infection risk and poorer vaccination response. Clinical manifestations of dysregulated adaptive immunity within the skin have been well-described and have been posited to play a role in cutaneous features of ESRD. However, our understanding of the mechanisms by which adaptive immunity within the skin is affected by uraemia is relatively limited. We provide an overview of how the cutaneous adaptive immune system is impacted both directly and indirectly by uraemia, highlighting that much work has been extrapolated from the circulating immune system and often has not been directly evaluated in the skin compartment. We identify knowledge gaps which may be addressed by future research. Ultimately, greater understanding of these pathways may facilitate novel therapeutic approaches to ameliorate widespread cutaneous symptomatology in ESRD.

Organization of the Skin Immune System and Compartmentalized Immune Responses in Infectious Diseases

The skin is an organ harboring several types of immune cells that participate in innate and adaptive immune responses. The immune system of the skin comprises both skin cells and professional immune cells that together constitute what is designated skin-associated lymphoid tissue (SALT). In this review, I extensively discuss the organization of SALT and the mechanisms involved in its responses to infectious diseases of the skin and mucosa. The nature of these SALT responses, and the cellular mediators involved, often determines the clinical course of such infections. I list and describe the components of innate immunity, such as the roles of the keratinocyte barrier and of inflammatory and natural killer cells. I also examine the mechanisms involved in adaptive immune responses, with emphasis on new cytokine profiles, and the role of cell death phenomena in host-pathogen interactions and control of the immune responses to infectious agents. Finally, I highlight the importance of studying SALT in order to better understand host-pathogen relationships involving the skin and detail future directions in the immunological investigation of this organ, especially in light of recent findings regarding the skin immune system.

Cell markers and determinants in fish immunology

Despite the impressive increase in the cloning and expression of genes encoding fish immunoregulatory molecules, the knowledge on "in vivo" and "in vitro" functional immunology of the corresponding peptide products is still at an initial stage. This is partly due to the lacking of specific markers for immunoregulatory peptides, that represent an indispensible tool to dissect immune reactions and to trace the fate of cellular events downstream of the activation. In this review we summarise the available information on functional immune activities of some teleost species and discuss the obtained data in an evolutionary and applied context.

A novel vicious cycle cascade in tumor chemotherapy

Dendritic cells (DCs) play a critical role in both the cellular and humoral immune response to tumor cells. The participation of co-stimulator molecules on DCs is of vital importance for full activation of T cells. Conventional tumor chemotherapy cannot only induce apoptosis of malignant cells, but also do harm to benign DCs. Expression levels of co-stimulatory molecules (especially CD80 and CD86) are downregulated during anticancer drug treatment. These DCs are defective in their antigen-presenting function being lack of sufficient co-stimulatory molecules. Immune defective DCs provide negative immune signals to CD4+ and CD8+ T cells. Thereby these T cells are induced to become tolerant to the tumor cells, and function as T regulatory/suppressor cells to induce tolerogenic DCs by cell-cell contact. These DCs tolerized to tumor antigens may further render tolerogenicity to many more T cells via intercellular contact, and thus lead to a vicious cycle cascade. This model allowed us to envisage modified strategies of antitumor chemotherapy. We may use anticancer drugs with higher specificity to tumor cells, or in combination with immunopotentiator to disrupt the vicious cycle cascade, and expect better clinical result.

Vaccine therapy for cutaneous T-cell lymphoma

We demonstrated that percutaneous peptide immunization by way of skin with impaired barrier function is a simple and noninvasive strategy to generate effective immune responses against tumors. This therapeutic strategy seems to be beneficial for the treatment of skin-associated malignancies, including CTCL, because specific CTLs are considered to be well-induced in lymph nodes that neighbor barrier-disrupted skin (Fig. 3). There remain unsolved issues concerning (1) the ability of cytokines and growth factors to enhance efficacy of this therapy and (2) the time schedule of clinical trials. It was recently shown that application of antigenic protein or its coding DNA to skin with increased permeability yields antigen-specific antibody responses. Because the skin represents an easily accessible site for immunization and vaccination, percutaneous immunization using corneum barrier-disrupted skin is an alternative to injection of CTL-inducing molecules and can readily be exploited for cancer treatment in humans. The effective induction of CTLs suggests that the method that uses barrier-disrupted skin can potentially be applied to treatments of virus and helminth infections with the use of certain antigenic peptides.

Delivery of liposome-encapsulated HIV type 1 proteins to human dendritic cells for stimulation of HIV type 1-specific memory cytotoxic T lymphocyte responses

An important aspect of vaccine development involves delivery of antigens to antigen-presenting cells for the induction of potent antigen-specific T lymphocyte responses. We investigated the effect of a cationic liposome, lipofectin, on delivery of whole proteins to human dendritic cells (DCs) derived from blood mononuclear cells by culture in interleukin 4 and granulocyte-monocyte colony-stimulating factor for stimulation of human immunodeficiency virus type 1 (HIV-1)-specific memory cytotoxic T lymphocyte (CTL) responses. Delivery of HIV-1 Gag, Pol, and Env proteins to DCs by lipofectin stimulated greater anti-HIV-1 memory CTL responses in cells from HIV-1-infected subjects than those induced by DCs loaded with protein alone. The CTLs were CD8+ and HLA class I restricted. Antigen presentation was enhanced by chloroquine, but blocked by brefeldin A and peptide aldehyde inhibitors of proteasomes, indicating that the classic MHC class I cytosolic pathway was used for processing and presentation of HIV-1 protein by the DCs. Stimulation of anti-HIV-1 CTLs by this safe, inexpensive, and broadly applicable approach may be used in DC-based therapies for HIV-1 infection.