Innate Immunity: A Cutaneous Perspective

The first responsibility for protection against microbial infection rests on the normal function of the innate immune system. This system establishes an antimicrobial barrier, recognizes attempts to breach this barrier, and responds rapidly to danger, all based on an innate defense system. Here, we review this system as it applies to mammalian skin, highlighting how a physical, cellular, and chemical barrier is formed to resist infection. When challenged, the diverse cellular components of the skin recognize the nature of the challenge and respond with an appropriate antimicrobial program including the release of antimicrobial peptides and, when necessary, recruitment and coordination with adaptive immune responses. Recent insights into these processes have advanced the understanding of disease pathogenesis and provided new therapeutic options for a variety of skin diseases.     

先天免疫的研究进展

近来,关于先天免疫的研究有了突飞猛进的进展.特别是在关于模式识别受体的发现和功能研究方面.模式识别受体能识别病原相关的分子模式.先天免疫不但提供抗感染的第一防线而且调控后天获得性免疫的激活.如果没有先天免疫,后天获得性免疫的功能会变得很微弱.Toll样受体是先天免疫的关键感受器和研究最多的模式识别受体.激活的Toll样受体信号传导通路可以很快引起与炎性反应和免疫反应相关的各种基因的表达.所有这些关于研究Toll样受体及其信号通路的新见解已经开始改变我们对炎性反应和免疫反应相关疾病的预防和治疗.     

先天免疫的研究进展

近来,关于先天免疫的研究有了突飞猛进的进展.特别是在关于模式识别受体的发现和功能研究方面.模式识别受体能识别病原相关的分子模式.先天免疫不但提供抗感染的第一防线而且调控后天获得性免疫的激活.如果没有先天免疫,后天获得性免疫的功能会变得很微弱.Toll样受体是先天免疫的关键感受器和研究最多的模式识别受体.激活的Toll样受体信号传导通路可以很快引起与炎性反应和免疫反应相关的各种基因的表达.所有这些关于研究Toll样受体及其信号通路的新见解已经开始改变我们对炎性反应和免疫反应相关疾病的预防和治疗.     

先天免疫的研究进展

近来,关于先天免疫的研究有了突飞猛进的进展。特别是在关于模式识别受体的发现和功能研究方面。模式识别受体能识别病原相关的分子模式。先天免疫不但提供抗感染的第一防线而且调控后天获得性免疫的激活。如果没有先天免疫,后天获得性免疫的功能会变得很微弱。Toll样受体是先天免疫的关键感受器和研究最多的模式识别受体。激活的Toll样受体信号传导通路可以很快引起与炎性反应和免疫反应相关的各种基因的表达。所有这些关于研究Toll样受体及其信号通路的新见解已经开始改变我们对炎性反应和免疫反应相关疾病的预防和治疗。     

miRNA与固有免疫

固有免疫是宿主防御病原体入侵的第一道防线, microRNA （ miRNA）是能够调节基因mRNA表达的一组非蛋白编码小RNA分子,其表达具有空间和时间上的特异性,是调控其它功能基因表达的重要分子。 miRNA参与固有免疫应答,并对其发挥重要的调控作用。文章从miRNA对固有免疫受体信号通路和固有免疫细胞的调节两方面阐述了miRNA对固有免疫的调节作用。     

Influence of Innate Immune Responses on Autoimmunity

Objective: To explore the therapeutic alliance effects of adenovirus vector-mediated gene transfer of ICOSIg and CTLA4Ig fusion protein on experimental autoimmune myocarditis (EAM).

Methods: Expression vector pAdeno-CTLA4Ig and pAdeno-ICOSIg was constructed and transfected into HEK293 cells. Adenovirus expresses CTLA4Ig and ICOSIg was produced. Ad-CMV-GFP was used as controls. EAM was induced in Lewis rats by injection of procine cardiac myosin. All the immunized rats were divided into four groups. Group A (n = 15) received adenovirus containing CTLA4Ig and ICOSIg from day 14–28; group B (n = 15), group C (n = 15) and group D (n = 15) received adenovirus containing CTLA4Ig, ICOSIg and GFP, respectively. Group E (n = 10) was normal controls never received immunization. On day 28, all the rats were killed after echocardiography examination. Histopathological examination was used to observe inflammation in the myocardium. Western blot was used to detect CTLA4, ICOS, ICOSL and competitive RT-PCR for B7-1, B7-2 expression. T lymphocyte proliferation assay was performed and ELISPOT was used to detect the Th1 and Th2 production.

Results: Alliance application of CTLA4Ig and ICOSIg exerts therapeutic effects on EAM. After a treatment duration of 14 days, cardiac function and myocardial inflammation improved significantly compared to group D. Expression of CTLA-4, ICOS and ICOSL, B7-1 was statistically decreased in group A, B and C compared with group D. T-cell proliferation was inhibited by costimulatory blockade in a dose-dependent style. ICOSIg blockade significantly augments IL-4 and IL-10 production while diminished IFN-γ production.

Conclusions: Blockade of costimulatory pathway with alliance therapy of CTLA4Ig and ICOSIg alleviated autoimmune damage in EAM and improved cardiac function. The mechanisms may be downregulation of costimulatory molecules and anti-inflammation.     

Symposium 11: Innate Immunity and Inflammation

Inflammation Research -     

Innate Immunity to Aspergillus Species

Summary: All humans are continuously exposed to inhaled Aspergillus conidia, yet healthy hosts clear the organism without developing disease and without the development of antibody- or cell-mediated acquired immunity to this organism. This suggests that for most healthy humans, innate immunity is sufficient to clear the organism. A failure of these defenses results in a uniquely diverse set of illnesses caused by Aspergillus species, which includes diseases caused by the colonization of the respiratory tract, invasive infection, and hypersensitivity. A key concept in immune responses to Aspergillus species is that the susceptibilities of the host determine the morphological form, antigenic structure, and physical location of the fungus. In this review, we summarize the current literature on the multiple layers of innate defenses against Aspergillus species that dictate the outcome of this host-microbe interaction.     

New Insights into Innate Immunity

Inflammation Research -     

Innate Immunity in Atopic Dermatitis

Atopic dermatitis (AD) is a clinically defined, highly pruritic, chronic inflammatory skin disease. In AD patients, the combination of a genetic predisposition for skin barrier dysfunction and dysfunctional innate and adaptive immune responses leads to a higher frequency of bacterial and viral skin infections. The innate immune system quickly mobilizes an unspecific, standardized first-line defense against different pathogens. Defects in this system lead to barrier dysfunction which results in increased protein allergen penetration through the epidermis and predisposes to secondary skin infections. Two loss-of-function mutations in the epidermal filaggrin gene are associated with AD. Also, inducible endogenous antibiotics such as the antimicrobial peptides cathelicidin and the beta-defensins may show defective function in lesional AD skin. Eczema herpeticum is a disseminated viral infection almost exclusively diagnosed in AD patients, which is based on unmasking of the viral entry receptor nectin-1, lack of cathelicidin production by keratinocytes, and depletion of Type I IFN-producing plasmacytoid dendritic cells from AD skin. Future therapeutic approaches to AD may include enhancement of impaired innate in addition to downregulation of dysfunctional adaptive immunity.     

Autoimmunity,Infectious Immunity,and Atherosclerosis

Introduction  

Vascular inflammation is common in certain systemic autoimmune diseases and contributes to the oxidation of low-density lipoprotein (oxLDL) and oxLDL/β2-glycoprotein I (β2GPI) complex formation. These complexes have been implicated as proatherogenic autoantigens that participate in the development of atherosclerotic disease.     

Neonatal Tolerant Immunity for Vaccination against Autoimmunity

Autoimmunity arises when the immune system no longer tolerates self and precipitates lymphocyte reactivity against our own antigens. Although the developing T cell repertoire is constantly purging, self-recognition events do exist when such tight control is evaded and autoreactive lymphocytes escape the thymus (the sites of T cell development) and migrate to the periphery. Upon activation these autoreactive cells may exert aggressive behavior toward one's own tissues and organs leading to autoimmune disease. Multiple sclerosis, Rheumatoid arthritis, and type I diabetes are autoimmune diseases mediated by autoreactive T cells. A logical approach to prevent such autoimmunity would be to reprogram those lymphocytes to tolerate the self antigen. Injection of antigen at the neonatal stage promotes a state of tolerance such that successive encounter with antigen does not precipitate aggressive reactions. The mechanism underlying neonatal tolerance involves priming of T cells whose effector functions do not cause inflammatory reactions upon recognition of antigen but rather induce protective immunity. This form of tolerant immunity provides an attractive strategy for vaccination against autoimmunity. Herein, it is shown that neonatal exposure to a self-peptide-immunoglobulin chimera drives a tolerant immunity toward the self-peptide and protects against the autoimmune disease, experimental allergic encephalomyelitis.