Chlamydial infection and spatial ascension of the female genital tract : a novel hybrid cellular automata and continuum mathematical model

Sexually transmitted chlamydial infection initially establishes in the endocervix in females, but if the infection ascends the genital tract, significant disease, including infertility, can result. Many of the mechanisms associated with chlamydial infection kinetics and disease ascension are unknown. We attempt to elucidate some of these processes by developing a novel mathematical model, using a cellular automata–partial differential equation model. We matched our model outputs to experimental data of chlamydial infection of the guinea-pig cervix and carried out sensitivity analyses to determine the relative influence of model parameters. We found that the rate of recruitment and action of innate immune cells to clear extracellular chlamydial particles and the rate of passive movement of chlamydial particles are the dominant factors in determining the early course of infection, magnitude of the peak chlamydial time course and the time of the peak. The rate of passive movement was found to be the most important factor in determining whether infection would ascend to the upper genital tract. This study highlights the importance of early innate immunity in the control of chlamydial infection and the significance of motility-diffusive properties and the adaptive immune response in the magnitude of infection and in its ascension.

SNAREing immunity : the role of SNAREs in the immune system

The trafficking of molecules and membranes within cells is a prerequisite for all aspects of cellular immune functions, including the delivery and recycling of cell surface proteins, secretion of immune mediators, ingestion of pathogens and activation of lymphocytes. SNARE (soluble-N-ethylmaleimide-sensitive-factor accessory-protein receptor)-family members mediate membrane fusion during all steps of trafficking, and function in almost all aspects of innate and adaptive immune responses. Here, we provide an overview of the roles of SNAREs in immune cells, offering insight into one level at which precision and tight regulation are instilled on immune responses.

Immunity against a Chlamydia infection and disease may be determined by a balance of IL-17 signaling

Most vaccines developed against Chlamydia using animal models provide partial protection against a genital tract infection. However, protection against the oviduct pathology associated with infertility is highly variable and often has no defining immunological correlate. When comparing two adjuvants (CTA1-DD and a combination of Cholera toxin plus CpG- oligodeoxynucleotide–CT/CpG) combined with the chlamydial major outer membrane protein (MOMP) antigen and delivered via the intranasal (IN), sublingual (SL) or transcutaneous (TC) routes, we identified two vaccine groups with contrasting outcomes following infection. SL immunization with MOMP/CTA1-DD induced a 70% reduction in the incidence of oviduct pathology, without significantly altering the course of infection. Conversely, IN immunization with MOMP/CT/CpG prevented an ascending infection, but not the oviduct pathology. This anomaly presented a unique opportunity to study the mechanisms by which vaccines can prevent oviduct pathology, other than by controlling the infection. The IL-17 signaling in the oviducts was found to associate with both the enhancement of immunity to infection and the development of oviduct pathology. This conflicting role of IL-17 may provide some explanation for the discordance in protection between infection and disease and suggests that controlling immunopathology, as opposed to the rapid eradication of the infection, may be essential for an effective human chlamydial vaccine that prevents infertility.

Vaccination of koalas (Phascolarctos cinereus) with a recombinant chlamydial major outer membrane protein adjuvanted with poly I:C, a host defense peptide and polyphosphazine, elicits strong and long lasting cellular and humoral immune responses

Chlamydial infections are wide spread in koalas across their range and a solution to this debilitating disease has been sought for over a decade. Antibiotics are the currently accepted therapeutic measure, but are not an effective treatment due to the asymptomatic nature of some infections and a low efficacy rate. Thus, a vaccine would be an ideal way to address this infectious disease threat in the wild. Previous vaccine trials have used a three-dose regimen; however this is very difficult to apply in the field as it would require multiple capture events, which are stressful and invasive processes for the koala. In addition, it requires skilled koala handlers and a significant monetary investment. To overcome these challenges, in this study we utilized a polyphosphazine based poly I:C and a host defense peptide adjuvant combined with recombinant chlamydial major outer membrane protein (rMOMP) antigen to induce long lasting (54 weeks) cellular and humoral immunity in female koalas with a novel single immunizing dose. Immunized koalas produced a strong IgG response in plasma, as well as at mucosal sites. Moreover, they showed high levels of C. pecorum specific neutralizing antibodies in the plasma as well as vaginal and conjunctival secretions. Lastly, Chlamydia-specific lymphocyte proliferation responses were produced against both whole chlamydial elementary bodies and rMOMP protein, over the 12-month period. The results of this study suggest that a single dose rMOMP vaccine incorporating a poly I:C, host defense peptide and polyphosphazine adjuvant is able to stimulate both arms of the immune system in koalas, thereby providing an alternative to antibiotic treatment and/or a three-dose vaccine regime.

Discovery of genes involved in defense/immunity functions in a haemocytes cDNA library from Fenneropenaeus chinensis by ESTs annotation

Crustacean haemocytes play important roles in the host immune response including recognition, phagocytosis, melanization, cytotoxicity and inter-cellular signal communication. Expressed sequence tags (ESTs) analysis is proved to be an efficient approach not only for gene discovery, but also for gene expression profiles performance. In order to further understand the innate immune system and defense mechanisms of Chinese shrimp at molecular level, complementary DNA library is constructed from the haemocyte tissue of Fenneropenaeus chinensis. A total of 2371 cDNA clones are successfully sequenced and the average sequence length is 460 bp. About 50% are identified as orthologs of known genes from other organisms by BLASTx and BLASTn program. By sequences comparability and analysis, 34 important genes including 177 ESTs are identified that may be involved in defense or immune functions in shrimp based on the known knowledge. These genes are categorized into five categories according to their putative functions in shrimp immune system: 13 genes are different types of antimicrobial peptides (AMP, penaeidin, antilipopolysaccharide factor, etc.), and their proportion is about 3 8%; 11 genes belong to prophenoloxidase system (prophenoloxidase, serine proteinase, serine proteinase inhibitor, etc.), and their proportion is about 32%; five genes have high homology with clotting protein (lectin, transglutaminase, etc), and their proportion is about 15%; three genes may be involved in inter-cell signal communication (peroxinectin, integrin), and their proportion is about 9%; two genes have been identified to be chaperone proteins (Hsc70, thioredoxin peroxidase), and their proportion is about 6%. These EST sequences enrich our understanding of the immune genes of F chinensis and will help farther experimental research into immune factors and improve our knowledge of the immune mechanisms of shrimp. (c) 2007 Elsevier B.V. All rights reserved.

An ancient C-type lectin in Chlamys farreri (CfLec-2) that mediate pathogen recognition and cellular adhesion

C-type lectins are a superfamily of Ca2+ dependent carbohydrate-recognition proteins which play significant diverse roles in nonself-recognition and clearance of invaders. In the present study, a C-type lectin (CfLec-2) from Zhikong scallop Chlamys farreri was selected to investigate its functions in innate immunity. The mRNA expression of CfLec-2 in hemocytes was significantly up-regulated (P < 0.01) after scallops were stimulated by LPS. PGN or beta-glucan, and reached the highest expression level at 12h post-stimulation, which was 72.5-, 23.6- or 43.8-fold compared with blank group, respectively. The recombinant Cflec-2 (designated as rCfLec-2) could bind LPS, PGN, mannan and zymosan in vitro, but it could not bind beta-glucan. Immunofluorescence assay with polyclonal antibody specific for Cflec-2 revealed that CfLec-2 was mainly located in the mantle, kidney and gonad. Furthermore, rCfLec-2 could bind to the surface of scallop hemocytes, and then initiated cellular adhesion and recruited hemocytes to enhance their encapsulation in vitro, and this process could be specifically blocked by anti-rCfLec-2 serum. These results collectively suggested that CfLec-2 from the primitive deuterostome C. farreri could perform two distinct immune functions, pathogen recognition and cellular adhesion synchronously, while these functions were performed by collectins and selectins in vertebrates, respectively. The synchronous functions of pathogen recognition and cellular adhesion performed by CfLec-2 tempted us to suspect that CfLec-2 was an ancient form of C-type lectin, and apparently the differentiation of these two functions mediated by C-type lectins occurred after mollusk in phylogeny. (C) 2010 Elsevier Ltd. All rights reserved.

A role of cellular prion protein in programming T-cell cytokine responses in disease.

The cellular prion protein (PrPC) is widely expressed in neural and non-neural tissues, but its function is unknown. Elucidation of the part played by PrPC in adaptive immunity has been a particular conundrum: increased expression of cell surface PrPC has been documented during T-cell activation, yet the functional significance of this activation remains unclear, with conflicting data on the effects of Prnp gene knockout on various parameters of T-cell immunity. We show here that Prnp mRNA is highly inducible within 8–24 h of T-cell activation, with surface protein levels rising from 24 h. When measured in parallel with CD69 and CD25, PrPC is a late activation antigen. Consistent with its up-regulation being a late activation event, PrP deletion did not alter T-cell-antigen presenting cell conjugate formation. Most important, activated PrP0/0 T cells demonstrated much reduced induction of several T helper (Th) 1, Th2, and Th17 cytokines, whereas others, such as TNF- and IL-9, were unaffected. These changes were investigated in the context of an autoimmune model and a bacterial challenge model. In experimental autoimmune encephalomyelitis, PrP-knockout mice showed enhanced disease in the face of reduced IL-17 responses. In a streptococcal sepsis model, this constrained cytokine program was associated with poorer local control of infection, although with reduced bacteremia. The findings indicate that PrPC is a potentially important molecule influencing T-cell activation and effector function.

Immune responses and vaccine-induced immunity against Porcine circovirus type 2

Porcine circovirus type 2 (PCV2) is essential but not sufficient for postweaning multi-systemic wasting syndrome (PMWS) occurrence in pigs. The outcome of PCV2 infection depends on the specific immune responses that are developing during the infection. Diseased pigs are immunosupressed and unable to mount effective immune responses to clear the virus from circulation. In the final stage, PMWS-affected pigs suffer from extensive lymphoid lesions and altered cytokine expression patterns in peripheral blood mononuclear cells (PBMCs) and lymphoid organs. PCV2 infection can also be asymptomatic, demonstrating that not every infection will guarantee the occurrence of severe immunopathological disturbances. Asymptomatic animals have higher virus specific and neutralising antibody titres than PMWS-affected animals. Recent results have pointed out that the mechanisms by which PCV2 can affect the immune responses involve the induction of IL-10, virus accumulation into and modulation of plasmacytoid dendritic cells and the role of viral DNA in regulation of immune cell functions. Fourteen years after the first description of PMWS in Canada, efficient commercial vaccines against PCV2 are available. The vaccine success is based on activated humoral and cellular immune responses against PCV2. This review focuses on the recent research on immunological aspects during PCV2 infections and summarizes what is currently known about the vaccine-induced immunity. (C) 2010 Elsevier B.V. All rights reserved.

Anthrax lethal toxin and the induction of CD4 T cell immunity

Bacillus anthracis secretes exotoxins which act through several mechanisms including those that can subvert adaptive immunity with respect both to antigen presenting cell and T cell function. The combination of Protective Antigen (PA) and Lethal Factor (LF) forming Lethal Toxin (LT), acts within host cells to down-regulate the mitogen activated protein kinase (MAPK) signaling cascade. Until recently the MAPK kinases were the only known substrate for LT; over the past few years it has become evident that LT also cleaves Nlrp1, leading to inflammasome activation and macrophage death. The predicted downstream consequences of subverting these important cellular pathways are impaired antigen presentation and adaptive immunity. In contrast to this, recent work has indicated that robust memory T cell responses to B. anthracis antigens can be identified following natural anthrax infection. We discuss how LT affects the adaptive immune response and specifically the identification of B. anthracis epitopes that are both immunogenic and protective with the potential for inclusion in protein sub-unit based vaccines.

Anthrax Lethal Factor as an Immune Target in Humans and Transgenic Mice and the Impact of HLA Polymorphism on CD4+ T Cell Immunity

Bacillus anthracis produces a binary toxin composed of protective antigen (PA) and one of two subunits, lethal factor (LF) or edema factor (EF). Most studies have concentrated on induction of toxin-specific antibodies as the correlate of protective immunity, in contrast to which understanding of cellular immunity to these toxins and its impact on infection is limited. We characterized CD4+ T cell immunity to LF in a panel of humanized HLA-DR and DQ transgenic mice and in naturally exposed patients. As the variation in antigen presentation governed by HLA polymorphism has a major impact on protective immunity to specific epitopes, we examined relative binding affinities of LF peptides to purified HLA class II molecules, identifying those regions likely to be of broad applicability to human immune studies through their ability to bind multiple alleles. Transgenics differing only in their expression of human HLA class II alleles showed a marked hierarchy of immunity to LF. Immunogenicity in HLA transgenics was primarily restricted to epitopes from domains II and IV of LF and promiscuous, dominant epitopes, common to all HLA types, were identified in domain II. The relevance of this model was further demonstrated by the fact that a number of the immunodominant epitopes identified in mice were recognized by T cells from humans previously infected with cutaneous anthrax and from vaccinated individuals. The ability of the identified epitopes to confer protective immunity was demonstrated by lethal anthrax challenge of HLA transgenic mice immunized with a peptide subunit vaccine comprising the immunodominant epitopes that we identified.

Trade-offs between personal immunity and reproduction in the burying beetle, Nicrophorus vespilloides

How are resources split between caring for offspring and self-maintenance? Is the timing of immune challenge important? In burying beetles challenging the immune system prior to breeding does not affect the total number and quality of offspring produced during the individual's lifetime. However, the immune system is suppressed during breeding and if an immune challenge is presented during this time the beetle will upregulate its immune system, but at the detriment to the number of offspring produced during that breeding opportunity.We know that parental investment and immune investment are costly processes, but it is unclear which trait will be prioritized when both may be required. Here, we address this question using the burying beetle Nicrophorus vespilloides, carrion breeders that exhibit biparental care of young. Our results show that immunosuppression occurs during provision of parental care. We measured phenoloxidase (PO) on Days 1-8 of the breeding bout and results show a clear decrease in PO immediately from presentation of the breeding resource onward. Having established baseline immune investment during breeding we then manipulated immune investment at different times by applying a wounding challenge. Beetles were wounded prior to and during the parental care period and reproductive investment quantified. Different effects on reproductive output occur depending on the timing of wounding. Challenging the immune system with wounding prior to breeding does not affect reproductive output and subsequent lifetime reproductive success (LRS). LRS is also unaffected by applying an immune elicitor prior to breeding, though different arms of the immune system are up/downregulated, perhaps indicating a trade-off between cellular and humoral immunity. In contrast, wounding during breeding reduces reproductive output and to the greatest extent if the challenge is applied early in the breeding bout. Despite being immunosuppressed, breeding beetles can still respond to wounding by increasing PO, albeit not to prebreeding levels. This upregulation of PO during breeding may affect parental investment, resulting in a reduction in reproductive output. The potential role of juvenile hormone in controlling this trade-off is discussed.

Impact of vitamin D3 on cutaneous immunity and antimicrobial peptide expression

Antimicrobial peptides (AMPs) are effectors of cutaneous innate immunity and protect primarily against microbial infections. An array of AMPs can be found in and on the skin. Those include peptides that were first discovered for their antimicrobial properties but also proteins with antimicrobial activity first characterized for their activity as chemokines, enzymes, enzyme inhibitors and neuropeptides. Cathelicidins were among the first families of AMPs discovered in skin. They are now known to exert a dual role in innate immune defense: they have direct antimicrobial activity and will also initiate a host cellular response resulting in cytokine release, inflammation and angiogenesis. Altered cathelicidin expression and function was observed in several common inflammatory skin diseases such as atopic dermatitis, rosacea and psoriasis. Until recently the molecular mechanisms underlying cathelicidin regulation were not known. Lately, vitamin D3 was identified as the major regulator of cathelicidin expression and entered the spotlight as an immune modulator with impact on both, innate and adaptive immunity. Therapies targeting vitamin D3 signalling may provide novel approaches for the treatment of infectious and inflammatory skin diseases by affecting both innate and adaptive immune functions through AMP regulation.

Innate immunity in the deep sea hydrothermal vent mussel Bathymodiolus azoricus

The interaction between microorganisms and host defense mechanisms is a decisive factor for the survival of marine bivalves. They rely on cell-mediated and humoral reactions to overcome the pathogens that naturally occur in the marine environment. In order to understand host defense reactions in animals inhabiting extreme environments we investigated some of the components from the immune system of the deep sea hydrothermal vent mussel Bathymodiolus azoricus. Cellular constituents in the hemolymph and extrapallial fluid were examined and led to the identification of three types of hemocytes revealing the granulocytes as the most abundant type of cell. To further characterize hemocyte types, the presence of cell surface carbohydrate epitopes was demonstrated with fluorescent WGA lectin, which was mostly ascribed to the granulocytes. Cellular reactions were then investigated by means of phagocytosis and by the activation of putative MAPKs using the microbial compounds zymosan, glucan, peptidoglycan and lipopolysaccharide. Two bacterial agents, Bacillus subtilis and Vibrio parahaemolyticus, were also used to stimulate hemocytes. The results showed that granulocytes were the main phagocytic cells in both hemolymph and extrapallial fluid of B. azoricus. Western blotting analyses using commercially available antibodies against ERK, p38 and JNK, suggested that these putative kinases are involved in signal transduction pathways during experimental stimulation of B. azoricus hemocytes. The fluorescent Ca²⁺ indicator Fura-2 AM was also insightful in demonstrating hemocyte stimulation in the presence of laminarin or live V. parahaemolyticus. Finally, the expression of the antibacterial gene mytilin was analyzed in gill tissues by means of RT-PCR and whole-mount in situ hybridization. Mytilin transcripts were localized in hemocytes underlying gill epithelium. Moreover, mytilin was induced by exposure of live animals to V. parahaemolyticus. These findings support the premise of a conserved innate immune system in B. azoricus. Such system is comparable to other Bivalves and involves the participation of cellular and humoral components. © 2008 Elsevier Inc. All rights reserved.

STAT5 in Cancer and Immunity

Signal transducers and activators of transcription 5 (STAT5a and STAT5b) are highly homologous proteins that are encoded by 2 separate genes and are activated by Janus-activated kinases (JAK) downstream of cytokine receptors. STAT5 proteins are activated by a wide variety of hematopoietic and nonhematopoietic cytokines and growth factors, all of which use the JAK-STAT signalling pathway as their main mode of signal transduction. STAT5 proteins critically regulate vital cellular functions such as proliferation, differentiation, and survival. The physiological importance of STAT5 proteins is underscored by the plethora of primary human tumors that have aberrant constitutive activation of these proteins, which significantly contributes to tumor cell survival and malignant progression of disease. STAT5 plays an important role in the maintenance of normal immune function and homeostasis, both of which are regulated by specific members of IL-2 family of cytokines, which share a common gamma chain (γc) in their receptor complex. STAT5 critically mediates the biological actions of members of the γc family of cytokines in the immune system. Essentially, STAT5 plays a critical role in the function and development of Tregs, and consistently activated STAT5 is associated with a suppression in antitumor immunity and an increase in proliferation, invasion, and survival of tumor cells. Thus, therapeutic targeting of STAT5 is promising in cancer.