Cell-mediated Immune Pathways Research Articles

Alginate microencapsulation of an attenuated O-antigen mutant of Francisella tularensis LVS as a model for a vaccine delivery vehicle.

Francisella tularensis is the etiologic agent of tularemia and a Tier I Select Agent. Subspecies tularensis (Type A) is the most virulent of the four subspecies and inhalation of as few as 10 cells can cause severe disease in humans. Due to its niche as a facultative intracellular pathogen, a successful tularemia vaccine must induce a robust cellular immune response, which is best achieved by a live, attenuated strain. F. tularensis strains lacking lipopolysaccharide (LPS) O-antigen are highly attenuated, but do not persist in the host long enough to induce protective immunity. Increasing the persistence of an O-antigen mutant may help stimulate protective immunity. Alginate encapsulation is frequently used with probiotics to increase persistence of bacteria within the gastrointestinal system, and was used to encapsulate the highly attenuated LVS O-antigen mutant WbtIG191V. Encapsulation with alginate followed by a poly-L-lysine/alginate coating increased survival of WbtIG191V in complement-active serum. In addition, BALB/c mice immunized intraperitoneally with encapsulated WbtIG191V combined with purified LPS survived longer than mock-immunized mice following intranasal challenge. Alginate encapsulation of the bacteria also increased antibody titers compared to non-encapsulated bacteria. These data suggest that alginate encapsulation provides a slow-release vehicle for bacterial deposits, as evidenced by the increased antibody titer and increased persistence in serum compared to freely suspended cells. Survival of mice against high-dose intranasal challenge with the LVS wildtype was similar between mice immunized within alginate capsules or with LVS, possibly due to the low number of animals used, but bacterial loads in the liver and spleen were the lowest in mice immunized with WbtIG191V and LPS in beads. However, an analysis of the immune response of surviving mice indicated that those vaccinated with the alginate vehicle upregulated cell-mediated immune pathways to a lesser extent than LVS-vaccinated mice. In summary, this vehicle, as formulated, may be more effective for pathogens that require predominately antibody-mediated immunity.

Effects of Type 1, 2, and 3 Immunity on the Viral Susceptibility of Human Keratinocytes

Atopic dermatitis (AD) is a chronic inflammatory skin condition characterized by increased susceptibility to cutaneous viral infections. Type 2 (T2) immunity predominates in AD skin lesions, but expression profiling has demonstrated involvement of Type 1 (T1) and/or Type 3 (T3) cytokines. We investigated whether these cell-mediated immune pathways effect cutaneous viral infection.

The host immune response to Clostridium difficile infection.

Clostridium difficile infection (CDI) is the most common infectious cause of healthcare-acquired diarrhoea. Outcomes of C. difficile colonization are varied, from asymptomatic carriage to fulminant colitis and death, due in part to the interplay between the pathogenic virulence factors of the bacterium and the counteractive immune responses of the host. Secreted toxins A and B are the major virulence factors of C. difficile and induce a profound inflammatory response by intoxicating intestinal epithelial cells causing proinflammatory cytokine release. Host cell necrosis, vascular permeability and neutrophil infiltration lead to an elevated white cell count, profuse diarrhoea and in severe cases, dehydration, hypoalbuminaemia and toxic megacolon. Other bacterial virulence factors, including surface layer proteins and flagella proteins, are detected by host cell surface signal molecules that trigger downstream cell-mediated immune pathways. Human studies have identified a role for serum and faecal immunoglobulin levels in protection from disease, but the recent development of a mouse model of CDI has enabled studies into the precise molecular interactions that trigger the immune response during infection. Key effector molecules have been identified that can drive towards a protective anti-inflammatory response or a damaging proinflammatory response. The limitations of current antimicrobial therapies for CDI have led to the development of both active and passive immunotherapies, none of which have, as yet been formally approved for CDI. However, recent advances in our understanding of the molecular basis of host immune protection against CDI may provide an exciting opportunity for novel therapeutic developments in the future.

Inflammatory and Cell-Mediated Immune Biomarkers in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Depression: Inflammatory Markers Are Higher in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome than in Depression

Background: Depression is an inflammatory disorder while many authors declare myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) to be a functional disorder. The aim of the present study is to compare inflammatory and cell-mediated immune (CMI) responses between depression and ME/CFS. Methods: We measured two proinflammatory cytokines (PICs) in plasma, interleukin-1 (IL-1) and tumor necrosis factor-α (TNF-α), with enzyme-linked immunosorbent assays, and serum neopterin with a radioimmunoassay in controls, ME/CFS and depressive patients. Results: Plasma PICs were significantly higher in ME/CFS than in depression and higher in both patient groups than in controls. Increased PIC levels in depression were attributable to the presence of fatigue and physio-somatic symptoms. Serum neopterin did not differ significantly between depression and ME/CFS but was higher in both patient groups than in controls. The significant positive correlations between neopterin and either IL-1 or TNF-α were significantly greater in depression than in ME/CFS. Conclusions: Since PICs cause depression-like behaviors and fatigue/malaise, we suggest that inflammation may play a role in the pathophysiology of ME/CFS and depression. Increased neopterin also seems to contribute to the pathophysiology of both disorders. This study has detected a shared ‘pathway phenotype’, i.e. disorders in inflammatory and CMI pathways, which underpins both ME/CFS and depression and, therefore, may explain the co-occurrence of both disorders. ME/CFS and depression are discriminated from each other by increased PICs in ME/CFS and differences in the immune cell communication networks.

New drug targets in depression: inflammatory, cell-mediated immune, oxidative and nitrosative stress, mitochondrial, antioxidant, and neuroprogressive pathways. And new drug candidates—Nrf2 activators and GSK-3 inhibitors

This paper reviews new drug targets in the treatment of depression and new drug candidates to treat depression. Depression is characterized by aberrations in six intertwined pathways: (1) inflammatory pathways as indicated by increased levels of proinflammatory cytokines, e.g. interleukin-1 (IL-1), IL-6, and tumour necrosis factor α. (2) Activation of cell-mediated immune pathways as indicated by an increased production of interferon γ and neopterin. (3) Increased reactive oxygen and nitrogen species and damage by oxidative and nitrosative stress (O&NS), including lipid peroxidation, damage to DNA, proteins and mitochondria. (4) Lowered levels of key antioxidants, such as coenzyme Q10, zinc, vitamin E, glutathione, and glutathione peroxidase. (5) Damage to mitochondria and mitochondrial DNA and reduced activity of respiratory chain enzymes and adenosine triphosphate production. (6) Neuroprogression, which is the progressive process of neurodegeneration, apoptosis, and reduced neurogenesis and neuronal plasticity, phenomena that are probably caused by inflammation and O&NS. Antidepressants tend to normalize the above six pathways. Targeting these pathways has the potential to yield antidepressant effects, e.g. using cytokine antagonists, minocycline, Cox-2 inhibitors, statins, acetylsalicylic acid, ketamine, ω3 poly-unsaturated fatty acids, antioxidants, and neurotrophic factors. These six pathways offer new, pathophysiologically guided drug targets suggesting that novel therapies could be developed that target these six pathways simultaneously. Both nuclear factor (erythroid-derived 2)-like 2 (Nrf2) activators and glycogen synthase kinase-3 (GSK-3) inhibitors target the six above-mentioned pathways. GSK-3 inhibitors have antidepressant effects in animal models of depression. Nrf2 activators and GSK-3 inhibitors have the potential to be advanced to phase-2 clinical trials to examine whether they augment the efficacy of antidepressants or are useful as monotherapy.

New perspective in immunotherapy: local imiquimod treatment

Imiquimod belongs to the family of synthetic small nucleotid-like molecules of imidazoquinolinamines. It is an immune response modifier with potent antiviral and antitumor effects, which are mediated by Toll-like receptors (TLR7 and TLR8). Imiquimod targets predominantly TLR7 expressing plasmacytoid dendritic cells and Langerhans cells, with secondary recruitment and activation of other inflammatory cells. Activation of TLR7 results in the stimulation of the innate and acquired immune responses, in particular cell mediated immune pathways. Topical imiquimod cream 5% (Aldara, MEDA Pharma) has been found to be effective for the treatment of actinic keratoses, superficial basal cell carcinoma and anogenital warts. Topical imiquimod is especially recommended for the treatment of large clinically asymptomatic fields containing tumor cells ("field cancerization"). Treatment with imiquimod applied at home by patient gives excellent cosmetic results. There are some data on its efficacy in nodular basal cell carcinoma and in some other skin cancers. The drug appears to be well tolerated with mild to moderate to local inflammation at the site of application. This paper provides a review about current experience and possible future development of imiquimod.

Immunity toAspergillus fumigatus: the basis for immunotherapy and vaccination

Efficient responses to fungi require different mechanisms of immunity. Dendritic cells (DCs) are uniquely able to decode the fungus-associated information and translate it into qualitatively different T helper (Th) immune responses. Murine and human DCs phagocytose conidia and hyphae of Aspergillus fumigatus through distinct recognition receptors. The engagement of distinct receptors translates into disparate downstream signaling events, ultimately affecting cytokine production and co-stimulation. Adoptive transfer of different types of DCs activates protective and non-protective Th cells as well as regulatory T cells, ultimately affecting the outcome of the infection in mice with invasive aspergillosis. The infusion of fungus-pulsed or RNA-transfected DCs also accelerates recovery of functional antifungal Th 1 responses in mice with allogeneic hematopoietic stem cell transplantation. Patients receiving T cell-depleted allogeneic hematopoietic stem cell transplantation are unable to develop antigen-specific T cell responses soon after transplant due to defective DC functions. Our results suggest that the adoptive transfer of DCs may restore immunocompetence in hematopoietic stem cell transplantation by contributing to the educational program of T cells. Thus, the remarkable furictional plasticity of DCs can be exploited for the deliberate targeting of cells and pathways of cell-mediated immunity in response to the fungus.

Prospects for Dendritic Cell Vaccination Against Fungal Infections in Hematopoietic Transplantation.

Dendritic cells (DCs) are uniquely able to initiate and control the immune response to fungi. DCs function at three levels in the manipulation of the immune response to these pathogens: 1) they mount an immediate or innate response to them, for example by producing inflammatory mediators upon capture and phagocytosis; 2) through these preceding innate functions, they decode the fungus-associated information and translate it in qualitatively different Th responses; 3) and they are key in containing and dampening inflammatory responses by tolerization through the induction of regulatory T cells (Treg). We demonstrated that both murine and human DCs sense fungi in a morphotype-specific manner, through the engagement of distinct recognition receptors ultimately affecting cytokine production and costimulation (Romani et al. Int Immunol. 2003). In this study we analyzed both myeloid and plasmacytoid murine and human DCs and we observed that they phagocytose fungi and undergo functional maturation in response to them. However, their activation program for cytokine production was different, being IL-12 mainly produced by myeloid DCs and IL-12, IL-10 and IFN-gamma mainly produced by plasmacytoid DCs. This resulted in a distinct ability for T-cell priming, being Th1, Th2 and Treg differently activated by the different DC subsets. The ability of fungus-pulsed DCs to prime for Th1, and Th2 cell activation upon adoptive transfer in vivo correlated with the occurrence of resistance and susceptibility to the infections, respectively. Antifungal protective immunity was also induced upon adoptive transfer of DCs transfected with fungal RNA (Bacci et al. J Immunol. 2002; Bozza et al. Blood. 2003). The efficacy was restricted to DCs transfected with RNA from yeasts or conidia but not with RNA from fungal hyphae. The effect was fungus-specific, as no cross-protection was observed upon adoptive transfer of DCs pulsed with either fungal species. The infusion of fungus-pulsed or RNA-transfected DCs accelerated the recovery of functional antifungal Th1 responses in mice with allogeneic hematopoietic stem cell transplantation (HSCT) without triggering graft-versus-host disease (GvHD) and affected the outcome of the infections. As the ability to respond to fungi was defective in peripheral DCs from patients with HSCT in terms of phagocytosis, cytokine production, and donor T-cell priming, our findings suggest that the adoptive transfer of DCs may restore immunocompetence in HSCT by contributing to the educational program of T-cells. Thus, the remarkable functional plasticity of DCs in response to fungi can be exploited for the deliberate targeting of cells and pathways of cell-mediated immunity in response to fungal vaccines.

Prospects for dendritic cell vaccination against fungal infections in hematopoietic transplantation

Dendritic cells (DCs) are uniquely able to initiate and control the immune response to fungi. DCs function at three levels in the manipulation of the immune response to these pathogens. First, they mount an immediate or innate response to them, for example, by producing inflammatory mediators upon capture and phagocytosis; second, through these preceding innate functions, they decode the fungus-associated information and translate it in qualitatively different Th responses, and third, they are key in containing and dampening inflammatory responses by tolerization through the induction of regulatory T cells (Treg). DCs sense fungi in a morphotype-specific manner, through the engagement of distinct recognition receptors ultimately affecting cytokine production and costimulation. Both myeloid and plasmacytoid murine and human DCs phagocytose fungi and undergo functional maturation in response to them. However, their activation program for cytokine production was different, being IL-12 mainly produced by myeloid DCs and IL-12, IL-10 and IFN-α mainly produced by plasmacytoid DCs. This resulted in a distinct ability for T cell priming, being Th1, Th2, and Treg differently activated by the different DC subsets. The ability of fungus-pulsed DCs to prime for Th1 and Th2 cell activation upon adoptive transfer in vivo correlated with the occurrence of resistance and susceptibility to the infections, respectively. Antifungal protective immunity was also induced upon adoptive transfer of DCs transfected with fungal RNA. The efficacy was restricted to DCs transfected with RNA from yeasts or conidia but not with RNA from fungal hyphae. The effect was fungus-specific, as no cross-protection was observed upon adoptive transfer of DCs pulsed with either fungal species. The infusion of fungus-pulsed or RNA-transfected DCs accelerated the recovery of functional antifungal Th1 responses in mice with allogeneic hematopoietic stem cell transplantation (HSCT) and affected the outcome of the infections. As the ability of phagocytose fungi was defective in peripheral DCs from patients with HSCT, soon after the transplant, our findings suggest that the adoptive transfer of DCs may restore immunocompetence in HSCT by contributing to the educational program of T cells. Thus, the remarkable functional plasticity of DCs in response to fungi can be exploited for the deliberate targeting of cells and pathways of cell-mediated immunity in response to fungal vaccines.

Dendritic cell-based vaccination against opportunistic fungi

Efficient responses to the different forms of fungi require different mechanisms of immunity. Dendritic cells (DCs) are uniquely able to decode the fungus-associated information and translate it in qualitatively different T helper (Th) immune responses, in vitro and in vivo. DCs sense fungi in a morphotype-specific manner, through the engagement of distinct recognition receptors ultimately affecting cytokine production and costimulation. Adoptive transfer of different types of DCs activates protective and non-protective Th cells as well as regulatory T cells and affects the outcome of the infections. DCs transfected with fungal RNA also restore antifungal resistance in hematopoietic transplantation. Thus, the remarkable functional plasticity of DCs in response to fungi can be exploited for the deliberate targeting of cells and pathways of cell-mediated immunity in response to fungal vaccines.

Successful management of viral infections and other dermatoses with imiquimod 5% cream.

) is a safe, effective and established treatmentfor external genital and perianal warts. It is the firstmember of the family of immune response modifiers,which stimulates innate and cell-mediated immunepathways, inducing potent antitumor, antiviral andimmunoregulatory effects (1, 2). Imiquimod stimulatesthe immune response through induction, synthesis andrelease of cytokines such as interferon (IFN) a, tumornecrosis factor (TNF) a and interleukin 12 (IL 12) (3, 4).In addition, imiquimod acts to stimulate other com-ponents of innate immunity such as natural killer cellactivity, secretion of nitric oxide from macrophages andproliferation and differentiation of B-lymphocytes (1).Imiquimod also stimulates the T-helper (Th)-1 cyto-kine, IFNc and enhances the migration of Langerhans’cells to the lymph nodes; these cells are importantantigen-presenting cells within the epidermis (5). Imi-quimod is not only a recommended treatment foranogenital warts (6–8), but has also been shown to beeffective in the treatment of other viral infections (9, 10)and epithelial neoplasms (11–13).IMIQUIMOD FOR THE TREATMENT OFEXTERNAL GENITAL WARTSHuman papillomavirus (HPV) is the most commonsexually transmitted infection in many countries. Figuresfrom the World Health Organization (WHO) and Com-municable Disease Surveillance Center (CDSC) showthat approximately 5.5 million new cases of HPV arereported every year, with 40 million cases in the UnitedStates of America (USA). In addition, 1% of sexuallyactive adults in the USA aged between 15 and 49 yearsdevelop genital warts. With a steady increase in world-wide incidence, genital warts are the most frequentlydiagnosed infection in sexually transmitted disease (STD)clinics in both the northern and southern hemispheres(14). Within the UK, HPV-associated anogenital wartsaccount for approximately 25% of total diagnoses atgenitourinary medicine (GUM) clinics (15). This increasein the epidemiology of anogenital warts is having asubstantial effect on the cost of healthcare services indeveloped countries, for instance in the UK in 2002 theestimated cost of external anogenital warts was threebillion dollars.HPV is prevalent in many different subtypes with theclinical manifestation being either anogenital or non-genital. Anogenital warts or condylomata acuminataare clinical conditions of HPV types 6 or 11. High-oncogenic risk anogenital lesions tend to arise fromHPV infections of subtypes 16, 18, 31, 33 and 35. HPVtypes 1, 2 and 3 have clinical manifestations that typifyverruca plantaris, verruca vulgaris and verruca planar,respectively (16, 17). In addition to being implicatedin many carcinomas of the skin (18), epidemiologicalstudieshaveunderlinedthatHPVsarethemainetiologicalfactor of anogenital cancer (19). Current recommendedtreatment options for genital warts are patient-appliedtherapies, which include imiquimod, or podophyllotoxin,an antimitotic agent. Alternative treatment optionsencompass physician-administered therapies, which mayeither be ablative, such as surgical excision, cryotherapy,laser therapy, and electrocautery or cytodestructive e.g.trichloroaceticacid(TCA).GuidelinesfromtheCentersforDisease Control and Prevention (USA), Australia andEurope for the management of genital warts stronglyrecommend patient-applied therapies as a first linetreatment option, with physician-administered therapiessuggested as alternative strategies (6–8).Imiquimod is available as a single-use sachet that isapplied directly to the lesion three times per week atnight and on the following morning, and the area washedwith mild soap and water. Treatment duration is recom-mended until wart clearance is achieved or for a maxi-mum of 16 weeks (20). The importance of ensuring athree times weekly application is highlighted by Gollnicket al. (21) who compared the safety and efficacy of threetimes weekly and once daily applications of imiquimod5% cream for the treatment of penile genital warts inuncircumcised men. Both groups showed similar levelsof efficacy and the only differences were in the sideeffects experienced. The most frequently reported localside effects were burning, pruritus, irritation or pain;however, the three times a week dosing regimen waswell-tolerated, with a lower incidence of local skin reac-tions than in the once daily group. The results indicatedthat the appropriate treatment regimen is three timesweekly, which demonstrated higher efficacy with toler-ability (21). Additional open-label studies have furtherestablished the successful and well tolerated use of imi-quimod for treating genital warts in both women andmen with low rates of recurrence (22, 23). With anytreatment modality, there are possible associated sideeffects, therefore it is important to highlight these to the

Carrageenan-Induced Suppression of T-Lymphocyte Proliferation in the Rat: Abrogation of Suppressor Factor Production by the Prostaglandin Synthesis Inhibitors, Indomethacin and ETYA

Carrageenan, an algal polygalactan reputed to be selectively toxic for macrophages, is widely employed as a tool to dissect pathways of cell-mediated immunity. In the present study, corn oil-elicited rat peritoneal macrophages after 72 h culture with 10 μg/ml Seakem® 9 Carrageenan secreted a soluble suppressor factor capable of abrogating T-cell activation by phytohemagglutinin-P (PHA). Addition of the prostaglandin synthesis inhibitors Indometha-cin or 5,8,11,14-eicosatetraynoic acid (ETYA) prevented inhibitor synthesis by Carrageenan-conditioned macrophages. Seakem ® 9 and lambda Carrageenans added directly into spleen cell cultures failed to diminish lymphocyte proliferation, but rather stimulated spleen cell division. Macrophages cultured with low concentrations of Carrageenan appeared to be activated on the basis of enhanced tumoristatic capacity against Schmidt-Ruppin sarcoma cells. Thus, macrophages activated by low concentrations of Carrageenan in vitro appear to secrete a product of arachidonic acid metabolism which is a potent inhibitor of PHA-induced spleen cell mitogenesis.