Vaccine potential of HLA‐A2 epitopes from Leishmania Cysteine Protease Type III (CPC)

Although the precise host‐defence mechanisms are not completely understood, T‐cell‐mediated immune responses are believed to play a pivotal role in controlling parasite infection. In this study, the potential HLA*A2 restricted peptides were predicted and the ability of peptides to bind HLA‐A*02 was confirmed by a MHC stabilization assay. Two of the peptides tested stabilized HLA‐A*02: (a) LLATTVSGL (P1) and (b) LMTNGPLEV (P3). The potential of the peptides to generate protective immune response was evaluated in patients with treated visceral leishmaniasis as well as in healthy control subjects. Our data suggest that CD8⁺ T‐cell proliferation against the selected peptide was significantly higher compared to unstimulated culture conditions. The stimulation of peripheral blood mononuclear cells with epitopes individually or as a cocktail upregulated IFN‐γ production, which indicates its pivotal role in protective immune response. The IFN‐γ production was mainly in a CD8⁺ T‐cells‐dependent manner, which suggested that these epitopes had an immunoprophylactic potential in a MHC class I‐dependent manner. Moreover, no role of the CD3⁺ T cell was observed in the IL‐10 production against the selected peptides, and no role was found in disease pathogenesis. Further studies on the role of these synthetic peptides may contribute significantly to developing a polytope vaccine idea towards leishmaniasis.     

Flt3 ligand treatment modulates parasitemia during infection with rodent malaria parasites via MyD88‐ and IFN‐γ‐dependent mechanisms

We previously showed that treatment of mice with the Flt3 ligand (Flt3L) prevents development of lethal experimental cerebral malaria and inhibits parasitemia during Plasmodium berghei ANKA (PbA) infection. In this study, we investigated the mechanisms underlying the reduction of parasitemia in Flt3L‐treated mice. Studies using gene knockout mice and antibody treatment indicated that the anti‐parasitemia effect of Flt3L was mediated by innate immune system and was dependent on MyD88, IFN‐γ, IL‐12 and natural killer (NK) cells. The number of NK cells and their ability to produce IFN‐γ was enhanced in Flt3L‐treated mice. Phagocytic activity of splenocytes was increased in Flt3L‐treated mice after PbA infection when compared with that in untreated mice, and this activity was mainly mediated by the accumulation of F4/80^midCD11b⁺ cells in the spleen. In both MyD88^?/? and IFN‐γ^?/? mice, the proportion of F4/80^midCD11b⁺ cells was not increased in the spleen of Flt3L‐treated mice after infection. These correlations suggest that NK cells produce IFN‐γ in Flt3L‐treated mice, and accumulation of F4/80^midCD11b⁺ cells in the spleen is promoted by an IFN‐γ ‐dependent manner, culminating in the inhibition of parasitemia. These findings imply that Flt3L promotes effective innate immunity against malaria infection mediated by interplay among varieties of innate immune cells.     

Dynamic changes in innate immune responses during direct‐acting antiviral therapy for HCV infection

The role of the endogenous interferon (IFN) system has been well characterized during IFN‐based therapy for chronic hepatitis C virus (HCV) infection; less is known for direct‐acting antivirals (DAAs). In this phase 3b open‐label study, we assessed changes in IFN‐stimulated genes (ISGs) in non‐cirrhotic treatment‐naïve or pegIFN/RBV‐experienced HCV‐GT1a‐infected patients receiving paritaprevir/ritonavir/ombitasvir + dasabuvir + ribavirin (PrOD + R) for 12 weeks. ISG expression was quantified from peripheral blood mononuclear cells at baseline, treatment weeks (TW)2, TW4, TW8, end of treatment (EOT) and at post‐treatment week 12. Paired sera were used to assess IFN‐α/IFN‐related chemokines/cytokines. Twenty‐five patients were enrolled. Overall sustained virologic response (SVR)12 was 92% (no virologic failure [VF]) and 100% for those completing the study protocol. Two patients were excluded from the ISG analysis due to lack of post‐treatment samples. The majority of ISGs were downregulated at TW2‐TW4 (nadir TW4); however, a relative increase was observed at TW8‐EOT, although levels were lower than baseline. This downregulation was accompanied by increases in IFN‐α/IFN‐related chemokines, a finding not observed with T_H1/2‐related cytokines. Following SVR, ISG expression returned to TW2 levels. In conclusion, PrOD + R for 12 weeks was well‐tolerated with no VF. Our data demonstrate dynamic alterations in innate immune profiles during highly potent IFN‐free DAA therapy. The downregulation of ISG post‐therapy suggests reversal of the “exhausted” ISG phenotype following SVR, and the rise in ISGs and IFN‐α/IFN‐responsive chemokines late during therapy suggests resetting of IFN responsiveness that may be relevant in determining duration of or immunological sequelae from DAA therapy, including HBV reactivation.     

Hepatitis C virus‐specific CD8+ T cell frequencies are associated with the responses of pegylated interferon‐α and ribavirin combination therapy in patients with chronic hepatitis C virus infection

Aim: Hepatitis C virus (HCV)‐specific cytotoxic T lymphocytes (CTLs) play critical roles in elimination of the HCV‐infected hepatocytes. However, the mechanism of HCV elimination by pegylated interferon‐α (peg‐IFNα) plus ribavirin is not fully understood. We examined HCV‐specific CTL responses during this combination therapy. Methods: CD8+ T cells were isolated from 16 HCV infected patients treated by this combination therapy and were subjected to IFN‐γ enzyme‐linked immunospot (ELISPOT) assay. Results: The numbers of IFN‐γ spots against HCV Core or NS3 protein‐derived peptides in HCV patients before treatment were similar to those in healthy donors, and those in HCV patients significantly increased 4 weeks after the initiation of combination therapy. All HCV Core or NS3 proteins‐derived peptides specific CD8+ T cells responses in pre‐treated patients were not associated with ALT levels and HCV viral loads of HCV patients before treatment. And those in pre‐treated patients were similar between sustained virologic responder (SVR) patients and non‐SVR patients. Significant increase of HCV Core or NS3 proteins‐derived peptides specific CD8+ T cells responses between before and 4 weeks after this combination therapy were observed in SVR patients, but not in non‐SVR patients. Conclusions: These results demonstrated that significant increase of HCV‐specific CD8+ T cells at 4 weeks after the initiation of IFN treatment might be associated with the elimination of HCV. Our findings suggest that the reactivity against HCV Core and NS3 proteins‐derived peptides might be useful in predicting the clinical outcome of the combination therapy of peg‐IFNα and ribavirin.     

Lactoferrin protects against concanavalin A‐induced liver injury in mice

Background: Liver diseases, caused by viral infection, autoimmune conditions, alcohol ingestion or the use of certain drugs, are a significant health issue, as many can develop into liver failure. Lactoferrin (Lac) is an iron‐binding glycoprotein that belongs to the transferrin family. Owing to its multiple biological functions, Lac has been evaluated in a number of clinical trials to treat infections, inflammation and cancer. Aim: The present study aims to reveal a profound hepatoprotective effect of Lac, using a mouse model of Concanavalin A (Con A)‐induced hepatitis, which mimics the pathophysiology of human viral and autoimmune hepatitis. Method: C57Bl/6J mice were injected with bovine Lac following Con A challenge. The effects of Lac on interferon (IFN)‐γ and interleukin (IL)‐4 expression were determined. The roles of Lac on T‐cell apoptosis and activation, and leukocytes infiltration were examined. Result: The data demonstrated that the protective effect of Lac was attributed to its ability to inhibit T‐cell activation and production of IFN‐γ, as well as to suppress IL‐4 production by hepatic natural killer T cells. Conclusion: These findings indicate a great therapeutic potential of Lac in treating in treating inflammatory hepatitis and possibly other inflammatory diseases.     

Impact of γ‐chain cytokines on T cell homeostasis in HIV‐1 infection: therapeutic implications

Abstract. Gougeon M‐L, Chiodi F (Institut Pasteur, Paris, France, and Karolinska Institutet, Stockholm, Sweden) Impact of γ‐chain cytokines on T cell homeostasis in HIV‐1 infection: therapeutic implications (Symposium). J Intern Med 2010; 267 : 502–514. CD4⁺ T cell lymphocytes are a major target for human immunodeficiency virus type‐1 (HIV‐1) infection. During this chronic infection, CD4⁺ T cell loss (induced through direct viral replication), generalized immune activation and increased susceptibility to apoptosis result in impaired T cell homeostasis with subsequent development of opportunistic infections and cancers. Highly active antiretroviral therapy (HAART) has a well‐defined, beneficial effect on HIV‐1‐related clinical outcome; however, it does not lead to normalization of immune dysregulation. In order to boost both CD4⁺ T cell restoration and HIV‐1 specific immunity, immunotherapy with γ‐chain cytokines has been used in HIV‐1‐infected patients during concomitant HAART. In this review, we summarize the role of γ‐chain cytokines, especially interleukin (IL)‐2 and IL‐7, in influencing T cell homeostasis and proliferation, and discuss how immunotherapy with these cytokines may be beneficial to reconstitute the T cell compartment in the context of HIV‐1 infection. The intriguing results of two large trials evaluating the efficacy of IL‐2 in restoring immune function during HIV‐1 infection are also discussed. In addition, we consider the promises and caveats of the first phase I/II clinical trials with IL‐7 in HIV‐1‐infected patients and the knowledge that is still lacking in the field of T cell reconstitution through γ‐chain cytokines.     

Extended indications for anti‐tumor necrosis factor‐α therapy

Tumour necrosis factor‐α is a pleiotropic cytokine which has a broad range of actions in inflammation, infection and immunity. TNF‐α is supposed to play a crucial role in the pathogenesis of various autoimmune diseases. TNF‐α blocking agents have been demonstrated to be highly effective in the treatment of rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, and juvenile rheumatoid arthritis. TNF‐α inhibitors also have been tried with other rheumatic diseases and have emerged as promising treatments. We here review the current evidences of effectiveness of the anti‐TNF‐α therapy in various autoimmune diseases.     

The effect of α and γ-interferon on proliferation and production of IgE and β2-microglobulin in the human myeloma cell line U-266 and in an α-interferon resistant U-266 subline

An IFN-resistant subline (U-266^r_α) was established from the IFN-α-sensitive myeloma cell line U-266 by subculturing U-266 cells with increasing doses of INF-α. The U-266^r_α secreted IgE at a higher rate than the U-266 (7.2 × 10^?13 g/c/8 h as compared to 3.3 × 10^?13 g/c/8 h). The 2 cell lines were found to be equally high producers of β₂m (9.2 and 9.6 × 10^?13 g/c/8 h). The U-266 produced 2.9 times less IgE and 5 times more β₂m compared to the initial production rates at establishment. INF-α and recombinant IFN-αM₂ (rIFN-α₂) inhibited proliferation and concomitantly decreased the rate of IgE and β₂m secretion in U-266 but not in U-266 IFN^r_α, which in contrast was slightly stimulated by IFN-α with respect to growth, IgE and β₂m secretion. In addition, IFN-α at a concentration of 100 U/ml was shown to decrease the IgE and β₂m production without exerting more than minimal cytotoxicity on U-266 cells. No antiproliferative effect was found for IFN-γ or recombinant IFN-γ (rIFN-γ) on either of the 2 cell lines. IFN-γ and rIFN-γ were, however, found to stimulate the production of β₂m. Our results show that the U-266 and the derived IFN-α-resistant subline can be used as models for studying some of the biological effects of IFN-α and -γ in vitro. The clinical implications of these in vitro results, in particular the usefulness of serum determinations of immunoglobulin and β₂m concentrations for monitoring the tumor cell mass, are discussed.     

Effects of 1‐O‐hexyl‐2,3,5‐trimethylhydroquinone on carbon tetrachloride‐induced hepatic cirrhosis in rats

Aim: The present study was undertaken to evaluate the effects of 1‐O‐hexyl‐2,3,5‐trimethylhydroquinone (HTHQ), a synthesized vitamin E derivative, on carbon tetrachloride (CCl₄)‐induced cirrhosis. Methods: Rats were treated with hypodermic injections of CCl₄ twice a week to induce the hepatic cirrhosis, and given drinking water containing HTHQ or solvent. Primary cultures of rat hepatocytes were performed to evaluate the effects of HTHQ on the expression of inducible nitric oxide synthase (iNOS). Results: Masson's staining of rat livers showed fibrosis around pseudo‐lobules in the CCl₄ group, the lesions being reduced in the CCl₄ HTHQ group. Increases in liver tissue hydroxyproline and α₁(I) collagen, α‐smooth muscle actin and iNOS induced by CCl₄, were also markedly diminished by HTHQ. Furthermore, both HTHQ and vitamin E attenuated interleukin‐1β‐induced iNOS protein expression in cultured hepatocytes, the potency of HTHQ being 10‐times higher than that of vitamin E. Conclusion: HTHQ may inhibit development of hepatic cirrhosis in rats, more potently than vitamin E, by inhibiting the iNOS expression in hepatocytes. Because vitamin E has a radical scavenging action, roles of NO and peroxynitrite will be discussed in the effects of HTHQ on the fibrosis.