Immunohistochemical Detection of Interferon-γ: Fake or Fact?

The potential therapeutic effect of Nigella sativa and Zingiber officinale extracts versus Nitazoxanide drug against experimentally induced cryptosporidiosis in laboratory mice

In this study, the potential anti-cryptosporidial effect of Nigella sativa (black seeds) and Zingiber officinale (ginger) alcoholic extracts versus Nitazoxanide (NTZ) medication was investigated in immunosuppressed (IS) laboratory mice. Parasitological, histopathological studies were used to assess their therapeutic efficacy. Serum level and tissue expression percentage of IFN-γ was also used. Nigella extract succeeded to reduce the mean oocyst counts in the feces of immunosuppressed mice followed by NTZ. Ginger-treated ones showed the lowest reduction percentage. Nigella sativa showed the best results in terms of restoring the normal architecture of ileal epithelium in histopathological sections stained with H&E. NTZ treatment sub-groups showed mild improvement, followed by ginger-treated mice, which showed a slight improvement in small intestine microenvironment. A significant substantial rise in serum and intestinal tissue IFN-γ cytokine levels were recorded in Nigella subgroups compared to those of NTZ and ginger respectively. According to our findings Nigella sativa outperformed Nitazoxanide in terms of anti-cryptosporidial effectiveness and regeneration characteristics revealing a promising medication. When compared to the commonly used Nitazoxanide medication or Nigella extracts, the outcomes of ginger extract were suboptimal.

IFNγ binding to extracellular matrix prevents fatal systemic toxicity

Interferon-γ (IFNγ) is an important mediator of cellular immune responses, but high systemic levels of this cytokine are associated with immunopathology. IFNγ binds to its receptor (IFNγR) and to extracellular matrix (ECM) via four positively charged C-terminal amino acids (KRKR), the ECM-binding domain (EBD). Across evolution, IFNγ is not well conserved, but the EBD is highly conserved, suggesting a critical function. Here, we show that IFNγ lacking the EBD (IFNγΔKRKR) does not bind to ECM but still binds to the IFNγR and retains bioactivity. Overexpression of IFNγΔKRKR in tumors reduced local ECM binding, increased systemic levels and induced sickness behavior, weight loss and toxicity. To analyze the function of the EBD during infection, we generated IFNγΔKRKR mice lacking the EBD by using CRISPR-Cas9. Infection with lymphocytic choriomeningitis virus resulted in higher systemic IFNγΔKRKR levels, enhanced sickness behavior, weight loss and fatal toxicity. We conclude that local retention of IFNγ is a pivotal mechanism to protect the organism from systemic toxicity during prolonged immune stimulation.

Comparative evaluation of host immune response and cytokine signature pertaining to Th1 and Th2 immune arms in serum and tissue among patients of acute localised vs. chronic disseminated dermatophytosis

BACKGROUND

India is witnessing an epidemic of dermatophytosis. The role of host immune response against fungi in chronicity and dissemination is topic of ongoing research. We conducted cross-sectional comparative study to determine the difference in Th1 (IFN-γ) and Th2 (IL4) response in serum and tissue between acute and localised vs. chronic and disseminated cases.

METHODS

Patients (18-60 years) were divided in two groups-group A (n = 114, BSA <5%, single anatomic site, duration <6 months, n = 118) and group B (n = 107 BSA >10%, > one anatomic site, duration >12 months, n = 118). Clinical parameters along with serum levels of IgE, IL-4 and IFN-γ and expression of IL4 and IFN-γ in dermal infiltrate were compared between group.

RESULTS

Trichophyton mentagrophytes complex was commonest causative fungi. Serum levels of IgE were significantly higher (median A-539.2, B-2901.0, p < .001) whereas levels IL-4(median A-21.3, B-20.4, p < .001) and IFN-γ(median A-9.6, B-5.1, p < .001) were significantly lower in chronic cases. Expression of IL-4 was observed in most biopsy specimens in both groups without any difference in intensity of staining. Expression of IFN-γ was not detected in all but one specimen across both the groups. Severe itching (OR:0.050, CI:0.018, 0.139, p < .001), sign of topical steroid abuse (OR:0.203,CI:0.077, 0.537; p = .001), ↓IFN-γ (OR:4.683, CI:1.634, 13.418; p = .004) correlated significantly and independently with chronic dermatophytosis.

CONCLUSION

Our study shows chronic and disseminated cases of dermatophytosis differ immunologically in terms of higher IgE, and lower IL4 and IFN-γ. Expression of IL4 is present in tissue of both acute, localised and chronic disseminated cases. Expression of IFN-γ cannot be established in our study.

Composition and Clinical Impact of the Immunologic Tumor Microenvironment in Oral Squamous Cell Carcinoma

Immunotherapy shows promising results and revolutionizes treatment of oral squamous cell carcinoma (OSCC). The immunologic microenvironment might have prognostic/predictive implications. Morphologic immunologic parameters (inflammatory infiltrate, stromal content, and budding activity [BA] [potentially indicating epithelial-mesenchymal transition]) were evaluated in 66 human primary therapy-naive OSCCs. Intraepithelial/stromal tumor-infiltrating lymphocytes (TILs; CD3⁺/CD4⁺/CD8⁺/CD4⁺FOXP3⁺/IL-17A⁺) were quantified, and ratios were calculated. HLA class I in tumor cells was evaluated immunohistochemically. mRNA in situ hybridization to detect IFN-γ was performed. Analysis was performed within invasive front (IF) and tumor center (TCe). Decreased HLA expression was associated with low TIL density, pronounced stromal content, and high BA; IFN-γ in TILs was correlated with high-density TILs; and IFN-γ in tumor cells was correlated with absence of BA (p < 0.05). Heterogeneity of parameters (TCe/IF) was rare. Low density of stromal CD4⁺FOXP3⁺ TILs within TCe and IF was identified as an independent prognostic factor for poor overall, disease-specific, and disease-free survival (p ≤ 0.011). Refining prognostication in OSCC with high-density CD4⁺FOXP3⁺ infiltrate within TCe and/or IF, high FOXP3:CD4 ratio was significantly correlated with favorable outcome in this subgroup. Furthermore, high-stromal CD8:CD4 ratio was found to be an independent favorable prognostic factor. In summary, immunologic parameters were closely intertwined. Morphologic correlates of epithelial-mesenchymal transition were associated with downregulation of HLA and decreased inflammation. Heterogeneity was infrequent. Low-density stromal CD4⁺FOXP3⁺ infiltrate within TCe and IF was an independent poor prognostic factor. Stratification of cases with high-density CD4⁺FOXP3⁺ TILs by FOXP3:CD4 ratio enables refinement of prognostication of this subgroup. CD8:CD4 ratio was identified as an independent prognostic factor.

Immunohistochemical investigation of the cross-reactivity of selected cell markers in formalin-fixed, paraffin-embedded lymphoid tissues of Franciscana (Pontoporia blainvillei)

A considerable amount of knowledge on natural and anthropogenic pathologic conditions affecting different cetacean species has been gained over the last decades. Nonetheless, the immunopathological bases for most of these processes have been poorly documented or remain unknown. Comparative immunopathological investigations in these species are precluded by the limited number of specific antibodies, most of which are not commercially available, and the reduced spectrum of validated and/or cross-reactive ones. To partially fill in this gap of knowledge, a set of commercially available primary antibodies were tested for cross-reactivity against leukocytes and cytokines in formalin-fixed, paraffin-embedded (FFPE) lymphoid tissues (lymph nodes, spleen and thymus) of three bycaught, apparently healthy and fresh Franciscanas (Pontoporia blainvillei) using immunohistochemistry. On the basis of similar region specificity within the lymphoid organs, cellular morphology and staining pattern with human control tissues, 13/19 primary antibodies (caspase 3, CD3, CD57, CD68, FoxP3, HLA-DRα, IFNγ, IgG, IL4, IL10, Lysozyme, TGFβ and PAX-5) exhibited satisfactory cross-reactivity. Our results expand the spectrum of suitable cross-reactive primary antibodies in FFPE cetacean tissues. Further comparative immunopathological studies focused on infectious diseases and ecotoxicology may benefit from establishment of baseline expression of immunologically relevant molecules in various cetaceans species.

Increased Indoleamine 2,3-Dioxygenase and Quinolinic Acid Expression in Microglia and Müller Cells of Diabetic Human and Rodent Retina

Purpose

We investigated the relationship between inflammation, neuronal loss, and expression of indoleamine 2, 3-dioxygenase (IDO) and quinolinic acid (QUIN) in the retina of subjects with type 1 diabetes (T1D) and type 2 diabetes (T2D) and in the retina of rats with T1D.

Methods

Retinas from T1D (n = 7), T2D (n = 13), and 20 age-matched nondiabetic human donors and from T1D (n = 3) and control rats (n = 3) were examined using immunohistochemistry for IDO, QUIN, cluster of differentiation 39 (CD39), ionized calcium-binding adaptor molecule (Iba-1, for macrophages and microglia), Vimentin (VIM; for Müller cells), neuronal nuclei (NeuN; for neurons), and UEA1 lectin (for blood vessels).

Results

Based on morphologic criteria, CD39⁺/ionized calcium binding adaptor molecule 1(Iba-1⁺) resident microglia and CD39⁻/Iba-1⁺ bone marrow–derived macrophages were present at higher density in T1D (13% increase) and T2D (26% increase) human retinas when compared with controls. The density and brightness of IDO⁺ microglia were increased in both T1D and T2D human retinas. The intensity of QUIN⁺ expression on CD39⁺ microglia and VIM⁺ Müller cells was greatly increased in both human T1D and T2D retinas. T1D retinas showed a 63% loss of NeuN⁺ neurons and T2D retinas lost approximately 43% when compared with nondiabetic human retinas. Few QUIN⁺ microglia-like cells were seen in nondiabetic retinas, but the numbers increased 18-fold in T1D and 7-fold in T2D in the central retina. In T1D rat retinas, the density of IDO⁺ microglia increased 2.8-fold and brightness increased 2.1-fold when compared with controls.

Conclusions

Our findings suggest that IDO and QUIN expression in the retinas of diabetic rats and humans could contribute to the neuronal degeneration that is characteristic of diabetic retinopathy.

Myxoma virus expressing a fusion protein of interleukin-15 (IL15) and IL15 receptor alpha has enhanced antitumor activity

Myxoma virus, a rabbit poxvirus, can efficiently infect various types of mouse and human cancer cells. It is a strict rabbit-specific pathogen, and is thought to be safe as a therapeutic agent in all non-rabbit hosts tested including mice and humans. Interleukin-15 (IL15) is an immuno-modulatory cytokine with significant potential for stimulating anti-tumor T lymphocytes and NK cells. Co-expression of IL15 with the α subunit of IL15 receptor (IL15Rα) greatly enhances IL15 stability and bioavailability. Therefore, we engineered a new recombinant myxoma virus (vMyx-IL15Rα-tdTr), which expresses an IL15Rα-IL15 fusion protein plus tdTomato red fluorescent reporter protein. Permissive rabbit kidney epithelial (RK-13) cells infected with vMyx-IL15Rα-tdTr expressed and secreted the IL15Rα-IL15 fusion protein. Functional activity was confirmed by demonstrating that the secreted fusion protein stimulated proliferation of cytokine-dependent CTLL-2 cells. Multi-step growth curves showed that murine melanoma (B16-F10 and B16.SIY) cell lines were permissive to vMyx-IL15Rα-tdTr infection. In vivo experiments in RAG1-/- mice showed that subcutaneous B16-F10 tumors treated with vMyx-IL15Rα-tdTr exhibited attenuated tumor growth and a significant survival benefit for the treated group compared to the PBS control and the control viruses (vMyx-IL15-tdTr and vMyx-tdTr). Immunohistological analysis of the subcutaneous tumors showed dramatically increased infiltration of NK cells in vMyx-IL15Rα-tdTr treated tumors compared to the controls. In vivo experiments with immunocompetent C57BL/6 mice revealed a strong infiltrate of both NK cells and CD8+ T cells in response to vMyx-IL15Rα-tdTr, and prolonged survival. We conclude that delivery of IL15Rα-IL15 in a myxoma virus vector stimulates both innate and adaptive components of the immune system.

Development of a manual self-assembled colloidal gold nanoparticle-immunochromatographic strip for rapid determination of human interferon-γ

Interferons (IFNs) play a role in inhibition of tumor growth and participate in immunoreactions. Among IFNs, interferon-γ (IFNγ) is one of the most important therapeutic proteins and its immunodulation ability is better than that of other types. The objective of this study is to develop a manual self-assembled colloidal gold nanoparticle-immunochromatographic strip for human IFNγ using anti-human IFNγ polyclonal and monoclonal antibodies. Colloidal gold with a 25 nm diameter was made from chloroauric acid (HAuCl4), and labeled on anti-IFNγ mAbs as a chrominance reagent. A good linear relationship existed between the pixel intensity and the human IFNγ concentrations from 10-1000 ng mL(-1) in mouse serum and buffer, respectively, the regression equation was Y = 0.159logX + 0.0648, R(2) = 0.992 in mouse serum; Y = 0.294logX + 0.091, R(2) = 0.9969 in phosphate buffer by this proposed strip. Moreover, in the determination for mouse serum samples no cross-reaction occurred and the detection time was approximately 10 minutes. The shelf life of the strip was above 28 days at room temperature. The major advantages of the manual operation model were no expensive instruments and less reagents required. This proposed strip was highly specific, economic, convenient, and no machine was needed in clinical diagnosis.

A focus on fixation

Three fixation issues related to immunostaining are discussed here: 1) Generally, a tissue block is fixed, then embedded and sectioned (pre-fixation). The type of fixative applied, crosslinking or coagulating, has an impact on selecting an epitope retrieval method. Individual antigens have a fixation-retrieval characteristic. 2) A long fixation time, especially with crosslinking fixatives, may compromise the result of immunostaining. This negative effect varies among different antigens and can be partially restored by applying a more sensitive/efficient detection system such as tyramide amplification. 3) Sections cut from a fresh frozen tissue block usually are acetone fixed(post-fixation). This was accepted as the "gold standard" for a long time. Post-fixation, however,may have serious consequences for preservation of small peptides leaking from the cut open cells,whereas this is not the case with pre-fixed intact cells. Consequently, the concept of an acetone post-fixed cryostat tissue section as "gold standard" no longer exists and a more appropriate use of the terms immunohistochemistry and immunocytochemistry therefore seems justified. For many antibodies, it is not known whether a formalin fixed, paraffin embedded tissue specimen is appropriate. Suggestions are made for creating a positive control cell block for testing such antibodies.

Assessing the potential of immunohistochemistry for systematic gene expression profiling

Immunohistochemistry (IHC) is a powerful technique for identifying sites of protein expression in tissues at the cellular and sub-cellular level. Here we have investigated the potential of using IHC for genome-wide expression screening by measuring the success rate and specificity of a panel of 35 monoclonal antibodies recognizing 5 well characterised CD antigens. Antibodies were pre-screened on acetone fixed frozen sections of spleen, tonsil and colon tissues. 19/35 antibodies gave staining with a success rate of 0/7 for JAM-2, 1/4 for CD99, 3/6 for CD138, 5/8 for CD45 and 10/10 for MHC-class II. 16/19 of these antibodies also gave staining on formalin fixed paraffin embedded tissue sections of tonsil and colon. All antibodies that had given staining were then profiled on tissues presented in human tissue microarrays. In the frozen microarrays 216 cores from 29 normal tissue types were present and in the formalin fixed paraffin array 344 cores from 35 normal and 4 cancers were represented. Where multiple antibodies were positive, there was evidence of consistent staining of the same tissues with several antibodies. In some cases differences in staining were observed potentially due to differential splice variants, polymorphisms or protein modification. With some antibodies there was evidence of cross-reactivity to inappropriate cells or structures. In addition the staining intensity with formalin fixation was changed quantitatively for some antibodies and in a few cases qualitatively, representing differential sensitivity of specific and non-specific epitopes to fixation. Accordingly, whilst IHC has potential for describing protein expression of unknown genes, these results emphasise a need to systematically address issues of specificity and sensitivity if appropriate profiles are to be described.

Interferon-gamma inhibits extravillous trophoblast cell invasion by a mechanism that involves both changes in apoptosis and protease levels

BACKGROUND

Extravillous trophoblast cell (EVT) invasion of decidua and inner third of the myometrium is critical for a successful pregnancy. Many decidual factors are likely to play a role in regulating this process, including uterine natural killer (uNK) cell-derived cytokines.

HYPOTHESES

1) uNK cells are a major source of IFN gamma (IFN-gamma) and 2) IFN-gamma inhibits EVT invasion via an increase in EVT apoptosis and/or a decrease in active protease levels.

METHODS

Total decidual and uNK cells from 8-10 wk and 12-14 wk gestational age were cultured. IFN-gamma mRNA (real-time RT-polymerase chain reaction) and protein levels (FastQuant multicytokine analysis) were determined. EVT invasion in the presence of IFN-gamma or anti-IFN-gamma-neutralizing antibodies was assessed. Trophoblast apoptosis and proliferation was assessed in explants by immunohistochemistry for M30 and Ki67. Substrate zymography was performed to determine levels of secreted MMP2, MMP9, and uPA.

RESULTS

mRNA and protein for IFN-gamma was detected in both total decidual and uNK cell fractions. Trophoblast invasion was inhibited by IFN-gamma. The level of M30-positive EVT was increased in the presence of IFN-gamma whereas levels of secreted MMP2 were decreased.

CONCLUSIONS

uNK cells are a source of IFN-gamma within early human pregnancy decidua. Mechanisms of IFN-gamma inhibition of EVT invasion include both increased EVT apoptosis and reduced levels of active proteases.

Interferon gamma-secreting HCV-specific CD8+ T cells in the liver of patients with chronic C hepatitis: relation to liver fibrosis--ANRS HC EP07 study

Little is known about the role of specific hepatitis C virus (HCV) CD8+ T cells in liver damage, especially for the progression of fibrosis, during the highly variable course of chronic C hepatitis. The aim of this study was to investigate the presence of HCV-specific CD8+ T cells in the liver of patients with chronic C hepatitis and to examine their clinical significance by relating the response to liver fibrosis and progression rate, serum viral load, serum aminotransferase levels, inflammatory activity and in situ characteristics of the intrahepatic infiltrate. Fifteen patients were prospectively included in the study. Intrahepatic lymphocytes were tested for interferon gamma (IFNg) production in response to HCV class I-restricted epitopic peptides using enzyme-linked immunospot analysis. Liver biopsy samples were evaluated for fibrosis, fibrosis progression rate, activity, and in situ number of CD8+ cytotoxic lymphocytes and apoptotic cells. An IFNg-specific CD8+ T-cell response was detected in the liver samples of 47% of patients which was significantly related to a lower stage of fibrosis (P = 0.02) and a lower progression rate of fibrosis (P = 0.01). It was neither related to the number of cytotoxic lymphocytes infiltrating the liver nor to hepatocyte apoptosis. In conclusion, our results indicate that the presence of HCV-specific IFNg-secreting T cells in the liver of patients with chronic C hepatitis is associated with low liver fibrosis and fibrosis progression rate, suggesting that these IFNg-secreting T cells might limit the progression of liver damage.

Interleukin-10 expression is positively correlated with oxidized LDL deposition and inversely with T-lymphocyte infiltration in atherosclerotic intimas of human coronary arteries

The inflammatory balance modulated by pro- and anti-inflammatory cytokines in atherosclerotic lesions is still unclear. The purpose of this study was to investigate the immunohistochemical localization of interleukin-10 (IL-10) and the topographical correlation between IL-10-positive cells and the other inflammatory cells in human coronary arteries. Coronary arteries (242 sections) were obtained from 43 Japanese patients (mean age: 72+/-14 years) at autopsy, and the intimal changes were classified according to the classification of the American Heart Association. The immunohistochemical distributions of IL-10, oxidized low-density lipoprotein (oxLDL), macrophages, and lymphocytes were examined morphometrically. We compared the ratios of IL-10-positive cells/macrophages and T-lymphocyte number among the shoulder and in other areas of type IV lesions and in atherosclerotic lesion types. IL-10 was expressed mainly by macrophages, and the positive cell number increased as the lesions became advanced (p<0.0001). The number of IL-10-positive cells was positively correlated with that of oxLDL-positive cells, and inversely with infiltrating T-lymphocytes (p<0.01). IL-10 expression in type IV-plaque shoulder was significantly lower than that in fibrous cap and the deeper portion under necrotic core (p<0.01). These findings suggest that IL-10 expression, seen mainly in macrophages, was possibly upregulated with oxLDL, and was inversely correlated with T-lymphocytic function in atherosclerotic coronary intimas.

Immunohistochemical analysis of PTEN in endometrial carcinoma: a tissue microarray study with a comparison of four commercial antibodies in correlation with molecular abnormalities

The tumor suppressor gene PTEN/MMAC1 is located on chromosome 10q23.3. Inactivation of PTEN, either by mutations, deletions, or promoter hypermethylation, has been identified in a wide variety of tumors. Inactivation of the two alleles of PTEN is required, because it is a tumor suppressor gene. Immunohistochemical staining may be an effective screening method to demonstrate the absence of the protein in tumors exhibiting PTEN inactivation. We studied a tissue microarray, constructed from paraffin-embedded blocks of 95 endometrial carcinomas, 38 of them previously evaluated for alterations in PTEN. We also studied cell blocks obtained from one PTEN-defective endometrial cancer cell line, after transfection with either a plasmid encoding wild-type PTEN or the empty vector. The tumor samples were tested with four different anti-PTEN commercial antibodies: a polyclonal antibody, the monoclonal antibody 28H6, the monoclonal antibody 10P03, and the monoclonal antibody 6.H2.1. Results were correlated with the presence of abnormalities in PTEN, as well as with the immunohistochemical expression of phosphorylated AKT. Antibody 28H6 produced a predominant nuclear staining, while the other three antibodies produced a predominant cytoplasmic staining. There was no significant correlation between the results obtained with the four antibodies. The monoclonal antibody 6.H2.1 was the only one that exhibited a correlation with the presence of molecular alterations in PTEN, and a statistically significant association with immunostaining for phosphorylated AKT (r=-0.249, P=0.037). The monoclonal antibody 10P03 exhibited an association with phospho-AKT that did not have statistical significance. Both 6.H2.1 and 10P03 antibodies stained PTEN-transfected cells, and were negative in the PTEN-deficient cell line blocks. The polyclonal antibody and the monoclonal antibody 28H6 produced positive staining in PTEN-deficient cell line blocks, suggesting nonspecific staining. The results indicate that monoclonal antibody 6.H2.1 may be a suitable alternative for tumors with inactivation of PTEN.

Development of antibodies to feline IFN-gamma as tools to elucidate the cellular immune responses to FeLV

An understanding of the nature of immune protection and the role of immune effector products such as interferon-gamma (IFN-gamma) in the control of infectious disease is fundamental to the rational design of effective vaccines and immunotherapeutic reagents. Murine monoclonal and sheep polyclonal antibodies (mAbs and pAbs) to feline IFN-gamma (fIFN-gamma) were generated firstly to facilitate further research into the role of cellular immune responses in the control of feline infectious disease, and secondly to enable evaluation of the efficacy of novel immunotherapeutic approaches. A hybridoma clone, D9, secreting IgG1 antibodies was selected for expansion and the mAbs affinity purified in vitro. Polyclonal antibodies were raised in a sheep against recombinant fIFN-gamma and affinity purified. The sensitivity of the D9 mAb and the sheep anti-fIFN-gamma pAb was determined using an indirect fIFN-gamma enzyme-linked immunosorbent assay (ELISA) and immunoblots. These antibodies were assessed for their ability to detect the production of fIFN-gamma by specific feline T cell populations ex vivo following coculture with mitogen or feline leukaemia virus (FeLV) antigens for 4 h in the presence of the protein secretion inhibitor brefeldin A (BFA). Production of fIFN-gamma was evaluated using flow cytometry to simultaneously detect PE-labelled surface molecules and fluorescein isothiocyanate (FITC)-labelled intracellular fIFN-gamma. Using this approach, our initial studies revealed an upregulation in virus-specific fIFN-gamma-secreting CD4(+)T cells in the lymph nodes of FeLV latently infected cats.

Infiltration of T-lymphocytes in the brain after anterior chamber inoculation of a neurovirulent and neuroinvasive strain of HSV-1

Following anterior chamber (AC) inoculation of BALB/c mice with the KOS strain of herpes simplex virus type 1 (HSV-1), or with H129, a neuroinvasive and neurovirulent strain of HSV-1, both strains of virus spread from the injected eye through the brain to cause retinitis. However, KOS-infected mice develop retinitis in the uninoculated eye only, whereas H129-infected mice develop bilateral retinitis. Previous studies have shown that infiltrating T-cells in the suprachiasmatic nuclei (SCN) of the hypothalamus of KOS-infected mice concomitant with or before virus protect KOS-infected mice from ipsilateral retinitis. To determine the timing of T cell infiltration and cytokine production in the brain of H129-infected mice, adjacent, frozen sections of the brain were immunostained for virus, T-cells, IL-2, TNF-alpha or IFN-gamma. T-cells infiltrated the brains of H129-infected mice and cytokines were produced in infected tissues. However, virus spread to the optic nerve and retina of both the inoculated and uninoculated eye before T-cells and cytokines were detected in the SCN of H129-infected mice. These results suggest that infiltrating T-cells in the SCN of H129-infected mice may arrive too late to prevent the spread of virus into the optic nerves and retinas and thus prevent development of bilateral retinitis in infected mice.

Cross-reactivity of anti-CagA antibodies with vascular wall antigens: possible pathogenic link between Helicobacter pylori infection and atherosclerosis

BACKGROUND

Helicobacter pylori-CagA positive strains have been shown to be associated with atherosclerosis. However, the pathogenesis is still undetermined. The aim of this study was to determine whether anti-CagA antibodies cross-react with antigens of normal and atherosclerotic arteries.

METHODS AND RESULTS

Eight umbilical cord sections, 14 atherosclerotic artery sections, and 10 gastrointestinal tract sections were examined by immunohistochemistry using polyclonal anti-CagA antibodies. Five atherosclerotic and 3 normal artery samples were also lysed in ice-cold lysis buffer containing protease inhibitors and were immunoprecipitated using the same antibodies. Anti-CagA antibodies reacted with cytoplasm and nuclei of smooth muscle cells in umbilical cord and atherosclerotic vessel sections, cytoplasm of fibroblasts-like cells in intimal atherosclerotic plaques, and the cell membranes of endothelial cells. Anti-CagA antibodies also specifically immunoprecipitated 2 high molecular weight antigens of 160 and 180 kDa from both normal and atherosclerotic artery lysates.

CONCLUSIONS

Anti-CagA antibodies cross-react with antigens of both normal and atherosclerotic blood vessels. We speculate that the binding of anti-CagA antibodies to those antigens in injured arteries could influence the progression of atherosclerosis in CagA-positive H pylori-infected patients.

Expression of interleukin (IL)-18 and functional IL-18 receptor on human vascular endothelial cells, smooth muscle cells, and macrophages: implications for atherogenesis

Although considerable evidence implicates the cytokine interferon (IFN)-gamma in atherogenesis, the proximal inducers and the range of sources of its expression remain unknown. This study tested the hypothesis that interleukin (IL)-18 regulates IFN-gamma expression during atherogenesis. Indeed, human atheroma in situ expressed IL-18 and elevated levels of its receptor subunits, IL-18Ralpha/beta, compared with nondiseased arterial tissue. IL-18 occurred predominantly as the mature, 18-kD form and colocalized with mononuclear phagocytes (MPhi), while endothelial cells (ECs), smooth muscle cells (SMCs), and MPhi all expressed IL-18Ralpha/beta. Correspondingly in vitro, only MPhi expressed IL-18, while all three cell types displayed the IL-18Ralpha/beta complex constitutively, exhibiting enhanced expression upon stimulation with LPS, IL-1beta, or tumor necrosis factor (TNF)-alpha. IL-18 signaling evoked effectors involved in atherogenesis, e.g., cytokines (IL-6), chemokines (IL-8), intracellular adhesion molecules (ICAM)-1, and matrix metalloproteinases (MMP-1/-9/-13), demonstrating functionality of the receptor on ECs, SMCs, and MPhi. Finally, IL-18, particularly in combination with IL-12, induced the expression of IFN-gamma in cultured MPhi and, surprisingly, in SMCs (but not in ECs). The expression of functional IL-18 and IL-18 receptor on human atheroma-associated ECs, SMCs, and MPhi, and its unexpected ability to induce IFN-gamma expression in SMCs, suggests a novel paracrine proinflammatory pathway operating during atherogenesis.