Immunosenescence and vaccination of the elderly II. New strategies to restore age-related immune impairment.

One of the greatest health-care challenges in the elderly is to ensure that vaccination against infections are optimally effective, but vaccination can only be effective if cells that are capable of responding are still present in the repertoire. The reversing of immunosenescence could be achieved by improving immune responses or altering vaccine formulation. Recent vaccination strategies in the elderly exert low effectiveness. Nutritional interventions and moderate exercise delay T cell senescence. Telomerase activity and expression of toll-like receptors can be improved by chemotherapy. Reversion of thymic atrophy could be achieved by thymus transplantation, depletion of accumulated dysfunctional naive T cells and herpesvirus-specific exhausted memory cells. Administration of immunostimulatory and anti-inflammatory cytokines show the best practical approach. Reduced dendritic cell activity and co-receptor expression might be increased by interleukin (IL)-2 administration. IL-7 protects both B and T lymphocytes, but IL-2, IL-10, keratinocyte growth factor, thymic stromal lymphopoietin, as well as leptin and growth hormone also have a stimulatory effect on thymopoiesis. In animals, several strategies have been explored to produce more efficacious vaccines including high dose vaccines, DNA vaccines with immunostimulatory patch, virosomal vaccines and vaccines containing new adjuvants. Hopefully, one of these approaches will be translated into human therapy in a short time.

Immunosenescence and vaccination of the elderly, I. Age-related immune impairment.

The sharp increase of life expectancy and the increasing ratio of ageing population pose new challenges for the public health system. The elderly suffer from more frequent and severe infections than young people. Theoretically, vaccination could protect the elderly against several infectious diseases, but due to their age-related immune impairment, vaccination might fail in many cases. Instead of ineffective vaccination campaigns, exploration and restoration of age-dependent dysregulation of their immune functions have to be placed into the focus of recent research. Frequent comorbidities in these people augment immune defects. Immunosenescence affects both the innate and adaptive immunity. Disturbances in macrophage-derived cytokine release and reduction of the natural killer cell mediated cytotoxicity lead to increased frequency of respiratory, gastrointestinal and skin infections. Although the humoral immunity retains most of its original activity through life span, ageing dampens the ability of B cells to produce antibodies against novel antigens. Age-related declination of the cellular immunity is the consequence of thymic atrophy, reduced output of new T lymphocytes, accumulation of anergic memory cells, deficiencies in the cytokine production and uncertain antigen presentation. Persistent infection by different herpesviruses and other parasites contribute to the loss of immunosurveillance and premature exhaustion of T cells.

Sexual and enteric bacterial infections eliciting reactive arthritis.

In this review synonymous definitions of reactive arthritis are discussed first. Major clinical symptoms, their infectious etiology and epidemiology define post-dysenteric and post-veneral forms of reactive arthritis. Classical (smear, culture, biochemistry, antigen detection) and molecular (DNA and RNA detections) techniques are used in the routine microbial diagnosis that is retrospective in the majority of cases. In the pathomechanism of this disorder, HLA-B27 antigen positivity of patients is a frequent risk factor. Molecular mimicry between microbial and self-antigens, abnormal antigen presentation leading to incomplete CD8+ T lymphocyte activation might contribute to the persistence of microbial antigens that elicit clinical symptoms. Treatment is rarely successful with antimicrobial chemotherapy.

Serological evidence of adenovirus infection in cats.

The widespread presence of adenoviruses in various species makes it probable that infection and the carrier state also exist in cats. On the basis of these considerations, investigations were carried out to find antibodies against adenovirus in sera from different cat populations kept under different conditions. For the antibody detection, purified adenovirus was used in an indirect ELISA. To produce positive serum, SPF cats were immunized with a purified hexon preparation. Altogether 632 field sera of different origin were tested. Among field samples, adenovirus seropositivity varied between 10-26%.

Unique morphological alterations of the HTLV-I transformed C8166 cells by infection with HIV-1.

C8166 cells express T lymphocyte markers, a monocyte-specific esterase, taxpolypeptide of HTLV-I. In spite of this transactivator, their HIV-1 yield is low. Their culture conditions were modified, and infected cells were immobilized on a poly-L-lysine sheet under semisolid overlays to study their phenotypic alterations and HIV-1 production by microscopy and electron microscopy. Another lymphoid cultures (MT-4, CEM, CEM-ss, AdCEM) similarly treated were infected with either HIV-1/RF or IIIB. Specificity of HIV-1 was compared to the effects of vesicular stomatitis virus (VSV). Unlike other cultures, HIV-1/RF infected C8166 cells in Eagle s MEM exhibited surface projections resembling hairy leukemia cells, which was followed by balloon degeneration and apoptosis. Immobilized HIV-1 infected cultures formed flat syncytia with several interdigitating dendritic projections. Syncytia shrunk with condensed nuclear material and axon-like filaments characteristic for infected macrophages. VSV induced enlargement and necrotic lysis of all cell types. Early postinfection with HIV-1, electron microscopy revealed irreversible membrane fusion above cell nuclei, and transient fusion between filaments. Transient presence of coated vesicles containing intact HIV-1 particles, Birbeck granule-like structures of Langerhans cells, fibrillar-lamellar structures resembling hairy leukemia or Sézary cells were detected. Late postinfection, high proportion of HIV-1 bud from polarized cytoplasm was empty particle, while that bud and entrapped in cytoplasmic vacuoles contained two or multiple cores in a fused envelope. The effect of early gene products of HIV-1 on HTLV-I and C8166 cells might elicit their latent potentials for monocyte or interdigitating dendritic cells, while in the later phase HTLV-I products might alter HIV-1 virion assembly.

A pilot study on the antibodies to HHV-6 variants and HHV-7 in CSF of MS patients.

In the possible role for human herpesviruses (HHV) in the pathogenesis of multiple sclerosis (MS) neither clear distinction between the two variants of HHV-6, nor the involvement of HHV-7 have been described. Therefore, we quantitated HHV-6 variant specific and HHV-7 reacting antibodies in the CSF of 13 patients with MS or other neurological disorders by ELISA. Predominance in the positivity of IgG (67%) and IgM (44%) to HHV-6B over that of IgG (44%) with no detectable IgM to HHV-6A, and no antibodies to HHV-7 were found in the CSF of MS patients. None of these antibodies were found in the CSF of controls. This suggests that, intrathecal chronic active or primary HHV-6B infection might contribute to MS progression, while the local effects of HHV-6A and HHV-7 seem to be less important.

Modulatory effects of human herpes virus-7 on cytokine synthesis and cell proliferation in human peripheral blood mononuclear cell cultures.

Human herpes virus-7 (HHV-7) infects cells of the immune system and thus may modulate their function. To investigate the potential immunomodulatory effects of this virus, we performed an in vitro study in which we investigated effects of HHV-7 on the synthesis of several key immunomodulatory cytokines, i.e. tumor necrosis factor alpha (TNF-alpha), interleukin-2 (IL-2), interferon-gamma (IFN-gamma), IL-4, IL-6, and transforming growth factor beta (TGF-beta). This was examined after in vitro infection of human peripheral blood mononuclear cells (PBMC) with HHV-7. We found elevated levels of TNF-alpha, TGF-beta, and IFN-gamma in the supernatants of HHV-7-infected cells. By reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, using cytokine-specific primers, we found that levels of TNF-alpha, TGF-beta, and IFN-gamma mRNA were increased in the infected cells. The HHV-7 infection also significantly (P < 0.05) decreased the production of IL-2 from activated, IL-2-producing PBMC. Furthermore, mitogen- and cytokine-induced cellular proliferative responses of human PBMC were found to be significantly (P < 0.05) down-regulated by this virus. On the other hand, HHV-7 did not affect IL-4 and IL-6 synthesis. Overall, our results indicate that HHV-7 infection causes significant immunomodulatory effects with regard to cytokine synthesis in these cells as well as inhibiting lymphocyte proliferation by various stimuli.

[Level of HHV-6A antibodies in symptomless HIV infection as well as in the course of AIDS]. / HHV-6A ellenes antitestek szintje tünetmentes HIV-fertözöttekben az AIDS lefolyása során.

HHV-6A in vitro augments expression of CD4 molecules on the surface of immune cells, facilitates HIV replication and cell death in dual infections. It is hardly known whether these processes take place in vivo; does HHV-6A enhance HIV infection and AIDS progression? To study HHV-6A fresh infections and reactivation, IgM, IgG and low avidity IgG were quantitated in the serum samples of patients with asymptomatic HIV infection, early and terminal AIDS, that of their HIV seronegative homo- or bisexual partners and healthy adults (altogether 65 persons). Indirect immunofluorescent assay on JJHAN cells infected with HHV-6A U1102 was used. It was found that as compared to controls, the mean level of IgM in the sexual partners of HIV infected subjects raised 30-fold, that of IgG increased 10-fold, and 80% of persons had low avidity IgG indicating fresh HHV-6A infection. These suggest that they are frequently infected through sexual intercourse. As compared to healthy adults, mean titre of IgM to HHV-6A remained 10-fold increased in each group of patients with HIV infection. The IgG level was 6-fold increased in asymptomatic HIV infected subjects, 4-fold in early and 5-fold in terminal AIDS patients. More than one quarter of AIDS patients had low avidity IgG to HHV-6A. As compared to slow progressors of AIDS, the IgG level continuously increased in progressor persons. These suggest that HHV-6A maintains a chronic persistent infection in a significant number of HIV infected subjects.

[In vitro cytokine induction in leukocytes by human herpesvirus 7]. / A 7-es humán herpeszvírus által kiváltott in vitro citokintermelés fehérvérsejtekben.

Virus infections of the immune system may alter the normal cytokine profile, which leads to symptoms of illnesses. HHV-7 revealed lately has been known as one of the causative agents of exanthem subitum and pityriasis rosea, while its latent infection can be reactivated in immunocompromised conditions. Their pathomechanism has not been explored yet, therefore, the production of some cytokines by separated leukocytes was studied upon primary and secondary infections. After combined treatments with live or inactivated viruses and/or mitogens, the cytokines were quantitated in the supernatant of cells by sandwich ELISA. It was established that, individual cytokines were produced at maximal output at different times postinfection. The quantity of their molecules depended on the primary or repeated infections. Inactivated viral particles also induced cytokine release. Production of IL-2 and IFN-gamma due to mitogen activation could be augmented in primary, but was diminished in secondary infections. Release of TNF-alpha and IL-1 beta was parallel, but the combinatory effect with mitogens increased the quantity of IL-1 beta. HHV-7 induced early IL-10 production, which is known to inhibit cytokine release from helper lymphocytes and consequently might play a role in those acute inflammatory skin diseases mentioned above. In contrast to the related HHV-6 found in severe immunosuppressed conditions, the effect of HHV-7 on the balanced production of different cytokines seems to be related to the mild symptoms of skin disorders caused and that of moderate immunosuppression upon reactivation.

[Serologic study of human herpesviruses 6 and 7 in lymphoma patients]. / Emberi 6-os és 7-es herpeszvírusok szerepének szerológiai vizsgálata lymphomás betegekben.

DNA sequences, antigens and elevated antibodies to HHV-6, and DNA sequences of HHV-7 in patients with Hodgkin's disease and non-Hodgkin's lymphoma have been detected. It is not known whether HHV-6 variants A and B, and HHV-7 contribute to the malignization by different ways, there is any interaction between these viruses, and their primary or recurrent infections occur during the disease progression. Total and high avidity IgG, IgM to HHV-6A, HHV-6B and HHV-7 were quantitated simultaneously in the sera of 12 patients with lymphomas and 12 control persons by indirect immunofluorescent assay and ELISA. It was established that, primary infection by HHV-6B in Hodgkin's disease, its primary or recurrent infections in non-Hodgkin's lymphoma; primary or recurrent infection by HHV-6A in Hodgkin's disease, its recurrent infection in non-Hodgkin's lymphoma; recurrent infection by HHV-7 in Hodgkin's disease may contribute to the deterioration of clinical conditions. Probably, HHV-7 exerts its effects through activating HHV-6B. The simultaneous effects of HHV-7 and HHV-6A, and that of HHV-6B and HHV-6A seem to be independent. Our results supports the recent opinion that, the effect of these herpesviruses on the tumorous cells is exerted indirectly by altered mediators of the immune system.

[Presence of antibodies to human herpesvirus type 6 and 7 in Hungarian children]. / Emberi 6-os és 7-es típusú herpesvírusok elleni antitestek megjelenése magyarországi gyermekekben.

Prevalence of antibodies to variants HHV-6A and B as well as HHV-7, the time of primary infections are not know in Hungarian children. Therefore, antibodies to these viruses were studied in 21 healthy children aged between 6 and 18 months. Lymphoid cultures were infected with standard virus strains for indirect immunofluorescence. IgM, IgG and high avidity IgG after 8M urea treatment were quantified in serial dilutions of sera. It was established that, three of 13 boys had low level (1:20) IgG or IgM antibodies to HHV-6A, but all girls were negative. With exception of one girl and one boy, all had antibodies to HHV-6B in different titres (1:20 to 1:640 by immunofluorescence), in 9 cases only IgM, in further 4 cases only low avidity IgG were detected. Children studied gradually acquired symptom-free HHV-6B infection between age of 8 and 18 months. Antibodies to HHV-7 were found in 3 boys and one girl before their age of 12 months, but the majority were infected after that age. Approximately three quarters of children acquired either HHV-6B or HHV-7 before age of 18 months. More than half of the children were infected with HHV-6B prior to HHV-7. Antibody level to HHV-6B was slightly higher in boys, while that to HHV-7 was higher in girls. In Hungary, childhood infection with HHV-6A seems to be a very rare event. Epidemiology of HHV-6B primary infection is similar to that of industrial countries, while that of HHV-7 resembles data of developing world: onset of antibodies occurs 1 or 2 years earlier than in the industrial nations.

[Additive effect of marihuana and retrovirus in the anergy of natural killer cells in mice]. / Marihuána és retrovírus additív hatása egerek természetes ölösejt-aktivitásának kimerülésében.

Among the immunosuppressive effects of marijuana, impairment of natural killer cell activity is significant. HIV also inhibits these cells. Friend leukemia virus complex and its helper component Rowson-Parr virus induce early immunosuppression in mice resembling human AIDS, and late leukemia, providing a small animal AIDS model. Leukemia susceptible BALB/c and resistant C57BL/6 mice were infected with these viruses. At different time points, their natural killer cells separated from spleens were treated with 0 to 10 micrograms/ml tetrahydrocannabinol, subsequently mixed with Yac-1 target cells for 4 and 18 h. The natural killer cell activity in both mouse strains infected by either virus complex or helper virus weakened on days 2 to 4 postinfection, normalized by day 8 and enhanced on days 11 to 14. Natural killer cell activity upon the effect of low concentration (1.0 to 2.5 micrograms/ml) of tetrahydrocannabinol slightly increased in BALB/c, was unaffected in C57BL/6, especially in 18 h assays. In the combined effects of marijuana and retrovirus, damages by marijuana dominated over those of retroviruses. Inhibition or reactive enhancement of natural killer cell activity on the effect of viruses are similar to those of infected but marijuana-free counterparts, but on the level of uninfected cells treated with marijuana. The effects of marijuana and retrovirus are additive resulting in anergy of natural killer cells.

[Human herpesvirus 6 A enhances HIV-1 replication in vitro by soluble mediators, this effect is diminished by endotoxin]. / Az emberi 6-os herpeszvírus A változata szolubilis mediátorok által fokozza a HIV-1 szaporodását in vitro, mely hatást az endotoxin csökkenti.

Simultaneous HHV-6A infection can activate HIV-1 latency and promote AIDS progression, but in this process the effects of HHV-6A induced soluble mediators on HIV-1 have not been studied yet. Recently, supernatants of HSB-2 cultures infected with HHV-6A and/or treated with endotoxin have been filtered virus free at time intervals until the cytopathic effect developed. Biological activity of some cytokines which might participate in HIV-1 activation was quantitated. Filtered supernatants were mixed into CEM-ss cultures, which had been HIV-1 infected at 1:1 cell:virus ratio, subsequently HIV-1 replication was quantitated and compared to controls. Supernatants filtered during the first 96 hours of HHV-6A replication without visible cytopathic effect augmented HIV-1 syncytium formation by tenfold, reverse transcriptase activity by threefold, p24 antigen production by 6-fold. Filtered supernatants obtained at onset of HHV-6A cytopathic effect did not modify HIV-1 replication. HSB-2 cultures produced no IL-2, and IFN-gamma induced by endotoxin diminished HIV-1 replication. HHV-6A delayed IFN-gamma release. An increase in the tumour necrosis factor activity upon the effect of HHV-6A and endotoxin was not parallel to HIV-1 activation. The putative mediator, different from those above which characterisation is in progress, might transmit similar transactivating effects between immune cells of lymph nodes and circulation.

Combined in vitro effect of marijuana and retrovirus on the activity of mouse natural killer cells.

Both marijuana and retroviruses impair natural killer (NK) cell functions. No data on their simulataneous effects are available. Similarities to human AIDS induced early by Friend leukemia complex (FLC) and its replication competent helper Rowson-Parr virus (RPV) provides a mouse model to study drug-virus action. Leukemia susceptible BALB/c and resistant C57BL/6 mice were infected, then at time intervals their nylon wool-separated splenocytes were exposed to tetrahydrocannabinol (THC) for 3h. Natural killer (NK) cell activity against Yac-1 cells was assayed by 51Cr-release for 4 and 18h. Recovery of splenocytes was found to be suppressed by FLC, but in BALB/c only by RPV. After a transient enhancement in C57BL/6 by FLC, NK cell activity of both mice became suppressed early (2 to 4 days), normalized subsequently and enhanced late (11 to 14 days) postinfection. A moderate increase in BALB/c, no change in C57BL/6 were induced by low (1-2.5 microgram/ml) THC doses. NK cell activity of BALB/c became suppressed exponentially by higher (5-10 microgrtam/ ml) THC doses in 18h as compared to 4h assays, while its proportional and moderate impairment was seen in C57BL/6. The magnitude of NK cell activity of infected mice was determined by THC: enhancement or impairment followed those of untreated, infected counterparts, but on the level of THC-treated cells. Low doses hardly, high doses additively influenced NK cells of infected BALB/c. THC hardly affected very early and late enhancement in NK cell activiy of FLC infected C57BL/6, but augmented RPV induced suppression late in 18h assays. Genetic factors similar to endotoxin resistance, altered cytokine profile might determine these effects. Similar phenomena in humans might result in earlier manifestation of AIDS.