Resistance of mice deficient in IL-4 to retrovirus-induced immunodeficiency syndrome (MAIDS)

Characterization of cytokine gene expression associated with noninfectious human immunodeficiency virus retinopathy in human autopsy eyes

PURPOSE

The purpose of this study was to determine the cytokine-related pathogenesis of human immunodeficiency virus retinopathy in human autopsy eyes.

METHODS

Fresh autopsy eyes were procured from clinically diagnosed patients with acquired immunodeficiency syndrome who had died as a result of disease-related complications; eyes were immediately immersed in RNAlater. Clean 2-mm trephines were used to punch individual pathologic retina in areas of cotton-wool spots and control punches. Total RNA was extracted using the TRIzol extraction protocol, and the optimal density of the RNA was measured at an optical density of 260 nm. [Delta]Ct (cytokine) values were calculated using the comparative cytokine analysis method. The results are expressed as a mean fold modulation and as a statistical comparison of Ct values controlling for retinal areas without a lesion in the same eye.

RESULTS

The fold modulations and the statistical comparisons of the cytokines studied in tissues from cotton-wool spots and control retina, respectively, regulated on activation normal T cell expressed and secreted (RANTES), macrophage inflammatory protein 1beta, macrophage inflammatory protein 1alpha (5.32x, P = 0.04), and Bcl-2-associated X protein (1.24x, P = 0.05) had a marked elevation of fold modulation and were statistically significant compared with control tissue. Interleukin-8 (1.09x, P = 0.18), interleukin-4, and interleukin-10 (2.7x, P = 0.30) were not significantly expressed in cotton-wool spots.

CONCLUSION

Certain inflammatory human immunodeficiency virus-associated and apoptotic cytokines are expressed in cotton-wool spots in eyes with human immunodeficiency virus retinopathy.

Inhibition of premature death by isothiocyanates through immune restoration in LP-BM5 leukemia retrovirus-infected C57BL/6 mice

The purpose of this study was to determine the effect of isothiocyanates (ITCs) in delaying the progression of the murine immunodeficiency virus to murine AIDS, resulting in increased life span. Furthermore, we investigated the role of ITCs in modulating immune dysfunction caused by LP-BM5 retrovirus infection. Among the tested ITCs, oral administration of sulforaphane (SUL), benzyl isothiocyante (BITC), and phenethyl isothiocyanate (PEITC) showed the inhibition of premature death caused by LP-BM5 retrovirus infection, while indolo[3,2-b] carbazole (ICZ) and indole-3-carbinol (I3C) did not delay the progress of the LP-BM5 retrovirus to murine AIDS. Inhibition of premature death by BITC, PEITC, and SUL could be explained by restoration of the immune system and down regulation of free radicals. Dysfunction of T and B cell mitogenesis caused by retrovirus infection in primary cultured splenocytes has been partially recovered with administration of BITC, PEITC, and SUL. There was a shift from imbalanced cytokine production (increased Th2 and decreased Th1 cell cytokine production) into balanced Th1/Th2 cell secretion of cytokines under administration of these ITCs during the development of murine AIDS. Hepatic vitamin E level was significantly restored by administration of these ITCs, in accordance with reduced hepatic lipid peroxidation levels. This study suggests that certain types of ITCs have beneficial effects in preventing premature death during progression to murine AIDS by restoration of immune dysfunction and removal of excessive free radicals, implying that selective usage of ITCs would be helpful in retarding the progression from HIV infection to AIDS.

Factors influencing Leishmania major infection in IL-4-deficient BALB/c mice

The outcome of Leishmania major infection in IL-4-deficient BALB/c mice has been a controversial subject. We have shown that IL-4-deficient BALB/c mice infected with Leishmania major developed progressive lesions and could not contain the replication of the parasites, whereas other studies have reported that IL-4-deficient mice were able to resist infection. Therefore, we examined different factors that can influence the course of Leishmania major infection. We tested different lines of IL-4-deficient BALB/c mice and show that the reported differences in the outcome of infection were not due to the different genetic origin of the embryonic stem cells used to disrupt the IL-4 gene. In addition, we infected IL-4-deficient mice with different isolates of L. major parasites and show that none of the parasite strains tested were cleared, although some of them caused milder pathology. Interestingly, this milder pathology was paralleled by a reduced arginase activity of the parasites. We also tested the influence of age on the course of Leishmania major infection in IL-4-deficient BALB/c mice and show that older mice express a transient resistance. Thus, we conclude that differences in the age of the mice and in the arginase activity of the different isolates of parasites are factors that can influence the non-healing phenotype of IL-4-/- BALB/c mice.

Chemical sympathectomy has no effect on the severity of murine AIDS: murine AIDS alone depletes norepinephrine levels in infected spleen

Numerous studies have shown that alterations in sympathetic nervous system (SNS) function produced by beta-adrenergic receptor blockade or chemical sympathectomy can produce changes in T and B lymphocyte function and both innate and acquired immune responses. However, fewer studies have investigated changes in immune response following SNS alterations in animal models of disease. We tested whether blocking SNS activity using 6-OHDA or the beta-receptor antagonist nadolol alters the typical pattern in production of T helper 1 (Th1) and Th2 cytokines seen in cultures of spleen cells from C57BL/6 mice infected with murine AIDS (MAIDS). We found that neither method of sympathetic blockade affected cytokine response to MAIDS. We also found that the norepinephrine concentration and content of the spleen were reduced dramatically by the MAIDS infection itself at 3 and 6 weeks after LP-BM5 inoculation. This finding has not been previously reported in mice with MAIDS and suggests that the viral infection itself produces a functional sympathectomy in the spleen, a target of that infection.

Susceptibility of thermally injured mice to cytomegalovirus infection

Thermally injured patients are very susceptible to infection with cytomegaloviruses. In this study a role of burn-associated type 2 T cell responses on the cytomegalovirus infection was examined in a mouse model of thermal injury. A predominance of type 2 T cell responses in splenic lymphocytes of thermally injured mice has been previously demonstrated. SCID mice inoculated with splenic T cells from thermally injured mice were susceptible to infection with a small amount (5 PFU/mouse) of murine cytomegalovirus (MCMV). Conversely, SCID mice inoculated with splenic T cells from normal mice were resistant to the same infection. High levels of IL-4 and IL-10, but not IFN-gamma and IL-2, were detected in sera of thermally injured mice (TI-mice) infected with MCMV when those were compared with sera of normal mice infected with MCMV. IL-4 and IL-10 (type 2 cytokines) were produced by splenic T cells from MCMV-infected TI-mice, when they were stimulated in vitro with anti-CD3 mAb. Type 1 cytokines (IFN-gamma and IL-2), however, were not produced by these T cells after the same stimulation. In contrast, splenic T cells from MCMV-infected normal mice produced type 1 cytokines by the stimulation with anti-CD3 mAb. These results suggest that the susceptibility of mice to MCMV infection is markedly influenced by burn-associated type 2 T cell responses.

Anti-inflammatory effects of theophylline: modulation of immune functions during murine leukemia virus infection

LP-BM5 murine leukemia virus induces immune dysfunction leading to B cell leukemia and murine AIDS with cytokine dsyregulation. Theophylline induces apoptosis of leukemia cells in humans. Therefore the effects of theophylline on immune dysfunction in a murine model of leukemia were investigated. C57BL/6 mice consumed drinking water containing 0.3% theophylline beginning 2 weeks after murine retrovirus infection for 4 months. Theophylline largely prevented the retrovirus induced splenomagaly, lymphodenopathy, reduction in B and T cell proliferation, and suppression of Thl cytokines (IL-2) secretion. It also suppressed Th2 cytokine (IL-4, TNF-alpha, and IL-10) production, which was otherwise stimulated by retrovirus infection. These data suggest that immune dysfunction, induced by murine retrovirus infection, was largely prevented by theophylline treatment.

Molecular pathways in virus-induced cytokine production

Virus infections induce a proinflammatory response including expression of cytokines and chemokines. The subsequent leukocyte recruitment and antiviral effector functions contribute to the first line of defense against viruses. The molecular virus-cell interactions initiating these events have been studied intensively, and it appears that viral surface glycoproteins, double-stranded RNA, and intracellular viral proteins all have the capacity to activate signal transduction pathways leading to the expression of cytokines and chemokines. The signaling pathways activated by viral infections include the major proinflammatory pathways, with the transcription factor NF-kappaB having received special attention. These transcription factors in turn promote the expression of specific inducible host proteins and participate in the expression of some viral genes. Here we review the current knowledge of virus-induced signal transduction by seven human pathogenic viruses and the most widely used experimental models for viral infections. The molecular mechanisms of virus-induced expression of cytokines and chemokines is also analyzed.

Role of interleukin-4 (IL-4), IL-12, and gamma interferon in primary and vaccine-primed immune responses to Friend retrovirus infection

The immunological resistance of a host to viral infections may be strongly influenced by cytokines such as interleukin-12 (IL-12) and gamma interferon (IFN-gamma), which promote T helper type 1 responses, and IL-4, which promotes T helper type 2 responses. We studied the role of these cytokines during primary and secondary immune responses against Friend retrovirus infections in mice. IL-4- and IL-12-deficient mice were comparable to wild-type B6 mice in the ability to control acute and persistent Friend virus infections. In contrast, more than one-third of the IFN-gamma-deficient mice were unable to maintain long-term control of Friend virus and developed gross splenomegaly with high virus loads. Immunization with a live attenuated vaccine virus prior to challenge protected all three types of cytokine-deficient mice from viremia and high levels of spleen virus despite the finding that the vaccinated IFN-gamma-deficient mice were unable to class switch from immunoglobulin M (IgM) to IgG virus-neutralizing antibodies. The results indicate that IFN-gamma plays an important role during primary immune responses against Friend virus but is dispensable during vaccine-primed secondary responses.

Disruption of T cell homeostasis in mice expressing a T cell-specific dominant negative transforming growth factor beta II receptor

The immune system, despite its complexity, is maintained at a relative steady state. Mechanisms involved in maintaining lymphocyte homeostasis are poorly understood; however, recent availability of transgenic (Tg) and knockout mouse models with altered balance of lymphocyte cell populations suggest that cytokines play a major role in maintaining lymphocyte homeostasis. We show here that transforming growth factor (TGF)-beta plays a critical role in maintaining CD8(+) T cell homeostasis in a Tg mouse model that specifically overexpresses a dominant negative TGF-beta II receptor (DNRII) on T cells. DNRII T cell Tg mice develop a CD8(+) T cell lymphoproliferative disorder resulting in the massive expansion of the lymphoid organs. These CD8(+) T cells are phenotypically "naive" except for the upregulation of the cell surface molecule CD44, a molecule usually associated with memory T cells. Despite their dominance in the peripheral lymphoid organs, CD8(+) T cells appear to develop normally in the thymus, suggesting that TGF-beta exerts its homeostatic control in the peripheral immune system.

HIV-1 gp120 induces IL-4 and IL-13 release from human Fc epsilon RI+ cells through interaction with the VH3 region of IgE

HIV-1 glycoprotein (gp) 120 from different clades is a potent stimulus for IL-4 and IL-13 release from basophils purified from healthy individuals seronegative for Abs to HIV-1 and HIV-2. IL-4 mRNA, constitutively present in basophils, was increased after stimulation by gp120 and was inhibited cyclosporin A and tacrolimus. IL-4 and IL-13 secretion from basophils activated by gp120 was not correlated. There was a correlation between the maximum gp120- and anti-IgE-induced IL-4 release from basophils. The average t1/2 gp120-induced IL-4 release was lower than for IL-13 release. Basophils from which IgE had been dissociated by brief exposure to lactic acid no longer released IL-4 in response to gp120 or to anti-IgE. The response to a mAb cross-linking the alpha-chain of high-affinity receptor for IgE (Fc epsilon RI) was unaffected by this treatment. Three human VH3+ monoclonal IgM inhibited gp120-induced secretion of IL-4 from basophils. In contrast, VH6+ monoclonal IgM did not inhibit the release of IL-4 induced by gp120. Synthetic peptides distant from the NH2 and COOH termini of gp120MN inhibited the activating property of gp120MN. These results indicate that gp120, which acts as a viral superantigen, interacts with the VH3 region of IgE to induce the release of IL-4 and IL-13 from human Fc epsilon RI+ cells.

Mice transgenic for a soluble form of murine cytotoxic T lymphocyte antigen 4 are refractory to murine acquired immune deficiency sydrome development

Interactions between B and CD4+ T cells are central to the pathogenesis of retrovirus-induced murine acquired immune deficiency virus (MAIDS). Prompted by previous work showing that treatment with cytotoxic T lymphocyte antigen 4 immunoglobulin (CTLA4Ig) partly inhibited the disease, we studied the course of infection in mice deficient for CD28-B7 interactions (mCTLA4-Hgamma1 transgenic mice). Despite a relative viral load identical to that of non-transgenic mice, the transgenic mice did not develop any of the major MAIDS symptoms (i.e. lymphoproliferation and immune anergy). The mCTLA4-Hgamma1 did not however, completely inhibit B-cell activation as indicated by a slight hypergammaglobulinaemia and microscopic blastic transformation. Absence of MAIDS in transgenic mice was associated with much lower levels of both interleukin-4 and interferon-gamma transcripts following viral infection. These results support the theory that the CD28/B7 costimulatory pathway is a critical determinant to MAIDS development.

Modern diets and diseases: NO-zinc balance. Under Th1, zinc and nitrogen monoxide (NO) collectively protect against viruses, AIDS, autoimmunity, diabetes, allergies, asthma, infectious diseases, atherosclerosis and cancer

Thanks to progress in zinc research, it is now possible to describe in more detail how zinc ions (Zn++) and nitrogen monoxide (NO), together with glutathione (GSH) and its oxidized form, GSSG, help to regulate immune responses to antigens. NO appears to be able to liberate Zn++ from metallothionein (MT), an intracellular storage molecule for metal ions such as zinc (Zn++) and copper (Cu++). Both Zn++ and Cu++ show a concentration-dependent inactivation of a protease essential for the proliferation of the AIDS virus HIV-1, while zinc can help prevent diabetes complications through its intracellular activation of the enzyme sorbitol dehydrogenase (SDH). A Zn++ deficiency can lead to a premature transition from efficient Th1-dependent cellular antiviral immune functions to Th2-dependent humoral immune functions. Deficiencies of Zn++, NO and/or GSH shift the Th1/Th2 balance towards Th2, as do deficiencies of any of the essential nutrients (ENs) - a group that includes methionine, cysteine, arginine, vitamins A, B, C and E, zinc and selenium (Se) - because these are necessary for the synthesis and maintenance of sufficient amounts of GSH, MT and NO. Via the Th1/Th2 balance, Zn++, NO, MT and GSH collectively determine the progress and outcome of many diseases. Disregulation of the Th1/Th2 balance is responsible for autoimmune disorders such as diabetes mellitus. Under Th2, levels of interleukin-4 (II-4), II-6, II-10, leukotriene B4 (LTB4) and prostaglandin E2 (PGE2) are raised, while levels of II-2, Zn++, NO and other substances are lowered. This makes things easier for viruses like HIV-1 which multiply in Th2 cells but rarely, if ever, in Th1 cells. AIDS viruses (HIVs) enter immune cells with the aid of the CD4 cell surface receptor in combination with a number of co-receptors which include CCR3, CCR5 and CXCR4. Remarkably, the cell surface receptor for LTB4 (BLTR) also seems to act as a co-receptor for CD4, which helps HIVs to infect immune cells. The Th2 cytokine II-4 increases the number of CXCR4 and BLTR co-receptors, as a result of which, under Th2, the HIV strains that infect immune cells are precisely those that are best able to accelerate the AIDS disease process. The II-4 released under Th2 therefore not only promotes the production of more HIVs and the rate at which they infect immune cells, it also stimulates selection for the more virulent strains. Zn++ inhibit LTB4 production and numbers of LTB4 receptors (BLTRs) in a concentration-dependent way. Zn++ help cells to keep their LTB4 'doors' shut against the more virulent strains of HIV. Moreover, a sufficiency of Zn++ and NO prevents a shift of the Th1/Th2 balance towards Th2 and thereby slows the proliferation of HIV, which it also does by inactivating the HIV protease. Research makes it look likely that deficiencies of ENs such as zinc promote the proliferation of Th2 cells at the expense of Th1 cells. Zinc deficiency also promotes cancer. Under the influence of Th1 cells, zinc inhibits the growth of tumours by activating the endogenous tumour-suppressor endostatin, which inhibits angiogenesis. The modern Western diet, with its excess of refined products such as sugar, alcohol and fats, often contains, per calorie, a deficiency of ENs such as zinc, selenium and vitamins A, B, C and E, which results in disturbed immune functions, a shifted Th1/Th2 balance, chronic (viral) infections, obesity, atherosclerosis, autoimmunity, allergies and cancer. In view of this, an optimization of dietary composition would seem to give the best chance of beating (viral) epidemics and common (chronic) diseases at a realistic price.

Atopy, anergic status, and cytokine expression in HIV-infected subjects

BACKGROUND

In HIV infection T-cell dysfunction resulting in anergy and hypersensitivity reactions precedes T-cell depletion. A shift in the cytokine profile from a type 1 to a type 2 response has been postulated.

OBJECTIVE

We sought to examine the cytokine expression patterns in HIV infection and the relationship to allergy, stage of HIV disease, and other laboratory parameters.

METHODS

A cross-sectional analysis of IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p35, IL-13, and IFN-gamma mRNA expression in PBMCs by noncompetitive dot-blot PCR was performed on blood obtained from 18 HIV-infected subjects. Delayed-type hypersensitivity multitests to detect anergy, skin prick testing and in vitro assay for specific IgE antibodies, assay for total IgE, and enumeration of eosinophils, CD4(+), and CD8(+) T cells were also performed on all subjects.

RESULTS

We found evidence of a decline in type 1 cytokines (IL-2, IL-12p35, and IFN-gamma) associated with AIDS, CD4(+) T cells less than 200/microL, anergy, and atopy, although this only reached statistical significance in anergy. There was no associated significant alteration in type 2 cytokines.

CONCLUSIONS

This is the first report of an association between low constitutive in vivo expression of IL-12 mRNA and anergy, which supports earlier data from in vitro stimulation studies. The presence of atopy was associated with a more global reduction in cytokine expression. Because the decline in type 1 cytokines was not accompanied by a similar decline in type 2 cytokines, this does suggest a shift in the type 1/type 2 balance.

T helper cell type 1-associated and cytotoxic T lymphocyte-mediated tumor immunity is impaired in interleukin 4-deficient mice

It is widely accepted that cellular immune responses are induced by CD4(+) T helper 1 (Th1) cells secreting interleukin (IL)-2 and interferon (IFN)-gamma. Tumor immunity is often mediated by cytotoxic T lymphocytes (CTLs) whose activation is supported by Th1 cytokines. Since IL-4 directs Th2 development and has been shown to inhibit Th1-dominated responses, we assumed that IL-4-deficient (IL-4(-/-)) mice would develop vigorous CTL-mediated tumor immunity compared with IL-4-competent (IL-4(+/+)) mice. Surprisingly, IL-4(-/-) mice were severely impaired to develop tumor immunity to both a mammary adenocarcinoma line and a colon carcinoma line. The lack of tumor immunity in IL-4(-/-) mice was associated with reduced IFN-gamma production, diminished levels of tumor-reactive serum IgG2a, and undetectable CTL activity, indicating a defective Th1 response in the absence of endogenous IL-4. Anti-IL-4 monoclonal antibody blocked tumor immunity in IL-4(+/+) mice when administered at the time of immunization but not at the time of challenge. Additionally, tumor immunity could be induced in IL-4(-/-) mice, if IL-4 was provided by gene-modified cells together with immunizing tumor cells. These results demonstrate that tumor immunity requires IL-4 in the priming phase for the generation of effector cells rather than for their maintenance and exclude secondary, developmental defects in the "knockout" strain. Together, our results demonstrate a novel and previously unanticipated role of IL-4 for the generation of Th1-associated, CTL-mediated tumor immunity.

CD40-deficient mice infected with the defective murine leukemia virus LP-BM5def do not develop murine AIDS but produce IgE and IgG1 in vivo

CD40-deficient mice, when inoculated with the LP-BM5def murine retorvirus, become infected and show virus expression similar to wild-type mice. However, unlike the wild-type mice, CD40-deficient mice do not develop symptoms of immunodeficiency, lymphoproliferative disease and the typical histological changes in the lymphoid tissue. These results show that the CD40-CD40 ligand (CD40L) interaction in vivo is essential for anergy induction and the subsequent development of immunodeficiency and pathologic expansion of lymphocytes. Infected CD40-deficient mice and their littermates express a similar pattern of cytokine mRNA, which is not biased towards a Th2 phenotype. Nevertheless, hypergammaglobulinemia is induced in infected wild-type and CD40-deficient mice. Surprisingly, murine AIDS infection even induces IgE production in CD40-deficient mice in vivo. Our data demonstrate that antibody class switch to IgE and IgG1 can be induced by a retroviral infection in vivo even in the absence of CD40-CD40L interaction and an apparent switch to a Th2 cytokine production.

Iron chelation therapy for malaria: a review

Malaria is one of the major global health problems, and an urgent need for the development of new antimalarial agents faces the scientific community. A considerable number of iron(III) chelators, designed for purposes other than treating malaria, have antimalarial activity in vitro, apparently through the mechanism of withholding iron from vital metabolic pathways of the intra-erythrocytic parasite. Certain iron(II) chelators also have antimalarial activity, but the mechanism of action appears to be the formation of toxic complexes with iron rather than the withholding of iron. Several of the iron(III)-chelating compounds also have antimalarial activity in animal models of plasmodial infection. Iron chelation therapy with desferrioxamine, the only compound of this nature that is widely available for use in humans, has clinical activity in both uncomplicated and severe malaria in humans.

Novel Diversity in Th1, Th2 Type Differentiation of Hemagglutinin-Specific T Cell Clones Elicited by Natural Influenza Virus Infection in Three Major Haplotypes (H-2b,d,k)

We report novel diversity in the lymphokine (LK) secretion profile of hemagglutinin-specific, CD4+ T cell clones elicited by influenza virus infection in three major haplotypes: I-Ad- or I-Ed-restricted T cell clones obtained from individual BALB/c donors, and specific for three distinct antigenic peptides (p56–76, or p186–205 or p177–199), were uniformly Th1 type, releasing only IFN-γ on activation. In contrast, extensive diversity was evident for the C57BL/10 or CBA/Ca repertoire. Sibling T cell clones, established from the same C57BL/10 donor and expressing identical TCR β-chains in their recognition of p186–205, released either (IFN-γ and IL-5) or (IFN-γ and IL-4 and IL-5) or (IL-4 and IL-5 and IL-10) following Ag-specific or nonspecific stimulation. Similarly, I-Ak-restricted T cell clones, specific for p120–139 secreted either (IFN-γ only) or (IFN-γ and IL-5) or (IFN-γ and IL-2 and IL-5) on activation. Despite such phenotypic diversity within the individual’s repertoire, all clones had been maintained under identical in vitro culture conditions. Moreover, sequence analyses of TCR β gene usage indicated that in most instances clones from the same donor expressed identical (VDJ)β rearrangements, indicative of a common progenitor cell. FACS analysis of cytoplasmic cytokine production confirmed that for the novel phenotype (IFN-γ and IL-5), both LKs were synthesized at the single cell level. Sibling families of T cell clones, established from a common donor following viral infection but differing in LK secretion, may offer a suitable model system for further studies of signal transduction mechanisms that discriminate between Th1- and Th2-specific responses to a well defined protective Ag.

Differences in the Immune Response During the Acute Phase of E-55+ Murine Leukemia Virus Infection in Progressor BALB and Long Term Nonprogressor C57BL Mice

E-55+ murine leukemia virus infection of both progressor (BALB) and long term nonprogressor (C57BL) mouse strains is characterized by an acute and a persistent phase of infection. During the acute phase, progressor strains require CD8+ T cells to decrease virus burden, whereas the long term nonprogressor strains do not. In the present studies the immune response in BALB and C57BL mice during the acute phase of E-55+ murine leukemia virus infection was examined. The results demonstrate that BALB mice produce both IL-4 and IFN-γ, in contrast to C57BL mice, which produce only IFN-γ. In BALB mice, IL-4 production results in the absolute requirement for CD8+ T cells to reduce the virus burden during the acute phase of infection. The anti-virus immune response in these mice is IFN-γ dependent. On the other hand, C57BL mice do not produce IL-4 and, in the absence of both CD8+ T cells and IFN-γ, still generate an effective anti-virus immune response. Genetic studies suggest that these distinct immune responses are regulated by more than one non-MHC-linked gene. Two candidate regions that may encode this gene(s), located on chromosomes 7 and 19, respectively, were identified by recombinant inbred strain linkage analysis.

HIV-1 envelope protein gp120 triggers a Th2 response in mice that shifts to Th1 in the presence of human growth hormone

Immunization of mice with HIV-1-gp120 results in predominant activation of the Th2 lymphocyte subset, leading to enhanced IL-4 production. Administration of human growth hormone at the time of gp120 immunization provokes a change in the cytokine production pattern, with lower IL-4 and higher gamma-IFN and IL-2 synthesis levels, indicating a preferential switch in stimulation from Th2 to Th1 cells. A growth hormone would thus be of great use for pharmacological intervention in those cases in which an infectious microorganism evades immune defenses by provoking a Th2 response. In addition, the ability of growth hormone to induce a Th1-type response upon vaccination with an HIV-antigen should be examined in the development of new therapeutic strategies or in the design of novel vaccines against HIV infection.

Th1/Th2 cytokine responses following HIV-1 immunization in seronegative volunteers. The AIDS Vaccine Evaluation Group

The Th1/Th2 profile that follows human vaccination may profoundly influence the subsequent course of disease after infection. However, the ability to detect IL-4 has been limited outside trials of live vaccination. By using methods in which memory effector cells are allowed to antigenically expand by short term culture, followed by low-dose mitogenic stimulation, we have been able to follow the Th1/Th2 profile in HIV-1 volunteers enrolled in two phase I studies of HIV immunogens (a recombinant gp120 and a multivalent, octomeric V3 loop peptide). Antigen-specific interferon-gamma (IFN-gamma) could be detected in primary stimulation, but IL-4 was observed only after antigenic expansion and restimulation. In both of these studies the responses after initial immunizations were dominated by IFN-gamma, with IL-4 appearing only after multiple rounds of immunization, and IL-4 was temporally related to antibody production. Concomitant with the IL-4 production, the amount of supernatant IFN-gamma declined. Antigen-specific IL-10 was not detected in either study. Such techniques, which have been shown to correlate with outcomes in immunotherapy, may prove useful as future surrogates of human vaccine response.

Relationship of cytokines and cytokine signaling to immunodeficiency disorders in the mouse

The contributions of cytokines to the development and progression of disease in a mouse model of retrovirus-induced immunodeficiency (MAIDS) are controversial. Some studies have indicated at etiologic role for type 2 cytokines, while others have emphasized the importance of type 1 cytokines. We have used mice deficient in expression of IL-4, IL-10, IL-4 and IL-10, IFN-gamma, or ICSBP-a transcriptional protein involved in IFN signaling-to examine their contributions to this disorder. Our results demonstrate that expression of type 2 cytokines is an epiphenomenon of infection and that IFN-gamma is a driving force in disease progression. In addition, exogenously administered IL-12 prevents many manifestations of disease while blocking retrovirus expression. Interruption of the IFN signaling pathways in ICSBP-/- mice blocks induction of MAIDS. Predictably, ICSBP-deficient mice exhibit impaired responses to challenge with several other viruses. This immunodeficiency is associated with impaired production of IFN-gamma and IL-12. Unexpectedly, however, the ICSBP-/- mice also develop a syndrome with many similarities to chronic myelogenous leukemia in humans. The chronic phase of this disease is followed by a fatal blast crisis characterized by clonal expansions of undifferentiated cells. ICSBP is thus an important determinant of hematopoietic growth and differentiation as well as a prominent signaling molecule for IFNs.

Zinc-controlled Th1/Th2 switch significantly determines development of diseases

Functional, excessive-possibly temporary-deficiencies of the trace element zinc can change immune functions prematurely from predominantly cellular Th1 responses to humoral Th2 responses. T helper (Th1) cells produce cytokines such as interleukin-2 (IL-2) and interferon gamma, thereby controlling viral infections and other intracellular pathogens more effectively than Th2 responses through cytokines such as IL-4, IL-5, IL-6 and IL-10. The accelerated shift from the production of extra Th1 cells during these cellular immune activities to more Th2 cells with their predominantly humoral immune functions, caused by such a zinc deficiency, adversely influences the course of diseases such as leprosy, schistosomiasis, leishmaniasis and AIDS, and can result in allergies. It is noteworthy that AIDS viruses (HIVs) do not replicate in Th1 cells, which probably contain more zinc, but preferentially in the Th0 and Th2 cells; all the more so, because zinc and copper ions are known to inhibit intracellular HIV replication. Considering the above Th1/Th2 switch, real prospects seem to be offered of vaccination against such parasites as Leishmania and against HIVs.

Modulation of murine AIDS-related pathology by concurrent antibody treatment and coinfection with Leishmania major

Infection of C57BL/6 mice with a mixture of murine leukemia viruses (MuLVs) designated LP-BM5 MuLV leads to a disease characterized by progressive immunodeficiency and lymphoproliferation, known as murine AIDS (MAIDS). The development of MAIDS is associated with increased B-cell lymphoblast proliferation, but there is reason to believe that T-cell function and, particularly, T-cell-derived cytokines may also play a role. We have previously shown that concurrent infection with Leishmania major (which induces a strongly polarized Th1 response in C57BL/6 mice) and LP-BM5 MuLV modulates the disease induced by both infections. Here we show by treatment of mice with anticytokine antibodies that this modulation is largely exerted through the balance of Th1 and Th2 cytokines. Infected mice treated with antibodies to interleukin-4 and interleukin-10 exhibited a delayed development of MAIDS-related pathology and maintained T-cell responsiveness longer than mice treated with control antibody. Gamma interferon induced by coinfection with L. major synergized with anti-IL-4 treatment to inhibit the development of MAIDS pathology. Conversely, treatment with anti-gamma interferon led to a significant increase in splenomegaly and lymphadenopathy and slightly exacerbated loss of T-cell function. These data suggest that the production of Th2-associated cytokines may promote MAIDS pathology, while Th1-associated cytokines may help control the disease.

Modulation of immune dysfunction during murine leukaemia retrovirus infection of old mice by dehydroepiandrosterone sulphate (DHEAS)

Ageing, leukaemia and acquired immune deficiency syndrome (AIDS) are conditions with dysregulated cytokine production. As dehydroepiandrosterone sulphate (DHEAS) restored normal cytokine production in old mice its effects on retrovirally infected old mice were investigated. Retrovirus infection and ageing-induced immune dysfunction. Murine retrovirus-infected old C57BL/6 female mice consumed 0.22 or 0.44 microgram of DHEAS/mouse/day beginning 2 weeks postinfection for 10 weeks. DHEAS largely prevented the retrovirus-induced reduction in T-cell and B-cell mitogenesis. DHEAS supplement prevented loss of cytokines [interleukin-2 (IL-2) and interferon-gamma] secretion by mitogen-stimulated splenocytes representing T helper 1 (Th1) cell phenotypes. It also suppressed the retrovirus-induced, excessive production of cytokines (IL-6 and IL-10) by Th2 cells. The highest dose of DHEAS reduced IL-6 production by splenocytes from uninfected old mice by 75% while increasing their IL-2 secretion by nearly 50%. Thus immune dysfunction induced by ageing, even when exacerbated by murine retrovirus infection, was largely prevented by DHEAS.

Alcohol consumption alters cytokine release during murine AIDS

Acquired immune deficiency syndrome (AIDS) is a clinical disorder caused by a human immunodeficiency virus (HIV), representing the end point in a progressive sequence of immunosuppressive changes. HIV, the key causative agent of AIDS, induces immunosuppression that render the body highly susceptible to opportunistic infections and neoplasm. However, the onset of clinical symptoms of AIDS (e.g., low CD4+ T cells count, opportunistic infections, and tumors) is quite variable among HIV+ individuals with a mean incubation times 3-10 years following seroconversion. Because of the deleterious effects of chronic alcohol (EtOH) consumption on cytokine release, immune response, host defense, nutritional status, and oxidative stress, it has been believed to be a possible cofactor that could enhance the host's susceptibility to HIV infection, and subsequently accelerate the development of AIDS. The purpose of this review is to present evidence of EtOH-induced cytokine dysregulation during murine AIDS. Our results done in murine AIDS indicate the EtOH consumption may accelerate the development of AIDS by disrupting cytokine production. These EtOH-induced abnormalities in cytokine release may promote a more rapid development of AIDS as a cofactor, which exacerbates the immune dysfunctions initiated by retrovirus infection.

The HIV/AIDS epidemic: its evolutionary implications for human ecology with special reference to the immune system

The epidemiology of AIDS in Africa is discussed. Serological and clinical data on virology and population genetics are related to current theories of heterosexual transmission and to cultural practices involving the exchange or transmission of body fluids between individuals, such as female and male genital mutilation and indigenous or 'folk' medicine, as well as non-Western medical uses of medical syringes. A review of the relationship of autoimmune conditions, graft-vs-host disease and the retrovirus/oncogene involvement is presented. These data place in a new perspective concepts of widespread heterosexual infection and transmission of HIVs as well as their relation to AIDS in the context of the evolution of the human immune system.

Efficient targeting of the IL-4 gene in a BALB/c embryonic stem cell line

Embryonic stem (ES) cell lines have been derived from the inner cell mass of day 3.5 blastocysts of the inbred mouse strain BALB/cJ. Twenty-three lines were karyotyped and three were selected for injection into C57BL/6J host blastocysts. Two of the three lines, BALB/c-I and BALB/c-IV, produced germ-line chimaeras. The suitability of the BALB/c-I line for gene targeting experiments was tested by transfecting a targeting construct for the interleukin-4 (IL-4) gene. Transfected BALB/c-I cells exhibited efficient homologous recombination of the targeting vector and transmitted the induced mutation through the germline. This newly-characterized BALB/c-ES cell line thus provides an alternative to the traditional 129-derived and the recently described C57BL/6 embryonic stem cell lines, and will be useful in disrupting genes involved in the immune system. Furthermore, the genetically pure BALB/c IL-4 deficient mice will aid in studying the role of IL-4 in several infectious disease models in which the BALB/c mouse is a susceptible strain.

Psychoneuroimmunology: animal models of disease

OBJECTIVE

Psychoneuroimmunology, which investigates the bidirectional communication between the central nervous system and the immune system, has been greatly advanced by the use of animal models. The objective of this paper is to describe animal models of disease that can or might be utilized to elucidate neural-immune interactions that alter pathogenesis.

METHODS

This paper reviews animal studies that have demonstrated a link among the brain, behavior, immunity, and disease, highlighting models in which the potential contribution of CNS-immune interactions has not yet been explored.

RESULTS

Animal studies allow for careful control of environmental stimuli, genetic background, and immunological challenge. As such, they are an important component of psychoneuroimmunology research. Models in which one might study the role of psychosocial factors in immunologically mediated disease processes, as in the case of other pathophysiologic processes, profit from an ability to manipulate both stressful events and the magnitude of the challenge to the immune system.

CONCLUSIONS

Animal studies in psychoneuroimmunology highlight the complexity of the interactions among behavior, the brain, the immune system, and pathogen. The genetic background of the animal (both in terms of central nervous and immune system responses), its previous history, the nature of the stressor, the nature of the pathogen and the type of immune response generated are some of the interacting factors that determine the magnitude and direction of stress-induced changes in disease outcome.

Interleukin (IL)-4-independent immunoglobulin class switch to immunoglobulin (Ig)E in the mouse

Immunoglobulin (Ig) class switching in B cells is regulated by stimuli transduced by cytokines and cell-cell contact. Among these stimuli, interleukin (IL)-4 has been considered an absolute prerequisite for class switching to IgE in the mouse. Here we report that IL-4-deficient (IL-4-/-) and wildtype mice had comparably elevated serum IgE levels during the course of a murine retrovirus-induced immunodeficiency syndrome, MAIDS. IgE switching in IL-4-/- mice was also induced by injection of anti-IgD antibody. Treatment with anti-IgD induced germline epsilon (g epsilon) transcripts with comparable efficiency in IL-4-/- mice and controls, but the levels of productive epsilon transcripts (p epsilon) were lower by a factor of 200 and serum IgE levels were lower by a factor of 300 in IL-4-/- mice as compared with controls. Induction of g epsilon after anti-IgD treatment of IL-4-/- mice was unaffected by simultaneous treatment with monoclonal antibodies to IL-4 and IL-4 receptor alpha chain. Infection of IL-4-/- mice with Nippostrongylus brasiliensis, a potent stimulus for IgE production, resulted in induction of g epsilon transcripts; however, p epsilon transcripts were barely detectable and serum IgE was not detected. These findings establish a novel IL-4-independent pathway for IgE switching in the mouse that is strongly activated in retroviral infection but weakly in nematode infection. This pathway appears to be dependent on distinct factors that separately control induction of g epsilon transcription and switch recombination to p epsilon.

Transcriptional up-regulation of interleukin 4 receptors by human immunodeficiency virus type 1 tat gene

The human immunodeficiency virus type 1 (HIV-1) regulatory gene, tat, encodes an early transactivator protein (Tat) necessary for virus replication. We have reported that the HIV-1 tat gene can up-regulate interleukin 4 receptors (IL-4R) however, the mechanism of this up-regulation is not understood. We now show that in Raji cells, 125I-labeled IL-4 cross-linked to three proteins of 140, 70, and 63 kDa, which were immunoprecipitated with an antibody to the human IL-4R. Although this level of all three IL-4 binding proteins increased in tat-transfected cells, the binding characteristics of IL-4R on control or mock transfected control and tat-transfected cells remained similar. The exogenous recombinant Tat protein or supernatant of tat transfected Raji cells also up-regulated the expression of the IL-4R on two renal cell carcinoma cell lines in a concentration-dependent manner. The actinomycin D chase experiments revealed that the half-lives of the IL-4R protein (t1/2 3.5 hr) and mRNA transcripts (t1/2 2.5 hr) were similar in both control and tat-transfected cells. In contrast, nuclear run-on experiments revealed that the rate of the IL-4R mRNA transcription increased 3- to 5-fold in Raji-tat compared to Raji cells. These data indicate that the HIV-1 tat gene up-regulates IL-4R expression by increasing the transcription rate rather than posttranscriptional stabilization of either the mRNA or the protein. HIV-tat inducible exogenous tumor necrosis factor (TNF-alpha) did not up-regulate IL-4R and IL-4R inducible activation of signal transducers and activators of transcription (STAT-6) was not observed by Tat even though IL-4R were up-regulated. These results allow us to speculate that HIV-1 tat may interact directly with the IL-4R gene and up-regulate IL-4R transcription.

Can we find a solution to the human immunodeficiency virus/acquired immune deficiency syndrome controversy? Is acquired immune deficiency syndrome the consequence of continuous excessive stressing of the body?

The time of re-evaluation of the role of human immunodeficiency viruses in the pathogenesis of acquired immune deficiency syndrome has now come, now that methods are available for the direct detection of human immunodeficiency viruses and for the detection of cellular anti-human immunodeficiency virus immune reactions. It has been shown that human immunodeficiency virus infections are common among anti-human immunodeficiency virus antibody negative high-risk individuals. The disease is brought under control by cellular immune reactions and the anti-human immunodeficiency virus antibody test remains negative. Apart from proof that infection with human immunodeficiency viruses has occurred, a positive result in an anti-human immunodeficiency virus-antibody test is also an indication of an independent immunosuppression state. According to the definition of the Centers of Disease Control classical acquired immune deficiency syndrome is the consequence of infection with human immunodeficiency virus in association with continuous excessive stress, such as observed in the known risk groups. At the center of the pathogenetic process is hypercortisolism-determined damage of T lymphocytes, in which insufficiency of thymus is prominent. For this reason, in our view, there are indications for shifting efforts from the prophylaxis of infection with human immunodeficiency viruses to the prophylaxis of acquired immune deficiency syndrome by reducing stress factors.

Susceptibility to Leishmania major infection in interleukin-4-deficient mice

Interleukin-4 (IL-4), a pleiotropic cytokine, is a major regulator of the immune system and is considered crucial for the development of T helper cell type 2 (TH2) responses. The susceptibility of BALB/c mice to infection with Leishmania major has been associated with a polarized TH2 response and an inability to down-modulate IL-4 production. The role of IL-4 in vivo was examined directly by disrupting the IL-4 gene in BALB/c embryonic stem cells. Despite the absence of IL-4, the genetically pure BALB/c mutant mice remained susceptible to L. major infection, showed no signs of lesion healing or parasite clearance, and did not switch to a TH1 phenotype.

2-Carboxyethylgermanium sesquioxide, a synthetic organogermanium compound, as an inducer of contrasuppressor T cells

2-Carboxyethylgermanium sesquioxide (Ge-132), a synthesized organogermanium compound with immunomodulating activities, was shown to be an inducer of anti-suppressor T cells in normal mice. The suppressor cell activity of T6S cells, a clone of burn-induced CD8+ IL-4-producing suppressor T cells, was clearly inhibited when a mixed lymphocyte-tumor cell reaction of the clone was conducted with splenic mononuclear cells from mice treated orally with a 100 mg/kg dose of Ge-132. The activity of anit-suppressor cells was demonstrated in spleens of mice 2 days after treatment with Ge-132 and reached its peak on day 3. The anti-suppressor cells induced by the compound were of a contrasuppressor T cell-linage, because they were characterized as CD4+ CD28+ TCRalpha/beta+ Vicia villosa lectin-adherent T cells. These cells produced IFN-gamma but did not produce IL-2, IL-4, IL-6 or IL-10 in their culture fluids. CD4+ anti-suppressor T cells induced by Ge-132 may be different from other subsets of CD4+ T cells because Th1 and Th2 cells generated in our laboratory did not adhere to Vicia villosa lectin-coated petri dishes, and each produced specific cytokines. Th1 cells produced IFN-gamma and IL-2 while Th2 cells produce IL-4 and IL-10 in vitro. These results suggest that Ge-132 may be useful as an inducer of contrasuppressor T cells in immunocompromised individuals bearing suppressor T cells. To eliminate suppressor T cells from immunocompromised hosts may result in improved resistance from various opportunistic infections.

T-cell-receptor dose and the time of treatment during murine retrovirus infection for maintenance of immune function

C57BL/6 mice were injected with different doses of human T-cell receptor (TCR) V beta 8.1 CDR1 peptide at different times after murine retrovirus (LP-BM5) infection. Injection with TCR V beta 8.1 CDR1 peptide largely prevented the retrovirus-induced reduction in B- and T-cell proliferation, and T-helper 1 (Th1) cytokines [interleukin-2 (IL-2) and interferon-gamma (IFN-gamma)] secretion. It also suppressed T-helper 2 (Th2) cytokines (IL-6 and IL-10) production, which was stimulated by retrovirus infection. These effects were accomplished using at least 100 micrograms of peptide per mouse and the most effective dose of peptide had to be given within 4 weeks after retrovirus infection. Immunization with doses above 100 micrograms/mouse as long as 4 weeks postinfection maintained natural killer (NK) cell activity during retrovirus infection. Reducing the dose of peptide or delaying it until the disease progressed towards early murine acquired immune deficiency syndrome (AIDS) allowed development of immune dysfunction. These studies provide data suggesting that immune dysfunction, induced by murine retrovirus infection, was largely prevented by TCR V beta CDR1 peptide injection.

Effect of HIV infection on the frequency of cytokine-secreting cells in human peripheral blood

A selective decrease in type 1 cytokine secretion by in vitro stimulated peripheral blood cells is reportedly associated with disease progression in HIV-infected individuals. To examine whether a similar change in cytokine secretion occurs under physiologic conditions in vivo, sensitive and specific ELIspot assays were used to compare the phenotype and frequency of PBMC spontaneously producing interleukin (IL)-2, IL-4, IL-10, and interferon-gamma (IFN-gamma) in 83 HIV-infected subjects and 60 normal controls. Phenotypic analysis of freshly isolated cytokine-secreting cells showed that T cells were the primary source of IL-2, IL-4, and IFN-gamma while CD14+ macrophages/monocytes were the dominant source of IL-10 in vivo. The number of peripheral blood mononuclear cells (PBMC) spontaneously secreting both type 1 and type 2 cytokines was significantly reduced in HIV-infected patients versus controls. The magnitude of this decrease did not correlate with disease severity. Changes in IL-2-secreting cell number correlated with CD4 count, while changes in the frequency of IFN-gamma-secreting cells correlated with disease duration. These findings do not support the contention that a selective reduction in type 1 cytokine production correlates with disease progression.

Thiols decrease human interleukin (IL) 4 production and IL-4-induced immunoglobulin synthesis

N-Acetyl-L-cysteine (NAC) is an antioxidant precursor of intracellular glutathione (GSH), usually given in human as a mucolytic agent. In vitro, NAC and GSH have been shown to act on T cells by increasing interleukin (IL) 2 production, synthesis and turnover of IL-2 receptors, proliferation, cytotoxic properties, and resistance to apoptosis. We report here that NAC and GSH decrease in a dose-dependent manner human IL-4 production by stimulated peripheral blood T cells and by T helper (Th) 0- and Th2-like T cell clones. This effect was associated with a decrease in IL-4 messenger RNA transcription. In contrast, NAC and GSH had no effect on interferon gamma and increased IL-2 production and T cell proliferation. A functional consequence was the capacity of NAC and GSH to selectively decrease in a dose-dependent manner IL-4-induced immunoglobulin (Ig) E and IgG4 production by human peripheral blood mononuclear cells. Interestingly, NAC and GSH also acted directly on purified tonsillar B cells by decreasing the mature epsilon messenger RNA, hence decreasing IgE production. In contrast, IgA and IgM production were not affected. At the same time, B cell proliferation was increased in a dose-dependent manner. Not all antioxidants tested but only SH-bearing molecules mimicked these properties. Finally, when given orally to mice, NAC decreased both IgE and IgG1 antibody responses to ovalbumin. These results demonstrate that NAC, GSH, and other thiols may control the production of both the Th2-derived cytokine IL-4 and IL-4-induced Ig in vitro and in vivo.

CD4+ Th2 cell response cytokine production in bacterial meningitis

There has been a growing body of evidence suggesting that CD4+ Th1/Th2 cell responses participate in pathologic and immunologic processes in infectious disease. Bacterial meningitis is a fatal disease of children and is associated with a spectrum of clinical syndromes. This study provides evidence of CD4+ enhanced interleukin (IL)-4 and IL-6 but decreased IL-2 and interferon-gamma (IFN-gamma) production, the induction of characteristic Th2 cell response cytokines in bacterial meningitis, which may play an important role in disease mechanism. Additionally, monocyte-induced enhanced IL-6, IL-8, and tumor necrosis factor-alpha production may be associated with distinct clinical features such as fever, seizures, and neurological sequelae. A striking finding was also the highly deficient monocyte-induced granulocyte-macrophage colony-stimulating factor production. Of particular interest, the CD(8+)-enhanced IFN-gamma production may be required for the cytolytic activity or protective response to be maintained in this disease. Taken together, these data reveal that monocytes and CD4+ (Th2) and CD8+ subsets produce distinct cytokines in bacterial meningitis, which may exert an immunoregulatory and immunopathologic effect and thus mediate some of the clinical manifestations of the disease.

Antigen presentation by naive macrophages, dendritic cells and B cells to primed T lymphocytes and their cytokine production following exposure to immunostimulating complexes

Influenza virus envelope proteins incorporated into immunostimulating complexes (iscoms) are taken up and processed by various kinds of antigen-presenting cells (APC), encompassing peritoneal cells (PEC), unfractionated splenocytes, splenic dendritic cells (DC) or B cells. The iscom-pulsed naive APC stimulated primed T cells to proliferate and produce cytokine in vitro. In contrast, only DC and B cells pulsed with the same antigen (Ag) in the micelle form functioned as accessory cells stimulating the primed T cells to proliferate and produce cytokine. In general, iscoms were better inducers of cell proliferation than micelles. Iscoms stimulated more secretion of IL-2 and interferon-gamma (IFN-gamma) than the micelles, but both antigenic forms stimulated secretion of IL-4. DC and B cells pulsed with iscoms stimulated most efficiently the secretion of IL-2 and IFN-gamma. DC were superior to the other APC in stimulating primed T cells to secrete IFN-gamma. On the other hand, micelles stimulated more efficiently than iscoms splenic T cells from micelle-primed as well as iscom-primed mice to secrete IL-10. These data indicate that influenza virus envelope proteins incorporated in iscoms stimulate a broad T cell response, possibly emphasizing a Th1 type of response. The same Ag in a micelle form induce a more prominent Th2 type of T cell response. The results indicate that the administration of an Ag in an adjuvant formulation can superimpose a different cytokine profile on the immune response than that induced by the protein Ag alone.