Induction of interleukin-3 by interleukin-1 in the absence of other exogenous stimuli

We have previously reported that lipopolysaccharide (LPS) could induce the production of interleukin-3 (IL-3) by mouse spleen cells. In the present study, we show that recombinant human interleukin-1, in the absence of other stimuli, is able to induce the production of IL-3. IL-3 was detected in the supernatants of adult, although neither in young nor in nude mouse splenocytes and was assessed by its capacity to support the growth of the IL-3-dependent FDC-P2 cell line. The presence of IL-3 was antigenically confirmed with a monoclonal anti-IL-3 antibody. Both recombinant IL-1 alpha and IL-1 beta had similar potential for inducing IL-3 production. IL-3 activity was detected in the supernatants of cells cultured in the presence of 100 pg/ml IL-1; maximal IL-3 levels were obtained with 10-30 ng/ml IL-1. Kinetic studies of IL-1-induced IL-3 production indicated that 4-6 days of culture were required for optimal production, whereas 1-2 days were sufficient in cultures stimulated with concanavalin A. Recombinant IL-6 failed to induce significant amounts of IL-3, and TNF alpha induced only weak IL-3 production. GM-CSF but not M-CSF could lead to the appearance of IL-3 in spleen cell culture supernatants. Removal of macrophages decreased the production of IL-3 induced by LPS and GMF-CSF though did not affect the IL-3 production induced by IL-1. This observation suggests that IL-1 production might be an intermediate event in IL-3 production induced by LPS and GM-CSF through the activation of macrophages. IL-3 was detected in culture supernatants of B-cell-depleted splenocytes indicating that T-cells were the source of IL-3. Surprisingly T-cell-depleted populations could also produce IL-3 upon IL-1 stimulation. Preliminary experiments with an autoreactive CD4- CD8- V beta 8+ clone suggested that these cells might also be involved in the described IL-3 production.     

Augmentation of interleukin-2 release by cytochalasins

Augmentation of mitogen-induced release of the T cell lymphokine interleukin-2 (IL-2) occurred using several cytochalasins in coculture with a T cell lymphoma line (JM) or with purified T cells. When added concurrently with mitogen, cytochalasins had no apparent negative effect either on the ability of mitogen to signal IL-2 production or on the total amount produced. Use of cytochalasins that affect submembranous actin in peripheral lymphocytes established a link between cytoskeletal alterations and lymphokine release, although direct membrane perturbation cannot be excluded. These data indicate that an intracellular pool of IL-2 may accumulate in both T cell lines and in purified peripheral T cells and that maintenance of that pool may be affected by alterations of the cytoskeletal elements. Cytochalasins not only increased IL-2 release, but could substitute for phorbol myristic acetate (PMA) in supporting mitogen-signaled IL-2 production. We interpret these data also to indicate that cytoskeletal attachment to the surface molecules that signal IL-2 production is not needed for the activation.     

Replicase gene of coxsackievirus B3.

A cDNA copy covering two-thirds of the coxsackievirus B3 genome was cloned in the PstI site of the pBR322 vector. A nucleotide sequence containing the gene for the viral replicase and the 3' noncoding region of the coxsackievirus B3 genome was determined. The predicted amino acid sequence of the coxsackievirus B3 replicase was shown to be remarkably similar to that of the poliovirus 1 replicase. The 3' noncoding region, in contrast, was only weakly homologous to the poliovirus 1 sequence but showed a close relationship to the sequence of swine vesicular disease virus, a variant of coxsackievirus B5. A 13-nucleotide-long segment located near the polyadenylic acid junction is conserved in several members of the enterovirus group and may thus serve an important function during replication of viral RNA.     

Differential Th1 and Th2 cell responses in male and female BALB/c mice infected with coxsackievirus group B type 3.

Male and female BALB/c mice differ dramatically in susceptibility to myocarditis subsequent to coxsackievirus B3 (CVB3) infection. CVB3 infection of male mice results in substantial inflammatory cell infiltration of the myocardium, and virus-immune lymphocytes from these animals give predominantly a Th1 cell phenotypic response, as determined by predominant immunoglobulin G2a isotypic antibody production and elevated numbers of gamma interferon and interleukin-2 (IL-2)-producing CD4+ T lymphocytes. Females infected with the same virus give predominantly a Th2 cell phenotypic response, as determined by preferential immunoglobulin G1 antibody isotypic responses and increased precursor frequencies of IL-4- and IL-5-producing CD4+ T cells. Treatment of females with testosterone or males with estradiol prior to infection alters subsequent Th subset differentiation, suggesting that the sex-associated hormones have either a direct or indirect effect on CD4+ lymphocyte responses in this model. Treatment of females with 0.1 mg of monoclonal antibody to IL-4 reduces precursor frequencies of IL-4-producing CD4+ T cells and increases frequencies of gamma interferon-producing cells. This treatment also enhances myocardial inflammation, indicating a correlation between Th1-like cell responses and pathogenicity in CVB3 infection. The Th2-like cell may regulate Th1 cell activation. Adoptive transfer of T lymphocytes from CVB3-infected female mice into male animals suppresses the development of myocarditis in the recipients. Treatment of the female donors with monoclonal antibodies to either CD3, CD4, or IL-4 molecules abrogates suppression.     

Protective effects of losartan in mice with chronic viral myocarditis induced by coxsackievirus B3

AimTo investigate whether losartan has protective effects in mice with chronic viral myocarditis induced by coxsackievirus B3 (CVB3).Main methodsThirty two male Balb/c mice were intraperitoneally injected with CVB3 (10 × TCID₅₀) to induce chronic viral myocarditis (CVM). Losartan at 12.5 mg/kg (n = 16) or normal saline (n = 16) were orally administered daily for 28 days to these mice. Uninfected mice (n = 6) were used as controls. On day 29, all mice underwent anesthesia and echocardiography prior to sacrifice. Serum IL-17, IL-4, IFN-γ and TNF-α levels were measured by enzyme-linked immunosorbent assay, and cardiac tissues were histologically examined after hematoxylin & eosin staining. In addition, the effect of losartan on the virus titers in primary cultured neonatal rat cardiomyocytes infected with CVB3 was measured on Hep-2 cells at 72 h post infection.Key findingsMice infected with CBV3 had significantly increased mortality, heart/body weight ratios, necrosis and inflammatory scores and decreased cardiac ejection fractions, compared with the controls (all P < 0.05). Losartan significantly decreased mortality from 40.0% to 12.5%, heart/body weight ratios from 7.08 ± 2.17 to 4.15 ± 0.99, and necrosis and inflammatory scores from 3.33 ± 0.50 to 2.50 ± 0.65 (all P < 0.05), and increased ejection fractions from 55.80 ± 9.25 to 72.31 ± 12.15 (P < 0.05). Losartan significantly enhanced IL-4, and decreased IFN-γ, TNF-α and IL-17 (all P < 0.05). In the in vitro experiment, losartan had no influence on virus titers.SignificanceLosartan protects mice against CVB3-induced CVM, most likely through upregulating Th2 responses, and down-regulating Th1 and Th17 responses.     

Blockade of interleukin-17A protects against coxsackievirus B3-induced myocarditis by increasing COX-2/PGE2 production in the heart

The Th17/interleukin (IL)-17 axis controls inflammation and might be important in the pathogenesis of experimental autoimmune myocarditis (EAM) and other autoimmune diseases. However, the mechanism underlying the increased Th17 cell response in coxsackievirus-induced myocarditis remains unclear. This study aimed to elucidate the regulatory mechanisms affected by blocking IL-17A responses in acute virus-induced myocarditis (AVMC) mice. The results showed that IL-17A and COX-2 proteins were significantly increased in the cardiac tissue of acute myocarditis, as were Th17 cells in the spleen. Using anti-mouse IL-17Ab to block IL-17A on day 7 of the viral myocarditis led to decreased expressions of cardiac tumor-necrosis factor alpha, IL-17A and transforming growth factor beta in AVMC mice compared to isotype control mice. COX-2 and prostaglandin E2 proteins were dramatically elevated, followed by marked reductions in CVB3 replication and myocardial injury. These results hint that the Th17/IL-17 axis is intimately associated with viral replication in acute myocarditis via induction of COX-2 and prostaglandin E2.     

Role of CD1d in coxsackievirus B3-induced myocarditis

The myocarditic (H3) variant of Coxsackievirus B3 (CVB3) causes severe myocarditis in BALB/c mice and BALB/c mice lacking the invariant J alpha 281 gene, but minimal disease in BALB/c CD1d(-/-) animals. This indicates that CD1d expression is important in this disease but does not involve the invariant NKT cell often associated with CD1d-restricted immunity. The H3 variant of the virus increases CD1d expression in vitro in neonatal cardiac myocytes whereas a nonmyocarditic (H310A1) variant does not. V gamma 4(+) T cells show increased activation in both H3-infected BALB/c and J alpha 281(-/-) mice compared with CD1d(-/-) animals. The activated BALB/c V gamma 4(+) T cells from H3-infected mice kill H3-infected BALB/c myocytes and cytotoxicity is blocked with anti-CD1d but not with anti-MHC class I (K(d)/D(d)) or class II (IA/IE) mAbs. In contrast, H3 virus-infected CD1d(-/-) myocytes are not killed. These studies demonstrate that CD1d expression is essential for pathogenicity of CVB3-induced myocarditis, that CD1d expression is increased early after infection in vivo in CD1d(+) mice infected with the myocarditic but not with the nonmyocarditic CVB3 variant, and that V gamma 4(+) T cells, which are known to promote myocarditis susceptibility, appear to recognize CD1d expressed by CVB3-infected myocytes.     

Role of coxsackievirus B4 in the pathogenesis of acute glomerulonephritis

Coxsackievirus B₄ was isolated from the throat, nose, blood, stools and urine of a 9-year-old boy with acute glomerulonephritis and a pneumonitis. Neutralization test showed a greater than fourfold rise in the antibody titre to coxsackievirus B₄. The antistreptolysin O titre was elevated, but the complement component was within the normal range. The importance of the coxsackievirus B₄ in the pathogenesis of acute glomerulonephritis is clearly indicated; however, further investigations are needed to understand the details of the virus-kidney interaction.     

Preliminary characterization of coxsackievirus B3 temperature-sensitive mutants.

Prototype temperature-sensitive (ts) mutants of a coxsackievirus B3 parent virus capable of replication to similar levels at 34 or 39.5 degrees C were examined for the nature of the temperature-sensitive event restricting replication in HeLa cells at 39.5 degrees C. The ts mutant prototypes represented three different non-overlapping complementation groups. The ts1 mutant (complementation group III) synthesized less than 1% of the infectious genomic RNA synthesized by the coxsackievirus B3 parent virus at 39.5 degrees C and was designated an RNA- mutant. Agarose gel analysis of glyoxal-treated RNA from cells inoculated with ts1 virus revealed that cell RNA synthesis continued in the presence of synthesis of the small amount of viral RNA. This mutant was comparatively ineffective in inducing cell cytopathology and in directing synthesis of viral polypeptides, likely due to the paucity of nascent genomes for translation. The ts5 mutant (complementation group II) directed synthesis of appreciable quantities of both viral genomes (RNA+) and capsid polypeptides; however, assembly of these products into virions occurred at a low frequency, and virions assembled at 39.5 degrees C were highly unstable at that temperature. Shift-down experiments with ts5-inoculated cells showed that capsid precursor materials synthesized at 39.5 degrees C can, after shift to 34 degrees C, be incorporated into ts5 virions. We suggest that the temperature-sensitive defect in this prototype is in the synthesis of one of the capsid polypeptides that cannot renature into the correct configuration required for stability in the capsid at 39.5 degrees C. The ts11 mutant (complementation group I) also synthesized appreciable amounts of viral genomes (RNA+) and viral polypeptides at 39.5 degrees C. Assembly of ts11 virions at 39.5 degrees C occurred at a low frequency, and the stability of these virions at 39.5 degrees C was similar to that of the parent coxsackievirus B3 virions. The temperature-sensitive defect in the ts11 prototype is apparently in assembly. The differences in biochemical properties of the three prototype ts mutants at temperatures above 34 degrees C may ultimately offer insight into the differences in pathogenicity observed in neonatal mice for the three prototype ts mutants.     

Augmentation of antileukemia lytic activity by OKT3 monoclonal antibody: synergism of OKT3 and interleukin-2

We have shown that short-term incubation (45 min) of peripheral blood lymphocytes of normal donors with OKT3 monoclonal antibody (MoAb), directed against T-cell-associated antigen CD3, resulted in an acquisition of lytic activity against fresh leukemic cells. Induction of such antileukemia activity was specific for OKT3, since Leu-1 MoAb (directed against another T cell surface molecule, CD5) did not induce a lytic effect. The OKT3-generated antileukemia effect was displayed against various types of leukemia including chronic myelogenous leukemia and acute myelogenous leukemia of various histological subtypes (M1, M2, M5). We furthermore demonstrated that OKT3 MoAb substantially enhanced leukemia killing by interleukin-2 (IL-2)-activated killer cells obtained from peripheral blood of patients with leukemia. Of most importance was the observation that the combined treatment of effector cells with IL-2 and OKT3 MoAb resulted in the highest levels of lysis of both autologous and allogeneic fresh leukemic cells that have been observed in leukemic patients to date. Of importance was to note that OKT3 treatment was effective in induction of cytotoxic activity also in patients whose effector cells were unresponsive to stimulation with IL-2 alone. All of these observations suggest that IL-2-activated and OKT3-MoAb-treated effector cells may represent the most aggressive population of antileukemia-directed killer cells and may play a significant role in the treatment of human leukemia.     

Molecular determinants for virulence in coxsackievirus B1 infection.

Studies demonstrated that a strain derived from an infectious clone of coxsackievirus B1 (CVB1N) (N. Iizuka, H. Yonekawa, and A. Nomoto, J. Virol. 65:4867-4873, 1991) was 3 to 4 log10 less virulent than the myotropic Tucson strain of CVB1 (CVB1T) following intraperitoneal inoculation of newborn mice. Replacement of nucleotides (nt) 69 to 804 from the 5' untranslated region (5' UTR) and 1A coding region of CVB1N or nt 117 to 161 from the 5' UTR with the corresponding part from CVB1T restored greater than 90% of the virulence. Sequencing of the 5' UTR of CVB1T demonstrated areas with a greater similarity to particular echoviruses than to CVB1N, suggesting that recombination events might have occurred, perhaps influencing the virulence phenotype.     

Survival of coxsackievirus B3 under diverse environmental conditions.

The survival of coxsackievirus B3 was studied under various conditions of incubation. The comparative study demonstrated that coxsackievirus B3 was stable for 24h (less than 0.4-log decrease in titer) when suspended at neutral pH (6 or 23 degrees C) in the presence of 0.25% bovine serum albumin in saline regardless of whether the preparations were subjected to evaporation. Bovine serum albumin provided increased stability to the virus for each of the conditions tested. At 37 degrees C, evaporation greatly reduced the virus infectivity between 6 and 20 h of incubation. Nevertheless, coxsackievirus B3 was found to be stable for at least 24 h under conditions similar to those of a household environment, and its presence represents a potential biohazard to nonimmune persons. These data provide a rationale for using coxsackievirus B3 as a model for investigating the role of environmental surfaces in the transmission of enteroviral diseases.     

Survival of coxsackievirus B3 under diverse environmental conditions.

The survival of coxsackievirus B3 was studied under various conditions of incubation. The comparative study demonstrated that coxsackievirus B3 was stable for 24h (less than 0.4-log decrease in titer) when suspended at neutral pH (6 or 23 degrees C) in the presence of 0.25% bovine serum albumin in saline regardless of whether the preparations were subjected to evaporation. Bovine serum albumin provided increased stability to the virus for each of the conditions tested. At 37 degrees C, evaporation greatly reduced the virus infectivity between 6 and 20 h of incubation. Nevertheless, coxsackievirus B3 was found to be stable for at least 24 h under conditions similar to those of a household environment, and its presence represents a potential biohazard to nonimmune persons. These data provide a rationale for using coxsackievirus B3 as a model for investigating the role of environmental surfaces in the transmission of enteroviral diseases.     

In vivo administration of interleukin-2 protects susceptible mice from Theiler's virus persistence.

In vivo administration of interleukin-2 (IL-2)-secreting tumor cells results in complete protection against persistent infection by Theiler's murine encephalomyelitis virus (TMEV) in susceptible DBA/2 mice. The IL-2-mediated protection was found to depend on the inoculum size as well as the timing of IL-2 administration. IL-2-treated and TMEV-infected mice displayed a three- to fourfold relative increase in virus-specific cytotoxic T-lymphocyte (CTL) precursors. Thus, we postulate that the persistence of TMEV infection in susceptible mice reflects limited numbers of relevant CTL precursors and their time course of induction and activation.     

Crystallization and preliminary X-ray diffraction studies of coxsackievirus B1.

Preparations of coxsackievirus B1 (CVB1) derived from an infectious cDNA clone have been crystallized in multiple crystal forms. Using high intensity synchrotron radiation, an orthorhombic form of the crystals was shown to diffract X-rays to at least 2.9 A resolution. The unit cell has a primitive lattice with dimensions a = 323 A, b = 450 A, and c = 522 A. A crystallographic asymmetric unit of these CVB1 crystals probably contains an entire virus particle, implying the presence of 60-fold non-crystallographic redundancy. This CVB1 crystal form appears to be suitable for high-resolution structure determination by X-ray crystallography.     

Pancreatic expression of interferon-gamma protects mice from lethal coxsackievirus B3 infection and subsequent myocarditis

Cardiovascular disease is one of the leading causes of death worldwide, and has been associated with many environmental risk factors. Recent evidence has indicated the involvement of pathogens such as viruses as causative agents, and specifically identified the coxsackievirus B serogroup as the leading culprit. Not only has coxsackievirus B3 (CB3) been identified from patients with cardiovascular disease, but also infection of mice with CB3 strains can reproduce human clinical heart disease in rodents. Several mechanisms have been proposed in an attempt to distinguish between pathology mediated by direct viral destruction of cardiac muscle cells or by the virus-induced immune response directed at infected myocytes or at 'mimicked' epitopes shared between viral and cardiac antigens. To distinguish between these mechanisms, we infected a unique mouse that diminishes the extent of infection and spread of the virus, but allows complete immunity to the virus. Transgenic mice expressing interferon-gamma in their pancreatic beta cells failed to develop CB-3-induced myocarditis. This work challenges the idea of the function of the immune response and 'molecular mimicry' in the CB-3-induced autoimmune myocarditis model, and instead favors the idea of virus-mediated damage. These results emphasize the benefit of reducing the level of viremia early during infection, thereby reducing the incidence of virus-mediated heart damage and autoimmunity.