The in vivo effects of neutralizing antibodies against IFN-gamma, IL-4, or IL-10 on the humoral immune response in young and aged mice

Mouse Liver B Cells Phagocytose Streptococcus pneumoniae and Initiate Immune Responses against Their Antigens

Recent studies have revealed that mammalian B cells ingest particulate Ags, such as bacteria, although little is known about the effect of this function on acquired immunity. We investigated the role of bacterium-phagocytosing B cells in acquired host immune responses. Cultured mouse liver B cells substantially phagocytosed serum-opsonized Streptococcus pneumoniae and produced IgM. On adoptive transfer of liver B cells that phagocytose S. pneumoniae labeled with pHrodo Red succinimidyl ester, recipient mice showed elevated plasma levels of IgG specific for bacterial Ags. In particular, the levels of IgG2a and IgG2b specific for pneumococcal surface protein A, as well as IgG3 for pneumococcal polysaccharide, were markedly increased compared with total IgG specific for each Ag. When phagocytic liver B cells were cultured with spleen CD4⁺ T cells obtained from mice primed with heat-killed S. pneumoniae 7 d before, they induced IL-2 production and proliferation of the CD4⁺ T cells, along with Th1 cytokine production. However, they induced neither the CD4⁺ T cell production of IL-21, a suggested marker promoting B cell proliferation and differentiation, nor the expression of genes important for somatic hypermutation or isotype switching; such responses were particularly evident when splenic B cells merely capturing S. pneumoniae without processing them were cultured with spleen CD4⁺ T cells. These findings suggest that phagocytic liver B cells may be involved in acquired immune responses by presenting derivative peptides to CD4⁺ T cells without their own somatic hypermutation or isotype switching.

Identification of Differentially Expressed Non-coding RNA Networks With Potential Immunoregulatory Roles During Salmonella Enteritidis Infection in Ducks

Salmonella enterica serovar Enteritidis (S. Enteritidis) is a pathogen that can colonize the preovulatory follicles of poultry, thereby causing both reduced egg production and an elevated risk of foodborne salmonellosis in humans. Although a few studies have revealed S. Enteritidis preferentially invades the granulosa cell layer within these follicles, it can readily persist and proliferate through mechanisms that are not well-understood. In this study, we characterized competing endogenous RNA (ceRNA) regulatory networks within duck granulosa cells following time-course of S. Enteritidis challenge. The 8108 long non-coding RNAs (lncRNAs), 1545 circular RNAs (circRNAs), 542 microRNAs (miRNAs), and 4137 mRNAs (fold change ≥2; P < 0.01) were differentially expressed during S. Enteritidis challenge. Also, eight mRNAs, eight lncRNAs and five circRNAs were selected and the consistent expression trend was found between qRT-PCR detection and RNA-seq. Moreover, the target genes of these differentially expressed ncRNAs (including lncRNAs, circRNAs and miRNAs) were predicted, and significantly enriched in the innate immune response and steroidogenesis pathways. Then, the colocalization and coexpression analyses were conducted to investigate relationships between ncRNAs and mRNAs. The 16 differentially expressed miRNAs targeting 60 differentially expressed mRNAs were identified in granulosa cells at 3 and 6 h post-infection (hpi) and enriched in the MAPK, GnRH, cytokine-cytokine receptor interaction, Toll-like receptor, endocytosis, and oxidative phosphorylation signaling pathways. Additionally, underlying lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA ceRNA networks were then constructed to further understand their interaction during S. Enteritidis infection. Lnc_012227 and novel_circ_0004892 were identified as ceRNAs, which could compete with miR-let-7g-5p and thereby indirectly modulating map3k8 expression to control S. Enteritidis infection. Together, our data thus identified promising candidate ncRNAs responsible for regulating S. Enteritidis infection in the preovulatory follicles of ducks, offering new insights regarding the ovarian transmission of this pathogen.

IL-10-producing Tfh cells accumulate with age and link inflammation with age-related immune suppression

Aging results in profound immune dysfunction, resulting in the decline of vaccine responsiveness previously attributed to irreversible defects in the immune system. In addition to increased interleukin-6 (IL-6), we found aged mice exhibit increased systemic IL-10 that requires forkhead box P3-negative (FoxP3-), but not FoxP3+, CD4+T cells. Most IL-10-producing cells manifested a T follicular helper (Tfh) phenotype and required the Tfh cytokines IL-6 and IL-21 for their accrual, so we refer to them as Tfh10 cells. IL-21 was also required to maintain normal serum levels of IL-6 and IL-10. Notably, antigen-specific Tfh10 cells arose after immunization of aged mice, and neutralization of IL-10 receptor signaling significantly restored Tfh-dependent antibody responses, whereas depletion of FoxP3+ regulatory and follicular regulatory cells did not. Thus, these data demonstrate that immune suppression with age is reversible and implicate Tfh10 cells as an intriguing link between "inflammaging" and impaired immune responses with age.

Restoration of Retarded Influenza Virus-specific Immunoglobulin Class Switch in Aged Mice

Objective

The declined immune response to infection causes significant higher morbidity and mortality in aging in spite of the coexisted hyperimmunoglobulinemia (HIG). This study is to reveal the cellular basis of HIG and mechanism of weakened HA-specific IgG response in aged mice and to test cell therapy in the treatment of age-related IgG antibody production deficiency with immunocyte adoptive transfer.

Methods

BALB/c mice was immunized with Influenza A/Taiwan vaccine and challenged with the same strain of virus. ELISA was used to assess the levels of total immunoglobulins and antigen specific antibody response. The flow cytometry and ELISPOT were used to evaluate the frequencies of total immunoglobulin- and specific antibody-producing and secreting B lymphocytes. In vitro expanded mononuclear cells, CD4+ T lymphocytes and CD20+ B lymphocytes from old and young mice were adoptively transferred into influenza virus-challenged aged mice, and HA-specific IgG responses were observed.

Results

It is found that old mice exhibited higher levels of total serum IgG, IgM and IgA, higher frequencies of IgG+, IgM+ and IgA+ cells, and greater antigen-specific IgM and IgA responses to influenza infection, in comparison to young mice. However, influenza antigen- specific IgG and its subclass responses in old mice were significantly lower.

Conclusion

The retarded specific IgG response could be attributed to an insufficiency of immunoglobulin class switch in aging. Correlation analysis indicated that HIG and deficient specific IgG production in aged mice could be independent to each other in their pathogenesis. Correction of deficient specific IgG production by adoptive transfer of in vitro expanded and unexpanded CD4+ cells from immunized young mice suggests the CD4+ cell dysfunction contributes to the insufficiency of immunoglobulin class switch in aged mice. The transfusion of in vitro expanded lymphocytes could be a potential effective therapy for the age-related immunodeficiency and could play a role in the infection prevention in aging.

Long term persistence of IgE anti-influenza virus antibodies in pediatric and adult serum post vaccination with influenza virus vaccine

The production of IgE specific to different viruses (HIV-1, Parvovirus B19, Parainfluenza virus, Varicella Zoster Virus), and the ability of IgE anti-HIV-1 to suppress HIV-1 production in vitro, strongly suggest an important role for IgE and/or anti viral specific IgE in viral pathogenesis. Nevertheless, the presence and persistence of IgE anti-Influenza virus antibodies has not been studied. Total serum IgE and specific IgE and IgG anti-Influenza virus antibodies were studied in children (N = 3) (m/f 14-16 y/o) and adults (N = 3) (m/f, 41-49 y/o) 2-20 months after vaccination with Influenza virus (Flumist(®) or Fluzone(®)), as well as in non-vaccinated children (N = 2). (UniCAP total IgE Fluoroenzymeimmunoassay, ELISA, Immunoblot). We found that serum of vaccinated children and adults contained IgE and IgG anti-Influenza virus antibodies approaching two years post vaccination. Non-vaccinated children did not make either IgE or IgG anti-Influenza antibodies. Similar levels of IL-2, IFN-γ, IL-4, and IL-10 cytokines were detected in serum of vaccinated compared with non vaccinated subjects (p > 0.05), as well as between vaccinated adults compared with vaccinated children and non vaccinated subjects (p > 0.05). Vaccinated children and adults continue to produce IgE anti-Influenza virus antibodies long term post vaccination. The long term production of IgE anti-Influenza virus antibodies induced by vaccination may contribute to protective immunity against Influenza.

Preferential expression and frequent IgG responses of a tumor antigen, SOX5, in glioma patients

We previously reported to identify SOX5 as a glioma antigen by serological screening using a testis cDNA library. The present study was designed to analyze SOX5 expression, its immunoreactivity, and the correlation between SOX5 IgG responses and clinical features in glioma patients to evaluate the possibility of its use as a diagnostic marker. Quantitative RT-PCR and Western blot analysis revealed that SOX5 was expressed in glioma tissues, but not in normal adult tissues, except in the testis. An immunohistochemical analysis showed that SOX5 was expressed in glioma cells, but only a few SOX5-positive cells were detected in non-neoplastic tissues from the cerebral cortex. IgG antibodies against SOX5 were detected in sera from 8 of the 27 glioma patients (27.6%), 0 of the 14 patients with other brain diseases (0%), 1 of the 54 other cancer patients (1.9%) and 1 of the 37 healthy individuals (2.7%). Patients with glioblastoma (GBM) who showed IgG responses against SOX5 exhibited significantly better survival periods than GBM patients without SOX5 antibodies. In summary, SOX5 is aberrantly expressed in glioma and can be recognized as a glioma antigen using IgGs from the sera of glioma patients. Furthermore, there is a statistically significant correlation between the presence of SOX5 IgGs and survival in GBM patients, suggesting that the glioma antigen SOX5 may be useful not only as a diagnostic marker, but also as a prognostic marker in glioma patients.

Properties of hybridomas generated by spleen cells of IL-4- and IL-13-knockout mice

Interleukin-4 (IL-4)- and IL-13-knockout mice were immunized with murine recombinant IL-4 or IL-13, and spleen cells were fused with P3X63-Ag8.653 myeloma cells. Selection of the antigen-positive hybridomas was fulfilled in the presence of IL-6 containing thymic stroma cell supernatant (TSS). All of the selected anti- IL-4- and anti-IL-13-specific hybridoma clones (eight and 10, respectively) required the presence of TSS (0.5-2.5%) for their cloning, stable growth in large-scale cultures, and production of monoclonal antibodies (MAbs). Several of the anti-IL-4-specific clones were adapted to growth without TSS. However, the loss of antibody-secreting capacity in the process of adaptation to TSS-free growth was detected. The data demonstrate that cytokine-deficient mice technology can be used for generation of MAbs to autologous cytokines.

Cytokine-deficient mice as a model for generation of autologous anti-cytokine monoclonal antibodies

The possibility of inducing immune responses to murine interleukin-4 (IL-4) and IL-13 and generating anti-cytokine monoclonal antibodies (mAbs) was studied in IL-4- and IL-13-knockout mice. The minimal doses of IL-4 or IL-13 that could induce significant anti-cytokine responses with titers of 5000-10,000 were 20 microg per injection with the total doses of 100 microg. The highest titers in a range of 20,480-40,960 were achieved by triple immunization of IL-13-knockout mice with 30 microg of IL-13 per injection. Anti-IL-4 mAbs were generated at an antibody serum titer about 400; however, only 0.5% of primary hybridoma clones were anti-IL-4-positive. Anti-IL-13 cell fusions were successful at titers of 20,480 and 40,960 with 50% of the primary clones positive. Both hybridomas secreted low-affinity IgMkappa mAbs and were IL-6-dependent. These data demonstrate that IL-4- and IL-13-deficient mice may develop high polyclonal immune responses to "syngeneic" murine cytokines but fail to generate high-affinity mAbs at the tested conditions.

Delineation of the role of platelet-activating factor in the immunoglobulin G2 antibody response

Localized aggressive periodontitis (LAgP) is a chronic inflammatory disease characterized by severe destruction of periodontal tissues surrounding the first molars and incisors. LAgP subjects produce large amounts of immunoglobulin G2 (IgG2) antibody against oral pathogens, and this response is inversely correlated with the severity of disease. We previously demonstrated that platelet-activating factor (PAF) is required for optimal IgG2 responses. The present investigation was designed to determine the mechanism of IgG2 induction by PAF. Exogenous PAF acetylhydrolase suppressed approximately 80% of pokeweed mitogen-stimulated IgG2 production, confirming that PAF is essential for optimal responses. PAF-activated leukocytes produced gamma interferon (IFN-gamma), a Th1 cytokine that has been associated with IgG2 responses in previous studies. The monocyte-derived cytokines interleukin-12 (IL-12) and IL-18 are upstream of IFN-gamma production, and IgG2 production was suppressed by neutralizing antibodies against these proteins. In addition, PAF induced monocyte-derived dendritic cells (DC) but not macrophages (MPhi) to secrete IL-12 and IL-18. This observation was interesting because monocyte differentiation in LAgP subjects is skewed to the DC phenotype. Although other investigators have implicated IFN-gamma in IgG2 production, its precise role in this response is controversial. Our studies suggest that IFN-gamma induces isotype switching to IgG2 but only in concert with the Th2 cytokine IL-4. Thus, it appears that the unique PAF metabolism of LAgP monocytes or DC promotes Th1 responses that are essential for optimal IgG2 antibody production. As IgG2 antibodies opsonize oral bacteria and promote their clearance and destruction, these alterations in PAF metabolism may be essential for limiting disease severity in LAgP patients.

Aging, immunity, and cancer

BACKGROUND

The prime function of the immune system is to protect the entire organism from a variety of insults and illnesses, including the development of cancer. The question of how age-related declines in immune function contribute to an increasing incidence of malignancies continues to be a focus of discussion and speculation.

METHODS

The recent literature from the National Library of Medicine database (1990 through the present) was searched for articles using the medical subject headings (MeSH terms) of aging, immunity, cancer, senescence, and apoptosis. Bibliographies of articles retrieved were also scanned.

RESULTS

Data from in vitro and in vivo animal and human studies demonstrate clear age-related alterations in both the cellular and humoral components of the immune system, but there is little evidence supporting direct causal links between immune senescence and most malignancies.

CONCLUSIONS

Senescent decline in immune surveillance leads to the accumulation of cellular and DNA mutations that could be a significant factor in the development of malignancy and programmed cell death or apoptosis observed in the elderly.

Cytokine profile of liver-infiltrating CD4+ T cells separated from murine primary biliary cirrhosis-like hepatic lesions induced by graft-versus-host reaction

BACKGROUND AND METHODS

We have previously reported that CD4+ T cells induced primary biliary cirrhosis (PBC)-like hepatic lesions in mice with graft-versus-host reaction due to major histocompatibility complex class II disparity. To clarify the relationship between the cytokine profile produced by CD4+ T cells and the formation of hepatic lesions, we sorted CD4+ T cells from the liver by using flow cytometry and examined their cytokine mRNA expression at various times after GVHR induction. We also examined the associated changes in the serum levels of antimitochondrial antibodies (AMA).

RESULTS

Histologically, the infiltration of CD4+ T cells around the bile ducts was observed from day 5, and the lesions deteriorated gradually until day 14. On day 14, CD8+, B220+ and Mac-1+ cells, as well as CD4+ T cells were seen around the bile ducts. In the liver-infiltrating CD4+ T cells, the expression level of interferon-gamma (IFN-gamma) mRNA was observed to increase at an early phase (day 3), whereas that of interleukin (IL)-10 mRNA was elevated at a later phase (day 14). The elevation of IFN-gamma mRNA expression at an early phase before the appearance of non-suppurative destructive cholangitis suggests that IFN-gamma may be related to the pathogenesis of PBC in this model. Serum levels of AMA on day 14 were significantly higher than those on day 5. Interleukin-10 was considered to stimulate antibody production, to show an inhibitory effect upon the function of T helper 1 cells, and to inhibit fibrosis.

CONCLUSIONS

Interferon-gamma may play an important role in the pathogenesis of this model. Moreover, delayed expression of IL-10 mRNA may control PBC-like hepatic lesions.

IFN-gamma-inducing factor (IL-18) increases allergic sensitization, serum IgE, Th2 cytokines, and airway eosinophilia in a mouse model of allergic asthma

We investigated the effects of IFN-gamma-inducing factor (IL-18) in a ragweed (RW) mouse model of allergic asthma. Administration of IL-18 in conjunction with allergic sensitization and challenge in wild-type, but not IFN-gamma -/- mice, inhibited the bronchoalveolar lavage (BAL) eosinophilia induced by RW challenge, and increased serum levels of RW-specific IgG2a and production of IFN-gamma from splenocytes cultured with RW, indicating a critical role for IFN-gamma in mediating these effects. Paradoxically, the same treatment schedule in WT mice increased serum levels of RW-specific IgE and IgG1, and production of IL-4 and IL-5 from splenocytes cultured with RW. When the effects of the same IL-18 treatment schedule were allowed to mature for 3 wk, the inhibition of lung eosinophil recruitment was replaced by augmentation of lung eosinophil recruitment. In another experiment, IL-18 administered only with allergic sensitization increased BAL eosinophilia and lung expression of IL-5 and IFN-gamma, while IL-18 administered only with RW challenge decreased BAL eosinophilia and increased lung IFN-gamma expression, while lung expression of IL-5 remained unchanged. IL-18 administered without RW or adjuvant to naive mice increased total serum IgE levels. Finally, intrapulmonary administrations of IL-18 plus RW in naive mice dramatically increased Th2 cytokine production, IgE levels, eosinophil recruitment, and airway mucus, demonstrating induction of allergic sensitization. This is the first report demonstrating that IL-18 promotes a Th2 phenotype in vivo, and potently induces allergic sensitization. These results suggest that IL-18 may contribute to the pathogenesis of allergic asthma.

Interleukin-10 enhances immune responses to pneumococcal polysaccharides and sheep erythrocytes in young and aged mice

Antibody responses to pneumococcal polysaccharides are decreased in aged mice. Using a system to measure murine antibody responses to the Pnu-Imune vaccine, here we demonstrate that interleukin-10 (IL-10) has an adjuvant effect in enhancing the vaccine response in the aged. IL-10 increased the vaccine responses of B cells from aged mice in vitro only if either T cells or macrophages were also present. The need for T cells or macrophages could be substituted by cytokines such as IL-1 or IL-5, which are normally made by these accessory cells. Thus, IL-10 appeared to act on B cells directly but it worked in conjunction with other cytokines to induce an antigen specific response. In vivo studies showed that IL-10 administration enhanced antibody responses not only to thymic independent antigens but also to thymic-dependent antigens such as sheep erythrocytes. These data suggest that IL-10 may be useful in enhancing vaccine-specific responses in situations in which the host is immunocompromised.

Age-associated decline in responses of naïve T cells to in vitro immunization reflects shift in glucocorticoid sensitivity

Naïve T lymphocytes from young mice can be immunized to protein antigens in vitro if the initial exposure to antigen is followed by a brief period of clonal expansion in the presence of both the glucocorticoid dexamethasone (at 10(-8) M) and antibodies to Interleukin-10 (IL-10). These cultures produce cell lines that respond to antigen rechallenge by proliferation and cytokine secretion. T cells from older mice, however, do not respond under these conditions unless the dexamethasone concentration is raised to levels (10(-7) M) that are inhibitory for T cells of young mice. Suitably timed exposure to dexamethasone can also increase proliferative responses to polyclonal activation via the CD3 component of the T cell receptor, and again optimal responses are obtained from old mice only at steroid concentrations that are super-optimal for young T cells. Diminished sensitivity to glucocorticoid effects may contribute to the poor responses of aged mice to novel immunogens.

Immunomodulatory properties of interferon-gamma. An update

During the early aspecific phase of host defense, production of interferon (IFN)-gamma by natural killer cells plays an important role in bringing about acute inflammation, mainly because of the activating effects of IFN-gamma on adhesive properties of endothelial cells and on mediator production by mononuclear phagocytes (MPCs). In the subsequent antigen-specific phase of the immune response, IFN-gamma acts as a regulator of antigen presentation and of proliferation and differentiation of lymphocyte populations. Immunosuppressive as well as immunostimulatory effects may result from these actions. High-level production of IFN-gamma during this phase of host defense is now classically seen as a hallmark of a T-helper 1 (TH1)-type reaction, characterized by activation of antimicrobial activity of macrophages and by inflammatory reactions with a DTH character. Development of TH1-type lymphocyte populations producing IFN-gamma is regulated by other cytokines including interleukin (IL)-12. In many systems IL-12 and IFN-gamma act in a similar fashion, and a current subject of debate is the question of whether all activities of IL-12 are mediated by IFN-gamma. Another question is whether IFN-gamma, by its ability to potentiate MPCs' ability to produce IL-12, plays a role in bringing about or stabilizing TH1 type responses. In two model systems of autoimmune disease, experimental autoimmune encephalomyelitis and collagen-induced arthritis, IL-12 and IFN-gamma were found to act independently.

Enhancement of in vivo production of IL-1 alpha and IL-6 in mice by Y-25510, a 1H-pyrazolo[3,4-b]pyridine-1 acetic acid derivative

The serum concentrations of interleukin(IL)-1 alpha and IL-6 in C57BL/6 and C3H/HeN mice reached the maximum at 12-16 h after the intravenous treatment with (+/-)-3-[4-(2-dimethylamino-1-methylethoxy)- phenyl]-1H-pyrazolo[3,4-b]pyridine-1-acetic acid (Y-25510) at a dose of 3 mg/kg, and the concentration of IL-10 did at 20 h after the treatment. By repeated treatments with Y-25510 to C57BL/6 mice for 14 days, the maximal values of IL-1 alpha and IL-6 at day 14 were respectively 6.6 times and 5.7 times relative to those on day 1. Neither the counts of peripheral leukocytes nor those of platelets were, however, increased until day 15. The repeated treatment with Y-25510 followed by anti-IL-10 antibody for 14 days was significantly more effective than that with Y-25510 alone in increasing the concentrations of IL-1 alpha and IL-6 in C3H/HeN mice. In addition, both the counts of peripheral leukocytes and platelets were significantly increased at day 18. In conclusion, Y-25510 enhanced not only the production of endogenous IL-1 alpha and IL-6 but also that of IL-10 in healthy mice. As a result, in normal conditions, both the counts of peripheral leukocytes and platelets were never increased because of the inhibitory effect of endogenously produced IL-10.