Effects of single intravenous doses of recombinant human interleukin-10 on subsets of circulating leukocytes in humans

Interleukin-10 induces interferon-γ-dependent emergency myelopoiesis

In emergency myelopoiesis (EM), expansion of the myeloid progenitor compartment and increased myeloid cell production are observed and often mediated by the pro-inflammatory cytokine interferon gamma (IFN-γ). Interleukin-10 (IL-10) inhibits IFN-γ secretion, but paradoxically, its therapeutic administration to humans causes hematologic changes similar to those observed in EM. In this work, we use different in vivo systems, including a humanized immune system mouse model, to show that IL-10 triggers EM, with a significant expansion of the myeloid progenitor compartment and production of myeloid cells. Hematopoietic progenitors display a prominent IFN-γ transcriptional signature, and we show that IFN-γ mediates IL-10-driven EM. We also find that IL-10, unexpectedly, reprograms CD4 and CD8 T cells toward an activation state that includes IFN-γ production by these T cell subsets in vivo. Therefore, in addition to its established anti-inflammatory properties, IL-10 can induce IFN-γ production and EM, opening additional perspectives for the design of IL-10-based immunotherapies.

Interleukin-10 and chronic liver disease

Interleukin (IL)-10 is an important immunoregulatory cytokine produced by many cell populations. Numerous investigations suggest that IL-10 plays a major role in chronic liver diseases. IL-10 gene polymorphisms are possibly associated with liver disease susceptibility or severity. Recombinant human IL-10 has been produced and is currently tested in clinical trials. These trials may give new insights into the immunobiology of IL-10 and suggest that the IL-10/IL-10 receptor system may become a new therapeutic target.

Interleukin-10 in viral diseases and cancer: exiting the labyrinth?

Interleukin-10 (IL-10) is unique among cytokines, as it is considered both as a potent immunostimulatory and immunosuppressive factor. This complex biology has been particularly challenging when trying to define the useful or harmful role of IL-10 in chronic viral diseases and cancer. In the present review, we emphasize how these multiple roles define IL-10 as an adaptive molecule, constantly tuning the host response against dangerous and resourceful pathogens.

Balance of tumor necrosis factor alpha and interleukin-10 in a buccal infection in a streptozotocin-induced diabetic rat model

This study evaluates the local levels of proinflammatory cytokine, tumor necrosis factor alpha (TNF-alpha), and anti-inflammatory cytokine, interleukin-10 (IL-10), in an experimental buccal abscess of a diabetic rat model. We prepared a buccal cavity induced by injection of carrageenin in a diabetic rat (blood glucose, 460.6 +/- 54.7 mg/dl, mean +/- SE) induced by streptozotocin (STZ). The buccal abscess was formed by the direct inoculation of Streptococcus pyogenes S-8 (2 x 10(7) cfu) into the buccal cavity at day 5 after carrageenin injection. Cytokine levels in the exudate of the buccal abscess were measured by enzyme-linked immunosorbent assay for 48 h after infection. Bacterial counts, weighing of exudate, and histological analysis were also performed. The mean TNF-alpha levels in the buccal abscess exudate of the diabetic group, which were generally higher than those of the control group, tended to increase over time until 48 h after infection, while the TNF-alpha levels in the control group peaked at 24 h after infection and then decreased. The IL-10 levels in the diabetic group remained almost unchanged until 48 h after infection, while the IL-10 levels in the control group were significantly higher than in the diabetic group at 12-24 h after infection. The mean ratio of TNF-alpha to IL-10 levels was 1.17-1.67 in the diabetic group, which was higher than the 0.26-0.69 of the control group. The bacterial counts in the buccal abscess and the weight of exudate were significantly higher in the diabetic group compared to the control group at 36-48 h. Histological findings showed that inflammatory cell infiltration was remarkable in the diabetic group compared to that of the control group. These results suggest that the elevated proinflammatory TNF-alpha levels and decreased anti-inflammatory IL-10 levels, which are produced at local infection sites, may at least in part be related to the severity of inflammation in this rat model with diabetes induced by STZ.

Interleukin-10 therapy--review of a new approach

Interleukin (IL)-10 is an important immunoregulatory cytokine produced by many cell populations. Its main biological function seems to be the limitation and termination of inflammatory responses and the regulation of differentiation and proliferation of several immune cells such as T cells, B cells, natural killer cells, antigen-presenting cells, mast cells, and granulocytes. However, very recent data suggest IL-10 also mediates immunostimulatory properties that help to eliminate infectious and noninfectious particles with limited inflammation. Numerous investigations, including expression analyses in patients, in vitro and animal experiments suggest a major impact of IL-10 in inflammatory, malignant, and autoimmune diseases. So IL-10 overexpression was found in certain tumors as melanoma and several lymphomas and is considered to promote further tumor development. Systemic IL-10 release is a powerful tool of the central nervous system to prevent hyperinflammatory processes by activation of the neuro-endocrine axis following acute stress reactions. In contrast, a relative IL-10 deficiency has been observed and is regarded to be of pathophysiological relevance in certain inflammatory disorders characterized by a type 1 cytokine pattern such as psoriasis. Recombinant human IL-10 has been produced and is currently being tested in clinical trials. This includes rheumatoid arthritis, inflammatory bowel disease, psoriasis, organ transplantation, and chronic hepatitis C. The results are heterogeneous. They give new insight into the immunobiology of IL-10 and suggest that the IL-10/IL-10 receptor system may become a new therapeutic target.

Antitumour potential of a polysaccharide-rich substance from the fruit juice ofMorinda citrifolia (Noni) on sarcoma 180 ascites tumour in mice

An immunomodulatory polysaccharide-rich substance (Noni-ppt) from the fruit juice of Morinda citrifolia has been found to possess both prophylactic and therapeutic potentials against the immunomodulator sensitive Sarcoma 180 tumour system. The antitumour activity of Noni-ppt produced a cure rate of 25%-45% in allogeneic mice and its activity was completely abolished by the concomitant administration of specific inhibitors of macrophages (2-chloroadenosine), T cells (cyclosporine) or natural killer (NK) cells (anti-asialo GM1 antibody). Noni-ppt showed synergistic or additive beneficial effects when combined with a broad spectrum of chemotherapeutic drugs, including cisplatin, adriamycin, mitomycin-C, bleomycin, etoposide, 5- fl uorouracil, vincristine or camptothecin. It was not beneficial when combined with paclitaxel, cytosine arabinoside, or immunosuppressive anticancer drugs such as cyclophosphamide, methotrexate or 6-thioguanine. Noni-ppt also demonstrated beneficial effects when combined with the Th1 cytokine, interferon gamma, but its activity was abolished when combined with Th2 cytokines, interleukin-4 or interleukin-10, thereby suggesting that Noni-ppt induces a Th1 dominant immune status in vivo. The combination of Noni-ppt with imexon, a synthetic immunomodulator, also demonstrated beneficial effects, but not when combined with the MVE-2 copolymer, a high molecular weight immunomodulator. It was also not effective when combined with interleukin-2 or interleukin-12.

In vivo IL-10 production reactivates chronic pulmonary tuberculosis in C57BL/6 mice

The production of immunosuppressive cytokines, such as IL-10 and TGF-beta, has been documented in individuals diagnosed with active tuberculosis. In addition, IL-10 production is increased within the lungs of mice that have chronic mycobacterial infection. Therefore, we hypothesized that the down-regulatory properties of IL-10 might contribute to the reactivation of chronic Mycobacterium tuberculosis infection in mice. To determine the influence of IL-10 on the course of infection, transgenic mice producing increased amounts of IL-10 under the control of the IL-2 promotor were infected with M. tuberculosis via the respiratory route. Mice that overexpressed IL-10 showed no increase in susceptibility during the early stages of infection, but during the chronic phase of the infection showed evidence of reactivation tuberculosis with a highly significant increase in bacterial numbers within the lungs. Reactivation was associated with the formation of macrophage-dominated lesions, decreased mRNA production for TNF and IL-12p40, and a decrease in Ag-specific IFN-gamma secretion. These data support the hypothesis that IL-10 plays a pivotal role during the chronic/latent stage of pulmonary tuberculosis, with increased production playing a potentially central role in promoting reactivation tuberculosis.

Interleukin-10 and the interleukin-10 receptor

Interleukin-10 (IL-10), first recognized for its ability to inhibit activation and effector function of T cells, monocytes, and macrophages, is a multifunctional cytokine with diverse effects on most hemopoietic cell types. The principal routine function of IL-10 appears to be to limit and ultimately terminate inflammatory responses. In addition to these activities, IL-10 regulates growth and/or differentiation of B cells, NK cells, cytotoxic and helper T cells, mast cells, granulocytes, dendritic cells, keratinocytes, and endothelial cells. IL-10 plays a key role in differentiation and function of a newly appreciated type of T cell, the T regulatory cell, which may figure prominently in control of immune responses and tolerance in vivo. Uniquely among hemopoietic cytokines, IL-10 has closely related homologs in several virus genomes, which testify to its crucial role in regulating immune and inflammatory responses. This review highlights findings that have advanced our understanding of IL-10 and its receptor, as well as its in vivo function in health and disease.

Tumor necrosis factor-alpha/interleukin-10 balance in normal and cystic fibrosis children

BACKGROUND

The balance between tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) is important for immune homeostasis maintenance. Exuberant production of TNF-alpha contributes to overwhelming inflammatory response and tissue damage. But, commonly, increase in TNF-alpha is counterbalanced by simultaneous synthesis of an anti-inflammatory cytokine IL-10, which suppresses production of many activating and regulatory mediators.

AIMS

In the present study, the relationships between TNF-alpha and IL-10 in the plasma of healthy school-children and cystic fibrosis (CF) patients have been investigated.

METHODS

Blood samples were obtained from 12 CF patients with chronic pulmonary disease and 18 healthy schoolchildren vaccinated with live attenuated rubella vaccine. IL-10 and TNF-alpha were determined in the plasma samples using commercially available enzyme-linked immunosorbent assay kits.

RESULTS

Before vaccination, most healthy children (13 of 18) demonstrated superiority of pro-inflammatory TNF-alpha over anti-inflammatory IL-10 (TNF-alpha/IL-10 > 1). In these subjects, a significant positive linear association between the cytokine values has been found. Vaccine challenge resulted in a marked reduction of TNF-alpha/IL-10 ratios. In addition, a disappearance of correlation between the cytokine values was observed. Such disturbance was related to exuberant elevation of the IL-10 levels after inoculation. On the contrary, in CF individuals, plasma cytokine values remained in strong linear association independently of TNF-alpha or IL-10 predominance. No spikes in the plasma levels of IL-10 in CF patients during a 6-month observation period have been revealed.

CONCLUSIONS

There were no fundamental differences between CF and healthy children in the regulation of TNF-alpha and IL-10 secretion. Thus, immune quiescence seemed to be associated with the predominance of TNF-alpha, whereas immune disturbance was characterized by IL-10 superiority. The only abnormality that was found in CF patients consisted of their inability to produce unlimitedly IL-10 in response to antigen stimuli.

Mechanisms for induction of immunosuppression during experimental cryptococcosis: role of glucuronoxylomannan

In previous work we have demonstrated that spleen mononuclear (Spm) cells from rats obtained 14 days after infection with Cryptococcus neoformans showed a diminution in proliferative response to Concanavalin A (Con A). In this study we further investigate some characteristics of the Spm cell population involved in the immunosuppressor phenomenon induced by C. neoformans. We observed that unstimulated Spm cells expressing T-cell receptor (TCR+) from infected rats were reduced in number after 96 h of culture. When the Spm cells from infected rats were stimulated with Con A, increased production of IL-10, reduced levels of IL-2, and decreased CD11a surface expression were shown. These immunosuppressor phenomena were also observed when the capsular polysaccharide, glucuronoxylomannan (GXM), was added to cultures of Spm cells from normal rats. However, GXM had a more pronounced effect in reducing the number of cells surviving in culture than that observed during infection and produced an increase in IL-4 production by Con-A-stimulated Spm cells. Addition of anti-IL-10 monoclonal antibody to cultures restored the lymphoproliferation of Spm cells from infected animals, indicating that IL-10 production is a suppressor mechanism of cell-mediated immunity during experimental infection. The results presented here indicate that at least two mechanisms mediate the nonspecific suppression in this model of cryptococcosis: IL-10 production and diminution of the number of T cells. GXM could be involved, since it has a pronounced effect in the reduction of Spm cells in vitro.

Interleukin-10 and the Interleukin-10 Receptor

Interleukin-10 (IL-10), first recognized for its ability to inhibit activation and effector function of T cells, monocytes, and macrophages, is a multifunctional cytokine with diverse effects on most hemopoietic cell types. The principal routine function of IL-10 appears to be to limit and ultimately terminate inflammatory responses. In addition to these activities, IL-10 regulates growth and/or differentiation of B cells, NK cells, cytotoxic and helper T cells, mast cells, granulocytes, dendritic cells, keratinocytes, and endothelial cells. IL-10 plays a key role in differentiation and function of a newly appreciated type of T cell, the T regulatory cell, which may figure prominently in control of immune responses and tolerance in vivo. Uniquely among hemopoietic cytokines, IL-10 has closely related homologs in several virus genomes, which testify to its crucial role in regulating immune and inflammatory responses. This review highlights findings that have advanced our understanding of IL-10 and its receptor, as well as its in vivo function in health and disease.

IL-10 kinetics in thyroiditis-prone BB/Wor rats

Cytokines modulate the course of autoimmunity, but their role in the evolution of spontaneous disease is unclear. This study compared the cytokine kinetics of T cell cultures from thyroiditis (LT)-prone NB line BB/Wor rats with those of Wistar (Wis) rat controls following activation with the thyroid-specific antigen thyroglobulin (Tg) or Concanavalin A (Con A).

DESIGN

T cell enhanced splenocytes from 60 day old Wis and NB rats were activated with 0.5 microg/ml rat thyroglobulin (Tg) or Con A in the presence of homologous irradiated splenocytes as antigen presenting cells (APC's). In addition, the effect of APC's was determined in a crisscross experiment which examined NB T cell responses to Con A in the presence of Wis APC's. ELISA and RT-PCR were used to examine IL-2, IL-4, IL-10, TNFalpha, IFNgamma, IL-I0 concentrations and mRNA expression in the supernatant and cells from parallel cultures harvested at specific intervals. Frozen thyroids from 60 day old NB, Wis and Fisher rats were examined for the presence of IL-10 by immunohistochemistry. T cell proliferation was measured by 3H thymidine uptake.

RESULTS

Following activation with either Tg or Con A, IL-10 concentrations exceeded IFNgamma in NB rat cultures, but IFNgamma exceeded IL-10 in Wis cultures. Wis splenocytes significantly enhanced NB T cell proliferation and cytokine responses to Con A. Thyroids from 60 day NB rats contained IL-10, but no IFNgamma. There was no IL-10 in thyroids from Wistar or Fisher rats.

CONCLUSION

Splenocyte responses in LT-prone BB/Wor rats favor IL-10 production. Future investigations will examine the source of intrathyroidal IL-10 and its role in LT.

New immunologic treatments for inflammatory bowel disease

After many years with little progress in new treatments for patients with inflammatory bowel disease, there is now rapid expansion of a new class of immunologic agents. These agents are designed to disrupt proinflammatory pathways at specific sites. Monoclonal antibodies to tumor necrosis factor-alpha (TNF-alpha) are already transforming the lives of some patients with previously intractable Crohn disease, and further TNF-alpha directed therapies are being developed. Clinical trials are now underway on agents that inhibit adhesion molecules and antiinflammatory cytokines, while attempts are being made to actively immunize against TNF-alpha. Promising data continue to be reported, although long-term safety data are still mostly unavailable. Although these agents are proving to be very effective in the treatment of patients with Crohn disease, their use should continue to be restricted while indications and dose regimens are defined.