IL-12–induced IFN-γ is dependent on caspase-1 processing of the IL-18 precursor

IL-12 and IL-18 are IFN-gamma-inducing cytokines. In the present study, the role of endogenous IL-18 in the induction of IFN-gamma by IL-12 was investigated in mice. In the presence of a specific inhibitor of caspase-1 (also known as IL-1beta-converting enzyme, or ICE) IL-12-induced IFN-gamma from splenocytes was reduced by 85%. Using splenocytes from ICE-deficient mice, IL-12-induced IFN-gamma was reduced by 80%. However, the role of ICE was not through processing and release of IL-1beta. Neutralizing anti-IL-18 IgG reduced IL-12-induced IFN-gamma in splenocytes by 85%. Splenocytes cultured in vitro spontaneously released IL-18 into the extracellular compartment over time. Extracellular levels of IL-18 significantly correlated with IL-12-induced IFN-gamma and were reduced in cells obtained from ICE-deficient mice. In vivo, IL-12 administration increased circulating levels of IL-18 in wild-type mice but not in ICE-deficient mice. Both neutralization of IL-18 and ICE deficiency significantly reduced induction of circulating IFN-gamma in mice receiving IL-12. The IL-18 precursor was constitutively expressed in the livers and spleens of untreated mice. Furthermore, administration of IL-12 significantly increased liver-associated IL-18 levels. These data demonstrate that endogenous, ICE-cleaved IL-18 significantly contributes to induction of IFN-gamma by IL-12.     

Microbiota-induced IL-1β, but not IL-6, is critical for the development of steady-state TH17 cells in the intestine

T(H)17 cells are a lineage of CD4(+) T cells that are critical for host defense and autoimmunity by expressing the cytokines IL-17A, IL-17F, and IL-22. A feature of T(H)17 cells at steady state is their ubiquitous presence in the lamina propria of the small intestine. The induction of these steady-state intestinal T(H)17 (sT(H)17) cells is dependent on the presence of the microbiota. However, the signaling pathway linking the microbiota to the development of intestinal sT(H)17 cells remains unclear. In this study, we show that IL-1β, but not IL-6, is induced by the presence of the microbiota in intestinal macrophages and is required for the induction of sT(H)17 cells. In the absence of IL-1β-IL-1R or MyD88 signaling, there is a selective reduction in the frequency of intestinal sT(H)17 cells and impaired production of IL-17 and IL-22. Myeloid differentiation factor 88-deficient (MyD88(-/-)) and germ-free (GF) mice, but not IL-1R(-/-) mice, exhibit impairment in IL-1β induction. Microbiota-induced IL-1β acts directly on IL-1R-expressing T cells to drive the generation of sT(H)17 cells. Furthermore, administration of IL-1β into GF mice induces the development of retinoic acid receptor-related orphan receptor γt-expressing sT(H)17 cells in the small intestine, but not in the spleen. Thus, commensal-induced IL-1β production is a critical step for sT(H)17 differentiation in the intestine, which may have therapeutic implications for T(H)17-mediated pathologies.     

IL-15 triggers an antiapoptotic pathway in human intraepithelial lymphocytes that is a potential new target in celiac disease–associated inflammation and lymphomagenesis

Enteropathy-associated T cell lymphoma is a severe complication of celiac disease (CD). One mechanism suggested to underlie its development is chronic exposure of intraepithelial lymphocytes (IELs) to potent antiapoptotic signals initiated by IL-15, a cytokine overexpressed in the enterocytes of individuals with CD. However, the signaling pathway by which IL-15 transmits these antiapoptotic signals has not been firmly established. Here we show that the survival signals delivered by IL-15 to freshly isolated human IELs and to human IEL cell lines derived from CD patients with type II refractory CD (RCDII) — a clinicopathological entity considered an intermediary step between CD and enteropathy-associated T cell lymphoma — depend on the antiapoptotic factors Bcl-2 and/or Bcl-xL. The signals also required IL-15Rβ, Jak3, and STAT5, but were independent of PI3K, ERK, and STAT3. Consistent with these data, IELs from patients with active CD and RCDII contained increased amounts of Bcl-xL, phospho-Jak3, and phospho-STAT5. Furthermore, incubation of patient duodenal biopsies with a fully humanized human IL-15–specific Ab effectively blocked Jak3 and STAT5 phosphorylation. In addition, treatment with this Ab induced IEL apoptosis and wiped out the massive IEL accumulation in mice overexpressing human IL-15 in their gut epithelium. Together, our results delineate the IL-15–driven survival pathway in human IELs and demonstrate that IL-15 and its downstream effectors are meaningful therapeutic targets in RCDII.     

Endogenous levels of C-C chemokines MIP-1α, MIP-1β, and RANTES do not reflect the disease course in HIV-seropositive individuals

It has been shown that the beta (C-C) chemokines macrophage inflammatory protein-1alpha/beta (MIP-1alpha/beta) and RANTES, which are released by CD8+ T cells, are potent inhibitors of HIV viral replication in vitro. To investigate whether serum concentrations of these chemokines reflect such a protective effect in vivo, we measured these in peripheral blood of 60 HIV seropositive patients, 10 healthy subjects, and 10 disease controls. Values were compared with the CDC disease stages and immunological surrogate markers of disease progression, such as CD4+ count, beta2-microglobulin and 5'-neopterin serum levels. In addition, HIV RNA was measured in sera. All three chemokines were not significantly different between HIV patients and healthy individuals, nor were differences of chemokine levels between the CDC stages significant. Instead, disease controls exhibited significantly more MIP-1alpha and MIP-1beta than normals or HIV patients. Furthermore, within the HIV-seropositive subjects we did not observe any relationship with the surrogate markers of HIV disease, CD4+ count, CD4+/CD8+ ratio, beta2-microglobulin, and 5'-neopterin (all correlations NS). HIV viral load did not correlate with the measured chemokine concentrations (r < 0.1, NS). In conclusion, endogenous levels of MIP-1alpha, MIP-1beta, and RANTES do not reflect the hypothesized protective effect on disease progression in HIV infection. Thus, despite potential beneficial effects of the investigated chemokines, other factors may equally contribute to HIV replication control in vivo.     

Targeting caspase-1 by inhalation-therapy: effects of Ac-YVAD-CHO on IL-1β, IL-18 and downstream proinflammatory parameters as detected in rat endotoxaemia

Objective We set out to investigate whether the nebulized and inhaled specific caspase-1 inhibitor Ac-YVAD-CHO has the potential to attenuate the pulmonary and systemic release of the caspase-1-dependent cytokines interleukin-1β (IL-1β) and interleukin-18 (IL-18) as well as their downstream enzymes iNOS and COX-2 in rat experimental endotoxaemia. Design and setting Controlled, randomized animal study in a university research facility. Subject Male Sprague–Dawley rats (n = 32) were randomly treated as follows: Inhaled Ac-YVAD-CHO was administered in eight rats at a inhaled total dosage of 5 mg and in eight rats at a inhaled total dose of 0.5 mg before infusion of lipopolysaccharide (LPS; 5 mg/kg, i.v.). Eight animals received LPS only. Eight animals served as controls without endotoxaemia. Measurements and results After 4 h of endotoxaemia, levels of IL-1β, IL-18 and TNF-α in plasma and bronchoalveolar fluid (BALF) were analyzed. Nitric oxide (NO) release from alveolar macrophages was measured by Griess assay. Amounts of iNOS protein in alveolar macrophages and COX-2 protein in lung homogenates were determined by Western blotting. Significant reductions in release of IL-1β (–58%, p < 0.05) and IL-18 (–51%, p < 0.05) in plasma and IL-1β (–59%, p < 0.05) in BALF were found in animals pretreated with inhaled caspase-1 inhibitor compared with animals without therapy. Expression of iNOS in alveolar macrophages and COX-2in lung tissue was concurrently decreased in the treatment groups compared with control animals. Conclusions Our data demonstrate that administration of the caspase-1 inhibitor Ac-YVAD-CHO by inhalation is able to reduce the pulmonary and systemic release of proinflammatory mediators in rat endotoxaemia. These results further underscore that inhalation may constitute an effective route of anti-inflammatory drug administration, beneficial in the clinical setting of ARDS. This article is discussed in the editorial available at: .     

Effect of irradiation on the quantity and activity of P65,TNF-αand IL-1 in rat wounds

Ourpresentexperimentsindicatedthatatcellularlevels,totalbodyirradiationwithlargedosehasbeenshowntoinhibitinflam-mation,decreasecytokineproduction,suppresscellproliferationandinduceapoptoticcelldeath.Withrespecttomolecularmechanisms,littleisknownabouttheeffectsofionizingradiationonhealingintheearlystage.NF-Bplayimportantrolesinin-flammationprocess.NF-Bactivation,inturn,leadstotheex-pressionofmanygenesinvolvedinimmunologicalandinflammatoryresponses,includinggenesthatencodecytokines,adhesionmol…     

Neutralization of IL-10 restores the downregulation of IL-18 receptor on natural killer cells and interferon-γ production in septic mice, thus leading to an improved survival

The objective of the study was to investigate the mechanisms of insufficient interferon-γ (IFN-γ) response to interleukin 18 (IL-18) and the treatment for the insufficient response in septic mice. Interleukin 18 stimulation does not restore IFN-γ production by blood mononuclear cells in septic patients but does restore its production in postoperative patients. Although sepsis impairs the IFN-γ response to IL-18, little is known about why the IL-18/IFN-γ-mediated immune response is ineffective in patients with sepsis. A cecal ligation and puncture was made in C57BL/6 mice following a sublethal lipopolysaccharide challenge to examine their IFN-γ response to IL-18, focusing on natural killer (NK) cells and cytokines. We next examined the effect of neutralization of IL-10 on the NK cell and survival in septic mice. Interleukin 18 injection did not restore IFN-γ production in septic (cecal ligation and puncture) mice. Despite an increase in the numbers of liver NK cells, the IL-18 receptor (IL-18R) expression was decreased in the septic mice compared with sham mice. Serum IL-10 levels were positively correlated with the percentage of liver NK cells, but negatively with their IL-18R expression. Neutralization of IL-10 restored the IL-18R expression on liver NK cells and restored the IFN-γ response in the septic mice, improving their survival. Sepsis might impair IL-18R expression on liver and spleen NK cells and impair the IL-18-mediated IFN-γ response. Neutralization of IL-10 may restore this response in septic hosts, thereby improving survival.     

‘I’ve put diabetes completely on the shelf till the mental stuff is in place’. How patients with doctor-assessed impaired self-care perceive disease,self-care,and support from general practitioners. A qualitative study

Objective: This paper investigated patients’ experiences of disease and self-care as well as perceptions of the general practitioner’s role in supporting patients with impaired self-care ability.

Design: Qualitative interviews with 13 patients with type 2 diabetes, concurrent chronic diseases, and impaired self-care ability assessed by a general practitioner. We analyzed our data using systematic text condensation. The shifting perspectives model of chronic illness formed the theoretical background for the study.

Results: Although most patients experienced challenges in adhering to recommended self-care activities, many had developed additional, personal self-care routines that increased wellbeing. Some patients were conscious of self-care trade-offs, including patients with concurrent mental disorders who were much more attentive to their mental disorder than their somatic diseases. Patients’ perspectives on diseases could shift over time and were dominated by emotional considerations such as insisting on leading a normal life or struggling with limitations caused by disease. Most patients found support in the ongoing relationship with the same general practitioner, who was valued as a companion or appreciated as a trustworthy health informant.

Conclusion: Patient experiences of self-care may collide with what general practitioners find appropriate in a medical regimen. Health professionals should be aware of patients’ prominent and shifting considerations about the emotional aspects of disease. Patients valued the general practitioner’s role in self-care support, primarily through the long-term doctor-patient relationship. Therefore, relational continuity should be prioritized in chronic care, especially for patients with impaired self-care ability who often have a highly complex disease burden and situational context.

• Key points

• Little is known about the perspectives of disease and self-care in patients with a doctor-assessed impaired ability of self-care.

• ??Although patients knew the prescribed regimen they often prioritized self-care routines that increased well-being at the cost of medical recommendations.

• ??Shifting emotional aspects were prominent in patients’ considerations of disease and sustained GPs’ use of a patient-centred clinical method when discussing self-care.

• ??Relational continuity with general practitioners was a highly valued support and should be prioritized for patients with impaired self-care.