The novel IFNGR1 mutation 774del4 produces a truncated form of interferon-gamma receptor 1 and has a dominant-negative effect on interferon-gamma signal transduction

Background

Patients with interferon‐γ receptor 1 (IFNγR1) deficiency show selective susceptibility to intracellular pathogens such as mycobacteria. IFNγR1 deficiency is an inherited immunodeficiency disorder, which can be either recessive or dominant. Dominant forms of IFNγR1 deficiency are known to be associated with mutations that introduce a premature stop codon in the intracellular domain of IFNγR1. One such mutation, 818del4, is believed to be the most common type. Although these mutations are presumed to exert a dominant‐negative effect on IFNγ signal transduction, the underlying molecular mechanism is unresolved.

Objective

We characterised the 774del4 mutant of IFNγR1 using a gene‐expression system to examine the effects of this mutation on IFNγ signal transduction.

Results

We identified a novel dominant mutation in IFNGR1, designated 774del4, which produced a truncated form of IFNγR1 in a patient with recurrent mycobacterial infections. IFNγR1 was overexpressed on the surfaces of CD14‐positive cells from the peripheral blood of this patient, and STAT1 phosphorylation in response to high doses of IFNγ was partially deficient. We expressed two truncated forms of IFNγR1, 774del4 and 818del4, in HEK 293 cells using transient transfection and found that these mutants overexpressed IFNγR1 on the cell surface because of impaired receptor stability, which resulted in a dominant‐negative effect on IFNγ signal transduction.

Conclusion

Like the 818del4 mutation, 774del4 produces a truncated form of IFNγR1, which has a dominant‐negative effect on IFNγ signal transduction through altered receptor stability.     

JIC Award 2003

Invasive aspergillosis has become a serious problem in clinical practice, but the actual factor that confers virulence on the fungus has not been thoroughly elucidated. To identify and isolate the immunosuppressive substances produced by the fungus, the bioactivity of culture filtrates was assessed, and analyses of the culture filtrates were carried out. Culture filtrates from different strains of Aspergillus fumigatus were assessed for their effect on human polymorphonuclear leukocytes and murine macrophages. To assess their activities in vivo, their effect on the survival of mice infected by the fungus was also studied. Subsequently, the composition of the culture filtrates was analyzed by gas chromatography-mass spectrometry. The analyses revealed that the culture filtrates contained gliotoxin at concentrations of 3 to 4µg/ml, and some other unidentified compounds. The bioactivities of the culture filtrates were similar to those of gliotoxin. The fungal culture filtrate reduced the survival of infected mice, but the filtrate itself did not cause the death of mice. However, all the bioactivities could not be accounted for by gliotoxin itself. These results indicate that gliotoxin in the culture filtrates may be responsible for part of the immunosuppressive activity, but some other components produced by A. fumigatus contribute, in an additive or synergistic manner, to the virulence of the fungus.     

Comparative analysis of antigen loading strategies of dendritic cells for tumor immunotherapy

Dendritic cells (DCs) loaded with antigens can effectively stimulate host immune responses to syngeneic tumors, but there is considerable controversy as to which forms of antigen-loading are most immunogenic. Here, the authors compared immunotherapeutic reactivities of DCs loaded with a variety of antigen preparations. Because DC maturation stages affect their capacities of antigen processing and presentation, two DC populations were used for the current analysis: in vivo Flt-3 ligand-induced mature DCs and in vitro bone marrow-derived DCs, which were less mature. To facilitate a direct comparison, the LacZ gene-transduced B16 melanoma model system was used, where beta-galactosidase served as the surrogate tumor-rejection antigen. DC loading strategies included pulsing with the beta-galactosidase protein, H-2K restricted peptide, tumor cell lysate, and irradiated tumor cells and fusion of DCs with tumor cells. Our results demonstrated that electrofusion of DCs and tumor cells generated a therapeutic vaccine far superior to other methods of DC loading. For the treatment of 3-day established pulmonary tumor nodules, a single intranodal vaccination plus IL-12 resulted in a significant reduction of metastatic nodules, while other DC preparations were only marginally effective. Immunotherapy mediated by the fusion cells was tumor antigen-specific. Consistent with their therapeutic activity, fusion hybrids were the most potent stimulators to induce specific IFN-gamma secretion from immune T cells. Furthermore, fusion cells also stimulated a small amount of IL-10 production from immune T cells. However, this IL-10 secretion was also induced by other DC preparations and did not correlate with in vivo therapeutic reactivity.     

Nicardipine actions on smooth muscle cells and neuromuscular transmission in the guinea-pig basilar artery

The effects of nicardipine on smooth muscle cells of the guinea-pig basilar artery were investigated by means of microelectrode and isometric tension recording methods. Nicardipine (1 X 10(-8) to 3 X 10(-6) M) did not modify the membrane potential and resistance of smooth muscle cells. The spike evoked by application of outward current pulse in the presence of tetraethylammonium (greater than 1 X 10(-3) M) was inhibited by 1 X 10(-9) M and was almost blocked by 3 X 10(-7) M nicardipine. Perivascular nerve stimulation evoked the excitatory junction potential which was slightly suppressed by 3 X 10(-6) M nicardipine. The contractions evoked by excess concentration of [K]0, NaCl-free solution or ATP was abolished and by 5-hydroxytryptamine was markedly inhibited in Ca-free ethylene glycol bis(beta-aminoethyl ether)N,N'-tetracetic acid-containing solution, but that induced by caffeine was only slightly inhibited. Nicardipine (greater than 3 X 10(-10) M) markedly inhibited the K-induced contraction noncompetitively as estimated from the Lineweaver-Burk's plot. The ATP-induced contractions were slightly inhibited by nicardipine (greater than 1 X 10(-8) M) to a lesser extent than the K-induced contraction. On the other hand, nicardipine (1 X 10(-6) M) had no effect on the NaCl-free-or 5-hydroxytryptamine-induced contraction. When nicardipine (1 X 10(-6) M) was applied during 2.5 mM Ca loading to muscle cells after depletion of the stored Ca, the subsequently generated caffeine-induced contraction was slightly inhibited due to inhibition of the passive Ca influx. These results indicate that nicardipine possesses a selective inhibitory action for the Ca channel, but the inhibition is limited to particular Ca influxes such as the voltage-dependent one, but not the receptor operated and NaCl-free-induced Ca influxes. This agent acts predominantly on the postjunctional muscle rather than the prejunctional nerve terminal.     

Topical benzydamine hydrochloride for prevention of postoperative sore throat in adults undergoing tracheal intubation for elective surgery: a systematic review and meta‐analysis

Postoperative sore throat has a negative impact on patient satisfaction and recovery. Benzydamine hydrochloride is a non‐steroidal anti‐inflammatory drug available for topical use. We performed a systematic review and meta‐analysis to assess the efficacy and safety of topical application of benzydamine to prevent postoperative sore throat in adults undergoing elective surgery under general anaesthesia. We searched PubMed, EMBASE, Web of Science and the Cochrane Central Register of Controlled Trials to identify relevant randomised controlled trials and pooled the data using a random effects model. The primary outcomes were the incidence and severity of sore throat 24 h after surgery/extubation, and adverse events. The quality of evidence was assessed using the grading of recommendations, assessment, development and evaluation (GRADE) criteria. Thirteen randomised controlled trials involving 1842 patients were included. Compared with control patients who did not receive analgesia, benzydamine was associated with a decreased incidence of postoperative sore throat, with a risk ratio (95%CI) of 0.31 (0.20–0.47), but not with significantly reduced severity, the standardised mean difference (95%CI) being ?0.27 (?0.63 to 0.08). There were no significant adverse events related to benzydamine. Benzydamine was also associated with a reduced incidence of postoperative sore throat when compared with lidocaine, with a risk ratio (95%CI) of 0.18 (0.07–0.43). We judged the evidence for the outcome ‘incidence of postoperative sore throat’ as high quality.     

Hypoglycaemia in patients with liver diseases administered levothyroxine

OBJECTIVE: Experience of a few hypoglycaemic patients with liver disease and receiving levothyroxine suggested to us that the prevalence of hypoglycaemia might be higher in such patients. The purpose of this study was to ascertain whether the prevalence of hypoglycaemia this was actually the case. METHODS: This study was a retrospective, cross-sectional analysis of a medical computerized database and/or written reports from our university hospital. Patients with primary liver disease who were admitted to our hospital between April 1998 and August 2000 were divided into two groups; the first group received levothyroxine and the second group did not. The patients in the second group were selected from three different time periods within the period shown. The prevalence of hypoglycaemia (blood glucose level <70 mg/dL) was compared between the two groups. RESULTS: The prevalence of hypoglycaemia was significantly higher in the group receiving levothyroxine compared with the group not receiving levothyroxine (four of eight patients (50.0%) vs. three of 59 (5.1%), P = 0.003, Fisher's exact test). CONCLUSIONS: The results suggest that levothyroxine may be a risk factor for hypoglycaemia in patients with liver disease. While a larger study, perhaps with an alternative study design is needed to confirm this, and to investigate possible mechanisms of effect, it would be prudent to monitor the blood glucose level of such patients closely.