Akira Motegi

IL‐15‐induced CD8+CD122+ T cells increase antibacterial and anti‐tumor immune responses: implications for immune function in aged mice

We previously proposed that mouse CD8+CD122+ T cells and human CD57+ T cells, which increase with age and exhibit potent IFN‐γ production, represent a double‐edged sword as they play critical roles in host defense and the lethal IL‐12/LPS‐induced generalized Shwartzman reaction (GSR). However, our proposal was based solely on comparisons of young and old mice. In this study, we attempted to increase CD8+CD122+ T cells in young mice with exogenous IL‐15 and confirm their countervailing functions in young mice. After young mice (6 weeks) were injected with IL‐15, they showed significant increases in CD8+CD122+ T cells in the liver and spleen. Liver CD8+CD122+ T cells from IL‐15‐pretreated mice had a potent capacity to produce IFN‐γ after IL‐12 injection or Escherichia coli infection. IL‐15‐pretreated mice showed increased survival to E. coli infections and enhanced anti‐tumor activities against liver metastatic EL4 cells, as well as an exacerbation of the GSR. Correspondingly, liver CD8+CD122+ T cells produced more perforin than CD8+CD122− T cells in EL4‐inoculated mice. Unexpectedly, comparable IL‐15 treatment did not induce further increases in CD8+CD122+ T cells in aged mice and did not enhance their defenses against bacterial infection or tumor growth. Interestingly, however, nontreated, aged mice (50 weeks) showed twofold higher IL‐15 levels (but not TNF or IFN‐γ) in liver homogenates compared with young mice. Our results further support that CD8+CD122+ T cells, which are increased physiologically or therapeutically by IL‐15, are involved in antibacterial immunity, anti‐tumor immunity, and the GSR.

Critical role of the liver CD8+ CD122+ T cells in the generalized Shwartzman reaction of mice.

We examined the role of mouse CD8+ CD122+ T cells, which increase in number with age, in the generalized Shwartzman reaction. This reaction was induced by IL‐12 priming and subsequent LPS challenge (after 24 h) in mice of various ages (4–50 weeks of age). Although most young mice (4 or 6 weeks of age) survived, mortality essentially increased with increasing age of the mice, and all mice of 20 weeks of age or older died within 48 h. Serum TNF‐α levels after LPS challenge also increased age dependently. The neutralization of either IL‐12‐induced IFN‐γ or LPS‐induced TNF‐α improved the survival of middle‐aged (25‐week‐old) mice. Both IFN‐γ production after IL‐12 priming and TNF‐α production from the liver mononuclear cells after LPS challenge were also prominent in the middle‐aged mice. CD8+CD122+ T cells cultured with IL‐12 produced a much larger amount of IFN‐γ than CD8+CD122– T cells. Although the depletion of NK/NK T cells did not decrease the IFN‐γ or TNF‐α production in the Shwartzman reaction of the middle‐aged mice, an additional depletion of CD8+CD122+ T cells did decrease such production and also improved mouse survival. Furthermore, young mice transferred with CD8+CD122+ T cells from aged B6 nude mice showed an enhanced Shwartzman reaction.

An in vitro Shwartzman reaction-like response is augmented age-dependently in human peripheral blood mononuclear cells

A lethal human septic shock model, mouse generalized Shwartzman reaction (GSR), was elicited by two consecutive lippolysaccharide (LPS) injections (24 h apart) in which interferon‐γ (IFN‐γ) induced by interleukin (IL)‐12 played a critical role in the priming phase, and tumor necrosis factor (TNF) was an important effector molecule in the second phase. We recently reported IL‐12/LPS‐induced mouse GSR age‐dependently enhanced. We herein demonstrate that human peripheral blood mononuclear cells (PBMC) from healthy adults/elderly, cultured with IL‐12 for 24 h and with LPS for an additional 24 h, produced a much larger amount of TNF (which increased age‐dependently) than did PBMC without IL‐12 priming. Whereas macrophages mainly produced TNF following LPS stimulation, macrophages and lymphocytes were necessary for a sufficient TNF production. IL‐12‐induced IFN‐γ up‐regulated Toll‐like receptor 4 (TLR‐4) on macrophages of adults. Although the PBMC from children produced a substantial amount of IFN‐γ after IL‐12 priming, the GSR response, with augmented TNF production and an up‐regulated TLR‐4 expression of macrophages, was not elicited by LPS stimulation. CD56+ natural killer cells, CD56+T cells, and CD57+T cells (NK‐T cells), which age‐dependently increased in PBMC, produced much larger amounts of IFN‐γ after IL‐12 priming than that of conventional CD56−CD57−T cells and also induced cocultured macrophages to produce TNF by subsequent LPS stimulation. The elder septic patients were consistently more susceptible to lethal shock with enhanced serum TNF levels than the adult patients. The NK cells, NK‐T cells, and macrophages, which change proportionally or functionally with aging, might be involved in the enhanced GSR response/septic shock observed in elderly patients.

A case of HHV-6 associated acute necrotizing encephalopathy with increase of CD56bright NKcells

We describe a 15-month-old girl with acute necrotizing encephalopathy (ANE) associated with HHV-6. Inflammatory cytokines were elevated in the CSF and serum and the number of CD56bright NK cells was significantly increased in the peripheral blood. CD56brightNK cells may be involved in the pathogenesis of ANE by producing inflammatory cytokines.

A non‐obese boy with Prader‐Willi syndrome shows cardiopulmonary impairment due to severe kyphoscoliosis

Prader-Willi syndrome (PWS, OMIM #176270) is a genetic disorder characterized by hypotonia, obesity, characteristic facial appearance, hypogonadism, short stature, and behavioral abnormalities. It results from deletion or disruption of one or more genes on the proximal long arm of the paternally derived chromosome 15, or from maternal uniparental disomy 15. Musculoskeletal abnormalities are common in these individuals. Scoliosis is very common in PWS being variously reported in 62–86% of patients [Holm and Laurnen, 1981; Laurance et al., 1981]. Here, we describe a non-obese boy with PWS who also presented with cardiopulmonary impairment due to severe kyphoscoliosis. This secondary manifestation was described by Guilleminault et al. [1981]. The male patient was born to healthy and nonconsanguineous parents at 41 weeks of gestation, with a birth weight of 2,430 g ( 1.9 SD) and length of 47.0 cm ( 1.4 SD). Other family members were healthy. He showed hypotonia with poor suck in infancy. He held his head at age 9 months, sat at 1 year, and walked at 41⁄2years. He had a normal male karyotype (46,XY) and therewasno SNRPN signal on FISH. Kyphoscoliosis that was recognized at 1 year of age had progressively deteriorated (Fig. 1A,B). He had received growth hormone (GH) therapy (0.175 mg/kg/week) from age 10 years. He had a restrictive deficit on spirometry at age 1011=12 years: the median forced expiratory volume in 1 sec (FEV1) and forced vital capacity (FVC) were 1.03 L and 1.15 L, respectively. Although he had no respiratory symptoms, he underwent combined anterior fusion with posterior corrective fusion surgery using spinal instrumentation for kyphoscoliosis at age 11 years. However, the instrumentation had to be removed due to deep postoperative infection, which did not resolve until age 116=12 years. His weight management had been controlled well without any obesity from birth. At age 1510=12 years, he was admitted because of a 1-month history of shortness of breath and edema of the legs. On admission, he measured 133.0 cm and weighed 41.2 kg. Under normal conditions, his weight was 33.0 kg and his calculated body mass index (BMI) was 18.7 kg/m. He had a characteristic facial appearance, narrow hands with a straight ulnar border, and chilblain scars on the legs. Physical examination revealed tachypnea, tachycardia, cyanosis, a systolic heart murmur and gallop rhythm, distended abdomen, and edema of the whole body, especially of the legs. Neurological examination showed normal deep tendon reflexes and mild hypotonia. Laboratory tests showed respiratory acidosis, hypercapnia, and heart failure: pH, 7.285; pCO2, 70.6 mmHg in room air; hANP, 557 pg/ml; and BNP, 862 pg/ml. Echocardiogram showed the interventricular septum curved toward the left