Human TLR-7-, -8-, and -9-mediated induction of IFN-alpha/beta and -lambda Is IRAK-4 dependent and redundant for protective immunity to viruses

Five TLRs are thought to play an important role in antiviral immunity, sensing viral products and inducing IFN-alpha/beta and -lambda. Surprisingly, patients with a defect of IRAK-4, a critical kinase downstream from TLRs, are resistant to common viruses. We show here that IFN-alpha/beta and -lambda induction via TLR-7, TLR-8, and TLR-9 was abolished in IRAK-4-deficient blood cells. In contrast, IFN-alpha/beta and -lambda were induced normally by TLR-3 and TLR-4 agonists. Moreover, IFN-beta and -lambda were normally induced by TLR-3 agonists and viruses in IRAK-4-deficient fibroblasts. We further show that IFN-alpha/beta and -lambda production in response to 9 of 11 viruses tested was normal or weakly affected in IRAK-4-deficient blood cells. Thus, IRAK-4-deficient patients may control viral infections by TLR-3- and TLR-4-dependent and/or TLR-independent production of IFNs. The TLR-7-, TLR-8-, and TLR-9-dependent induction of IFN-alpha/beta and -lambda is strictly IRAK-4 dependent and paradoxically redundant for protective immunity to most viruses in humans.     

NEMO mutations in 2 unrelated boys with severe infections and conical teeth

X-linked recessive anhidrotic ectodermal dysplasia with immunodeficiency is a developmental and immunologic disorder caused by mutations in nuclear factor-kappaB essential modulator (NEMO), which is essential for nuclear factor-kappaB activation. Early in life, affected boys present a typical appearance, with hypotrichosis or atrichosis, hypohidrosis or anhidrosis, and hypodontia or anodontia with conical incisors. They are also susceptible to various microorganisms, mostly pyogenic bacteria and mycobacteria. Here we report 2 unrelated boys, aged 6 and 11 years, who have novel mutations in NEMO and present conical incisors and hypodontia as their sole and long-unrecognized developmental anomaly. One child had isolated recurrent pneumococcal disease, whereas the other had multiple infections. Our observations indicate that conical incisors should prompt the search for NEMO mutations in boys with unusual infectious diseases.     

Delayed encephalopathy after carbon monoxide intoxication--long-term prognosis and correlation of clinical manifestations and neuroimages

In order to understand the correlation between the clinical and neuroimaging manifestations and the long-term prognosis in delayed encephalopathy after carbon monoxide (CO) intoxication, we retrospectively reviewed 12 patients who had delayed encephalopathy from 89 patients with CO intoxication. There were 8 men and 4 women, with a mean age of 54.4 +/- 17.2 years (range: 11-79 years). All patients had prominent consciousness disturbance in the acute stage and received high flow of O2 or hyperbaric oxygen therapy. All of them regained consciousness within 1-7 days, but subsequently developed delayed encephalopathy. The delayed encephalopathy occurred from 14 to 45 days after recovery from the acute stage. The clinical manifestations included cognitive impairment, akinetic mutism, sphincter incontinence, gait ataxia and extrapyramidal syndromes such as chorea, dystonia, and parkinsonism. Brain MRI revealed multiple lesions in the subcortical white matter and basal ganglia, mostly in the globus pallidus, and to a lesser degree in the putamen, and caudate. In the follow-up period, sphincter incontinence first disappeared. The cognitive impairment improved greatly in the following few months, but the involuntary movements were improved only slightly. Some patients had persistent neurological sequelae, such as dystonia. Similary, the follow-up brain MRI showed a steady improvement. In conclusion, the delayed encephalopathy usually developed 2 weeks to 1.5 months after the acute phase of CO intoxication. Globus pallidus and subcortical white matter were commonly involved. The neurological manifestations improved and correlated roughly with the neuroimaging changes.     

Life-Threatening Enterovirus 71 Encephalitis in Unrelated Children with Autosomal Dominant TLR3 Deficiency

Journal of Clinical Immunology - Enterovirus A71 (EV71) causes a broad spectrum of childhood diseases, ranging from asymptomatic infection or self-limited hand-foot-and-mouth disease (HFMD) to...     

Selective predisposition to bacterial infections in IRAK-4-deficient children: IRAK-4-dependent TLRs are otherwise redundant in protective immunity

Human interleukin (IL) 1 receptor–associated kinase 4 (IRAK-4) deficiency is a recently discovered primary immunodeficiency that impairs Toll/IL-1R immunity, except for the Toll-like receptor (TLR) 3– and TLR4–interferon (IFN)-a/b pathways. The clinical and immunological phenotype remains largely unknown. We diagnosed up to 28 patients with IRAK-4 deficiency, tested blood TLR responses for individual leukocyte subsets, and TLR responses for multiple cytokines. The patients' peripheral blood mononuclear cells (PBMCs) did not induce the 11 non-IFN cytokines tested upon activation with TLR agonists other than the nonspecific TLR3 agonist poly(I:C). The patients' individual cell subsets from both myeloid (granulocytes, monocytes, monocyte-derived dendritic cells [MDDCs], myeloid DCs [MDCs], and plasmacytoid DCs) and lymphoid (B, T, and NK cells) lineages did not respond to the TLR agonists that stimulated control cells, with the exception of residual responses to poly(I:C) and lipopolysaccharide in MDCs and MDDCs. Most patients (22 out of 28; 79%) suffered from invasive pneumococcal disease, which was often recurrent (13 out of 22; 59%). Other infections were rare, with the exception of severe staphylococcal disease (9 out of 28; 32%). Almost half of the patients died (12 out of 28; 43%). No death and no invasive infection occurred in patients older than 8 and 14 yr, respectively. The IRAK-4–dependent TLRs and IL-1Rs are therefore vital for childhood immunity to pyogenic bacteria, particularly Streptococcus pneumoniae. Conversely, IRAK-4–dependent human TLRs appear to play a redundant role in protective immunity to most infections, at most limited to childhood immunity to some pyogenic bacteria.