Joseph B. Domachowske

Clinical features and outcome of patients with IRAK-4 and MyD88 deficiency

Autosomal recessive interleukin-1 receptor-associated kinase (IRAK)-4 and myeloid differentiation factor (MyD)88 deficiencies impair Toll-like receptor (TLR)- and interleukin-1 receptor-mediated immunity. We documented the clinical features and outcome of 48 patients with IRAK-4 deficiency and 12 patients with MyD88 deficiency, from 37 kindreds in 15 countries. The clinical features of IRAK-4 and MyD88 deficiency were indistinguishable. There were no severe viral, parasitic, and fungal diseases, and the range of bacterial infections was narrow. Noninvasive bacterial infections occurred in 52 patients, with a high incidence of infections of the upper respiratory tract and the skin, mostly caused by Pseudomonas aeruginosa and Staphylococcus aureus, respectively. The leading threat was invasive pneumococcal disease, documented in 41 patients (68%) and causing 72 documented invasive infections (52.2%). P. aeruginosa and Staph. aureus documented invasive infections also occurred (16.7% and 16%, respectively, in 13 and 13 patients, respectively). Systemic signs of inflammation were usually weak or delayed. The first invasive infection occurred before the age of 2 years in 53 (88.3%) and in the neonatal period in 19 (32.7%) patients. Multiple or recurrent invasive infections were observed in most survivors (n = 36/50, 72%). Clinical outcome was poor, with 24 deaths, in 10 cases during the first invasive episode and in 16 cases of invasive pneumococcal disease. However, no death and invasive infectious disease were reported in patients after the age of 8 years and 14 years, respectively. Antibiotic prophylaxis (n = 34), antipneumococcal vaccination (n = 31), and/or IgG infusion (n = 19), when instituted, had a beneficial impact on patients until the teenage years, with no seemingly detectable impact thereafter. IRAK-4 and MyD88 deficiencies predispose patients to recurrent life-threatening bacterial diseases, such as invasive pneumococcal disease in particular, in infancy and early childhood, with weak signs of inflammation. Patients and families should be informed of the risk of developing life-threatening infections; empiric antibacterial treatment and immediate medical consultation are strongly recommended in cases of suspected infection or moderate fever. Prophylactic measures in childhood are beneficial, until spontaneous improvement occurs in adolescence. Abbreviations: CRP = C-reactive protein, ELISA = enzyme-linked immunosorbent assay, IFN = interferon, IKBA = I&kgr;B&agr;, IL = interleukin, IL-1R = interleukin-1 receptor, InvBD = invasive bacterial disease, IRAK = interleukin-1 receptor-associated kinase, MyD = myeloid differentiation factor, NEMO = nuclear factor-kappaB essential modulator, NInvBD = noninvasive bacterial disease, TIR = Toll/IL-1R, TLR = Toll-like receptor, TNF = tumor necrosis factor.

Eosinophils, eosinophil ribonucleases, and their role in host defense against respiratory virus pathogens

Eosinophils remain among the most enigmatic of cells, as our appreciation of their detrimental activities—e.g., asthma and allergic disease—far outweighs our understanding of their beneficial effects. Among the major secretory effector proteins of eosinophils are the ribonucleases eosinophil‐derived neurotoxin (EDN) and eosinophil cationic protein (ECP) in primates and their orthologs, the eosinophil‐associated ribonucleases (EARs) in rodents. The rapid diversification observed among these ribonucleases suggested that the ultimate target(s) might be similarly efficient at generating sequence diversity while maintaining an unalterable susceptibility to ribonucleolytic cleavage. This has prompted us to consider a role for these proteins and by extension, for eosinophils, in host defense against single‐stranded RNA virus pathogens. We detail our studies of the antiviral activity of eosinophils and eosinophil ribonucleases against respiratory syncytial virus (RSV) in vitro and the related, natural rodent pathogen, pneumonia virus of mice (PVM), in vivo, and consider the possibility that antiviral host defense and the dysregulated responses leading to asthma represent opposing sides of an eosinophil‐mediated double‐edged sword.

Recombinant Human Eosinophil-Derived Neurotoxin/RNase 2 Functions as an Effective Antiviral Agent against Respiratory Syncytial Virus

A dose-dependent decrease in infectivity was observed on introduction of eosinophils into suspensions of respiratory syncytial virus group B (RSV-B). This antiviral effect was reversed by ribonuclease inhibitor, suggesting a role for the eosinophil secretory ribonucleases. Recombinant eosinophil-derived neurotoxin (rhEDN), the major eosinophil ribonuclease, promoted a dose-dependent decrease in RSV-B infectivity, with a 40-fold reduction observed in response to 50 nM rhEDN. Ribonucleolytically inactivated rhEDN (rhEDNdK38) had no antiviral activity. Semiquantitative reverse transcriptase-polymerase chain reaction demonstrated loss of viral genomic RNA in response to rhEDN, suggesting that this protein promotes the direct ribonucleolytic destruction of extracellular virions. Ribonuclease A had no antiviral activity even at approximately 1000-fold higher concentrations, suggesting that rhEDN has unique features other than ribonuclease activity that are crucial to its effectiveness. These results suggest that rhEDN may have potential as a therapeutic agent for prevention or treatment of disease caused by RSV.

The Chemokine Macrophage-Inflammatory Protein-1α and Its Receptor CCR1 Control Pulmonary Inflammation and Antiviral Host Defense in Paramyxovirus Infection

In this work, we explore the responses of specific gene-deleted mice to infection with the paramyxovirus pneumonia virus of mice (PVM). We have shown previously that infection of wild type mice with PVM results in pulmonary neutrophilia and eosinophilia accompanied by local production of macrophage-inflammatory protein-1α (MIP-1α). Here we examine the role of MIP-1α in the pathogenesis of this disease using mice deficient in MIP-1α or its receptor, CCR1. The inflammatory response to PVM in MIP-1α-deficient mice was minimal, with ∼10–60 neutrophils/ml and no eosinophils detected in bronchoalveolar lavage fluid. Higher levels of infectious virus were recovered from lung tissue excised from MIP-1α-deficient than from fully competent mice, suggesting that the inflammatory response limits the rate of virus replication in vivo. PVM infection of CCR1-deficient mice was also associated with attenuated inflammation, with enhanced recovery of infectious virus, and with accelerated mortality. These results suggest that the MIP-1α/CCR1-mediated acute inflammatory response protects mice by delaying the lethal sequelae of infection.

Animal models of human respiratory syncytial virus disease

Infection with the human pneumovirus pathogen, respiratory syncytial virus (hRSV), causes a wide spectrum of respiratory disease, notably among infants and the elderly. Laboratory animal studies permit detailed experimental modeling of hRSV disease and are therefore indispensable in the search for novel therapies and preventative strategies. Present animal models include several target species for hRSV, including chimpanzees, cattle, sheep, cotton rats, and mice, as well as alternative animal pneumovirus models, such as bovine RSV and pneumonia virus of mice. These diverse animal models reproduce different features of hRSV disease, and their utilization should therefore be based on the scientific hypothesis under investigation. The purpose of this review is to summarize the strengths and limitations of each of these animal models. Our intent is to provide a resource for investigators and an impetus for future research.

Acute manifestations and neurologic sequelae of Epstein-Barr virus encephalitis in children.

BACKGROUND Complications of Epstein-Barr virus (EBV) infection are diverse and include a number of neurologic manifestations such as meningitis, meningoencephalitis, cerebellitis, cranial neuritis and others. In general encephalitis caused by EBV in pediatric patients has been considered a self-limited illness with few or no sequelae. METHODS Charts were reviewed from all patients < 18 years of age admitted to or discharged from the State University of New York Health Science Center at Syracuse between 1982 and 1992 with a diagnosis of encephalitis or meningo-encephalitis. Eleven cases of EBV encephalitis diagnosed during a 10-year period were reviewed to characterize the clinical and laboratory findings in the acute setting and the extent of neurologic sequelae on follow-up. RESULTS Acute neurologic manifestations were diverse and included combative behavior (55%), seizures (36%), headache (36%) and evidence of focal involvement (27%). Classic findings of infectious mononucleosis were noted infrequently; 18% each had pharyngitis, adenopathy, positive heterophile antibody tests or atypical lymphocytosis. Two patients (18%) had abnormal neuroimaging studies, one in the acute stage and the other at the time of follow-up. Seven patients (64%) had abnormal electroencephalograms (EEGs) in the acute setting; of these three had persistent abnormalities on follow-up. Forty percent developed persistent neurologic abnormalities including global impairment, perseverative autistic-like behavior and persistent left upper extremity paresis. CONCLUSIONS Classic signs, symptoms and laboratory findings in infectious mononucleosis may be absent in Epstein-Barr virus encephalitis. Neurologic sequelae occur in a substantial number of patients.

A Randomized Trial of Candidate Inactivated Quadrivalent Influenza Vaccine versus Trivalent Influenza Vaccines in Children Aged 3–17 Years

Background. Two antigenically distinct influenza B lineages have cocirculated since 2001, yet trivalent influenza vaccines (TIVs) contain 1 influenza B antigen, meaning lineage mismatch with the vaccine is frequent. We assessed a candidate inactivated quadrivalent influenza vaccine (QIV) containing both B lineages vs TIV in healthy children aged 3–17 years. Methods. Children were randomized 1:1:1 to receive QIV or 1 of 2 TIVs (either B/Victoria or B/Yamagata lineage; N = 2738). Hemagglutination-inhibition assays were performed 28 days after 1 or 2 doses in primed and unprimed children, respectively. Immunological noninferiority of QIV vs TIV against shared strains, and superiority against alternate-lineage B strains was based on geometric mean titers (GMTs) and seroconversion rates. Reactogenicity and safety were also assessed (Clinicaltrials.gov NCT01196988). Results. Noninferiority against shared strains and superiority against alternate-lineage B strains was demonstrated for QIV vs TIV. QIV was highly immunogenic; seroconversion rates were 91.4%, 72.3%, 70.0%, and 72.5% against A/H1N1, A/H3N2, B/Victoria, and B/Yamagata, respectively. Reactogenicity and safety of QIV was consistent with TIV. Conclusions. QIV vs TIV showed superior immunogenicity for the additional B strain without interfering with immune responses to shared strains. QIV may offer improved protection against influenza B in children compared with current trivalent vaccines.

Early-life viral infection and allergen exposure interact to induce an asthmatic phenotype in mice

BackgroundEarly-life respiratory viral infections, notably with respiratory syncytial virus (RSV), increase the risk of subsequent development of childhood asthma. The purpose of this study was to assess whether early-life infection with a species-specific model of RSV and subsequent allergen exposure predisposed to the development of features of asthma.MethodsWe employed a unique combination of animal models in which BALB/c mice were neonatally infected with pneumonia virus of mice (PVM, which replicates severe RSV disease in human infants) and following recovery, were intranasally sensitised with ovalbumin. Animals received low-level challenge with aerosolised antigen for 4 weeks to elicit changes of chronic asthma, followed by a single moderate-level challenge to induce an exacerbation of inflammation. We then assessed airway inflammation, epithelial changes characteristic of remodelling, airway hyperresponsiveness (AHR) and host immunological responses.ResultsAllergic airway inflammation, including recruitment of eosinophils, was prominent only in animals that had recovered from neonatal infection with PVM and then been sensitised and chronically challenged with antigen. Furthermore, only these mice exhibited an augmented Th2-biased immune response, including elevated serum levels of anti-ovalbumin IgE and IgG1 as well as increased relative expression of Th2-associated cytokines IL-4, IL-5 and IL-13. By comparison, development of AHR and mucous cell change were associated with recovery from PVM infection, regardless of subsequent allergen challenge. Increased expression of IL-25, which could contribute to induction of a Th2 response, was demonstrable in the lung following PVM infection. Signalling via the IL-4 receptor α chain was crucial to the development of allergic inflammation, mucous cell change and AHR, because all of these were absent in receptor-deficient mice. In contrast, changes of remodelling were evident in mice that received chronic allergen challenge, regardless of neonatal PVM infection, and were not dependent on signalling via the IL-4 receptor.ConclusionIn this mouse model, interaction between early-life viral infection and allergen sensitisation/challenge is essential for development of the characteristic features of childhood asthma, including allergic inflammation and a Th2-biased immune response.

Functional Antagonism of Chemokine Receptor CCR1 Reduces Mortality in Acute Pneumovirus Infection In Vivo

ABSTRACT We present an antiviral-immunomodulatory therapeutic strategy involving the chemokine receptor antagonist Met-RANTES, which yields significant survival in the setting of an otherwise fatal respiratory virus infection. In previous work, we demonstrated that infection with the natural rodent pathogen pneumonia virus of mice involves robust virus replication accompanied by cellular inflammation modulated by the CC chemokine macrophage inflammatory protein 1α (MIP-1α). We found that the antiviral agent ribavirin limited virus replication in vivo but had no impact on morbidity and mortality associated with this disease in the absence of immunomodulatory control. We show here that ribavirin reduces mortality, from 100% to 10 and 30%, respectively, in gene-deleted CCR1−/− mice and in wild-type mice treated with the small-molecule chemokine receptor antagonist, Met-RANTES. As MIP-1α-mediated inflammation is a common response to several distantly related respiratory virus pathogens, specific antiviral therapy in conjunction with blockade of the MIP-1α/CCR1 inflammatory cascade may ultimately prove to be a useful, generalized approach to severe respiratory virus infection and its pathological sequelae in human subjects.

Pneumonia virus of mice: severe respiratory infection in a natural host

Pneumonia virus of mice (PVM; family Paramyxoviridae, genus Pneumovirus) is a natural mouse pathogen that is closely related to human and bovine respiratory syncytial viruses. Among the prominent features of this infection, robust replication of PVM takes place in bronchial epithelial cells in response to a minimal virus inoculum. Virus replication in situ results in local production of proinflammatory cytokines (MIP-1alpha, MIP-2, MCP-1 and IFNgamma) and granulocyte recruitment to the lung. If left unchecked, PVM infection and the ensuing inflammatory response ultimately lead to pulmonary edema, respiratory compromise and death. In this review, we consider the recent studies using the PVM model that have provided important insights into the role of the inflammatory response in the pathogenesis of severe respiratory virus infection. We also highlight several works that have elucidated acquired immune responses to this pathogen, including T cell responses and the development of humoral immunity. Finally, we consider several immunomodulatory strategies that have been used successfully to reduce morbidity and mortality when administered to PVM-infected, symptomatic mice, and thus hold promise as realistic therapeutic strategies for severe respiratory virus infections in human subjects.