Contribution of IL-18 to Th1 response and host defense against infection by Mycobacterium tuberculosis: a comparative study with IL-12p40

The present study was conducted to critically determine the protective role of IL-18 in host response to Mycobacterium tuberculosis infection. IL-18-deficient (knockout (KO)) mice were slightly more prone to this infection than wild-type (WT) mice. Sensitivity of IL-12p40KO mice was lower than that of IL-12p40/IL-18 double KO mice. IFN-gamma production caused by the infection was significantly attenuated in IL-18KO mice compared with WT mice, as indicated by reduction in the levels of this cytokine in sera, spleen, lung, and liver, and its synthesis by spleen cells restimulated with purified protein derivatives. Serum IL-12p40 level postinfection and its production by peritoneal exudate cells stimulated with live bacilli were also significantly lower in IL-18KO mice than WT mice, suggesting that attenuated production of IFN-gamma was secondary to reduction of IL-12 synthesis. However, this was not likely the case, because administration of excess IL-12 did not restore the reduced IFN-gamma production in IL-18KO mice. In further studies, IL-18 transgenic mice were more resistant to the infection than control littermate mice, and serum IFN-gamma level and its production by restimulated spleen cells were increased in the former mice. Taken together, our results indicate that IL-18 plays an important role in Th1 response and host defense against M. tuberculosis infection although the contribution was not as profound as that of IL-12p40.     

Use of scanning electron microscopy and energy dispersive X-ray spectroscopy to identify key fouling species during alternating tangential filtration

Alternating tangential flow filtration (ATF) has become one of the primary methods for cell retention and clarification in perfusion bioreactors. However, membrane fouling can cause product sieving losses that limit the performance of these systems. This study used scanning electron microscopy and energy dispersive X-ray spectroscopy to identify the nature and location of foulants on 0.2 μm polyethersulfone hollow fiber membranes after use in industrial Chinese hamster ovary cell perfusion bioreactors for monoclonal antibody production. Membrane fouling was dominated by proteinaceous material, primarily host cell proteins along with some monoclonal antibody. Fouling occurred primarily on the lumen surface with much less protein trapped within the depth of the fiber. Protein deposition was also most pronounced near the inlet/exit of the hollow fibers, which are the regions with the greatest flux (and transmembrane pressure) during the cyclical operation of the ATF. These results provide important insights into the underlying phenomena governing the fouling behavior of ATF systems for continuous bioprocessing.     

Reduced host resistance and Th1 response to Cryptococcus neoformans in interleukin-18 deficient mice

Using interleukin (IL)-18 deficient (IL-18(-/-)) mice, we examined the role of IL-18 in the host resistance and Th1 response against infection with Cryptococcus neoformans. Fungal clearance in the lung was reduced in IL-18(-/-) mice, although there was no significant change in the level of dissemination to the brain. The DTH response, as determined by footpad swelling, was also diminished in IL-18(-/-) mice compared to control wild-type (WT) mice. The levels of IL-12 and interferon (IFN)-gamma in the sera were significantly lower in IL-18(-/-) mice than in WT mice. Spleen cells from infected WT mice produced a high level of IFN-gamma upon stimulation with the microbe, while only a low level of IFN-gamma production was detected in spleen cells from infected IL-18(-/-) mice. Administration of IL-18 almost completely restored the reduced response in IL-18(-/-) mice, while IL-12 showed a marginal effect. These results demonstrated the important role of IL-18 in the resistance and Th1 response of mice to C. neoformans by potentiating the production of IFN-gamma.     

IL-18 contributes to host resistance against infection with Cryptococcus neoformans in mice with defective IL-12 synthesis through induction of IFN-gamma production by NK cells

The aim of this study was to examine the contribution of IL-18 in host defense against infection caused by Cryptococcus neoformans in mice with defective IL-12 production. Experiments were conducted in mice with a targeted disruption of the gene for IL-12p40 subunit (IL-12p40-/- mice). In these mice, host resistance was impaired, as shown by increased number of organisms in both lungs and brains, compared with control mice. Serum IFN-gamma was still detected in these mice at a considerable level (20-30% of that in control mice). The host resistance was moderately impaired in IL-12p40-/- mice compared with IFN-gamma-/- mice. Neutralizing anti-IFN-gamma mAb further increased the lung burdens of organisms. In addition, treatment with neutralizing anti-IL-18 Ab almost completely abrogated the production of IFN-gamma and also impaired the host resistance. Host resistance in IL-12p40-/- IL-18-/- mice was more profoundly impaired than in IL-12p40-/- mice. Administration of IL-12 as well as IL-18 increased the serum levels of IFN-gamma and significantly restored the reduced host resistance. Spleen cells obtained from infected IL-12p40-/- mice did not produce any IFN-gamma upon restimulation with the same organisms, while those from infected and IL-12-treated mice produced IFN-gamma. In contrast, IL-18 did not show such effect. Finally, depletion of NK cells by anti-asialo GM1 Ab mostly abrogated the residual production of IFN-gamma in IL-12p40-/- mice. Our results indicate that IL-18 contributes to host resistance to cryptococcal infection through the induction of IFN-gamma production by NK cells, but not through the development of Th1 cells, under the condition in which IL-12 synthesis is deficient.     

Anti-CD11 b monoclonal antibody suppresses brain dissemination of Cryptococcus neoformans in mice

To elucidate the role of the beta2 integrin family of adhesion molecules in the disseminated infection of Cryptococcus neoformans from the lung to the central nervous system, we examined the effects of monoclonal antibodies (mAbs) against CD11a, CD11b, CD11c and CD18 on the number of live microorganisms in both the lung and brain of mice three weeks after intratracheal infection. Administration of anti-CD11b mAb partially, but reproducibly, reduced the fungal loads in the brain in three independent experiments, while the lung loads were not affected. In addition, the same treatment significantly decreased the number of live microorganisms in the blood. In sharp contrast, the brain loads one week after intravenous injection with C. neoformans were not affected by treatment with anti-CD11b mAb. Finally, administration of mAb against other adhesion molecules (CD11a, CD11c or CD18) failed to affect the fungal loads in the brain as well as in the lung three weeks after intratracheal instillation, except for anti-CD18 mAb which rather increased the brain loads. Our results suggested that CD11b might be involved at least in part in the process of fungal dissemination from lung to brain, although the significance of other beta2 integrin family adhesion molecules remains to be substantiated.     

Minimal contribution of Valpha14 natural killer T cells to Th1 response and host resistance against mycobacterial infection in mice

We elucidated the contribution of Valpha14 NKT cells to Th1 response and host resistance against mycobacterial infection. In Valpha14 NKT cell-deficient mice, host defense and DTH response to Mycobacterium bovis BCG were not different from wild-type mice after pulmonary infection. There was no significant difference in the lung concentrations of IFN-gamma between the two strains of mice. In addition, host defense to systemic infection with M. tuberculosis was similar to that of M. bovis. Our results indicate that Valpha14 NKT cells play only a marginal role, if any, in the Th1 response and host resistance to mycobacterial infection.     

Therapeutic Hypothermia Modifies Perinatal Asphyxia-Induced Changes of the Corpus Callosum and Outcome in Neonates

What Is Known about this Subject?

Diffusion-weighted MRI has demonstrated changes in the corpus callosum of term neonates with perinatal asphyxia. The severity of cerebral changes demonstrated using diffusion-weighted MRI is difficult to assess without measuring values of the Apparent Diffusion Coefficient (ADC).

What Is New?

ADC values of the anterior part of the corpus callosum are slightly higher than of the posterior part in full term infants with perinatal asphyxia. Low ADC values of the corpus callosum were associated with an adverse outcome in infants with perinatal asphyxia. In infants treated with hypothermia lower ADC values than with normothermia were associated with a poor outcome, supporting neuroprotective effects of hypothermia

Background

Using MRI, changes can be detected in the corpus callosum (CC) following perinatal asphyxia which are associated with later neurodevelopmental outcome.

Aim

To study the association between the apparent diffusion coefficient of water (ADC) in the CC on MRI in neonates with perinatal asphyxia and neurodevelopmental outcome at 18 months of age.

Subjects, Methods

Of 121 infants 32 (26%) died and 13 (11%) survived with an adverse neurological outcome. Sixty-five (54%) received therapeutic hypothermia. MRI was performed within 7 days after birth using a 1.5 T or 3.0 T system, and ADC values were measured in the anterior and posterior CC. The association between ADC and composite outcome (death or abnormal neurodevelopment) was analyzed for both normothermia and hypothermia cases using receiver operating characteristics.

Results

ADC values of the posterior CC were lower than of the anterior part (mean difference 0.050 x 10^-3 mm²/s, p<0.001). Field strength did not affect ADC values. ADC values of the posterior part of the CC were significantly lower in infants with basal ganglia/thalamus or near total brain injury (p<0.001). Lower ADC values were associated with an adverse outcome, but cut-off levels were lower after hypothermia (1.024 x 10^-3 mm²/s vs 0.969 x 10^-3 mm²/s)

Conclusion

Low ADC values of the posterior part of the corpus callosum are associated with an adverse outcome in term or near term neonates with perinatal asphyxia. Therapeutic hypothermia slightly modifies this association, showing that lower values were needed for an adverse outcome.     

Epstein-Barr Virus and Human Papillomavirus Infections and Genotype Distribution in Head and Neck Cancers

ObjectiveTo investigate the prevalence, genotypes, and prognostic values of Epstein-Barr virus (EBV) and human papillomavirus (HPV) infections in Japanese patients with different types of head and neck cancer (HNC).ResultsOf the 209 HNC patients, 63 (30.1%) had HPV infection, and HPV-16 was the most common subtype (86.9%). HPV E6/E7 mRNA expression was found in 23 of 60 (38.3%) HPV DNA-positive cases detected. The site of highest prevalence of HPV was the oropharynx (45.9%). Among 146 (69.9%) HNCs in which EBV DNA was identified, 107 (73.3%) and 27 (18.5%) contained types A and B, respectively, and 124 (84.9%) showed the existence of del-LMP-1. However, only 13 (6.2%) HNCs were positive for EBER, 12 (92.3%) of which derived from the nasopharynx. Co-infection of HPV and EBER was found in only 1.0% of HNCs and 10.0% of NPCs. Kaplan-Meier survival analysis showed significantly better disease-specific and overall survival in the HPV DNA+/mRNA+ oropharyngeal squamous cell carcinoma (OPC) patients than in the other OPC patients (P = 0.027 and 0.017, respectively). Multivariate analysis showed that stage T1–3 (P = 0.002) and HPV mRNA-positive status (P = 0.061) independently predicted better disease-specific survival. No significant difference in disease-specific survival was found between the EBER-positive and -negative NPC patients (P = 0.155).ConclusionsOur findings indicate that co-infection with HPV and EBV is rare in HNC. Oropharyngeal SCC with active HPV infection was related to a highly favorable outcome, while EBV status was not prognostic in the NPC cohort.     

European Ancestry Predominates in Neuromyelitis Optica and Multiple Sclerosis Patients from Brazil

Background

Neuromyelitis optica (NMO) is considered relatively more common in non-Whites, whereas multiple sclerosis (MS) presents a high prevalence rate, particularly in Whites from Western countries populations. However, no study has used ancestry informative markers (AIMs) to estimate the genetic ancestry contribution to NMO patients.

Methods

Twelve AIMs were selected based on the large allele frequency differences among European, African, and Amerindian populations, in order to investigate the genetic contribution of each ancestral group in 236 patients with MS and NMO, diagnosed using the McDonald and Wingerchuck criteria, respectively. All 128 MS patients were recruited at the Faculty of Medicine of Ribeirão Preto (MS-RP), Southeastern Brazil, as well as 108 healthy bone marrow donors considered as healthy controls. A total of 108 NMO patients were recruited from five Neurology centers from different Brazilian regions, including Ribeirão Preto (NMO-RP).

Principal Findings

European ancestry contribution was higher in MS-RP than in NMO-RP (78.5% vs. 68.7%) patients. In contrast, African ancestry estimates were higher in NMO-RP than in MS-RP (20.5% vs. 12.5%) patients. Moreover, principal component analyses showed that groups of NMO patients from different Brazilian regions were clustered close to the European ancestral population.

Conclusions

Our findings demonstrate that European genetic contribution predominates in NMO and MS patients from Brazil.     

Use of Expansion Factors to Estimate the Burden of Dengue in Southeast Asia: A Systematic Analysis

Background

Dengue virus infection is the most common arthropod-borne disease of humans and its geographical range and infection rates are increasing. Health policy decisions require information about the disease burden, but surveillance systems usually underreport the total number of cases. These may be estimated by multiplying reported cases by an expansion factor (EF).

Methods and Findings

As a key step to estimate the economic and disease burden of dengue in Southeast Asia (SEA), we projected dengue cases from 2001 through 2010 using EFs. We conducted a systematic literature review (1995–2011) and identified 11 published articles reporting original, empirically derived EFs or the necessary data, and 11 additional relevant studies. To estimate EFs for total cases in countries where no empirical studies were available, we extrapolated data based on the statistically significant inverse relationship between an index of a country''s health system quality and its observed reporting rate. We compiled an average 386,000 dengue episodes reported annually to surveillance systems in the region, and projected about 2.92 million dengue episodes. We conducted a probabilistic sensitivity analysis, simultaneously varying the most important parameters in 20,000 Monte Carlo simulations, and derived 95% certainty level of 2.73–3.38 million dengue episodes. We estimated an overall EF in SEA of 7.6 (95% certainty level: 7.0–8.8) dengue cases for every case reported, with an EF range of 3.8 for Malaysia to 19.0 in East Timor.

Conclusion

Studies that make no adjustment for underreporting would seriously understate the burden and cost of dengue in SEA and elsewhere. As the sites of the empirical studies we identified were not randomly chosen, the exact extent of underreporting remains uncertain. Nevertheless, the results reported here, based on a systematic analysis of the available literature, show general consistency and provide a reasonable empirical basis to adjust for underreporting.