Gene Polymorphisms of TLR4 and TLR9 and Haemophilus influenzae Meningitis in Angolan Children.

Bacterial meningitis (BM) is a severe disease caused by various bacterial pathogens. Toll-like receptors (TLRs) protect humans from invading pathogens. In this study, we determined whether single nucleotide polymorphisms (SNPs) of TLR4 and TLR9 are associated with susceptibility to and outcome of BM in Angolan children. Samples were taken from 241 patients and 265 age-matched ethnic controls. The SNPs TLR4 rs4986790 (896A > G) and TLR9 rs187084 (-1486T > C) were determined by high-resolution melting analysis (HRMA). The frequency of variant genotypes in TLR4 was significantly higher in patients with Haemophilus influenzae meningitis than controls (odds ratio (OR), 2.5; 95% confidence interval (CI), 1.2-5.4; p = 0.021), whereas the frequency of variant genotypes in TLR9 was significantly lower in patients with H. influenzae meningitis than controls (OR, 0.4; 95% CI, 0.2-0.9; p = 0.036). No such differences were found with other causative pathogens, such as Streptococcus pneumoniae and Neisseria meningitidis. At the time of discharge, patients with meningitis caused by Gram-negative bacteria who were carriers of variant TLR4 genotypes had a higher risk of ataxia (OR, 12.91; 95% CI, 1.52-109.80; p = 0.019) and other neurological sequelae (OR, 11.85; 95% CI, 1.07-131.49; p = 0.044) than those with the wild-type TLR4 genotype. Our study suggests an association between H. influenzae meningitis and genetic variation between TLR4 and TLR9 in Angolan children.

Kinetics of adaptive immunity to Haemophilus influenzae type b meningitis in transgenic mice: evidence from diverse expression of double T1/T2 transgenes and Th1/Th2-related cytokines.

To investigate the kinetic changes in adaptive immunity during experimental Haemophilus influenzae type b (Hib) meningitis, we established a murine meningitis model based on T1/T2 doubly transgenic mice. These mice carry two transgenes that express two distinct cell-surface markers: a human Thy1 transgene (hThy1) under the control of the murine IFN-gamma promoter, and a murine Thy1.1 transgene (mThy1.1) under the control of the murine IL-4 promoter, designated T1 and T2, respectively. Mice infected with Hib displayed severest symptoms and lowest total splenocyte counts on day 3 after infection. Simultaneously, we examined the significantly low percentage of CD19+ B cells, the relatively high level of CD4+ T cells and significantly high percentage of CD8+ T cells in Hib-infected mice. Furthermore, we observed the early induction of both Th1 and Th2 responses, in terms of the augmentation of Th1 cells (IFN-gamma-producing CD4+ T cells) and Th2 cells (IL-4-producing CD4+ T cells) in Hib-infected mice. On day 7 after infection, the Th1 response gradually declined and the Th2 response rather sustained. Two weeks after infection, both Th1 and Th2 cells were barely detectable. Moreover, we demonstrated using an antigen-specific re-stimulation test to analyze the effector function of lymphocyte subsets that CD8+ T cells contributed to more predominantly production of IFN-gamma than CD4+ T cells did; and CD4+ T cells partly contributed to the secretion of IL-4 from flowcytometry of intracellular cytokine staining. Our results support that these transgenic mice provide an available model to dissect the complex kinetic change of adaptive immunity in bacterial infectious diseases.

Decreased frequency of rearrangement due to the synergistic effect of nucleotide changes in the heptamer and nonamer of the recombination signal sequence of the V kappa gene A2b, which is associated with increased susceptibility of Navajos to Haemophilus influenzae type b disease.

Navajos and genetically related populations have a 10-fold increased incidence of Haemophilus influenzae type b (Hib) disease compared with control populations. The Vkappa gene A2 is used to encode the majority of anti-Hib Abs, and these are the highest affinity anti-Hib Abs. Navajos carry a different allele of the A2 gene segment (A2b) that is defective in its ability to undergo V-J recombination. The A2b allele has only three nucleotide changes from the commonly occurring A2a allele, two of which could potentially affect its ability to recombine. In this study we used two independent in vitro assays to test whether the nucleotide change found in the A2b promoter and/or in the A2b recombination signal sequence (RSS) might be responsible for the decrease in recombination frequency observed in vivo. Using a luciferase reporter gene assay, we found no significant difference between A2a and A2b promoter activities. However, the competition recombination substrate assay showed a 4.5-fold reduction in the relative frequency of recombination of the A2b RSS compared with A2a. We show that this decreased frequency is due to a synergistic effect of the unique nucleotide change present in the heptamer of the A2b RSS and the shared nucleotide change present in the nonamer of both A2b and A2a. This in vitro relative frequency of rearrangement is not significantly different from that observed in vivo; therefore, the A2b RSS is probably the factor associated with the increased susceptibility to Hib disease among individuals carrying the A2b allele.

Cytokine mRNA profiles during the course of experimental Haemophilus influenzae bacterial meningitis.

Intraperitoneal inoculation of Haemophilus influenzae type b (Hib) to 3-week-old Sprague-Dawley rats resulted in nonlethal meningitis with high levels of leukocytes in the cerebrospinal fluid (CSF) and positive bacterial culture. Using in situ hybridization, levels of cytokine mRNA-expressing cells were determined in the brain, CSF, and spleen from Hib-inoculated and uninfected control rats. IFN-gamma, IL-1 beta, IL-4, IL-6, IL-10, IL-12, and TNF-alpha mRNA levels were elevated at 12 hr postinoculation (pi) in spleen and CSF. At this time point, strong expression of IL-6 and TGF-beta was detected in the brain, and also of IL-10 at 48 hr while IFN-gamma and IL-12 were expressed at very low levels throughout the observation time. Delayed cytokine induction occurred in CSF compared to spleen and brain. TGF-beta was high in CSF at 48 hr, and some elevation of IL-1 beta, IL-6, IL-10, TNF-alpha, IFN-gamma, and IL-12 was evident at 72 hr pi. This may suggest measures that promote production of TGF-beta and/or IL-10 should be evaluated in treatment of bacterial meningitis.

[Familial infection caused by Haemophilus influenzae]. / Familiaer infektion med Haemophilus influenzae.

A three-year-old girl developed purulent arthritis and her nine-month-old younger brother meningitis with Haemophilus influenzae type b, after an interval of 43 days. Attention should be drawn to the spread of Haemophilus disease other than meningitis.

[Familial deficiency of complement factor 7: association with bacterial meningitis. Apropos of 3 recent cases]. / Déficit familial en facteur sept du complément: association avec les méningites bactériennes. A propos de trois cas récents.

Three recent cases of inherited deficiency of the seventh component of complement (C7) associated with recurrent infectious meningitis are described. Two cases were associated with meningococcal meningitis, the third is the first case report of C7 inherited deficiency associated with Haemophilus parainfluenzae meningitis. Family studies are consistent with inheritance and non-HLA-linked, autosomal codominant trait of the C7 deficiency. The three patients have remained well, following antibiotic treatment.

Response to immunization with Haemophilus influenzae type b polysaccharide-pertussis vaccine and risk of Haemophilus meningitis in children with the Km(1) immunoglobulin allotype.

In experimental animals, immune responses to certain antigens are regulated by immunoglobulin allotype-linked genes. In an effort to detect such genes in humans, we examined the antibody responses of 74 healthy children with different Km(1) or Gm(23) allotypes to a Haemophilus influenzae type b vaccine (type b polysaccharide capsule-pertussis vaccine). The anticapsular antibody responses of black or white children with the Km(1) allotype were 4.6- to 9.5-fold higher than those of children who lacked this determinant (P less than 0.004). No significant differences were found in antibody response with respect to the Gm(23) allotype. The frequencies of Km(1) and Gm(23) also were examined in 170 patients with Haemophilus meningitis, 71 patients with epiglottitis, and 173 control children. Km(1) was detected less frequently in black patients with meningitis (38%) than in those with epiglottitis (81%, P less than 0.002) or in controls (66%, P less than 0.0007). The relative risk of meningitis thus was 3.2-fold lower among black children with the Km(1) allotype than in those who lacked this allotype (odds ratio = 0.3, 95% confidence interval 0.2 to 0.6). However, the risk of meningitis was not decreased in white children with the Km(1) allotype (odds ratio = 1.0). There were no significant differences in the frequency of Gm(23) among the patient groups and controls. The Km(1) allotype but not the Gm(23) thus defines a subpopulation of children of both races who are high responders to this vaccine, and black children but not white children with the Km(1) allotype are at decreased risk of developing Haemophilus meningitis. These data indicate that in blacks, genes associated with Km(1) may affect immune response to a prototype type b Haemophilus vaccine, and perhaps interact with another factor related to race to affect susceptibility to Haemophilus meningitis.

Histocompatibility leukocyte antigen and erythrocyte MNSs specificities in patients with meningitis or epiglottitis due to Haemophilus influenzae type b.

The frequencies of erythrocyte MNSs antigens and certain histocompatibility leukocyte antigen (HLA) specificities (HLA-A, HLA-B, and HLA-DR) were determined in white patients with meningitis or epiglottitis due to Haemophilus influenzae type b and in controls. The frequency of the erythrocyte MNSs genotype was significantly lower among patients with meningitis than among those with epiglottitis (P = 0.03); this observation confirms a trend observed previously. However, the frequencies of the HLA specificities did not differ significantly in the three groups studied; this result fails to confirm previous reports of disease associations with several HLA-A and HLA-B specificities. Although susceptibility to different clinical manifestations of haemophilus disease may be influenced by genetic factors, our studies indicate that the major loci conferring susceptibility are not in linkage disequilibrium with specificities in the major histocompatibility complex.

Siblings of patients with Haemophilus meningitis have impaired anticapsular antibody responses to Haemophilus vaccine.

Siblings of patients with type b Haemophilus influenzae meningitis are at increased risk of developing Haemophilus disease. We immunized 26 healthy siblings and 25 control subjects using a vaccine containing the type b polysaccharide capsule (10 micrograms PRP) and pertussis vaccine (4 opacity units) (Lederle Laboratories) to determine whether siblings of patients with Haemophilus meningitis had an impaired antibody response to PRP. Using two intramuscular injections one month apart, we found that the siblings had a lower response to PRP. One month after the second injection, 12 of 24 of the siblings had serum concentrations of anticapsular (PRP) antibody thought to be sufficient to confer protection against Haemophilus disease (greater than or equal to 300 ng/ml), compared with 19 of 24 of the control children tested (50% vs 79%, P = 0.035 by chi-square analysis). In comparison with the normal controls, the siblings produced significantly less IgG anti-PRP antibody but similar amounts of IgM. The impaired responsiveness to PRP was most evident among the 16 children born after their sibling had meningitis and who were not known to have been exposed to type b Haemophilus infection previously. These data indicate that siblings of some patients with type b Haemophilus meningitis have reduced ability to form IgG anti-PRP antibody, which may be associated with increased susceptibility to Haemophilus disease.

Rifampin prophylaxis v placebo for household contacts of children with Hemophilus influenzae type b disease.

The efficacy of rifampin prophylaxis (20 mg/kg/day in two doses for four days) in eliminating pharyngeal Hemophilus influenzae type b from household contacts of 38 patients with invasive Hemophilus disease was evaluated in a prospective, placebo-controlled fashion. At the end of treatment, rifampin efficacy was 91% in subjects younger than 5 years of age and 100% in those subjects older than 5 years. The H influenzae type b carrier rate of rifampin-treated subjects was significantly smaller than that of placebo-treated subjects one month after prophylaxis. However, 22% to 25% of rifampin-treated carriers younger than 5 years of age were colonized with H influenzae type b, based on cultures obtained one to four weeks after prophylaxis, while approximately 75% of placebo-treated carriers were still positive at this time.

Haemophilus influenzae type b meningitis: occurrence in three siblings over a two-year period.

Haemophilus influenzae type b meningitis occurred in all three siblings in one family over a 24-month period. Investigations of the organisms involved and immunologic studies of the family revealed low percentages of E-rosette-forming cells (T-cells) in both surviving children and in the father. This report suggests that host susceptibility to H influenzae is genetically controlled and that T-cell functions, as yet undetermined, may be involved.

Haemophilus influenzae type B meningitis: a contagious disease of children.

The families of 126 consecutive patients with Haemophilus influenzae type B meningitis were surveyed for secondary invasive H influenzae disease among household contacts. A total of 120 of the families were contacted. In six cases no contact was possible and the medical record was reviewed. Some 555 household contacts were found; 31% (171) were under 5 years of age. A secondary case was defined as a household contact with H influenzae type B isolated from blood or cerebrospinal fluid more than 24 hours, but less than 30 days, after admission to hospital of the index case. Four secondary cases were identified, all in children aged under 5 years. The secondary attack rate in children under 5 years or less in the month after exposure to an index case was thus 2.3%, 800 times the endemic attack rate for H influenzae meningitis. This is a conservative estimate since five additional contact cases were documented, but not included in the secondary attack rate. Young contacts of a child with H influenzae meningitis are thus at significant risk of life-threatening secondary disease.

Haemophilus influenzae meningitis. A national study of secondary spread in household contacts.

To determine the risk of severe Haemophilus influenzae illness among household contacts of patients with H. influenzae meningitis, we studied prospective data obtained in 19 states from January 1, 1977, to June 30, 1978. H. influenzae meningitis was reported in 1403 patients, and 1147 (82 per cent) of the exposed families were investigated for the occurrence of H. influenzae disease within 30 days after its onset in the index patient. During this interval, nine of 1687 household contacts (0.5 per cent) under the age of six years had systemic disease confirmed to be caused by H. influenzae Type b. The risk in children less than one year of age was 6 per cent, and the risk in those less than four years of age was 2.1 per cent. None of 2624 contacts above the age of five was affected. In the 30 days after onset of meningitis, the risk of this infection alone, aside from other types of serious H. influenzae disease, is 585 times greater in household contacts than the age-adjusted risk in the general population. The risk of H. influenzae disease in household contacts under six years of age is similar to the risk of secondary meningococcal disease in all household contacts--indicating a need for effective antimicrobial prophylaxis.

Spread of Haemophilus influenzae. Secondary illness in household contacts of patients with H influenzae meningitis.

To determine the risk of severe secondary illness in household contacts of patients with Haemophilus influenzae meningitis, telephone interviews were conducted with contacts of patients with reported cases. Four probable or proved secondary cases of severe disease were identified for a secondary attack rate of 0.4%. The secondary attack rate for household contacts of patients 2 years of age and younger was 4.9%. Until safe, effective prophylactic measures become available, physicians should explain to parents that any person who becomes ill in the month after a household case of H influenzae meningitis should be brought to the attention of a physician for appropriate evaluation and treatment.