Case report: Cerebellar swelling and hydrocephalus in familial hemophagocytic lymphohistiocytosis

Familial hemophagocytic lymphohistiocytosis (FHL) is a severe inborn error of immunity caused by a genetic defect that impairs the function of cytotoxic T and NK cells. There are only a few reported cases of FHL with diffuse swelling of the cerebellum and obstructive hydrocephalus. We report a case of FHL3 with neurological symptoms associated with cerebellar swelling and obstructive hydrocephalus. A male patient was hospitalized several times due to fever and decreased feeding, hepatosplenomegaly, and cytopenia since the first month of life. At 7 months of age, disturbance of consciousness was seen. Brain magnetic resonance imaging revealed signal intensity in the bilateral cerebellar hemispheres, diffusely increased periventricular white matter, and ventriculomegaly. Although he was treated with methylprednisolone pulse therapy, he was unresponsive to the treatment. He was then transferred to a local hospital after tracheotomy but died. Targeted clinical sequencing revealed a homozygous splice-site mutation in UNC13D. Pediatric hemophagocytic lymphohistiocytosis (HLH) includes some cases of central nervous symptom (CNS)-isolated HLH or CNS HLH preceding systemic lesions, which often do not initially meet the diagnostic criteria for FHL. Patients with FHL initiated by cerebellar symptoms may present with an atypical clinical course for HLH, leading to delayed diagnosis and poor outcomes. Despite the usefulness of a combination of a high percentage of lymphocytes in the peripheral leukocytes, a low lactate dehydrogenase level, and a high sIL-2R/ferritin ratio for identifying FHL, the diagnosis may be missed due to the absence of these results. Presymptomatic diagnosis of FHL by screening of newborns and subsequent early treatment of patients with a predicted poor prognosis may contribute to better outcomes

<i>Campylobacter jejuni pdxA</i> Affects Flagellum-Mediated Motility to Alter Host Colonization

<div><p>Vitamin B6 (pyridoxal-5'-phosphate, PLP) is linked to a variety of biological functions in prokaryotes. Here, we report that the <i>pdxA</i> (putative 4-hydroxy-L-threonine phosphate dehydrogenase) gene plays a pivotal role in the PLP-dependent regulation of flagellar motility, thereby altering host colonization in a leading foodborne pathogen, <i>Campylobacter jejuni</i>. A <i>C. jejuni pdxA</i> mutant failed to produce PLP and exhibited a coincident loss of flagellar motility. Mass spectrometric analyses showed a 3-fold reduction in the main flagellar glycan pseudaminic acid (Pse) associated with the disruption of <i>pdxA</i>. The <i>pdxA</i> mutant also exhibited reduced growth rates compared with the WT strain. Comparative metabolomic analyses revealed differences in respiratory/energy metabolism between WT <i>C. jejuni</i> and the <i>pdxA</i> mutant, providing a possible explanation for the differential growth fitness between the two strains. Consistent with the lack of flagellar motility, the <i>pdxA</i> mutant showed impaired motility-mediated responses (bacterial adhesion, ERK1/2 activation, and IL-8 production) in INT407 cells and reduced colonization of chickens compared with the WT strain. Overall, this study demonstrated that the <i>pdxA</i> gene affects the PLP-mediated flagellar motility function, mainly through alteration of Pse modification, and the disruption of this gene also alters the respiratory/energy metabolisms to potentially affect host colonization. Our data therefore present novel implications regarding the utility of PLP and its dependent enzymes as potent target(s) for the control of this pathogen in the poultry host.</p></div

Deletion of the <i>pdxA</i> gene impairs <i>in vitro</i> cellular responses and <i>in vivo</i> colonization.

<p>(A) INT407 cells were infected for 1 h with the <i>C. jejuni</i> WT, pdxA−, pdxA−/+, and flaA− strains. The number of cell-adherent bacteria was measured by counting the plates after washing three times with PBS. (B) ERK1/2 activation upon infection. Western blotting was performed to detect the levels of phosphorylated and total ERK1/2 in the lysates from infected cells. (C) IL-8 production in INT407 cells was measured at 4 h and 16 h <i>p.i. via</i> ELISA. The data are presented in sections A and C as the mean values ± standard deviations from samples run in duplicate in at least three experiments. (D) Disruption of the <i>pdxA</i> gene reduces the colonization of the chicken cecum by <i>C. jejuni</i>. Groups of 14-day-old chickens (n = 10 per group) were orally inoculated with approximately 3×10⁷ CFU of WT or <i>pdxA</i> mutant <i>C. jejuni</i>. At 1 week and 4 weeks <i>p.i.</i>, the ceca were aseptically removed from the infected animals (n = 5 for each time point) and homogenized. Serial dilutions of the suspensions were plated on mCCDA agar to count CFU numbers. The closed diamonds and open circles represent the numbers of WT and <i>pdxA</i> mutant CFUs recovered from the animals, respectively.</p

Representative metabolites that are altered between the <i>C. jejuni</i> WT and <i>pdxA</i> mutant strains.

<p>The detected metabolites exhibiting >2.0-fold differences between the WT and pdxA- strains are shown. Each mean represents average from two independent tests. Candidate compounds are identified based on the detection peak (<i>m</i>/<i>z</i>)^*1 and migration time (MT)^*2 through HTM database. ^*3 Relative mean of the pdxA-/WT ratio. Full lists are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0070418#pone.0070418.s006" target="_blank">Table S2</a>.</p

The <i>C. jejuni pdxA</i> mutant shows altered growth kinetics and respiratory/energy metabolism.

<p>(A) Growth curves of <i>C. jejuni</i> 81–176 WT, pdxA−, and the complemented mutant strains in MH broth not supplemented (left panel) or supplemented (right panel) with PLP (10 mg l⁻¹). (B) Intracellular ATP levels of <i>C. jejuni</i> 81–176 WT, pdxA−, and the complemented mutant strains. ATP contents of four serial dilutions of the bacteria (shown as CFU 100 μl⁻¹) under investigation were measured. The results are shown as means ± SD of data from triplicate wells of a representative experiment. (C) Focused dynamics of the <i>C. jejuni</i> TCA-cycle pathway. The pathway, the relative mean concentrations of the related metabolites in the WT (blue bars) and the <i>pdxA</i> mutant (red bars) strains, and the genes associated with the enzymatic conversion of each metabolite were illustrated with the PATRIC pathway analysis program.</p

Bacterial strains and plasmids used in this study.

<p>Bacterial strains and plasmids used in this study.</p