Mohammad A. A. Ibrahim

Differential Effect of Helicobacter pylori Eradication on Time-Trends in Brady/Hypokinesia and Rigidity in Idiopathic Parkinsonism

Background:  We examine the effect of eradicating Helicobacter in idiopathic parkinsonism (IP). Marked deterioration, where eradication‐therapy failed, prompted an interim report in the first 20 probands to reach de‐blinding. The null‐hypothesis, “eradication has no effect on principal outcome, mean stride length at free‐walking speed,” was rejected. We report on study completion in all 30 who had commenced post‐treatment assessments.

Helicobacter hypothesis for idiopathic parkinsonism: before and beyond.

We challenge the concept of idiopathic parkinsonism (IP) as inevitably progressive neurodegeneration, proposing a natural history of sequential microbial insults with predisposing host response. Proof‐of‐principle that infection can contribute to IP was provided by case studies and a placebo‐controlled efficacy study of Helicobacter eradication. “Malignant” IP appears converted to “benign”, but marked deterioration accompanies failure. Similar benefit on brady/hypokinesia from eradicating “low‐density” infection favors autoimmunity. Although a minority of UK probands are urea breath test positive for Helicobacter, the predicted probability of having the parkinsonian label depends on the serum H. pylori antibody profile, with clinically relevant gradients between this “discriminant index” and disease burden and progression. In IP, H. pylori antibodies discriminate for persistently abnormal bowel function, and specific abnormal duodenal enterocyte mitochondrial morphology is described in relation to H. pylori infection. Slow intestinal transit manifests as constipation from the prodrome. Diarrhea may flag secondary small‐intestinal bacterial overgrowth. This, coupled with genetically determined intense inflammatory response, might explain evolution from brady/hypokinetic to rigidity‐predominant parkinsonism.

Expression of a chimeric antigen receptor specific for donor HLA class I enhances the potency of human regulatory T cells in preventing human skin transplant rejection

Regulatory T cell (Treg) therapy using recipient‐derived Tregs expanded ex vivo is currently being investigated clinically by us and others as a means of reducing allograft rejection following organ transplantation. Data from animal models has demonstrated that adoptive transfer of allospecific Tregs offers greater protection from graft rejection compared to polyclonal Tregs. Chimeric antigen receptors (CAR) are clinically translatable synthetic fusion proteins that can redirect the specificity of T cells toward designated antigens. We used CAR technology to redirect human polyclonal Tregs toward donor‐MHC class I molecules, which are ubiquitously expressed in allografts. Two novel HLA‐A2‐specific CARs were engineered: one comprising a CD28‐CD3ζ signaling domain (CAR) and one lacking an intracellular signaling domain (ΔCAR). CAR Tregs were specifically activated and significantly more suppressive than polyclonal or ΔCAR Tregs in the presence of HLA‐A2, without eliciting cytotoxic activity. Furthermore, CAR and ΔCAR Tregs preferentially transmigrated across HLA‐A2‐expressing endothelial cell monolayers. In a human skin xenograft transplant model, adoptive transfer of CAR Tregs alleviated the alloimmune‐mediated skin injury caused by transferring allogeneic peripheral blood mononuclear cells more effectively than polyclonal Tregs. Our results demonstrated that the use of CAR technology is a clinically applicable refinement of Treg therapy for organ transplantation.

Role of chronic infection and inflammation in the gastrointestinal tract in the etiology and pathogenesis of idiopathic parkinsonism. Part 2: response of facets of clinical idiopathic parkinsonism to Helicobacter pylori eradication. A randomized, double-blind, placebo-controlled efficacy study.

Background.  Links between etiology/pathogenesis of neuropsychiatric disease and infection are increasingly recognized.

Selective deficits in blood dendritic cell subsets in common variable immunodeficiency and X-linked agammaglobulinaemia but not specific polysaccharide antibody deficiency

Myeloid and plasmacytoid dendritic cells (MDCs, PDCs) play critical roles in B cell development and antibody production. Primary antibody deficiencies in humans might therefore reflect a deficit in MDCs and/or PDCs. We tested this hypothesis by measuring dendritic cell (DC) subset numbers in patients with common variable immunodeficiency (CVID), X-linked agammaglobulinaemia (XLA) and specific polysaccharide antibody deficiency (SPAD). In CVID both MDC and PDC numbers were markedly reduced. There was a graded reduction in all DC subsets across the Freiburg CVID groups (memory B cell classification) and the greatest deficit was seen in group Ia cases with the most severe disease. In contrast, MDC numbers alone were reduced in XLA whilst in SPAD the DC numbers were normal. In CVID, the number of MDCs correlated strongly with switched memory B cell percentage and total B cell count. Low numbers of DCs correlated with a greater incidence of autoimmunity, splenomegaly and granulomatous disease, and a higher incidence of clinical complications. Measurement of MDC and PDC numbers provides both prognostic information for clinical management and classification of CVID cases for future pathogenetic research. Our findings are consistent with the hypothesis that deficits in DC subsets are a critical feature in CVID.

Leukocyte-subset counts in idiopathic parkinsonism provide clues to a pathogenic pathway involving small intestinal bacterial overgrowth. A surveillance study

BackgroundFollowing Helicobacter pylori eradication in idiopathic parkinsonism (IP), hypokinesia improved but flexor-rigidity increased. Small intestinal bacterial-overgrowth (SIBO) is a candidate driver of the rigidity: hydrogen-breath-test-positivity is common in IP and case histories suggest that Helicobacter keeps SIBO at bay.MethodsIn a surveillance study, we explore relationships of IP-facets to peripheral immune/inflammatory-activation, in light of presence/absence of Helicobacter infection (urea-breath- and/or stool-antigen-test: positivity confirmed by gastric-biopsy) and hydrogen-breath-test status for SIBO (positivity: >20 ppm increment, 2 consecutive 15-min readings, within 2h of 25G lactulose). We question whether any relationships found between facets and blood leukocyte subset counts stand in patients free from anti-parkinsonian drugs, and are robust enough to defy fluctuations in performance consequent on short t½ therapy.ResultsOf 51 IP-probands, 36 had current or past Helicobacter infection on entry, 25 having undergone successful eradication (median 3.4 years before). Thirty-four were hydrogen-breath-test-positive initially, 42 at sometime (343 tests) during surveillance (2.8 years). Hydrogen-breath-test-positivity was associated inversely with Helicobacter-positivity (OR 0.20 (95% CI 0.04, 0.99), p<0.05).In 38 patients (untreated (17) or on stable long-t½ IP-medication), the higher the natural-killer count, the shorter stride, slower gait and greater flexor-rigidity (by mean 49 (14, 85) mm, 54 (3, 104) mm.s-1, 89 (2, 177) Nm.10-3, per 100 cells.μl-1 increment, p=0.007, 0.04 & 0.04 respectively, adjusted for patient characteristics). T-helper count was inversely associated with flexor-rigidity before (p=0.01) and after adjustment for natural-killer count (-36(-63, -10) Nm.10-3 per 100 cells.μl-1, p=0.007). Neutrophil count was inversely associated with tremor (visual analogue scale, p=0.01). Effect-sizes were independent of IP-medication, and not masked by including 13 patients receiving levodopa (except natural-killer count on flexor-rigidity). Cellular associations held after allowing for potentially confounding effect of hydrogen-breath-test or Helicobacter status. Moreover, additional reduction in stride and speed (68 (24, 112) mm & 103 (38, 168) mm.s-1, each p=0.002) was seen with Helicobacter-positivity. Hydrogen-breath-test-positivity, itself, was associated with higher natural-killer and T-helper counts, lower neutrophils (p=0.005, 0.02 & 0.008).ConclusionWe propose a rigidity-associated subordinate pathway, flagged by a higher natural-killer count, tempered by a higher T-helper, against which Helicobacter protects by keeping SIBO at bay.

Peripheral aetiopathogenic drivers and mediators of Parkinson’s disease and co-morbidities: role of gastrointestinal microbiota

We seek an aetiopathogenic model for the spectrum of Parkinson’s disease (PD), functional bowel disease, depression and cognitive impairment. The adopted concept is that systemic immuno-inflammatory processes mediate neuro-inflammation. The model would be based on phenotype, exposome (including gastrointestinal microbiome), milieu (immuno-inflammatory and metabolome), human genetics and their interactions. It would enable a patient’s position, to be understood in terms of drivers, perpetuators and mediators, and a future position, with and without intervention, predicted. Even the cardinal facets of PD may have different drivers: halting one may allow escape down subordinate pathways. Peptic ulceration is prodromal to PD. In our randomised placebo-controlled trial, hypokinesia improved over the year following biopsy-proven Helicobacter pylori eradication and rigidity worsened. This was independent of any (stable, long t½) antiparkinsonian medication. There are pointers to an autoimmune process: for example, surveillance-confirmed hypokinesia effect was indication specific. During surveillance, successive antimicrobial courses, other than for Helicobacter, were associated with cumulative increase in rigidity. Exhibiting laxatives appeared to stem the overall temporal increase, despite antiparkinsonian medication, in rigidity. Thus, intestinal dysbiosis may be a major source of bystander neuronal damage. There are biological gradients of objective measures of PD facets on circulating inflammatory markers and leucocyte subset counts. Moreover, lactulose hydrogen breath test positivity for small-intestinal bacterial overgrowth (present in two thirds of PD patients) is associated with the same subsets: higher natural killer and total CD4+ counts and lower neutrophils. With greater aetiopathogenic understanding, relatively low cost and on-the-shelf medication could have a major impact. A new generation of animal models, based on the gut microbiome, is envisaged.

Modulation of dendritic cell differentiation by colony‐stimulating factor‐1: role of phosphatidylinositol 3′‐kinase and delayed caspase activation

Monocytes acquire a dendritic cell (DC) phenotype when cultured with GM‐CSF and IL‐4. By contrast, CSF‐1 is a potent inducer of monocyte‐to‐macrophage differentiation. Increasing evidence indicates that DC development is impaired in conditions characterized by CSF‐1 overproduction, including pregnancy, trauma, and diverse malignancies. To study this, we have exposed newly established monocyte‐derived DC cultures to conditions of CSF‐1 excess. As a consequence, differentiation is skewed toward a unique intermediate phenotype, which we have termed DC‐M. Such cells exhibit macrophage‐like morphology with impaired allostimulatory capacity, altered cytokine production, and a distinctive cell surface immunophenotype. In light of the emerging role of caspase activation during macrophage differentiation, the activity of caspases 3, 8, and 9 was examined in DC and DC‐M cultures. It is striking that DC‐M cultures exhibit a delayed and progressive increase in activation of all three caspases, associated with depolarization of mitochondrial membrane potential. Furthermore, when DC‐M cultures were supplemented with an inhibitor of caspase 8 or caspase 9, impairment of DC differentiation by CSF‐1 was counteracted. To investigate upstream regulators of caspase activation in DC‐M cultures, experiments were performed using inhibitors of proximal CSF‐1 receptor signaling. These studies demonstrated that the PI‐3K inhibitors, wortmannin and LY294002, antagonize the ability of CSF‐1 to inhibit DC differentiation and to promote caspase activation. Together, these data identify a novel, PI‐3K‐dependent pathway by which CSF‐1 directs delayed caspase activation in monocytes and thereby modulates DC differentiation.

Successful desensitization to immunoglobulin A in a case of transfusion-related anaphylaxis

BACKGROUND: A history of anaphylaxis after transfusion of immunoglobulin A (IgA)‐containing blood products in selective IgA‐deficient (sIgAD) patients can be a major problem, particularly in emergencies, when large quantities of blood products are required.

Anaphylactic shock: the great mimic.

Anaphylaxis, acute coronary syndrome and pulmonary embolism are conditions commonly seen in the acute medical setting which can be difficult to diagnose. Delay in establishing the correct diagnosis can result in either delayed or inappropriate treatment, and subsequent morbidity and mortality. The cases we present highlight the necessity of good clinical assessment when evaluating such patients.