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.

Recently, we reported that Campylobacter jejuni, an important gastrointestinal pathogen, has the genetic determinants to produce a capsular polysaccharide (Karlyshev et al., Mol. Microbiol. 35:529–541, 2000). Despite these data, the presence of a capsule in these bacteria has remained controversial. In this study we stain C. jejuni cells with the cationic dye Alcian blue and demonstrate for the first time by electron microscopy that C. jejuni cells produce a polysaccharide capsule that is retained in the coccoid form but is absent in a kpsM mutant

Plasma membrane-derived vesicles (PMVs) are small intact vesicles released from the cell surface that play a role in intercellular communication. We have examined the role of PMVs in the terminal differentiation of monocytes. The myeloid-differentiating agents all-trans retinoic acid/PMA and histamine, the inflammatory mediator that inhibits promonocyte proliferation, induced an intracellular Ca2+-mediated PMV (as opposed to exosome) release from THP-1 promonocytes. These PMVs cause THP-1 cells to enter G0–G1 cell cycle arrest and induce terminal monocyte-to-macrophage differentiation. Use of the TGF-β receptor antagonist SB-431542 and anti–TGF-β1 Ab showed that this was due to TGF-β1 carried on PMVs. Although TGF-β1 levels have been shown to increase in cell culture supernatants during macrophage differentiation and dendritic cell maturation, the presence of TGF-β1 in PMVs is yet to be reported. In this study, to our knowledge we show for the first time that TGF-β1 is carried on the surface of PMVs, and we confirm the presence within PMVs of certain leaderless proteins, with reported roles in myeloid cell differentiation. Our in vitro findings support a model in which TGF-β1–bearing PMVs, released from promonocytic leukemia cells (THP-1) or primary peripheral blood monocytes on exposure to sublytic complement or after treatment with a differentiation therapy agent, such as all-trans retinoic acid, significantly reduce proliferation of THP-1 cells. Such PMVs also induce the terminal differentiation of primary peripheral blood monocytes as well as THP-1 monocytes.

We have used immunoelectron microscopy to investigate the subcellular location of Pfs16 in Plasmodium falciparum. It was detected in the outer membrane region of gametocytes and more specifically on the parasitophorous vacuole membrane (pvm), since, during gametogenesis when the pvm disintegrates, the majority of the antigen was detected on the remains of this membrane in multilaminated whorls and not on the gamete plasma membrane. The antigen was also present on other gametocyte cellular structures, including those which we believe to be Garnham bodies, present in the host cell cytoplasm of some gametocytes. The antigen was present too on the membrane surrounding cytosomes and the resulting food vacuoles in the parasite cytoplasm.

Unselected, disposable acupuncture needles from various manufacturers and retail suppliers were taken from a pool of donated and bought samples. Three needles of each type were prepared for electron-microscopy. The needle tips were inspected at two magnifications (x39.37 and x612.5): 52 electron-micrographs were taken of 31 individual needles from 11 different types. No needle-tip looked perfect and significant faults were seen in most; some appeared seriously deformed. The faults noted were: scratch marks along or across the needle, metallic scuff, lumps and irregularities in the needle surface, needle-tip stubbed or malformed, and needle point off-centre. An additional test made was to wipe a number of needles firmly on white paper tissue. Some left grey lines, and these were regarded as evidence of metallic or oily residue from the needle surface which could have been deposited in the patient. These unexpected findings, in a variety of popularly used needles from well-respected suppliers, suggest that most manufacturers need to reassess their quality control procedures.

The susceptibility of Brugia malayi microfilariae and adults to injury by the murine macrophage cell line J774 activated with gamma interferon and bacterial lipopolysaccharide has been examined in vitro. Parasites of both stages showed a decline in viability over 48 h of coculture with activated macrophages, assessed by their capacity to reduce the tetrazolium salt 3-[4,5-diethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), although adult parasites were more resistant than microfilariae. Removal of parasites to cell-free medium following exposure to activated macrophages for up to 48 h resulted in partial recovery of their capacity to reduce MTT, suggesting that the effects were primarily cytostatic. However, prolonged exposure to activated J774 cells for 72 h resulted in parasite death. Addition of the nitric oxide synthase inhibitor L-NMMA (N Gmonomethyl-L-arginine monoacetate) indicated that nitric oxide derivatives were responsible for cytostasis and ultimate toxicity. The toxicity of nitric oxide derivatives was confirmed by coincubation of parasites with chemical donors, although far higher concentrations were required than those generated by activated J774 cells, implying additional complexity in macrophage-mediated cytotoxicity. These experiments further suggested that peroxynitrite or its by-products were more potently damaging to filariae than nitric oxide per se. Examination of ultrastructural changes on exposure of parasites to activated macrophages or donors of nitric oxide indicated that hypodermal mitochondria were highly vacuolated, with less prominent cristae. The data are discussed with reference to immunity to lymphatic filariae and their mechanisms of energy generation.

Processing of antigen for recognition by class II-restricted CD4+ T cells occurs within acidic compartments of the antigen-presenting cell. The exact nature of this compartment has yet to be precisely defined, however, but may vary depending upon the cell type studied and the antigen used. The acidic compartments of macrophages are also responsible for the degradation of ingested micro-organisms and play host to others which are adapted to an intracellular existence. To determine whether the phagolysosome (PL) formed in activated macrophages after ingestion of Leishmania parasites is also a site for entry of antigen into the class II presentation pathway, we have used the approach of genetic transformation. Hence, Leishmania were transfected with the genes for the protein antigens ovalbumin (OVA) and beta-galactosidase (beta-gal) and after infection were able to deliver these antigens specifically into the PL. Delivery of antigen to this site resulted in the ability of infected macrophages to present these antigens to antigen-specific CD4+ T cells. After taking into account the absolute levels of antigen uptake by macrophages, a 4-h processing period for OVA delivered by this or a soluble route led to equivalent levels of T cell activation. Unlike macrophages pulsed with soluble OVA, those with PL-targeted OVA still retained the ability to stimulate T cells after a 24-h processing period. This enhanced lifespan of antigen in macrophages corresponded to the kinetics of degradation of the parasite, suggesting slow release of antigen into the processing pathway. beta-gal presentation from the PL was tenfold less efficient under the same conditions. In addition to providing the first information on antigen processing in a protozoan PL, these studies highlight the usefulness of genetically transformed parasites for these types of studies.

No abstract