Endotoxin and nanobacteria in polycystic kidney disease.

BACKGROUND: Microbes have been suspected as provocateurs of polycystic kidney disease (PKD), but attempts to isolate viable organisms have failed. Bacterial endotoxin is the most often reported microbial product found in PKD fluids. We assessed potential microbial origins of endotoxin in cyst fluids from 13 PKD patients and urines of PKD and control individuals. METHODS: Fluids were probed for endotoxin and nanobacteria, a new bacterium, by the differential Limulus Amebocyte Lysate assay (dLAL), genus-specific antilipopolysaccharide (LPS) antibodies, monoclonal antibodies to nanobacteria, and hyperimmune serum to Bartonella henselae (HS-Bh). Selected specimens were also assessed by transmission electron microscopy (TEM) and nanobacterial culture methods. RESULTS: LPS or its antigenic metabolites were found in more than 75% of cyst fluids tested. Nanobacteria were cultured from 11 of 13 PKD kidneys, visualized in 8 of 8 kidneys by TEM, and immunodetected in all 13 PKD kidneys. By immunodetection, nanobacterial antigens were found in urine from 7 of 7 PKD males, 1 of 7 PKD females, 3 of 10 normal males, and 1 of 10 normal females. "Nanobacterium sanguineum" was dLAL positive and cross-reactive with antichlamydial LPS and HS-Bh. Some cyst fluids were also positive for LPS antigens from Escherichia coli, Bacteroides fragilis and/or Chlamydia, and HS-Bh, as were liver cyst fluids from one patient. Tetracycline and citrate inhibited nanobacterial growth in vitro. CONCLUSION: Nanobacteria or its antigens were present in PKD kidney, liver, and urine. The identification of candidate microbial pathogens is the first step in ascertaining their contribution, if any, to human disease.

Platelet ultrastructure of high-risk premature infants.

Hemorrhagic and thrombotic complications are common in the term and preterm infant. Limited information is currently available about neonatal platelet structure and function, and how these may predispose infants to bleeding problems. This study comparing platelet ultrastructure of 71 different term and preterm infants with that of 15 adult control subjects revealed certain platelet morphological differences. Specifically, the adult platelets had more pseudopods, larger glycogen deposits, more visible microtubular structure, markedly fewer alpha granules, and smaller areas/perimeters than the infant platelets. Also, in infants greater than 31 weeks gestation, the platelets of vaginally-delivered infants were larger than those of both infants delivered by C-section and normal adults. These differences in platelet size and morphology may be related to developmental differences and/or the stress of delivery. These findings provide a framework for further exploration of neonatal platelet structure and function.

Autosomal recessive polycystic kidney disease: characterization of human peritoneal and cystic kidney cells in vitro.

Renal cystic epithelia and peritoneal mesothelia from two humans with autosomal recessive polycystic kidney disease (ARPKD) were grown in culture. Cystic epithelial and mesothelial cells formed continuous monolayers in vitro. By electron microscopy, cystic renal cells exhibited a single apical cilium and numerous short, stubby microvilli, both in situ and in vitro. Mesothelial cells exhibited intra- and extracellular membrane-limited, lipid-filled vesicles and surface microvilli. Cystic kidney cells in vitro stained positive for lectins from Cancanavalia ensiformis (concanavalin A), Triticum vulgaris, Erythrina cristagalli, Ulex europeaus, and Arachis hypogaea. Immunocytochemical and lectin staining revealed the renal and peritoneal cells to be of collecting tubule and mesothelial origin, respectively. Both cell types showed large depositions of glycogen granules in the cytoplasm during propagation in certain culture media; in kidney cells, dibutyryl cyclic adenosine monophosphate (cAMP) abolished glycogen depositions. Glycogen deposition also was observed in liver tissue obtained by needle biopsy from one patient. No bacteria were cultured from nor endotoxin detected in the renal cyst fluid. Relative to serum, the cyst fluids contained low sodium, potassium, and chloride levels. Thus, cultured ARPKD cells demonstrate a number of characteristics that are different from cells derived from the autosomal dominant form of renal cystic disease (ADPKD).