Disturbed homeostasis of lung intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 during sepsis

Cecal ligation and puncture (CLP)-induced sepsis in mice was associated with perturbations in vascular adhesion molecules. In CLP mice, lung vascular binding of (125)I-monoclonal antibodies to intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 revealed sharp increases in binding of anti-ICAM-1 and significantly reduced binding of anti-VCAM-1. In whole lung homogenates, intense ICAM-1 up-regulation was found (both in mRNA and in protein levels) during sepsis, whereas very little increase in VCAM-1 could be measured although some increased mRNA was found. During CLP soluble VCAM-1 (sVCAM-1) and soluble ICAM-1 (sICAM-1) appeared in the serum. When mouse dermal microvascular endothelial cells (MDMECs) were incubated with serum from CLP mice, constitutive endothelial VCAM-1 fell in association with the appearance of sVCAM-1 in the supernatant fluids. Under the same conditions, ICAM-1 cell content increased in MDMECs. When MDMECs were evaluated for leukocyte adhesion, exposure to CLP serum caused increased adhesion of neutrophils and decreased adhesion of macrophages and T cells. The progressive build-up in lung myeloperoxidase after CLP was ICAM-1-dependent and independent of VLA-4 and VCAM-1. These data suggest that sepsis disturbs endothelial homeostasis, greatly favoring neutrophil adhesion in the lung microvasculature, thereby putting the lung at increased risk of injury.     

Tumor necrosis factor alpha- and inducible nitric oxide synthase-producing dendritic cells are rapidly recruited to the bladder in urinary tract infection but are dispensable for bacterial clearance

The role of dendritic cells (DC) in urinary tract infections (UTI) is unknown. These cells contribute directly to the innate defense against various viral and bacterial infections. Here, we studied their role in UTI using an experimental model induced by transurethral instillation of the uropathogenic Escherichia coli (UPEC) strain 536 into C57BL/6 mice. While few DC were found in the uninfected bladder, many had been recruited after 24 h, mostly to the submucosa and uroepithelium. They expressed markers of activation and maturation and exhibited the CD11b+ F4/80+ CD8- Gr-1- myeloid subtype. Also, tumor necrosis factor alpha (TNF-alpha)- and inducible nitric oxide synthase (iNOS)-producing CD11bINT DC (Tip-DC) were detected, which recently were proposed to be critical in the defense against bacterial infections. However, Tip-DC-deficient CCR2-/- mice did not show reduced clearance of UPEC from the infected bladder. Moreover, clearance was also unimpaired in CD11c-DTR mice depleted of all DC by injection of diphtheria toxin. This may be explained by the abundance of granulocytes and of iNOS- and TNF-alpha-producing non-DC that were able to replace Tip-DC functionality. These findings demonstrate that some of the abundant DC recruited in UTI contributed innate immune effector functions, which were, however, dispensable in the microenvironment of the bladder.     

Extended-spectrum beta-lactamase-producing Enterobacteriaceae in Bulgarian hospitals

The aim of the study was to describe the emergence, the spread, and the prevalence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in Bulgaria. Over eight years (1996-2003), 442 ESBL-screen-positive isolates were collected in nine medical institutions in four Bulgarian towns. Class A ESBLs of the SHV, TEM, and CTX-M groups were identified in seven species. SHV-type enzymes persisted during the whole study period, TEM-ESBLs appeared first in 1999, and CTX-M-types appeared first in 2001. The rate of CTX-M enzyme producers increased rapidly between 2001 and 2003, while the rate of SHV producers decreased. Six different ESBL-types were identified, namely, SHV-2, -5, and -12, CTX-M-3 and -15, and a new TEM-3-like variant (TEM-139). The most widespread enzymes were SHV-12, CTX-M-15, and CTX-M-3 found in seven centers. TEM-139 was identified mainly in one center. A trend for strains harboring more than one ESBL gene, for example, CTX-M + SHV, was observed since 2002. Plasmid fingerprinting and random amplified polymorphic DNA analysis typing revealed wide dissemination of identical plasmids among different bacterial species and hospitals, as well as clonal spread of ESBL producers. Our data contribute to clarify the dynamics in the prevalence of ESBLs in Bulgaria and demonstrate the importance of molecular procedures for their analysis.     

The dermal arteries in the cutaneous angiosome of the descending genicular artery

Studies examining thick skin of the thumb pad have challenged the existence of an arterial plexus in the papillary dermis. Instead of a plexus, discrete arterial units, interconnected by arterio‐arterial anastomoses, were identified. We hypothesise that the dermal arteries of thin skin are arranged likewise and that there are fewer arterio‐arterial anastomoses in the centre of an angiosome than in zones where neighbouring angiosomes overlap. To test these hypotheses, we examined the dermal arteries in the centre of the cutaneous angiosome of the descending genicular artery (DGA) and its zone of overlap with neighbouring angiosomes. Using traditional perfusion techniques, the cutaneous angiosomes of the DGA and the popliteal artery were identified in 11 fresh frozen human lower limbs. Biopsies were harvested from the centre of the cutaneous DGA angiosome and from the zone where neighbouring vascular territories overlapped. Employing high‐resolution episcopic microscopy (HREM), digital volume data were generated and the dermal arteries were three‐dimensionally reconstructed and examined. In all examined skin areas, the dermal arteries showed tree‐like ramifications. The branches of the dermal arteries were connected on average by 1.73 ± 1.01 arterio‐arterial anastomoses in the centre of the DGA angiosome and by 3.27 ± 1.27 in the zone where angiosomes overlapped. We demonstrate that discrete but overlapping dermal arterial units with a mean dimension of 1.62 ± 1.34 and 1.80 ± 1.56 mm², respectively, supply oxygen and nutrients to the superficial dermis and epidermis of the thin skin of the medial femur. This forms the basis for diagnosing and researching skin pathologies.     

Frequency and clinicopathological features of fibroelastotic changes in the gastrointestinal tract

Fibroelastotic changes (FEC) and especially elastotic polyps of the gastrointestinal (GI) tract are considered rare benign lesions. They consist of accumulations of elastic fibers within the mucosal, submucosal, or muscular layer, occurring in all parts of the GI tract and often appearing as polyps, but also as diffuse non-polyp-forming deposits. They have been the subject of only a few studies. To explore the clinical and histopathological features of FEC in the GI tract, a series of 162 elastotic lesions was collected within a 2-year period. The clinical data and endoscopic findings were correlated. FEC appeared as polyp-forming lesions of the large intestine in 23 samples (14 %), all other samples concerning histological findings without an identifiable gross mass. Frequently related findings were postinterventional status (9 %), previous irradiation (7 %), and history of GI lymphoma (4 %). Eight samples (5 %) presented endoscopically with lesions justifying surgical intervention. We identified three different histological patterns of FEC, which we have called fibroelastosis, angioelastosis, and elastofibroma. Consistent with previous studies, CD34 immunohistochemical staining (performed on 38 polypoid FEC specimens) showed an increase of CD34-positive mesenchymal cells in 95 % of immunostained samples, suggesting a potential role for CD34-positive mesenchymal cells in the accumulation of elastic fibers. In conclusion, FEC are more common in the GI tract than previously recognized. They often present as a benign polyp. Many accompany other diseases like ulcers and atrophic gastritis or represent a residual finding after an intervention.     

Predominance of IncL/M and IncF plasmid types among CTX‐M‐ESBL‐producing Escherichia coli and Klebsiella pneumoniae in Bulgarian hospitals

Our objective was to investigate the plasmid replicon‐types involved in spread of ESBLs among Bulgarian Klebsiella pneumoniae and Escherichia coli. Sixty‐three isolates, with transferable beta‐lactam resistance determinants, collected between 2007 and 2009 in six medical institutions, were analysed with respect to their antimicrobial susceptibility, ESBL‐, RAPD‐, and plasmid replicon‐type. Phylogenetic typing and screening for the O25b‐ST131 lineage were carried out for E. coli. The predominant ESBLs were CTX‐M‐15 (81%) among E. coli and CTX‐M‐3 (58%) among K. pneumoniae. Other sporadically found ESBLs were SHV‐12 and TEM‐139, and for the first time in Bulgaria, CTX‐M‐1 and CTX‐M‐14. Replicon typing revealed that plasmids carrying bla_CTX‐M‐3 exclusively belonged to IncL/M‐type, while bla_CTX‐M‐15 was predominantly (94%) associated with IncF‐type plasmids. Among E. coli, 59% of the isolates were clonally related. Isolates of that cluster produced CTX‐M‐15, belonged to the O25b‐ST131 lineage, predominantly harboured plasmids with the FIA replicon, and were found in five centres. Among CTX‐M‐3‐producing K. pneumoniae, two prevailing RAPD‐types were found, one remained restricted to one centre and the second was found in three centres. The incompatibility groups IncN and IncA/C linked with bla_SHV‐12 respectively bla_TEM‐139 were found only once. To the best of our knowledge, this is the first detailed investigation of plasmids carrying ESBL genes among Bulgarian isolates demonstrating wide distribution of conjugative IncF plasmids among CTX‐M‐15‐producing E. coli and IncL/M plasmids among CTX‐M‐3 positive K. pneumoniae isolates.