Blaine L. Beaman

Interferon‐γ activation of polymorphonuclear neutrophil function

As current research illuminates the dynamic interplay between the innate and acquired immune responses, the interaction and communication between these two arms has yet to be fully investigated. Polymorphonuclear neutrophils (PMNs) and interferon‐γ (IFN‐γ) are known critical components of innate and acquired immunity, respectively. However, recent studies have demonstrated that these two components are not entirely isolated. Treatment of PMNs with IFN‐γ elicits a variety of responses depending on stimuli and environmental conditions. These responses include increased oxidative burst, differential gene expression, and induction of antigen presentation. Many of these functions have been overlooked in PMNs, which have long been classified as terminal phagocytic cells incapable of protein synthesis. As this review reports, the old definition of the PMN is in need of an update, as these cells have demonstrated their ability to mediate the transition between the innate and acquired immune responses.

Bacterial Clearance and Survival Are Dependent on CXC Chemokine Receptor-2 Ligands in a Murine Model of Pulmonary Nocardia asteroides Infection

Survival from murine pulmonary nocardiosis is highly dependent on CXC chemokine receptor-2 (CXCR2) ligand-mediated neutrophil chemotaxis and subsequent clearance of the infectious agent Nocardia asteroides. Intratracheal inoculation of N. asteroides rapidly up-regulated the CXC chemokines macrophage inflammatory protein-2 (MIP-2) and KC within 24 h, with levels remaining elevated through day 3 before returning to near baseline levels by day 7. Coinciding with elevated MIP-2 and KC were the rapid recruitment of neutrophils and clearance of the organism. Anti-Ly-6G Ab-mediated neutrophil depletion before bacterial challenge resulted in strikingly increased mortality to N. asteroides infection. The relative contribution of MIP-2 in neutrophil recruitment was examined by anti-MIP-2 Ab treatment before nocardial infection. MIP-2 neutralization had no detrimental effects on survival, neutrophil recruitment, or bacterial clearance, suggesting the usage of additional or alternative CXCR2-binding ligands. The importance of the CXC family of chemokines was determined by the administration of an anti-CXCR2 Ab capable of blocking ligand binding in vivo. Anti-CXCR2 treatment greatly increased mortality by preventing neutrophil migration into the lung. Paralleling this impaired neutrophil recruitment was a 100-fold increase in lung bacterial burden. Combined, these observations indicate a critical role for neutrophils and CXC chemokines during nocardial pneumonia. These data directly link CXCR2 ligands and neutrophil recruitment and lend further support to the concept of CXC chemokine redundancy. For infections highly dependent on neutrophils, such as nocardial pneumonia, this is of critical importance.

Murine polymorphonuclear neutrophils produce interferon‐γ in response to pulmonary infection with Nocardia asteroides

Nocardia asteroides causes an acute, necrotizing pneumonia characterized by extensive infiltration of polymorphonuclear neutrophils (PMNs) into the lungs. Although PMNs have historically been classified as end‐point cells, recent investigations have indicated that PMNs have the ability to secrete cytokines such as interleukin (IL)‐4 and IL‐12. This study investigated the ability of PMNs to produce cytokines in a murine model of N. asteroides pulmonary infection. Flow cytometric analysis demonstrated the production of interferon‐γ (IFN‐γ), but not IL‐4, by PMNs in response to this infection. IFN‐γ production correlated with peak infiltration of PMNs into the lungs. Cell sorting and enzyme‐linked immunosorbent assay were used to confirm cytokine production by cells with nuclear morphology characteristic of PMNs. This is the first report of IFN‐γ production by neutrophils in response to an infection in vivo. These results suggest that PMNs play an important role in directing the host toward a T helper cell type 1 phenotypic response in the lungs.

Characterization of marine luminous bacteria isolated off the Coast of China and description ofVibrio orientalis sp. nov.

Luminous strains of marine bacteria, isolated off the Coast of China, were subjected to a phenotypic characterization, which included a test of their ability to utilize 82 organic compounds as sole or principal sources of carbon and energy. A numerical analysis of the data revealed five clusters which were readily identified asPhotobacterium phosphoreum, P. leiognathi, Vibrio harveyi, andV. splendidus biotype I. The remaining cluster of luminous isolates was phenotypically distinct from all the previously described species ofVibrio andPhotobacterium and was given the species designation,Vibrio orientalis. This species differed from all the other luminous species ofVibrio by its ability to accumulate poly-β-hydroxybutyrate as an intracellular reserve product. Additional distinctive properties were the presence of an arginine dihydrolase system, growth at 4° but not 40°C, and the ability to utilize putrescine and spermine.

Nocardia crassostreae sp. nov., the causal agent of nocardiosis in Pacific oysters.

Seven strains of bacteria were isolated from Pacific oysters, Crassostrea gigas, with a focal or systemic disease. The strains were aerobic, Gram-positive, acid-fast, produced a mycelium which fragmented into irregular rod-like elements, had a peptidoglycan containing meso-diaminopimelic acid, arabinose and galactose as major sugars, mycolic acids with 46-58 carbon atoms and G + C-rich DNA. All of these properties are consistent with the classification of the organisms in the genus Nocardia. A partial sequence of the 16S rRNA gene of isolate NB4H was determined following isolation and cloning of the PCR-amplified gene. The sequence was aligned with those of representative mycolic-acid-containing taxa and a phylogenetic tree was generated using the neighbour-joining method. It was evident from the phylogenetic tree that the three strains tested, RB1, OB3P and NB4H, were identical and belonged to the Nocardia otitidiscaviarum rRNA sub-group. The biochemical, chemical, morphological and physiological properties of the isolates were also essentially identical and served to distinguish them from representative nocardiae. It is, therefore, proposed that the strains isolated from the diseased Pacific oysters be assigned to a new species, Nocardia crassostreae. The type strain is NB4H (= ATCC 700418).

Captive Rhesus Monkeys (Macaca mulatta) Are Commonly Infected with Helicobacter cinaedi

ABSTRACT Helicobacter cinaedi may cause proctocolitis or bacteremia in homosexual men infected with human immunodeficiency virus or occasionally in other immunocompromised hosts. There are scattered reports of H. cinaedi isolated from a variety of animal hosts, but to date only hamsters have been found to be a common natural reservoir. Microaerophillic cultures of feces from 5 of 16 asymptomatic rhesus monkeys (Macaca mulatta) (31%) were positive for a curved gram-negative rod. A polyphasic taxonomic approach was used to identify the organism as H. cinaedi. These results show that H. cinaedi frequently colonizes asymptomatic captive rhesus monkeys, which may serve as another potential reservoir for human infection.

Taxonomy of Marine Pseudomonas Species: P. stanieri sp. nov.; P. perfectomarina sp. nov., nom. rev.; P. nautica: and P. doudoroffii

Recent studies of the evolutionary relationships of nonfermentative, gram-negative, rod-shaped, polarly flagellated, marine bacteria have indicated that some are members of the lineage which includes the type species of the genus Pseudomonas, Pseudomonas aeruginosa. As a result of these findings, one species equivalent (group G-1) with a guanine plus cytosine content slightly beyond the lower limit proposed for Pseudomonas is now included in this genus under the designation Pseudomonas stanieri sp. nov. (type strain 146 = ATCC 27130). In addition, “Pseudomonas perfectomarinus,” an organism not included in the Approved List of Bacterial Names, is a recognizable species and part of this lineage. This name has, therefore, been revived and corrected to Pseudomonas perfectomarina sp. nov. nom. rev. (type strain 218 = ATCC 14405). The phenotypes of these two species and their type strains are described along with those for two other marine Pseudomonas, Pseudomonas nautica and Pseudomonas doudoroffii.

Increase of γδ T lymphocytes in murine lungs occurs during recovery from pulmonary infection by Nocardia asteroides

ABSTRACT Previous studies have demonstrated that γδ T lymphocytes are important for host resistance to pulmonary infection of the murine lung by log-phase cells of Nocardia asteroides. To study the role of γδ T cells in nocardial interactions in the murine lung, C57BL/6J wild type and C57BL/6J-Tcrd (γδ T-cell knockout mice) were infected intranasally with log-phase cells of N. asteroidesGUH-2. At 3, 5, and 7 days after infection, the γδ T cells were quantified by multiparameter flow cytometry. At the same time, Gram and hematoxylin-eosin stains of paraffin sections were performed to monitor the host responses. The data showed that γδ T lymphocytes increased significantly within the lungs after intranasal infection, and the peak of this cellular increase occurred at 5 days. Furthermore, at this time, greater than 50% of the CD3 T-cell receptor (TCR)-positive (CD3+) cells were γδ TCR positive. Histological examination clearly showed divergent inflammatory responses in the lungs of wild-type mice compared to γδ T-cell knockout mice. The C57BL/6J-Tcrd mice were less capable of clearing the organism, and the polymorphonuclear leukocyte response lasted longer than in wild-type C57BL/6J mice. These results showed that γδ T cells were actively involved in modulating the innate host responses to murine pulmonary infection by N. asteroides.

Intraepithelial γδ T lymphocytes: sentinel cells at mucosal barriers

ConclusionsIt is clear that γδ T cells, especially IEL, play more than an accessory role to αβ T cells in immune responses at mucosal borders. They are clearly unique and required for protective immune responses and repair of damaged epithelium. In fact, their role in epithelial surveillance, response and repair may reflect a fundamental role for this lineage of T cells in the overall homeostasis of microenvironments that comprise the mucosal barriers of the host. The consequence of this would make them ideal targets for therapeutic intervention in irreversible and degenerative diseases of the lung and other mucosal environments. In the near future it is anticipated that we will make definitive connections between their physiological stimuli and patterns of responsiveness. Once this is accomplished we may finally be able to construct a more comprehensive map of the functions of T cell immunity in host defense and homeostasis.

In situ hybridization for detection of nocardial 16S rRNA: reactivity within intracellular inclusions in experimentally infected cynomolgus monkeys—and in Lewy body-containing human brain specimens

Our previous studies found that experimental infection of BALB/c mice with the Gram-positive bacterium Nocardia asteroides induced a parkinsonian-type syndrome with levodopa-responsive movement abnormalities, loss of nigrostriatal dopaminergic neurons, depletion of striatal dopamine, and intraneuronal inclusions in the substantia nigra (SN) with an appearance similar to Lewy bodies. In the present study, an in situ hybridization technique was developed to detect nocardial 16S ribosomal RNA (rRNA), using a Nocardia-specific probe (B77). Cerebral cortical specimens from cynomolgus monkeys were examined for the presence of nocardial RNA 48 h, 3.5 months, and 1 year after experimental infection with N. asteroides. Hybridization reactions were detected within Nocardia-like structures 48 h after infection and within intracellular inclusion bodies (immunoreactive for alpha-synuclein and ubiquitin) in one of two 3.5-month-infected monkeys. The in situ hybridization procedure was then applied in a blinded fashion to 24 human SN specimens with Lewy bodies and 11 human SN specimens without Lewy bodies (including five normal controls). Hybridization reactions were detected in nine Lewy body-containing specimens and none of the others. Reactivity was limited to inclusions with the appearance of Lewy bodies, with the exception of one specimen in which intracellular reactivity was also observed in Nocardia-like structures. These results suggest a possible association between Nocardia and neurodegenerative disorders in which Lewy bodies are present.