Beta-lactam antibiotics: from antibiosis to resistance and bacteriology KONG, KOK-FAI; SCHNEPER, LISA; MATHEE, KALAI
APMIS : acta pathologica, microbiologica et immunologica Scandinavica,
2010, 2010-01, January 2010, 2010-Jan, 2010-01-00, 20100101, Volume:
118, Issue:
1
Journal Article
Peer reviewed
Open access
Kong K-F, Schneper L, Mathee K. Beta-lactam antibiotics: from antibiosis to resistance and bacteriology. APMIS 2010; 118: 1-36. This review focuses on the era of antibiosis that led to a better ...understanding of bacterial morphology, in particular the cell wall component peptidoglycan. This is an effort to take readers on a tour de force from the concept of antibiosis, to the serendipity of antibiotics, evolution of beta-lactam development, and the molecular biology of antibiotic resistance. These areas of research have culminated in a deeper understanding of microbiology, particularly in the area of bacterial cell wall synthesis and recycling. In spite of this knowledge, which has enabled design of new even more effective therapeutics to combat bacterial infection and has provided new research tools, antibiotic resistance remains a worldwide health care problem.
The protein kinase C (PKC) family, discovered in the late 1970s, is composed of at least 10 serine threonine kinases, divided into three groups based on their molecular architecture and cofactor ...requirements. PKC enzymes have been conserved throughout evolution and are expressed in virtually all cell types; they represent critical signal transducers regulating cell activation, differentiation, proliferation, death, and effector functions. PKC family members play important roles in a diverse array of hematopoietic and immune responses. This review covers the discovery and history of this enzyme family, discusses the roles of PKC enzymes in the development and effector functions of major hematopoietic and immune cell types, and points out gaps in our knowledge, which should ignite interest and further exploration, ultimately leading to better understanding of this enzyme family and, above all, its role in the many facets of the immune system.
Biofilms are surface-attached agglomerations of microorganisms embedded in an extracellular matrix. Biofilm-associated infections are difficult to eradicate and represent a significant reservoir for ...disseminating and recurring serious infections. Infections involving biofilms frequently develop on indwelling medical devices in hospitalized patients, and Staphylococcus epidermidis is the leading cause of infection in this setting. However, the molecular determinants of biofilm dissemination are unknown. Here we have demonstrated that specific secreted, surfactant-like S. epidermidis peptides--the β subclass of phenol-soluble modulins (PSMs)--promote S. epidermidis biofilm structuring and detachment in vitro and dissemination from colonized catheters in a mouse model of device-related infection. Our study establishes in vivo significance of biofilm detachment mechanisms for the systemic spread of biofilm-associated infection and identifies the effectors of biofilm maturation and detachment in a premier biofilm-forming pathogen. Furthermore, by demonstrating that antibodies against PSMβ peptides inhibited bacterial spread from indwelling medical devices, we have provided proof of principle that interfering with biofilm detachment mechanisms may prevent dissemination of biofilm-associated infection.
Signaling via the inducible costimulator ICOS fuels the stepwise development of follicular helper T cells (TFH cells). However, a signaling pathway unique to ICOS has not been identified. We found ...here that the kinase TBK1 associated with ICOS via a conserved motif, IProx, that shares homology with the tumor-necrosis-factor receptor (TNFR)-associated factors TRAF2 and TRAF3. Disruption of this motif abolished the association of TBK1 with ICOS, TRAF2 and TRAF3, which identified a TBK1-binding consensus. Alteration of this motif in ICOS or depletion of TBK1 in T cells severely impaired the differentiation of germinal center (GC) TFH cells and the development of GCs, interfered with B cell differentiation and disrupted the development of antibody responses, but the IProx motif and TBK1 were dispensable for the early differentiation of TFH cells. These results reveal a previously unknown ICOS-TBK1 signaling pathway that specifies the commitment of GC TFH cells.
Follicular helper T (T
) cells represent a highly specialized CD4
T cell subpopulation that supports the generation of germinal centers (GC) and provides B cells with critical signals promoting ...antibody class switching, generation of high affinity antibodies, and memory formation. T
cells are characterized by the expression of the chemokine receptor CXCR5, the transcription factor Bcl-6, costimulatory molecules ICOS, and PD-1, and the production of cytokine IL-21. The acquisition of a T
phenotype is a complex and multistep process that involves signals received through engagement of the TCR along with a multitude of costimulatory molecules and cytokines receptors. Members of the Tumor necrosis factor Receptor Associated Factors (TRAF) represent one of the major classes of signaling mediators involved in the differentiation and functions of T
cells. TRAF molecules are the canonical adaptor molecules that physically interact with members of the Tumor Necrosis Factor Receptor Superfamily (TNFRSF) and actively modulate their downstream signaling cascades through their adaptor function and/or E3 ubiquitin ligase activity. OX-40, GITR, and 4-1BB are the TRAF-dependent TNFRSF members that have been implicated in the differentiation and functions of T
cells. On the other hand, emerging data demonstrate that TRAF proteins also participate in signaling from the TCR and CD28, which deliver critical signals leading to the differentiation of T
cells. More intriguingly, we recently showed that the cytoplasmic tail of ICOS contains a conserved TANK-binding kinase 1 (TBK1)-binding motif that is shared with TBK1-binding TRAF proteins. The presence of this TRAF-mimicking signaling module downstream of ICOS is required to mediate the maturation step during T
differentiation. In addition, JAK-STAT pathways emanating from IL-2, IL-6, IL-21, and IL-27 cytokine receptors affect T
development, and crosstalk between TRAF-mediated pathways and the JAK-STAT pathways can contribute to generate integrated signals required to drive and sustain T
differentiation. In this review, we will introduce the molecular interactions and the major signaling pathways controlling the differentiation of T
cells. In each case, we will highlight the contributions of TRAF proteins to these signaling pathways. Finally, we will discuss the role of individual TRAF proteins in the regulation of T cell-dependent humoral responses.
•PKC enzymes have crucial and diverse roles in multiple signaling pathways utilized by adaptive and innate immune cells.•Various immune system defects were documented in gene knockout mice ...genetically deficient in most individual PKC (Prkc) genes.•A null mutation of one Prkc gene (Prkcd), which largely phenocopies the corresponding gene knockout mouse, was identified in a human with immune disorders.•Single nucleotide polymorphisms in human Prkc gene loci are associated with various immune-related disorders, including rheumatoid arthritis and juvenile diabetes.•The function and regulation of PKCs in the human immune system and the degree of redundancy among PKC family members represent important future research areas.•Strategies that inhibit the catalytic activity of PKC enzymes or their essential regulatory processes represent attractive therapeutic approaches for treating immune-related disorders.
Protein kinase C (PKC) proteins are a group of well-conserved, intracellular signaling enzymes expressed in all cells and tissues, including immune cells. Much of the molecular insight into PKC immunobiology has been gleaned from studies using PKC gene (Prkc) knockout mice and the analysis of different disease models in these animals. More-recent studies have revealed that PKCs also have crucial roles in the pathogenesis of human immune disorders. Therefore, strategies to modulate the functions of PKC enzymes could have a major impact on the treatment and therapies of autoimmune diseases and other immune disorders.
Polymorphonuclear leukocytes (PMNs) are key in innate immunity, but their role in viral pathogenesis is incompletely understood. In infection due to West Nile virus (WNV), we found that expression of ...2 PMNattracting chemokines, Cxcl1 and Cxcl2, was rapidly and dramatically elevated in macrophages. PMNs are rapidly recruited to the site of WNV infection in mice and support efficient replication of WNV. Mice depleted of PMNs after WNV inoculation developed higher viremia and experienced earlier death, compared with the control group, which suggest a protective role for PMNs. In contrast, when PMNs were depleted prior to infection with WNV, and in mice deficient in Cxcr2 (a chemokine receptor gene), viremia was reduced and survival was enhanced. Collectively, these data suggest that PMNs have a biphasic response to WNV infection, serving as a reservoir for replication and dissemination in early infection and later contributing to viral clearance.
The immunological synapse (IS) formed between immune cells and antigen-presenting cells (APCs) provides a platform for signaling. Protein kinase C (PKC)θ localizes in the T cell IS within the central ...supramolecular activation cluster (cSMAC), where it associates with CD28 and mediates T cell receptor (TCR)/CD28 signals leading to effector T (Teff) cell activation. In regulatory T (Treg) cells, PKCθ is sequestered away from the IS, and inhibits suppressive function. Other PKCs localizing in the IS mediate additional functions in various immune cells. Further work is needed to identify mechanisms underlying PKC recruitment or exclusion at the IS, potential redundancy among IS-localized PKCs, and the relevance of PKC localization for IS dynamics and lymphocyte activation.
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