Antimicrobial peptides (AMPs) are host-defense agents capable of both bacterial membrane disruption and immunomodulation. However, the development of natural AMPs as potential therapeutics is hampered by their moderate activity and susceptibility to protease degradation. Herein we report lipidated cyclic γ-AApeptides that have potent antibacterial activity against clinically relevant Gram-positive and Gram-negative bacteria, many of which are resistant to conventional antibiotics. We show that lipidated cyclic γ-AApeptides mimic the bactericidal mechanism of AMPs by disrupting bacterial membranes. Interestingly, they also harness the immune response and inhibit lipopolysaccharide (LPS) activated Toll-Like Receptor 4 (TLR4) signaling, suggesting that lipidated cyclic γ-AApeptides have dual roles as novel antimicrobial and anti-inflammatory agents.

Toll-like receptors (TLRs) are type I transmembrane proteins that are key regulators of both innate and adaptive immune responses. To protect the host from viral and bacterial threats, TLRs trigger a pro-inflammatory immune response by detecting pathogen and danger associated molecular patterns. Considerable evidence has accumulated to show that the dysregulation of TLR signaling contributes to the development and progression of numerous diseases. Therefore, TLRs are emerging as important drug discovery targets. Currently, there is great interest in the development of TLR small molecule modulators for interrogating TLR signaling and treating diseases caused by TLR signaling malfunctions. In this Tutorial Review, we will outline methods for the discovery of TLR small molecule modulators and the up-to-date progress in this field. Small molecules targeting TLRs not only provide an opportunity to identify promising drug candidates, but also unveil knowledge regarding TLR signaling pathways.

Associations between the presence of a constitutional variant of delta-aminolevulinic acid dehydratase (ALAD-2) and lead concentrations in blood and bone, as well as between this allele and indices of kidney function, were investigated among 691 members of a construction trade union. The average blood lead level in this group was 7.78 micrograms/dl. No significant difference was observed in blood lead concentration in ALAD-2 carriers compared to those homozygous for the more common ALAD-1 allele (7.78 +/- 3.62 micrograms Pb/dl vs. 7.73 ( +/- 3.48 micrograms Pb/dl, respectively; p = 0.73). Bone lead was measured in a subset of 122 of the study subjects. Patella minus tibia lead concentrations for each individual averaged 3.35 +/- 11.99 micrograms Pb/g bone mineral in ALAD-1 homozygotes and 8.62 +/- 9.47 micrograms Pb/g bone mineral in ALAD-2 carriers (p = 0.06). Comparisons of blood urea nitrogen (BUN) and uric acid by genotype indicated elevated levels among ALAD-2 individuals (p = 0.03 and 0.07, respectively). In logistic regression models accounting for other variables potentially associated with BUN and uric acid levels, BUN was significantly associated with blood lead levels (p = 0.01). Associations of BUN and uric acid levels with ALAD-2 were of borderline statistical significance in these models (p = 0.06 and 0.07). Taken together, these results suggest that the ALAD-2 genotype may influence the pharmacokinetic distribution and chronic renal toxicity of lead, perhaps due to differential binding of lead to the variant protein.Imagesp248-aFigure 1.

Rifampin has been used for the treatment of bacterial infections for many years. Clinically, rifampin has been found to possess immunomodulatory effects. However, the molecular target responsible for the immunosuppressive effects of rifampin is not known. Herein, we show that rifampin binds to myeloid differentiation protein 2 (MD-2), the key coreceptor for innate immune TLR4. Rifampin blocked TLR4 signaling induced by LPS, including NF-κB activation and the overproduction of proinflammatory mediators nitric oxide, interleukin 1β, and tumor necrosis factor α in mouse microglia BV-2 cells and macrophage RAW 264.7 cells. Rifampin's inhibition of TLR4 signaling was also observed in immunocompetent rat primary macrophage, microglia, and astrocytes. Further, we show that rifampin (75 or 100 mg/kg b.i.d. for 3 d, intraperitoneal) suppressed allodynia induced by chronic constriction injury of the sciatic nerve and suppressed nerve injury-induced activation of microglia. Our findings indicate that MD-2 is a important target of rifampin in its inhibition of innate immune function and contributes to its clinically observed immune-suppressive effect. The results also suggest that rifampin may be repositioned as an agent for the treatment of neuropathic pain.

Summary Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most commonly used drugs in the world. While the role of NSAIDs as cyclooxygenase (COX) inhibitors is well established, other targets may contribute to anti-inflammation. Here we report caspases as a new pharmacological target for NSAID-family drugs such as ibuprofen, naproxen, and ketorolac at physiologic concentrations both in vitro and in vivo. We characterize caspase activity both in vitro and in cell culture, and combine computational modeling and biophysical analysis to determine the mechanism of action. We observe that inhibition of caspase catalysis reduces cell death and the generation of pro-inflammatory cytokines. Further, NSAID inhibition of caspases is COX-independent, representing a new anti-inflammatory mechanism. This finding expands upon existing NSAID anti-inflammatory behaviors, with implications for patient safety and next-generation drug design.