Dual functional therapeutics: mitigating bacterial infection and associated inflammation

The emergence of antimicrobial resistance, coupled with the occurrence of persistent systemic infections, has already complicated clinical therapy efforts. Moreover, infections are also accompanied by strong inflammatory responses, generated by the host's innate and adaptive immune systems. The closely intertwined relationship between bacterial infection and inflammation has multiple implications on the ability of antibacterial therapeutics to tackle infection and inflammation. Particularly, uncontrolled inflammatory responses to infection can lead to sepsis, a life-threatening physiological condition. In this review, we discuss dual-functional antibacterial therapeutics that have potential to be developed for treating inflammation associated with bacterial infections. Immense research is underway that aims to develop new therapeutic agents that, when administered, regulate the excess inflammatory response, i.e. they have immunomodulatory properties along with the desired antibacterial activity. The classes of antibiotics that have immunomodulatory function in addition to antibacterial activity have been reviewed. Host defense peptides and their synthetic mimics are amongst the most sought-after solutions to develop such dual-functional therapeutics. This review also highlights the important classes of peptidomimetics that exhibit both antibacterial and immunomodulatory properties.

Effect of feeding protein deficient diet on phospholipid turnover and protein kinase C mediated protein phosphorylation in rat brain

Feeding of protein deficient diet is known to alter the transmembrane signalling in brain of rat by reducing total protein kinase C (PKC) activity. Phospholipid metabolism regulates the activation of PKC through generation of second messengers and the extent of PKC activation accordingly influences the magnitude of phosphorylation of its endogenous substrate proteins. Thus it was speculated that ingestion of protein deficient diet may modify the turnover rate of membrane phospholipids and magnitude of phosphorylation of endogenous substrate proteins of PKC. The experiments were conducted on rats fed on three different types of laboratory prepared diets viz. casein (20% casein), deficient (4% protein, rice flour as source of protein) and supplemented (deficient diet supplemented with L-lysine and DL-threonine) for 28 days. The metabolism of phosphoinositides (PIs) and phosphatidyl choline (PC) was studied by equilibrium labeling with [3H] myo inositol and [14C methyl] choline chloride respectively. The phosphorylation of endogenous substrate proteins of PKC was studied by using 32P-gamma-ATP followed by SDS-PAGE and autoradiography. The results suggest that in deficient group, there is an increased incorporation of [3H] myo inositol in PIs and inositol phosphate pool in comparison to the casein group. The phosphatidyl inositol (PI) turnover reduced, although there was a marginal increase in the phosphatidyl inositol monophosphate (PIP) and phosphatidyl inositol bis phosphate (PIP2). Supplementation of diet showed a reversal of the pattern towards control to a considerable extent. In the deficient group, PC metabolism showed an increased incorporation of [14C methyl] choline in choline phospholipids but decreased incorporation in phosphoryl choline in comparison with the casein group. The increase in total PC contents was significant but marginal in residue contents. The turnover rate of PC increased only marginally and that of residue declined. Supplementation of diet reduced the total contents of PC and residue, but the turnover rate of PC and residue remained still higher. Phosphorylation of endogenous proteins showed four different proteins of 78, 46, 33 and 16 kDa to be the substrates of PKC in casein group. In deficient group, phosphorylation of these proteins increased markedly while supplementation of diet had a reversing effect rendering the values to be intermediate between casein and the supplemented group. The changes in phospholipid metabolism and in phosphorylation of endogenous substrate proteins of PKC suggest that dietary protein deficiency causes alterations in transmembrane signalling mechanism in rat brain. These effects are partially reversed by improving the quality of proteins in the diet.

Antisphingolipid antibodies in the sera of leprosy patients

Earlier we reported the presence of significant levels of antigalactocerebroside (GalC) antibodies in the sera of leprosy patients. This study corroborates the above result and also gives evidence for the presence of antibodies to the nonpolar ceramide (Cer) moiety of GalC. AntiCer antibody titres were higher as compared to antiGalC antibodies in all categories of leprosy. The specificity of antibodies directed to the Cer moiety was confirmed using Lactosyl-BSA and neutralization assays. Statistically significant and positive correlations were observed between antiGalC and antiCer antibodies. Responsiveness factors were computed using natural logarithmic transformation of the variables.