TLR8: the forgotten relative revindicated

The endosomal Toll-like receptors (TLRs) TLR3, TLR7, TLR8 and TLR9 are important in sensing foreign nucleic acids encountered by phagocytes. Because TLR8 was initially thought to be non-functional in mice, less is known about TLR8 than the genetically and functionally related TLR7. Originally associated with the recognition of single-stranded RNA of viral origin, there is now evidence that human TLR8 is also able to sense bacterial RNA released within phagosomal vacuoles, inducing the production of both nuclear factor (NF)-κB-dependent cytokines and type I interferons (IFNs), such as IFN-β. The functions of TLR8 extend beyond the recognition of foreign pathogens and include cross-talk with other endosomal TLRs, a process that may also have a role in the generation of autoimmunity.     

II. A Brief Introduction to the thought of Armando B. Ferrari

This paper describes the work of Armando Bianco Ferrari whose central tenet is the very direct relationship between the body (Concrete Original Object) and the mind to which it gives rise, but which is also mind's first and essentially only real object. Ferrari's approach offers an important avenue of approach to the treatment of psychosis, psychosomatic illness and anorexia, for instance, as is recorded in a by now growing Anglophone literature. The direct relationship between body and mind is in contrast to the object relations model in which this relationship is mediated through the breast. The paper starts with a short biological sketch of Ferrari's life before describing his theoretical position. This is largely concerned with the relationship between the mind and its body, the so‐called ‘vertical axis’, and that with the external world which he calls, the ‘horizontal axis’. The relationship between body and mind is achieved through the means of a ‘contact net’ (as opposed to Bion's contact barrier) and the evolution of ‘language registers’ out of patterns of bodily experience. Ferrari's formulation also involves modifications of the ways he conceives the ego and the oedipal situation (‘Oedipal constellation’), especially in the light of what he takes to be an innate femininity and masculinity in either sex, as well as the way in which he frames ideas about health and illness. The fact that the emphasis is directed towards the subject's direct apperception of the sensational and emotional life of his body rather than one mediated exclusively via the object involves a parallel shift away from the transference as always necessarily central to interpretation, without of course dispensing with it or suggesting that it is not ubiquitous. This is one of the various clinical implications of Ferrari's model which is discussed before offering an illustrative clinical vignette, and finally relating Ferrari's thought to some other current theoretical and clinical formulations.     

Serpin-1 splicing isoform J inhibits the proSpätzle-activating proteinase HP8 to regulate expression of antimicrobial hemolymph proteins in Manduca sexta

The innate immune system of insects include the Toll pathway, which is mediated by an extracellular serine proteinase cascade. In the tobacco hornworm, Manduca sexta, hemolymph proteinase 8 (HP8) promotes the synthesis of antimicrobial proteins by cleaving proSpätzle, the putative ligand of M. sexta Toll. HP8 has been observed to form a complex in hemolymph with M. sexta serpin-1, which has multiple alternative splicing isoforms. To investigate the regulation of HP8 and its processing of proSpätzle, we characterized the interaction of recombinant HP8 with serpin-1 isoform J (serpin-1J). Recombinant serpin-1J formed an SDS-stable complex with HP8 in vitro. The association rate constant of serpin-1J and HP8 was 1.3 × 10⁴ M⁻¹ s⁻¹, with a stoichiometry of inhibition of 5.4. Serpin-1J inhibited the cleavage of proSpätzle by HP8. Injection of serpin-1J into M. sexta larvae resulted in decreased bacteria-induced antimicrobial activity in hemolymph and reduced expression of cecropin, attacin and hemolin mRNA in fat body. Altogether, these results suggest that serpin-1J functions to inhibit HP8 and thereby modulates the concentration of active Spätzle to regulate the Toll pathway response in M. sexta.     

Human immunodeficiency virus-1 infection protects against a Tc1-to-Tc2 shift in CD8(+) T cells

Despite the reports of dysfunction of the lytic abilities of CD8(+) T cells during human immunodeficiency virus-1 (HIV-1) disease progression, the effects of infection on the noncytolytic functions of CD8(+) T cells have not been well characterized to date. We examined the effect of HIV-1 infection on the cytokine and chemokine responses of peripheral blood-derived CD8(+) T cells in an in vitro system. Activation of HIV-1-infected CD8(+) T cells with phytohemagglutinin resulted in a 4- to 8-fold increase in the production of macrophage inflammatory protein (MIP)-1α, MIP-1β, regulated on activation normal T-cell expressed and secreted, and interleukin (IL)-16. Treatment of activated HIV-1-infected CD8(+) T cells with anti-CD3 monoclonal (M) antibody (Ab) and IL-15 induced strong production of interferon-γ (IFN-γ). Treatment of cells with anti-IL-12 MAb and IL-4 to induce a Tc1-to-Tc2 shift resulted in no change in viral production levels or IFN-γ production within the HIV-1-infected CD8(+) T cell population. Initiation of a Tc2-to-Tc1 shift resulted in a 6-fold increase in HIV-1 replication and 2- to 3-fold higher levels of IFN-γ, demonstrating that infection can protect against a Tc1-to-Tc2 shift in CD8(+) T cells.     

The inflammasome: an integrated view

An inflammasome is a multiprotein complex that serves as a platform for caspase-1 activation and caspase-1-dependent proteolytic maturation and secretion of interleukin-1β (IL-1β). Though a number of inflammasomes have been described, the NLRP3 inflammasome is the most extensively studied but also the most elusive. It is unique in that it responds to numerous physically and chemically diverse stimuli. The potent proinflammatory and pyrogenic activities of IL-1β necessitate that inflammasome activity is tightly controlled. To this end, a priming step is first required to induce the expression of both NLRP3 and proIL-1β. This event renders the cell competent for NLRP3 inflammasome activation and IL-1β secretion, and it is highly regulated by negative feedback loops. Despite the wide array of NLRP3 activators, the actual triggering of NLRP3 is controlled by integration a comparatively small number of signals that are common to nearly all activators. Minimally, these include potassium efflux, elevated levels of reactive oxygen species (ROS), and, for certain activators, lysosomal destabilization. Further investigation of how these and potentially other as yet uncharacterized signals are integrated by the NLRP3 inflammasome and the relevance of these biochemical events in vivo should provide new insight into the mechanisms of host defense and autoinflammatory conditions.     

Neuropsin--a possible modulator of synaptic plasticity

Accumulating evidence has suggested pivotal roles for neural proteases in development, maturation, aging, and cognitive functions. Among such proteases, neuropsin, a kallikrein gene-related (KLK) endoprotease, appears to have a significant plasticity function that has been analyzed primarily in the hippocampal Schaffer-collateral pathway. In this article, after reviewing the general features of neuropsin, its role in Schaffer-collateral synaptic plasticity is discussed in some detail. Enzymatically active neuropsin is necessary to establish the early phase of long-term potentiation (LTP). This type of LTP, which can be elicited by rather weak tetanic stimulation, is significant in synaptic late association between two independent hippocampal synapses. Neuropsin deficiency completely impaired the early phase of LTP, leading to the absence of late associativity. Associations between early and persistent-LTP synapses may be related to mammalian working memory and consequently integration in learning and memory.     

Relationship between toll-like receptor 8 gene polymorphisms and pediatric pulmonary tuberculosis

Objectives: Genetic variants in Toll-like receptors (TLRs) are considered a potential indicator for host susceptibility to and outcome of several infectious diseases including tuberculosis. The aim of this study was to determine whether −129 C/G and Met1Val polymorphisms of TLR8 were associated with pediatric pulmonary tuberculosis in Turkish population. Methods: The −129 C/G and Met1Val polymorphisms were studied in 124 children with pulmonary tuberculosis compared to 150 age-matched healthy control subjects. Results: We did not identify any statistically significant differences between the patients with TB and control groups with regard to the frequency of genotypes GG or G/(−), CG, and CC or C/(−); and alleles G and C at rs3764879 (p > 0.05). We found a strong association with genotype A/(−) at rs3764880 with susceptibility to pulmonary TB in males (OR 2.87, 95%CI 1.38–5.98, p = 0.007). Conclusions: Our results provide evidence, for the first time, of a role for the TLR8 gene in susceptibility to pulmonary TB in male children. Additional research to verify our results are necessary. Tuberculosis in children presents particularly difficult challenges, but research priorities and advances in pediatric tuberculosis could provide wider insights and opportunities for tuberculosis control.     

Double- and monofunctional CD4⁺ and CD8⁺ T-cell responses to Mycobacterium tuberculosis DosR antigens and peptides in long-term latently infected individuals

More than 2 billion individuals are latently infected with Mycobacterium tuberculosis (Mtb). Knowledge of the key Mtb antigens and responding T-cell subsets mediating protection against Mtb is critical for developing improved tuberculosis (TB) vaccines. We previously reported that Mtb DosR-regulon-encoded antigens are recognized well by human T cells in association with control of Mtb infection. The characteristics of the responding T-cell subsets, however, remained unidentified. We have therefore studied the cytokine production and memory phenotypes of Mtb DosR-regulon-encoded antigen-specific T cells from individuals who had been infected with Mtb decades ago, yet never developed TB (long-term latent Mtb-infected individuals). Using multi-parameter flow cytometry and intracellular cytokine staining for IFN-γ, TNF-α and IL-2, we found double and single cytokine-producing CD4(+) as well as CD8(+) T cells to be the most prominent subsets, particularly IFN-γ(+) TNF-α(+) CD8(+) T cells. The majority of these T cells comprised effector memory and effector T cells. Furthermore, CFSE labeling revealed strong CD4(+) and CD8(+) T-cell proliferative responses induced by several "immunodominant" Mtb DosR antigens and their specific peptide epitopes. These findings demonstrate the prominent presence of double- and monofunctional CD4(+) and CD8(+) T-cell responses in naturally protected individuals and support the possibility of designing Mtb DosR antigen-based TB vaccines.