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Adult T cell leukaemia (ATL), caused by infection with human T‐ lymphotropic virus type 1 (HTLV‐1), is often complicated by hypercalcemia and osteolytic lesions. Therefore, we studied the communication between patient‐derived ATL cells (ATL‐PDX) and HTLV‐1 immortalized CD4+ T cell lines (HTLV/T) with osteoclasts and their effects on bone mass in mice. Intratibial inoculation of some HTLV/T leads to a profound local decrease in bone mass similar to marrow‐replacing ATL‐PDX, despite the fact that few HTLV/T cells persisted in the bone. To study the direct effect of HTLV/T and ATL‐PDX on osteoclasts, supernatants were added to murine and human osteoclast precursors. ATL‐PDX supernatants from hypercalcemic patients promoted the formation of mature osteoclasts, while those from HTLV/T were variably stimulatory, but had largely consistent effects between human and murine cultures. Interestingly, this osteoclastic activity did not correlate with expression of osteoclastogenic cytokine receptor activator of nuclear factor kappa‐B ligand (RANKL), suggesting an alternative mechanism. HTLV/T and ATL‐PDX produce small extracellular vesicles (sEV), known to facilitate HTLV‐1 infection. We hypothesized that these sEV also mediate bone loss by targeting osteoclasts. We isolated sEV from both HTLV/T and ATL‐PDX, and found they carried most of the activity found in supernatants. In contrast, sEV from uninfected activated T cells had little effect. Analysis of sEV (both active and inactive) by mass spectrometry and electron microscopy confirmed absence of RANKL and intact virus. Viral proteins Tax and Env were only present in sEV from the active, osteoclast‐stimulatory group, along with increased representation of proteins involved in osteoclastogenesis and bone resorption. sEV from osteoclast‐active HTLV/T injected over mouse calvaria in the presence of low‐dose RANKL caused more osteolysis than osteoclast‐inactive sEV or RANKL alone. Thus, HTLV‐1 infection of T cells can cause release of sEV with strong osteolytic potential, providing a mechanism beyond RANKL production that modifies the bone microenvironment, even in the absence of overt leukaemia. [ABSTRACT FROM AUTHOR]

Objective: Milk production during lactation places a high demand for calcium that is fulfilled both from maternal bone resorption and diet. While it is known that mammary gland-derived PTHrP drives bone resorption during lactation, the impact of postpartum estrogen loss on bone has been unclear. Methods: We used a case-control study design to test the effect of estrogen loss in lactating mice. Results: In the present study, we show for the first time that estrogen loss during lactation activates memory T-cells (TM) to produce TNFα and IL-17A to aid in bone resorption and calcium release. Our studies reveal a new mechanism for the release of calcium from bone postpartum. The findings provide several new insights. First, the immune system plays a critical role in milk production postpartum. Second, evolutionarily, the pathway serves the physiological purpose of increasing bone resorption to release calcium for breastmilk production postpartum but becomes maladaptive postmenopause, leading to osteoporosis. Finally, these results highlight the crosstalk between the brain–bone–breast–endocrine axis and the immune system during lactation. [ABSTRACT FROM AUTHOR]

Immune cells play an Important functional role In bone fracture healing. Fracture repair is a well-choreographed process that takes approximately 21 days in healthy mice. While the process is complex, conceptually it can be divided into four overlapping stages: inflammation, cartilaginous callus formation, bony callus formation, and remodeling. T cells play a key role in both the cartilaginous and bony callus phases by producing IL-17A. In this issue of the JCI, Dar et al. showed that T cells were recruited from the gut, where the gut microbiota determined the pool of T cells that expressed IL-17A. Treatment with antibiotics and dysbiosis reduced the expansion of IL-17-expressing [CD4.sup.+] T cells (Th17) and impaired callus formation. These findings demonstrate crosstalk among the gut microbiota, the adaptive immune system, and bone that has clinical implications for fracture healing., Stages of fracture healing A fracture initiates a complex cascade of molecular, cellular, and tissue events that typically leads to bone healing that is dependent on an appropriately stable mechanical [...]

Hepatitis C virus (HCV) is a common RNA virus that causes hepatitis and liver cancer. Infection is treated with IFN-[alpha] and ribavirin, but this expensive and physically demanding therapy fails in half of patients. The genomic sequences of independent HCV isolates differ by approximately 10%, but the effects of this variation on the response to therapy are unknown. To address this question, we analyzed amino acid covariance within the full viral coding region of pretherapy HCV sequences from 94 participants in the Viral Resistance to Antiviral Therapy of Chronic Hepatitis C (Virahep-C) clinical study. Covarying positions were common and linked together into networks that differed by response to therapy. There were 3-fold more hydrophobic amino acid pairs in HCV from nonresponding patients, and these hydrophobic interactions were predicted to contribute to failure of therapy by stabilizing viral protein complexes. Using our analysis to detect patterns within the networks, we could predict the outcome of therapy with greater than 95% coverage and 100% accuracy, raising the possibility of a prognostic test to reduce therapeutic failures. Furthermore, the hub positions in the networks are attractive antiviral targets because of their genetic linkage with many other positions that we predict would suppress evolution of resistant variants. Finally, covariance network analysis could be applicable to any virus with sufficient genetic variation, including most human RNA viruses., Introduction HCV chronically infects about 3.8 million Americans and causes 8,000-10,000 deaths each year in the United States by inducing liver failure or hepatocellular carcinoma (1). HCV infection is treated [...]

A predictive rule for protein folding is presented that involves two recurrent glycine-based motifs that cap the carboxyl termini of α helices. In proteins, helices that terminated in glycine residues were found predominantly in one of these two motifs. These glycine structures had a characteristic pattern of polar and apolar residues. Visual inspection of known helical sequences was sufficient to distinguish the two motifs from each other and from internal glycines that fail to terminate helices. These glycine motifs--in which the local sequence selects between available structures--represent an example of a stereochemical rule for protein folding., The folded structure of a protein is encrypted in its amino acid sequence (1), written in a code that remains obscure. Is this fold the inevitable outcome of an energetically [...]

Studies of the Oct-1 POU domain reveal that it is a bipartite DNA-binding unit made up of two structurally-distinct DNA-binding domains linked by a flexible linker. The POU-specific domain contacts with the ATGC sequence while the homeodomain contacts the AAAT sequence. This results in binding on opposite sides of the double helix without any protein-protein contacts. The POU domains have specific subsite spacing preferences.

A study determines the solution structure of the Octamer-1 POU-specific domain by applying multidimensional nuclear magnetic resonance spectroscopy. The structure has strong similarities with the bacteriophage lambda repressor DNA-binding domain. However, the POU-specific domain has an unusual helix-turn-helix (HTH) structure that differs from the canonical HTH motif in the length of the first alpha helix and the turn. Thus, the complete POU domain is comprised of two physically connected but separate domains that belong to an individual family of HTH-containing DNA-binding proteins.

Abstract Background The adaptation of pathogenic fungi to the host environment via large-scale genomic changes is a poorly characterized phenomenon. Cryptococcus neoformans is the leading cause of fungal meningoencephalitis in HIV/AIDS patients, and we recently discovered clinical strains of the fungus that are disomic for chromosome 13. Here, we examined the genome plasticity and phenotypes of monosomic and disomic strains, and compared their virulence in a mouse model of cryptococcosis Results In an initial set of strains, melanin production was correlated with monosomy at chromosome 13, and disomic variants were less melanized and attenuated for virulence in mice. After growth in culture or passage through mice, subsequent strains were identified that varied in melanin formation and exhibited copy number changes for other chromosomes. The correlation between melanin and disomy at chromosome 13 was observed for some but not all strains. A survey of environmental and clinical isolates maintained in culture revealed few occurrences of disomic chromosomes. However, an examination of isolates that were freshly collected from the cerebrospinal fluid of AIDS patients and minimally cultured provided evidence for infections with multiple strains and copy number variation. Conclusions Overall, these results suggest that the genome of C. neoformans exhibits a greater degree of plasticity than previously appreciated. Furthermore, the expression of an essential virulence factor and the severity of disease are associated with genome variation. The occurrence of chromosomal variation in isolates from AIDS patients, combined with the observed influence of disomy on virulence, indicates that genome plasticity may have clinical relevance.

The full value of sequence databases will only be evident when they are fully integrated with data from biochemical and physiological experiments, and even from human genetic studies. This integration must be made in a way that will allow simulations of outcomes to be made when individual components of the system are modified.

Altered immune parameters associated with hepatitis C virus (HCV) genotype 1b infection and their correlation with virus eradication in direct‐acting antivirals (DAA)‐treated patients were examined. Thirty‐one HCV‐infected patients were treated with DAAs for 12 weeks. Pre‐DAA‐treatment and post‐DAA‐treatment sera were analyzed for cytokines/chemokines using MILLIPLEX MAP. Serum complement level and antibody neutralization activity were measured separately. Sera from 11 spontaneously cleared HCV subjects were included for comparison. Rapid virological responders (RVR) or end‐of‐treatment responders (EOTR) were defined as patients with HCV RNA negative at week 4 or positive at week 4 and negative at week 12, respectively. HCV RNA eradication and a decrease in liver fibrosis‐related cytokines after treatment were observed when compared with pretreatment sera from RVR and EOTR. In pretreatment sera, interferons and T‐helper 1 or 2 cell‐associated cytokines/chemokines were significantly higher among RVR as compared with EOTR. Furthermore, serum complement and virus neutralizing antibody levels were higher in pretreatment RVR sera. Eradication of HCV RNA by DAA decreased liver fibrosis‐related cytokines. Pretreatment sera from RVR displayed an enhanced cytokine/chemokine, complement and virus neutralizing antibody response as compared with EOTR sera. Our results suggested that enhanced host immune status may play an additive role on HCV RNA clearance by DAA. [ABSTRACT FROM AUTHOR]