No evidence of occult hepatitis C virus (HCV) infection in serum of HCV antibody‐positive HCV RNA‐negative kidney‐transplant patients

Persistence of hepatitis C virus (HCV) in patients who cleared HCV is still debated. Occult HCV infection is described as the presence of detectable HCV RNA in liver or peripheral blood mononuclear cells (PBMCs) of patients with undetectable plasma HCV‐RNA by conventional PCR assays. We have assessed the persistence of HCV in 26 kidney‐transplant patients, followed up for 10.5 years (range 2–16), after HCV elimination while on hemodialysis. If HCV really did persist, arising out of the loss of immune control caused by institution of the regimen of immunosuppressive drugs after kidney transplantation, HCV reactivation would have taken place. Their immunosuppression relied on calcineurin inhibitors (100%), and/or steroids (62%), and/or antimetabolites (94%). An induction therapy, given to 22 patients, relied on rabbit antithymocyte globulin (59%) or anti‐IL2‐receptor blockers (32%). All patients had undetectable HCV RNA as ascertained by several conventional tests. At the last follow‐up, no residual HCV RNA was detected in the five liver biopsies, the 26 plasma, and in the 37 nonstimulated and 24 stimulated PBMCs tested with an ultrasensitive RT‐PCR assay (detection limit, 2 IU/ml). No biochemical or virologic relapse was seen during follow‐up. The absence of HCV relapse in formerly HCV‐infected immunocompromised patients suggests the complete eradication of HCV after its elimination while on dialysis.     

Antibody persistence and immune memory in healthy adults following vaccination with a two-dose inactivated hepatitis A vaccine: long-term follow-up at 15 years

Long‐term persistence of vaccine‐induced immune response in adults was assessed annually for 15 years following primary immunization with a two‐dose inactivated hepatitis A vaccine. In 1992, 119 and 194 subjects aged 17–40 years and naïve for hepatitis A virus (HAV) were enrolled in two studies to receive 1,440 ELISA units (El.U) of inactivated hepatitis A vaccine (Havrix?, GlaxoSmithKline Biologicals, Belgium) according to a standard 0, 6 or an extended 0, 12 months schedule, respectively. Serum samples were taken 1 month after the second vaccine dose and every consecutive year up to 15 years after primary vaccination for measurement of anti‐HAV antibody concentrations (NCT00291876 and NCT00289757). At year 15, 100% (48/48) and 97.3% (108/111) of subjects vaccinated at 0, 6 or 0, 12 months remained seropositive for anti‐HAV antibodies, with geometric mean concentrations (GMCs) of 289.2 and 367.4 mIU/ml, respectively. An additional dose of HAV vaccine (1,440 El.U) was administered to the six subjects who had become seronegative for anti‐HAV antibodies since year 11. All subjects mounted a humoral immune response to the additional HAV challenge dose, although post‐challenge anti‐HAV antibody levels remained low in one subject. These studies represent the longest annual follow‐up of hepatitis A vaccine in healthy adults. The immune response induced by two doses of this inactivated HAV vaccine was shown to persist for at least 15 years. No difference in long‐term antibody persistence was observed between the two primary vaccination schedules, reinforcing the potential for flexibility in the timing of the second primary vaccine dose. J. Med. Virol. 83:1885–1891, 2011. © 2011 Wiley‐Liss, Inc.     

Memory impairment induced by IL-1β is reversed by α-MSH through central melanocortin-4 receptors

Interleukin-1beta (IL-1β) significantly influences memory consolidation. Treatments that raise the level of IL-1β in the brain, given after training, impair contextual fear conditioning. The melanocortin α-MSH exerts potent anti-inflammatory actions by physiologically antagonizing the effect of pro-inflammatory cytokines. Five subtypes of melanocortin receptors (MC1R–MC5R) have been identified, with MC3R and MC4R predominating in the central nervous system. The present experiments show that injection of IL-1β (5 ng/0.25 μl) in dorsal hippocampus up to 15 min after training decreased freezing during the contextual fear test. The treatment with IL-1β (5 ng/0.25 μl) 12 h after conditioning cause amnesia when animals were tested 7 days post training. Thus, our results also demonstrated that IL-1β can influence persistence of long-term memory. We determined that animals previously injected with IL-1β can acquire a new contextual fear memory, demonstrating that the hippocampus was not damaged. Treatment with α-MSH (0.05 μg/0.25 μl) blocked the effect of IL-1β on contextual fear memory. Administration of the MC4 receptor antagonist HS014 (0.5 μg/0.25 μl) reversed the effect of α-MSH. However, treatment with γ-MSH (0.5 μg/0.25 μl), an MC3 agonist, did not affect IL-1β-induced impairment of memory consolidation. These results suggest that α-MSH, through central MC4R can inhibit the effect of IL-1β on memory consolidation.     

Lactase persistence-related genetic variant: population substructure and health outcomes

Lactase persistence is an autosomal-dominant trait that is common in European-derived populations. A basic tendency for lactase persistence to increase from the southeast to the northwest across European populations has been noted, but such trends within countries have not been extensively studied. We genotyped the C/T(-13910) variant (rs4988235) that constitutes the putatively causal allele for lactase persistence (T allele representing persistence) in a general population sample of 3344 women aged 60-79 years from 23 towns across Britain. We found an overall frequency of 0.253 for the C (lactase non-persistence) allele, but with considerable gradients of decreasing frequency from the south to the north and from the east to the west of Britain for this allele. Daily sunlight was positively related to C (non-persistence) allele prevalence. However, sunlight exposure and latitude are strongly correlated, and it was not possible to identify which is the primary factor statistically underlying the distribution of lactase persistence. The C/T(-13910) variant (rs4988235) was not related to drinking milk or bone health (although drinking milk itself was protective of bone health), and was essentially unrelated to a wide range of other lifestyle, health and demographic characteristics. One exception was general health being rated as being poor or fair, for which there was an odds ratio of 1.38 (1.04, 1.84) for women homozygous for the C allele; on adjustment for latitude and longitude of place of birth, this attenuated to 1.19 (0.87, 1.64). The lactase persistence variant could contribute to the examination of data for the existence of, and then statistical control for, population substructure in genetic association studies.     

Antagonistic expression of hepatitis C virus and alpha interferon in lymphoid cells during persistent occult infection

Detection of residual HCV in individuals with SVR after treatment of CHC can be significantly heightened by analyzing ex vivo mitogen-activated T and B lymphocytes and applying sensitive nucleic acid amplification assays. However, it remained unknown if synergistic activation of lymphocytes and monocytes would further augment HCV detection, if viral replication becomes universally upregulated in treated cells, and if examining sequential sera and lymphoid cells would improve detection of occult infection. Using paired sera and lymphoid cells collected 1 year apart from 17 individuals with normal liver enzymes for up to 72 months after SVR, it was found that simultaneous activation of lymphocytes and monocytes enhanced identification of silent HCV infection and revealed that in some cases monocytes were the principal immune cell type where HCV persisted. Testing of serial samples further increased detection of occult infection. Ultimately, by combining the above two approaches, all individuals with SVR were found to be silent carriers of HCV. Clonal sequencing revealed HCV variations in sera and lymphoid cells and evolution of viral genomes confirming ongoing virus replication. Surprisingly, similar to those with CHC, naive lymphoid cells from some individuals carried approximately 10(3) HCV copies/microg total RNA. HCV loads in naive lymphoid cells predetermined the outcome of ex vivo stimulation with respect to upregulation or inhibition of HCV replication. HCV RNA levels in occult infection were inversely proportional to the expression of IFNalpha and IFN-inducible MxA, but not to IFNgamma or tumour necrosis factor alpha in naive and mitogen-treated lymphoid cells.     

Molecularly defined adult-type hypolactasia among working age people with reference to milk consumption and gastrointestinal symptoms

AIM: To study milk consumption and subjective milk- related symptoms in adults genotyped for adult-type hypolactasia. METHODS: A total of 1900 Finnish adults were genotyped for the C/T-13910 variant of adult-type hypolactasia and filled in a structured questionnaire concerning milk consumption and gastrointestinal problems. RESULTS: The C/C-13910 genotype of adult-type hypolactasia was present in 18% of the study population. The prevalence of the C/C-13910 genotype was higher among subjects who were undergoing investigations because of abdominal symptoms (24%, P < 0.05). Those with the C/C-13910 genotype drank less milk than subjects with either the C/T-13910 or the T/T-13910 genotype of lactase persistence (18% vs 38%; 18% vs 36%, P < 0.01). Subjects with the C/C-13910 genotype had experienced more gastrointestinal symptoms (84%) during the preceding three-month period than those with the C/T-13910 (79%, P < 0.05) or the T/T-13910 genotype (78 %, P < 0.05). Only 9% (29/338) of the subjects with the C/C-13910 genotype consumed milk and reported no symptoms from it.CONCLUSION: Gastrointestinal symptoms are more common among adults with the C/C-13910 genotype of adult-type hypolactasia than in those with genotypes of lactase persistence.     

Bacterial Persistence in Dentoalveolar Bone Following Extraction: A Microbiological Study and Implications for Dental Implant Treatment

Background: The microbiological status of apparently healed alveolar bone implant sites is unknown. Implant success may be compromised by site‐specific persistence of bacterial biofilm co‐aggregations contaminating healed alveolar bone. Purpose: The purpose of the present study was to investigate whether extraradicular infection can persist in apparently healed alveolar bone and to develop a surgical debridement strategy that favors implant osseointegration. Materials and Methods: The study was conducted on 32 private practice patients. Seventy‐seven microbiological samples were taken from 16 pre‐implant extraction sockets, 56 healed post‐extraction osteotomies at fixture placement, and five failed fixtures. Two of the healed osteotomy samples were healed retreatment sites. Tissue fluid and bone samples were analyzed by either anaerobic/aerobic culturing or DNA molecular techniques. All patients were treated ad modum Brånemark, with a two‐stage sterile surgical procedure. A search of the medical and dental literature revealed no evidence‐based or best practice recommendations for the use of debridement in implant therapy. Thus, we developed a new technique for the debridement of alveolar bone found to be contaminated by persistent biofilm or planktonic bacteria. Results: The results of the microbiological analysis of 77 bone and effusion samples from 47 implant sites of the 32 patients showed that overall, 32% (n = 25) had bacteria present in the sample. In 16 pre‐implant extraction sockets, 69% of samples were positive for the presence of bacteria (n = 11). Of 56 osteotomies with a minimum 3‐month healing at fixture placement, 21% revealed a positive culture (n = 12). Two‐stage failed fixtures had 100% positive cultures (n = 5) and it was evident from radiographs that all of these failed fixtures had the apical ends close to the former tooth root end. Based on these findings, we have developed a microbiologically based surgical debridement strategy to successfully re‐treat early infective failures and to place successful two‐stage fixtures. Conclusion: Bacteria can persist as a contaminant in apparently healed alveolar bone following extraction of teeth with apical or radicular pathosis. A new technique for surgical debridement to reduce and limit this bacterial contamination has been described.     

Review: Pathogen-induced inflammation at sites distant from oral infection: bacterial persistence and induction of cell-specific innate immune inflammatory pathways

A hallmark of infection with the gram‐negative pathogen Porphyromonas gingivalis is the induction of a chronic inflammatory response. P. gingivalis induces a local chronic inflammatory response that results in oral inflammatory bone destruction, which manifests as periodontal disease. In addition to chronic inflammation at the initial site of infection, mounting evidence has accumulated supporting a role for P. gingivalis‐mediated periodontal disease as a risk factor for several systemic diseases including, diabetes, preterm birth, stroke, and atherosclerotic cardiovascular disease. A growing number of in vitro studies have demonstrated that P. gingivalis infection stimulates cell activation commensurate with expected responses paralleling inflammatory atherosclerotic‐type responses. Furthermore, various mouse models have been used to examine the ability of P. gingivalis to stimulate chronic inflammatory plaque accumulation and recent studies have pointed to a pivotal role for innate immune signaling via the Toll‐like receptors in the chronic inflammation associated with P. gingivalis infection. In this review we discuss the pathogen and host cell specificity of these responses and discuss possible mechanisms by which this oral pathogen can induce and maintain a chronic state of inflammation at sites distant from oral infection.