Periodontitis in the absence of B cells and specific anti-bacterial antibody.

Periodontitis (PD) results from complex interactions between a dysbiotic oral microbiota and a dysregulated host immune response. The inflammatory infiltrate in the gingiva of PD patients includes an abundance of B cells, implicating these cells in the immunopathology. We sought to investigate the role of B cells in PD using a murine model. Wild-type or B-cell-deficient (µMT) mice were orally infected with Porphyromonas gingivalis. One or six weeks following infection, lymphocyte populations in the gingiva and cervical draining lymph nodes (dLN) were analysed by flow cytometry; serum anti-P. gingivalis IgG antibody titers were measured by enzyme-linked immunosorbent assay, and alveolar bone loss was determined. In wild-type mice, the percentage of gingival B cells expressing receptor activator of nuclear factor-κB ligand (RANKL) was significantly increased 1 week post-infection (5.36% control versus 11% PD, P < 0.01). The percentage of Fas(+) GL7(+) germinal centre B cells in the dLN was significantly increased at both 1 week (2.03% control versus 6.90% PD, P < 0.01) and 6 weeks (4.45% control versus 8.77% PD, P < 0.05) post-infection. B-cell-deficient mice were protected from P. gingivalis-induced alveolar bone loss, with a lack of B-cell proliferation and lack of CD4(+) CD44(+) CD62L(-) T-cell generation in the dLN, and absence of serum anti-P. gingivalis antibodies. Our data imply a pathological role for B cells in PD, and that selective targeting of this immune axis may have a role in treating severe periodontal disease.

Intrinsic autoimmune capacities of hematopoietic cells from female New Zealand hybrid mice.

Most systemic autoimmune diseases occur more frequently in females than in males. This is particularly evident in Sjögren's syndrome, systemic lupus erythromatosis (SLE) and thyroid autoimmunity, where the ratio of females to males ranges from 20:1 to 8:1. Our understanding of the etiology of SLE implies important roles for genetics, environmental factors and sex hormones, but the relative significance of each remains unknown. Using the New Zealand hybrid mouse model system of SLE, we present here a new fetal liver chimera-based system in which we can segregate effects of immune system genes from that of sex hormones in vivo. We show that female hematopoietic cells express an intrinsic capacity to drive lupus-like disease in both male and female recipient mice, suggesting that this capacity is hormone independent. Particularly, only chimeric mice with a female hematopoietic system showed significantly increased numbers of germinal center B cells, memory B cells and plasma cells followed by a spontaneous loss of tolerance to nuclear components and hence elevated serum antinuclear autoantibodies. A protective effect of testosterone was noted with regard to disease onset, but not disease incidence. Thus, genetic factors encoded within the female hematopoietic system can effectively drive lupus-like disease even in male recipients.

Pressure sores-a reappraisal.

Pressure sores are a common problem. They are casually accepted, their etiology is well defined, and treatment is standardized. How, therefore, can the subject justify reappraisal? On detailed review, evidence is presented showing that pressure sores can be minimized, that their pathophysiology is far from certain, and that their management is changing dramatically. During the past decade, new preventive measures have been adopted consisting of multidisciplinary tissue trauma clinics for paraplegic patients, based in rehabilitation hospitals, as well as early identification of the "at-risk" subgroup of geriatric patients who will require aggressive nursing care. Although pressure is the most widely accepted etiological factor, no sophisticated experimental studies have corroborated this hypothesis, and in fact, the majority of research conflicts with clinical observations. Recently, new surgical proceudres-myocutaneous and sensory skin flaps-have been devised to solve complex coverage problems which will possibly reduce the recurrence rate. An in-depth review of pressure sores is therefore warranted and will, we hope, stimulate renewed interest in this all-too-frequent clinical affliction.