Nfkb2 variants reveal a p100-degradation threshold that defines autoimmune susceptibility

NF-κB2/p100 (p100) is an inhibitor of κB (IκB) protein that is partially degraded to produce the NF-κB2/p52 (p52) transcription factor. Heterozygous NFKB2 mutations cause a human syndrome of immunodeficiency and autoimmunity, but whether autoimmunity arises from insufficiency of p52 or IκB function of mutated p100 is unclear. Here, we studied mice bearing mutations in the p100 degron, a domain that harbors most of the clinically recognized mutations and is required for signal-dependent p100 degradation. Distinct mutations caused graded increases in p100-degradation resistance. Severe p100-degradation resistance, due to inheritance of one highly degradation-resistant allele or two subclinical alleles, caused thymic medullary hypoplasia and autoimmune disease, whereas the absence of p100 and p52 did not. We inferred a similar mechanism occurs in humans, as the T cell receptor repertoires of affected humans and mice contained a hydrophobic signature of increased self-reactivity. Autoimmunity in autosomal dominant NFKB2 syndrome arises largely from defects in nonhematopoietic cells caused by the IκB function of degradation-resistant p100

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Setting us up to fail: Pulmonary dendritic cells promote immunopathology during mycoplasma respiratory disease

The purpose of these studies was to define the contributions of T helper 2 cells and dendritic cells toward the development of immunopathology during mycoplasma respiratory disease. IFN-γ+ CD8+ T cells, IFN-γ+ Th1 cells and IL-13+ Th2 cells developed over the course of mycoplasma infection. By day 14 post-infection, the results demonstrated a significant and preferential increase of an IL-13 + Th2 cell sub-population in the LRNs. Additional studies using STAT4 -/- animals, which have a Th2 polarized environment, demonstrated no difference in disease compared to the wild-type animals. Absence of STAT6, which strongly contributes to a Th1 polarized environment, conveyed significantly more protection from mycoplasma disease in immunized mice compared to STAT4 -/- and WT mice. By day 14 post-infection, all mice had significantly more IL-13+ Th2 cells than IFN-γ + Th1 in the LRN compared to STAT6-/- immunized mice, thus suggesting that the reduction in the IL-13+ Th2 population leads to protection, while an increase in Th2 is pathogenic. Additional studies demonstrated that pulmonary dendritic cells support the mycoplasma-specific CD4+ and CD8+ T cell activation when stimulated with mycoplasma antigen. Knowing that T cells and DCs have an intimate relationship during mycoplasma disease, sub-classes of cytokine differentiated BMDCs were created to attempt to skew to the protective arm of immunity against mycoplasma disease. However, in vivo adoptive transfer studies demonstrated antigen pulsed DCs accelerated and exacerbated the pathological effects of mycoplasma disease. The exacerbation was antigen-specific and lymphocyte dependent. Mice that received antigen pulsed DCs demonstrated a significant increase in IL-13+ Th2 cell sub-population in the LRNs with a similar trend found in the lungs prior to infection. The same exacerbation was seen when antigen pulsed pulmonary DCs were adoptively transferred into mice, but not with antigen pulsed splenic DCs. Prior to infection, mice that received antigen-pulsed pulmonary DC, not splenic DC, had a significant increase in a IL-13+ Th2 population in the LRNs. Taken collectively, these studies demonstrate two key players in the development of the detrimental response against mycoplasma disease. This knowledge will assist in the development of targeted vaccines that will promote protection over pathology

Evidence of Borrelia lonestari DNA in Amblyomma americanum (Acari: Ixodidae) Removed from Humans

We used a nested PCR with Borrelia flagellin gene (flaB) primers and DNA sequencing to determine if Borrelia lonestari was present in Amblyomma americanum ticks removed from military personnel and sent to the Tick-Borne Disease Laboratory of the U.S. Army Center for Health Promotion and Preventive Medicine. In our preliminary investigation, we detected Borrelia sequences in 19 of 510 A. americanum adults and nymphs from Ft. A. P. Hill, Va. During the 2001 tick season, the flaB primers were used to test all A. americanum samples as they were received, and 29 of 2,358 A. americanum samples tested individually or in small pools were positive. PCRs with 2,146 A. americanum samples in 2002 yielded 26 more Borrelia-positive samples. The positive ticks in 2001 and 2002 were from Arkansas, Delaware, Kansas, Kentucky, Maryland, New Jersey, North Carolina, Tennessee, and Virginia. The last positive sample of the 2001 season was a pool of larvae. To further investigate larval infection, we collected and tested questing A. americanum larvae from Aberdeen Proving Ground, Md.; 4 of 33 pools (40 larvae per pool) were positive. Infection of unfed larvae provides evidence of the maintenance of B. lonestari by means of transovarial transmission. Sequence analysis revealed that the amplicons were identical to sequences of the B. lonestari flaB gene in GenBank. Despite the low prevalence of infection, the risk of B. lonestari transmission may be magnified because A. americanum is often abundant and aggressive, and many tick bite victims receive multiple bites