An unappreciated cell survival-independent role for BAFF initiating chronic lymphocytic leukemia

Background

Chronic Lymphocytic Leukemia (CLL) is characterized by the expansion of CD19+ CD5+ B cells but its origin remains debated. Mutated CLL may originate from post-germinal center B cells and unmutated CLL from CD5+ mature B cell precursors. Irrespective of precursor types, events initiating CLL remain unknown. The cytokines BAFF and APRIL each play a significant role in CLL cell survival and accumulation, but their involvement in disease initiation remains unclear.

Methods

We generated novel CLL models lacking BAFF or APRIL. In vivo experiments were conducted to explore the impact of BAFF or APRIL loss on leukemia initiation, progression, and dissemination. Additionally, RNA-seq and quantitative real-time PCR were performed to unveil the transcriptomic signature influenced by BAFF in CLL. The direct role of BAFF in controlling the expression of tumor-promoting genes was further assessed in patient-derived primary CLL cells ex-vivo.

Results

Our findings demonstrate a crucial role for BAFF, but not APRIL, in the initiation and dissemination of CLL cells. In the absence of BAFF or its receptor BAFF-R, the TCL1 transgene only increases CLL cell numbers in the peritoneal cavity, without dissemination into the periphery. While BAFF binding to BAFF-R is dispensable for peritoneal CLL cell survival, it is necessary to activate a tumor-promoting gene program, potentially linked to CLL initiation and progression. This direct role of BAFF in controlling the expression of tumor-promoting genes was confirmed in patient-derived primary CLL cells ex-vivo.

Conclusions

Our study, involving both mouse and human CLL cells, suggests that BAFF might initiate CLL through mechanisms independent of cell survival. Combining current CLL therapies with BAFF inhibition could offer a dual benefit by reducing peripheral tumor burden and suppressing transformed CLL cell output.

The effects of B-cell-activating factor on the population size, maturation and function of murine natural killer cells

The role of B-cell-activating factor (BAFF) in B-lymphocyte biology has been comprehensively studied, but its contributions to innate immunity remain unclear. Natural killer (NK) cells form the first line of defense against viruses and tumors, and have been shown to be defective in patients with systemic lupus erythematosus (SLE). The link between BAFF and NK cells in the development and progression of SLE remains unstudied. By assessing NK cell numbers in wild-type (WT), BAFF^-/- (BAFF deficient), BAFF-R^-/- (BAFF receptor deficient), TACI^-/- (transmembrane activator and calcium modulator and cyclophilin ligand interactor deficient), BCMA^-/- (B-cell maturation antigen deficient) and BAFF transgenic (Tg) mice, we observed that BAFF signaling through BAFF-R was essential for sustaining NK cell numbers in the spleen. However, according to the cell surface expression of CD27 and CD11b on NK cells, we found that BAFF was dispensable for NK cell maturation. Ex vivo and in vivo models showed that NK cells from BAFF^-/- and BAFF Tg mice produced interferon-γ and killed tumor cells at a level similar to that in WT mice. Finally, we established that NK cells do not express receptors that interact with BAFF in the steady state or in the BAFF Tg mouse model of SLE. Our findings demonstrate that BAFF has an indirect effect on NK cell homeostasis and no effect on NK cell function.

The molecular basis of JAK/STAT inhibition by SOCS1

The SOCS family of proteins are negative-feedback inhibitors of signalling induced by cytokines that act via the JAK/STAT pathway. SOCS proteins can act as ubiquitin ligases by recruiting Cullin5 to ubiquitinate signalling components; however, SOCS1, the most potent member of the family, can also inhibit JAK directly. Here we determine the structural basis of both these modes of inhibition. Due to alterations within the SOCS box domain, SOCS1 has a compromised ability to recruit Cullin5; however, it is a direct, potent and selective inhibitor of JAK catalytic activity. The kinase inhibitory region of SOCS1 targets the substrate binding groove of JAK with high specificity and thereby blocks any subsequent phosphorylation. SOCS1 is a potent inhibitor of the interferon gamma (IFNγ) pathway, however, it does not bind the IFNγ receptor, making its mode-of-action distinct from SOCS3. These findings reveal the mechanism used by SOCS1 to inhibit signalling by inflammatory cytokines.

The molecular basis of JAK/STAT inhibition by SOCS1

The SOCS family of proteins are negative-feedback inhibitors of signalling induced by cytokines that act via the JAK/STAT pathway. SOCS proteins can act as ubiquitin ligases by recruiting Cullin5 to ubiquitinate signalling components; however, SOCS1, the most potent member of the family, can also inhibit JAK directly. Here we determine the structural basis of both these modes of inhibition. Due to alterations within the SOCS box domain, SOCS1 has a compromised ability to recruit Cullin5; however, it is a direct, potent and selective inhibitor of JAK catalytic activity. The kinase inhibitory region of SOCS1 targets the substrate binding groove of JAK with high specificity and thereby blocks any subsequent phosphorylation. SOCS1 is a potent inhibitor of the interferon gamma (IFNγ) pathway, however, it does not bind the IFNγ receptor, making its mode-of-action distinct from SOCS3. These findings reveal the mechanism used by SOCS1 to inhibit signalling by inflammatory cytokines.

Cytokines are key molecules in controlling haematopoiesis that signal via the JAK/STAT pathway. Here the authors present the structures of SOCS1 bound to its JAK1 target as well as in complex with elonginB and elonginC, providing a molecular explanation for the potent JAK- inhibitory activity of SOCS1.

Sexual orientation and health: comparisons in the women's health initiative sample

CONTEXT

Little is known about older lesbian and bisexual women. Existing research rarely compares characteristics of these women with comparable heterosexual women.

OBJECTIVE

To compare heterosexual and nonheterosexual women 50 to 79 years on specific demographic characteristics, psychosocial risk factors, screening practices, and other health-related behaviors associated with increased risk for developing particular diseases or disease outcomes.

DESIGN

Analysis of data from 93,311 participants in the Women's Health Initiative (WHI) study of health in postmenopausal women, comparing characteristics of 5 groups: heterosexuals, bisexuals, lifetime lesbians, adult lesbians, and those who never had sex as an adult.

SETTING

Subjects were recruited at 40 WHI study centers nationwide representing a range of geographic and ethnic diversity.

PARTICIPANTS

Postmenopausal women aged 50 to 79 years who met WHI eligibility criteria, signed an informed consent to participate in the WHI clinical trial(s) or observational study, and responded to the baseline questions on sexual orientation.

MAIN OUTCOME MEASURES

Demographic characteristics, psychosocial risk factors, recency of screening tests, and other health-related behaviors as assessed on the WHI baseline questionnaire.

RESULTS

Although of higher socioeconomic status than the heterosexuals, the lesbian and bisexual women more often used alcohol and cigarettes, exhibited other risk factors for reproductive cancers and cardiovascular disease, and scored lower on measures of mental health and social support. Notable is the 35% of lesbians and 81% of bisexual women who have been pregnant. Women reporting that they never had sex as an adult had lower rates of Papanicolaou screening and hormone replacement therapy use than other groups.

CONCLUSIONS

This sample of older lesbian and bisexual women from WHI shows many of the same health behaviors, demographic, and psychosocial risk factors reported in the literature for their younger counterparts, despite their higher socioeconomic status and access to health care. The lower rates of recommended screening services and higher prevalence of obesity, smoking, alcohol use, and lower intake of fruit and vegetables among these women compared with heterosexual women indicate unmet needs that require effective interactions between care providers and nonheterosexual women.

The medical care system and prevention: the need for a new paradigm

The American medical care system falls to provide effective prevention services even though some prevention services are among the most cost-effective medical procedures available. Many prevention services are routinely delivered in inefficient or ineffective ways, and new technologies may be widely and aggressively implemented despite serious doubts about their efficacy and cost-effectiveness. The barriers to effective prevention services result from conceptual limitations in our model of medical care systems, particularly the lack of a population-based perspective. A change in paradigm is needed before reforms in our health care system can improve health without bankrupting the nation.

Firearm ownership and health care workers

OBJECTIVE

Health professionals have increasingly become aware of the public health hazards caused by firearms. This study was designed to determine the firearm ownership and storage practices of a group of health care workers.

METHODS

All 6436 nonphysician employees of a large health maintenance organization were surveyed as part of an ongoing effort to enhance the organization's effectiveness. Two questions regarding firearm ownership and storage practices were included in the 85-question survey instrument. A total of 4999 surveys were returned, for a response rate of 78%.

RESULTS

Forty-two percent of the health workers surveyed reported keeping a firearm in their home, and 35% of firearm owners stored that firearm loaded. Men were more likely than women to report having a firearm in the home. Firearm ownership and storage of a loaded firearm decreased with higher levels of education in both sexes. A measure of increased alcohol consumption was related to higher rates of firearm ownership and storage of loaded firearms in men.

CONCLUSIONS

A substantial number of health care workers had firearms in their homes and did not store them safely. Counseling regarding the risks associated with easy access to firearms should be considered for inclusion in employee health programs as well as in employee assistance and alcohol treatment programs.

Report from AMRA manpower survey. Part III: Non-management positions

This is the third in a series of three articles reporting results of the 1986 AMRA Manpower Survey. The purpose of this article is to provide information on the following non-management positions: coding, transcription, record deficiency analysis, release of information, record retrieval/filing, and general clerical. The first article described the survey and provided information on directors of medical record departments. The second article addressed other management positions in the medical record department.

Radioimmunoassay of drugs subject to abuse: critical evaluation of urinary morphine-barbiturate, morphine, barbiturate, and amphetamine assays

Radioimmunoassays for morphine-barbiturate (MOR-BARB), morphine, barbiturate, and amphetamine were evaluated by a direct comparison with differential elution extraction thin-layer chromatography, the "enzyme multiplied immunoassay technique," and XAD-2 resin extraction thin-layer chromatography for the detection in urine of drugs subject to abuse. Statistically significant (Psmaller than 0.01) concentrations for detection were: 50-100 mug/liter for MOR-BARB; 5 Mug/liter for morphine, 10 mug/liter for barbiturate, and 100 mug/liter for amphetamine. Unconfirmed and unaccounted-for radioimmunoassay positives (false) were: 0% for morphine in the radioimmunoassay for MOR-BARB and that for morphine alone; 2.8% for barbiturates in the MOR-BARB assay and that for barbiturates alone; 0-6% when a combination of these drugs was present in the MOR-BARB, morphine, or barbiturate assay; and 2.4% in the amphetamine radioimmunoassay. Less than 1% of all radioimmunoassay-negative samples were unconfirmed (false). Cross-reactivity was observed with drugs of a similar chemical structure in each of the radioimmunoassays tested. All the radio-immunoassays were easy to use, highly sensitive, and extremely reliable for detecting drug use or abuse.