Acute alcohol intoxication impairs the hematopoietic precursor cell response to pneumococcal pneumonia

Integrated single cell analysis shows chronic alcohol drinking disrupts monocyte differentiation in the bone marrow

Chronic heavy alcohol drinking (CHD) rewires monocytes and macrophages toward heightened inflammatory states with compromised antimicrobial defenses that persist after 1-month abstinence. To determine whether these changes are mediated through alterations in the bone marrow niche, we profiled monocytes and hematopoietic stem cell progenitors (HSCPs) from CHD rhesus macaques using a combination of functional assays and single cell genomics. CHD resulted in transcriptional profiles consistent with increased activation and inflammation within bone marrow resident monocytes and macrophages. Furthermore, CHD resulted in transcriptional signatures associated with increased oxidative and cellular stress in HSCP. Differentiation of HSCP in vitro revealed skewing toward monocytes expressing "neutrophil-like" markers with greater inflammatory responses to bacterial agonists. Further analyses of HSCPs showed broad epigenetic changes that were in line with exacerbated inflammatory responses within monocytes and their progenitors. In summary, CHD alters HSCPs in the bone marrow leading to the production of monocytes poised to generate dysregulated hyper-inflammatory responses.

Pneumococcal Vaccine for Adults Aged ≥19 Years: Recommendations of the Advisory Committee on Immunization Practices, United States, 2023

This report compiles and summarizes all published recommendations from CDC’s Advisory Committee on Immunization Practices (ACIP) for use of pneumococcal vaccines in adults aged ≥19 years in the United States. This report also includes updated and new clinical guidance for implementation from CDC

Before 2021, ACIP recommended 23-valent pneumococcal polysaccharide vaccine (PPSV23) alone (up to 2 doses), or both a single dose of 13-valent pneumococcal conjugate vaccine (PCV13) in combination with 1–3 doses of PPSV23 in series (PCV13 followed by PPSV23), for use in U.S. adults depending on age and underlying risk for pneumococcal disease. In 2021, two new pneumococcal conjugate vaccines (PCVs), a 15-valent and a 20-valent PCV (PCV15 and PCV20), were licensed for use in U.S. adults aged ≥18 years by the Food and Drug Administration

ACIP recommendations specify the use of either PCV20 alone or PCV15 in series with PPSV23 for all adults aged ≥65 years and for adults aged 19–64 years with certain underlying medical conditions or other risk factors who have not received a PCV or whose vaccination history is unknown. In addition, ACIP recommends use of either a single dose of PCV20 or ≥1 dose of PPSV23 for adults who have started their pneumococcal vaccine series with PCV13 but have not received all recommended PPSV23 doses. Shared clinical decision-making is recommended regarding use of a supplemental PCV20 dose for adults aged ≥65 years who have completed their recommended vaccine series with both PCV13 and PPSV23

Updated and new clinical guidance for implementation from CDC includes the recommendation for use of PCV15 or PCV20 for adults who have received PPSV23 but have not received any PCV dose. The report also includes clinical guidance for adults who have received 7-valent PCV (PCV7) only and adults who are hematopoietic stem cell transplant recipients

Chronic ethanol exposure impairs alveolar leukocyte infiltration during pneumococcal pneumonia, leading to an increased bacterial burden despite increased CXCL1 and nitric oxide levels

Ethanol abuse is a risk factor for the development of pneumonia caused by Streptococcus pneumoniae, a critical pathogen for public health. The aim of this article was to investigate the inflammatory mechanisms involved in pneumococcal pneumonia that may be associated with chronic ethanol exposure. Male C57BL6/J-Unib mice were exposed to 20% (v/v) ethanol for twelve weeks and intranasally infected with 5x10⁴ CFU of S. pneumoniae. Twenty-four hours after infection, lungs, bronchoalveolar lavage and blood samples were obtained to assess the consequences of chronic ethanol exposure during infection. Alcohol-fed mice showed increased production of nitric oxide and CXCL1 in alveoli and plasma during pneumococcal pneumonia. Beside this, ethanol-treated mice exhibited a decrease in leukocyte infiltration into the alveoli and reduced frequency of severe lung inflammation, which was associated with an increase in bacterial load. Curiously, no changes were observed in survival after infection. Taken together, these results demonstrate that chronic ethanol exposure alters the inflammatory response during S. pneumoniae lung infection in mice with a reduction in the inflammatory infiltrate even in the presence of higher levels of the chemoattractant CXCL1.

Integrated single cell analysis shows chronic alcohol drinking disrupts monocyte differentiation in the bone marrow niche

Chronic alcohol drinking rewires circulating monocytes and tissue-resident macrophages towards heightened inflammatory states with compromised anti-microbial defenses. As these effects remain consistent in short-lived monocytes after a 1-month abstinence period it is unclear whether these changes are restricted to the periphery or mediated through alterations in the progenitor niche. To test this hypothesis, we profiled monocytes/macrophages and hematopoietic stem cell progenitors (HSCP) of the bone marrow compartment from rhesus macaques after 12 months of ethanol consumption using a combination of functional assays and single cell genomics. Bone marrow-resident monocytes/macrophages from ethanol-consuming animals exhibited heightened inflammation. Differentiation of HSCP in vitro revealed skewing towards monocytes expressing neutrophil-like markers with heightened inflammatory responses to bacterial agonists. Single cell transcriptional analysis of HSCPs showed reduced proliferation but increased inflammatory markers in mature myeloid progenitors. We observed transcriptional signatures associated with increased oxidative and cellular stress as well as oxidative phosphorylation in immature and mature myeloid progenitors. Single cell analysis of the chromatin landscape showed altered drivers of differentiation in monocytes and progenitors. Collectively, these data indicate that chronic ethanol drinking results in remodeling of the transcriptional and epigenetic landscapes of the bone marrow compartment leading to altered functions in the periphery.

Ethanol Intoxication Impairs Respiratory Function and Bacterial Clearance and Is Associated With Neutrophil Accumulation in the Lung After Streptococcus pneumoniae Infection

Alcohol consumption is commonplace in the United States and its prevalence has increased in recent years. Excessive alcohol use is linked to an increased risk of infections including pneumococcal pneumonia, mostly commonly caused by Streptococcus pneumoniae. In addition, pneumonia patients with prior alcohol use often require more intensive treatment and longer hospital stays due to complications of infection. The initial respiratory tract immune response to S. pneumoniae includes the production of pro-inflammatory cytokines and chemokines by resident cells in the upper and lower airways which activate and recruit leukocytes to the site of infection. However, this inflammation must be tightly regulated to avoid accumulation of toxic by-products and subsequent tissue damage. A majority of previous work on alcohol and pneumonia involve animal models utilizing high concentrations of ethanol or chronic exposure and offer conflicting results about how ethanol alters immunity to pathogens. Further, animal models often employ a high bacterial inoculum which may overwhelm the immune system and obscure results, limiting their applicability to the course of human infection. Here, we sought to determine how a more moderate ethanol exposure paradigm affects respiratory function and innate immunity in mice after intranasal infection with 10⁴ colony forming units of S. pneumoniae. Ethanol-exposed mice displayed respiratory dysfunction and impaired bacterial clearance after infection compared to their vehicle-exposed counterparts. This altered response was associated with increased gene expression of neutrophil chemokines Cxcl1 and Cxcl2 in whole lung homogenates, elevated concentrations of circulating granulocyte-colony stimulating factor (G-CSF), and higher neutrophil numbers in the lung 24 hours after infection. Taken together, these findings suggest that even a more moderate ethanol consumption pattern can dramatically modulate the innate immune response to S. pneumoniae after only 3 days of ethanol exposure and provide insight into possible mechanisms related to the compromised respiratory immunity seen in alcohol consumers with pneumonia.

Probiotic Combination CBLEB Alleviates Streptococcus pneumoniae Infection Through Immune Regulation in Immunocompromised Rats

Background

Streptococcus pneumoniae (SP) is the most common cause of bacterial pneumonia, especially for people with immature or compromised immune systems. In addition to vaccination and antibiotics, immune regulation through microbial intervention has emerged in recent anti-SP infection research. This study investigated the therapeutic effect of a combination of live Bifidobacterium, Lactobacillus, Enterococcus, and Bacillus (CBLEB), a widely used probiotic drug, on SP infection in rats.

Methods

An immunocompromised SP-infection rat model was established by intraperitoneal injection of cyclophosphamide and nasal administration of SP strain ATCC49619. Samples from SP-infected, SP-infected and CBLEB-treated, and healthy rats were collected to determine blood indicators, serum cytokines, gut microbiota, faecal and serum metabolomes, lung- and colon-gene transcriptions, and histopathological features.

Results

CBLEB treatment alleviated weight loss, inflammation, organ damage, increase in basophil percentage, red cell distribution width, and RANTES levels and decrease in total protein and albumin levels of immunocompromised SP-infection rats. Furthermore, CBLEB treatment alleviated dysbiosis in gut microbiota, including altered microbial composition and the aberrant abundance of opportunistic pathogenic bacterial taxa such as Eggerthellaceae, and disorders in gut and serum metabolism, including altered metabolomic profiles and differentially enriched metabolites such as 2,4-di-tert-butylphenol in faeces and L-tyrosine in serum. The transcriptome analysis results indicated that the underlying mechanism by which CBLEB fights SP infection is mainly attributed to its regulation of immune-related pathways such as TLR and NLR signalling in the lungs and infection-, inflammation- or metabolism-related pathways such as TCR signalling in the colon.

Conclusion

The present study shows a potential value of CBLEB in the treatment of SP infection.

Innate Immunity and Alcohol

The innate immunity has evolved during millions of years, and thus, equivalent or comparable components are found in most vertebrates, invertebrates, and even plants. It constitutes the first line of defense against molecules, which are either pathogen-derived or a danger signal themselves, and not seldom both. These molecular patterns are comprised of highly conserved structures, a common trait in innate immunity, and constitute very potent triggers for inflammation mediated via extracellular or intracellular pattern recognition receptors. Human culture is often interweaved with the consumption of alcohol, in both drinking habits, its acute or chronical misuse. Apart from behavioral effects as often observed in intoxicated individuals, alcohol consumption also leads to immunological modulation on the humoral and cellular levels. In the last 20 years, major advances in this field of research have been made in clinical studies, as well as in vitro and in vivo research. As every physician will experience intoxicated patients, it is important to be aware of the changes that this cohort undergoes. This review will provide a summary of the current knowledge on the influence of alcohol consumption on certain factors of innate immunity after a hit, followed by the current studies that display the effect of alcohol with a description of the model, the mode of alcohol administration, as well as its dose. This will provide a way for the reader to evaluate the findings presented.

Alcohol abuse and disorder of granulopoiesis

Granulocytes are the major type of phagocytes constituting the front line of innate immune defense against bacterial infection. In adults, granulocytes are derived from hematopoietic stem cells in the bone marrow. Alcohol is the most frequently abused substance in human society. Excessive alcohol consumption injures hematopoietic tissue, impairing bone marrow production of granulocytes through disrupting homeostasis of granulopoiesis and the granulopoietic response. Because of the compromised immune defense function, alcohol abusers are susceptible to infectious diseases, particularly septic infection. Alcoholic patients with septic infection and granulocytopenia have an exceedingly high mortality rate. Treatment of serious infection in alcoholic patients with bone marrow inhibition continues to be a major challenge. Excessive alcohol consumption also causes diseases in other organ systems, particularly severe alcoholic hepatitis which is life threatening. Corticosteroids are the only therapeutic option for improving short-term survival in patients with severe alcoholic hepatitis. The existence of advanced alcoholic liver diseases and administration of corticosteroids make it more difficult to treat serious infection in alcoholic patients with the disorder of granulopoieis. This article reviews the recent development in understanding alcohol-induced disruption of marrow granulopoiesis and the granulopoietic response with the focus on progress in delineating cell signaling mechanisms underlying the alcohol-induced injury to hematopoietic tissue. Efforts in exploring effective therapy to improve patient care in this field will also be discussed.

Impairment of Hematopoietic Precursor Cell Activation during the Granulopoietic Response to Bacteremia in Mice with Chronic-Plus-Binge Alcohol Administration

Alcohol abuse impairs immune defense. To study the effect of chronic-plus-binge alcohol exposure on the granulopoietic response, acute alcohol intoxication (intraperitoneal injection of 5 g alcohol/kg body weight) was introduced to mice chronically fed on the Lieber-DeCarli low-fat liquid alcohol diet for 5 weeks. Bacteremia was induced by intravenous injection of Escherichia coli Bacteremia caused a remarkable increase in marrow lin^- c-kit⁺ Sca-1⁺ cells. Activation of cell proliferation supported the increase in marrow lin^- c-kit⁺ Sca-1⁺ cells. Alcohol administration inhibited this activation of lin^- c-kit⁺ Sca-1⁺ cells. The bone marrow of pair-fed control mice receiving intraperitoneal saline stored a large number of mature granulocytes expressing a high level of Gr1 (Gr1^hi cells). The proportion of Gr1^hi cells and the total number of Gr1⁺ cells were markedly reduced in the bone marrow, along with an increase in the ratio of Gr1⁺ granulocytes in peripheral white blood cells following bacteremia. E. coli infection stimulated proliferation of granulopoietic precursor cells, resulting in a marked increase in the ratio of immature Gr1^lo cells in the bone marrow. Alcohol administration itself triggered marrow release of Gr1⁺ cells, resulting in reduction of the marrow granulocyte reserve with an elevation of granulocytes in the circulation. Alcohol also impaired activation of granulopoietic precursor proliferation following bacteremia. Alcohol disrupted lipopolysaccharide (LPS)-TLR4-ERK1/2-cyclin D1 signaling and inhibited upregulation of Sca-1 and C/EBPβ expression by lineage-negative marrow cells in response to bacteremia. These results indicate that chronic-plus-binge alcohol exposure inhibits the granulopoietic response by disrupting key cell signaling for hematopoietic precursor cell activation and commitment to granulocyte lineage development.

Alcohol, aging, and innate immunity

The global population is aging: in 2010, 8% of the population was older than 65 y, and that is expected to double to 16% by 2050. With advanced age comes a heightened prevalence of chronic diseases. Moreover, elderly humans fair worse after acute diseases, namely infection, leading to higher rates of infection-mediated mortality. Advanced age alters many aspects of both the innate and adaptive immune systems, leading to impaired responses to primary infection and poor development of immunologic memory. An often overlooked, yet increasingly common, behavior in older individuals is alcohol consumption. In fact, it has been estimated that >40% of older adults consume alcohol, and evidence reveals that >10% of this group is drinking more than the recommended limit by the National Institute on Alcohol Abuse and Alcoholism. Alcohol consumption, at any level, alters host immune responses, including changes in the number, phenotype, and function of innate and adaptive immune cells. Thus, understanding the effect of alcohol ingestion on the immune system of older individuals, who are already less capable of combating infection, merits further study. However, there is currently almost nothing known about how drinking alters innate immunity in older subjects, despite innate immune cells being critical for host defense, resolution of inflammation, and maintenance of immune homeostasis. Here, we review the effects of aging and alcohol consumption on innate immune cells independently and highlight the few studies that have examined the effects of alcohol ingestion in aged individuals.

RSV-specific anti-viral immunity is disrupted by chronic ethanol consumption

Alcohol-use disorders (AUD) persist in the United States and are heavily associated with an increased susceptibility to respiratory viral infections. Respiratory syncytial virus (RSV) in particular has received attention as a viral pathogen commonly detected in children and immune-compromised populations (elderly, asthmatics), yet more recently was recognized as an important viral pathogen in young adults. Our study evaluated the exacerbation of RSV-associated illness in mice that chronically consumed alcohol for 6 weeks prior to infection. Prior studies showed that lung viral titers remained elevated in these animals, leading to a hypothesis that T-cell activation and immune specificity were deficient in controlling viral spread and replication in the lungs. Herein, we confirm a reduction in RSV-specific IFNγ production by CD8 T cells and a depolarization of Th1 (CD4+IFNγ+) and Th2 (CD4+IL-4+) T cells at day 5 after RSV infection. Furthermore, over the course of viral infection (day 1 to day 7 after RSV infection), we detected a delayed influx of neutrophils, monocytes/macrophages, and lymphocytes into the lungs. Taken together, the data show that both the early and late adaptive immunity to RSV infection are altered by chronic ethanol consumption. Future studies will determine the interactions between the innate and adaptive immune systems to delineate therapeutic targets for individuals with AUD often hospitalized by respiratory infection.

Blood Leukocyte Counts and Genetic Polymorphisms of Alcohol Dehydrogenase-1B and Aldehyde Dehydrogenase-2 in Japanese Alcoholic Men

BACKGROUND

Roughly 40% of East Asians have inactive aldehyde dehydrogenase-2 (ALDH2) encoded by the ALDH2*2 allele, and 90% have highly active alcohol dehydrogenase-1B (ADH1B) encoded by the ADH1B*2 allele. Macrocytosis and macrocytic anemia in alcoholics have been associated with ADH1B and ALDH2 gene variants which increase acetaldehyde (AcH) levels.

METHODS

We investigated the relationship between ADH1B*2, ALDH2*2, and leukocyte counts of Japanese alcoholic men (N = 1,661).

RESULTS

After adjusting for age, drinking habits, smoking habits, body mass index, presence of liver cirrhosis, and serum levels of C-reactive protein, we found that total and differential leukocyte counts were lower in the presence of the ALDH2*1/*2 genotype (vs. ALDH2*1/*1 genotype). ALDH2*2/*2 carriers were not found in our study population. Leukocyte, granulocyte, and monocyte counts were also lower in the presence of ADH1B*2 (vs. ADH1B*1/*1 genotype), but the lymphocyte count was higher. The ALDH2*1/*2 genotype was associated with leukocytopenia (<4,000/μl; adjusted odds ratio [95% confidence interval] = 1.89 [1.27 to 2.80]), granulocytopenia (<2,000/μl; 1.86 [1.22 to 2.82]), monocytopenia (<250/μl; 2.22 [1.49 to 3.29]), and lymphocytopenia (<1,000/μl; 1.93 [1.32 to 2.83]). In contrast, the ADH1B*2 had the opposite effect on lymphocytopenia (0.65 [0.46 to 0.93]). Considering genotype effects under conditions of immune stimulation, we observed suppressive effects of ADH1B*2 allele on leukocytosis (≥9,000/μl; 0.69 [0.50 to 0.97]), granulocytosis (≥6,500/μl; 0.66 [0.47 to 0.93]), and monocytosis (≥750/μl; 0.56 [0.39 to 0.79]). The ADH1B*2 plus ALDH2*1/*2 combination had the greatest suppressive effects on the leukocyte, granulocyte, and monocyte counts.

CONCLUSIONS

The total and differential blood leukocyte counts of Japanese alcoholics were strongly affected by their ADH1B and ALDH2 gene variants. High AcH exposure levels probably play a critical role in the suppression of blood leukocyte counts in alcoholics.

Risk of pneumonia in central nervous system injury with alcohol intake: a meta-analysis

OBJECTIVE

Central nervous system (CNS) injury can increased the risk of secondary mortality because of its late inflammatory complications. Alcohol intake increases the risk of damage and complications subsequent to a (CNS) injury. How about the risk of pneumonia after CNS injury under the effect of alcoholic drink? Though animal trails of material prosperity and studies for human have been investigated in recent decades, the outcome maintains poor understanding. Pneumonia is one of the serious complication at the time of hospitalization and it should be known as more as possible for steadying patient conditions in intensive care unit and shortening length of stay. Thus, we conducted a meta-analysis of published materials to assess the association between alcohol intake and pneumonia in CNS injury.

METHODS

Two authors searched the PUBMED, EMBASE, Cochrane Library, and web of science up to September, 2014 for published literatures without any limitations. Reference lists from identified studies were also screened carefully by us for additional data. The summary relative risks (RRs) and 95% confidence intervals (CI) were calculated by statistical analysis software (Stata 12.0) with fixed-effects models to estimate the risk.

RESULT

The results indicated that a higher incidence of pneumonia was found in CNS injury under the influence of alcohol (RR = 1.32, 95% CI = 1.21-1.43), and the risk has no relation to blood alcohol concentration (BAC) (BAC ≥ 80 mg/dl vs < 80 mg/dl, BAC ≥ 100 mg/dl vs < 100 mg/dl).

CONCLUSION

Traumatic brain injury (TBI) and spinal cord injury patients who are under the influence of alcoholic drink have a higher risk of pneumonia.

Alcohol and HIV Effects on the Immune System

HIV disease and alcohol independently influence the human immune system, so it stands to reason that, together, their influence may be additive. Here, we review the evidence that alcohol can exacerbate HIV's influence on the immune system, thereby affecting disease progression and transmission. We focus particularly on alcohol's effect on the mucosal immune system in the tissues of the gastrointestinal tract, the genital tract and the lungs, all of which play a role in transmission and progression of HIV disease.

Alcohol's Effects on Lung Health and Immunity

It has long been known that people with alcohol use disorder (AUD) not only may develop physical dependence but also may experience devastating long-term health problems. The most common and identifiable alcohol-associated health problems include liver cirrhosis, pancreatitis, cardiomyopathies, neuropathies, and dementia. However, the lung also is adversely affected by alcohol abuse, a fact often overlooked by clinicians and the public. Individuals with AUD are more likely to develop pneumonia, tuberculosis (TB), respiratory syncytial virus (RSV) infection, and acute respiratory distress syndrome (ARDS). Increased susceptibility to these and other pulmonary infections is caused by impaired immune responses in people with AUD. The key immune cells involved in combating pulmonary conditions such as pneumonia, TB, RSV infection, and ARDS are neutrophils, lymphocytes, alveolar macrophages, and the cells responsible for innate immune responses. Researchers are only now beginning to understand how alcohol affects these cells and how these effects contribute to the pathophysiology of pulmonary diseases in people with AUD.

Alcohol's Effect on Host Defense

Alcohol affects many organs, including the immune system, with even moderate amounts of alcohol influencing immune responses. Although alcohol can alter the actions of all cell populations involved in the innate and adaptive immune responses, the effect in many cases is a subclinical immunosuppression that becomes clinically relevant only after a secondary insult (e.g., bacterial or viral infection or other tissue damage). Alcohol's specific effects on the innate immune system depend on the pattern of alcohol exposure, with acute alcohol inhibiting and chronic alcohol accelerating inflammatory responses. The proinflammatory effects of chronic alcohol play a major role in the pathogenesis of alcoholic liver disease and pancreatitis, but also affect numerous other organs and tissues. In addition to promoting proinflammatory immune responses, alcohol also impairs anti-inflammatory cytokines. Chronic alcohol exposure also interferes with the normal functioning of all aspects of the adaptive immune response, including both cell-mediated and humoral responses. All of these effects enhance the susceptibility of chronic alcoholics to viral and bacterial infections and to sterile inflammation.

Does prolonged onset of symptoms have a prognostic significance in community-acquired pneumonia?

BACKGROUND AND OBJECTIVE

Severity assessment is made at the time of the initial clinical presentation in patients with community-acquired pneumonia (CAP). It is unclear how the gap between time of presentation and duration of symptoms onset may impact clinical outcomes. Here we evaluate the association of prolonged onset of symptoms (POS) and the impact on clinical outcomes among hospitalized patients with CAP.

METHODS

This was a prospective, multicentre study of CAP in Spain. The primary outcomes were the clinical factors associated with POS defined as days from symptoms onset to pneumonia diagnosis >7 days. The secondary outcomes were intensive care unit (ICU) admission, the presence of suppurative complications, septic shock and 30-day mortality.

RESULTS

We enrolled 1038 patients diagnosed of CAP: 152 (14.6%) patients had a POS. In multivariate analysis, the presence of prior corticosteroid therapy, alcohol abuse, prior antibiotic therapy, and confusion, urea, respiratory rate, blood pressure and age 65 years or older score 0-1 was independently associated with POS. Patients with POS had a higher incidence of suppurative complications, but not of 30-day mortality when compared with a shorter onset of symptoms.

CONCLUSIONS

Approximately 15% of patients diagnosed with CAP had POS. Risk factors associated with POS were previous corticosteroids and antibiotic therapy, alcoholism and less severe pneumonia. POS was associated with a higher rate of suppurative complications and less need for ICU admission.

Neutropenia during HIV infection: adverse consequences and remedies

Neutropenia frequently occurs in patients with Human immunodeficiency virus (HIV) infection. Causes for neutropenia during HIV infection are multifactoral, including the viral toxicity to hematopoietic tissue, the use of myelotoxic agents for treatment, complication with secondary infections and malignancies, as well as the patient's association with confounding factors which impair myelopoiesis. An increased prevalence and severity of neutropenia is commonly seen in advanced stages of HIV disease. Decline of neutrophil phagocytic defense in combination with the failure of adaptive immunity renders the host highly susceptible to developing fatal secondary infections. Neutropenia and myelosuppression also restrict the use of many antimicrobial agents for treatment of infections caused by HIV and opportunistic pathogens. In recent years, HIV infection has increasingly become a chronic disease because of progress in antiretroviral therapy (ART). Prevention and treatment of severe neutropenia becomes critical for improving the survival of HIV-infected patients.

Acute alcohol intoxication impairs methicillin-resistant Staphylococcus aureus clearance in the lung by impeding epithelial production of Reg3γ

The incidence of community-associated methicillin-resistant Staphylococcus aureus (MRSA) pneumonia in previously healthy individuals has increased in the past 5 years. Such infections are associated with bronchiectasis and high mortality rates, making them a significant public health concern. The mechanisms of host defense against this pathogen are not well characterized. However, patients diagnosed with MRSA, as opposed to methicillin-susceptible S. aureus (MSSA), are more likely to have abused alcohol in the past, and these patients are more likely to die from sepsis. In the United States, USA300 is the predominant strain that causes necrotizing pneumonia. To investigate whether acute ethanol exacerbates MRSA pneumonia, mice were intraperitoneally (i.p.) administered 2 or 4 g/kg of ethanol 30 min prior to oropharyngeal inoculation of 2 × 10(7) CFU of USA300. An increased pulmonary bacterial burden was observed in alcohol-intoxicated mice at 16 and 24 h and was associated with decreased levels of interleukin 6 (IL-6). IL-6 activates signal transducer and activator of transcription 3 (STAT3) as part of an acute-phase response of infection. Reg3γ is an antimicrobial C-type lectin that is induced by STAT3 signaling in response to Gram-positive bacteria. Previously, in situ hybridization studies showed that Reg3g is highly expressed in lung epithelium. In the present study, we found that acute ethanol exacerbated USA300 in a murine model of USA300 pneumonia. This was associated with reduced IL-6 expression in vivo as well as inhibition of IL-6 induction of STAT3 signaling and Reg3g expression in mouse lung epithelial (MLE12) cells in vitro. Furthermore, recombinant Reg3γ administration 4 h after MRSA infection in alcohol-intoxicated mice rescued USA300 clearance in vivo. Therefore, acute alcohol intoxication leads to decreased MRSA clearance in part by inhibiting IL-6/STAT3 induction of the antimicrobial protein Reg3γ in the pulmonary epithelium.

Toll-like receptor 4/stem cell antigen 1 signaling promotes hematopoietic precursor cell commitment to granulocyte development during the granulopoietic response to Escherichia coli bacteremia

In response to severe bacterial infection, bone marrow hematopoietic activity shifts toward promoting granulopoiesis. The underlying cell signaling mechanisms remain obscure. To study the role of Toll-like receptor 4 (TLR4)/stem cell antigen-1 (Sca-1) signaling in this process, bacteremia was induced in mice by intravenous injection of Escherichia coli. A subgroup of animals also received intravenous 5-bromo-2-deoxyuridine (BrdU). In a separate set of experiments, bone marrow lineage-negative (lin(-)) stem cell growth factor receptor-positive (c-kit(+)) Sca-1(-) cells containing primarily common myeloid progenitors were cultured in vitro without or with E. coli lipopolysaccharide (LPS). In genotypic background control mice, bacteremia significantly upregulated Sca-1 expression by lin(-) c-kit(+) cells, as reflected by a marked increase in BrdU-negative lin(-) c-kit(+) Sca-1(+) cells in the bone marrow. In mice with the TLR4 gene deletion, this bacteremia-evoked Sca-1 response was blocked. In vitro, LPS induced a dose-dependent increase in Sca-1 expression by cultured marrow lin(-) c-kit(+) Sca-1(-) cells. LPS-induced upregulation of Sca-1 expression was regulated at the transcriptional level. Inhibition of c-Jun N-terminal kinase/stress-activated protein kinase (JNK) activity with the specific inhibitor SP600125 suppressed LPS-induced upregulation of Sca-1 expression by marrow lin(-) c-kit(+) Sca-1(-) cells. Engagement of Sca-1 with anti-Sca-1 antibodies enhanced the expression of Sfpi1 spleen focus-forming virus (SFFV) proviral integration 1 (PU.1) in marrow lin(-) c-kit(+) Sca-1(-) cells cultured with LPS. Sca-1 null mice failed to maintain the marrow pool of granulopoietic cells following bacteremia. These results demonstrate that TLR4/Sca-1 signaling plays an important role in the regulation of hematopoietic precursor cell programming and their enhancement of granulocyte lineage commitment in response to E. coli bacteremia.

Acute oral ethanol exposure triggers asthma in cockroach allergen-sensitized mice

Asthma may be triggered by multiple mediators, including allergen-IgE cross-linking and non-IgE mechanisms. Several clinical studies have shown acute ethanol consumption exacerbates asthma, yet no animal model exists to study this process. We developed a model of ethanol-triggered asthma in allergen-sensitized mice to evaluate the mechanisms of ethanol inducing asthma-like responses. Outbred mice were exposed to cockroach allergens on Days 0 and 14; and on Day 21, mice received ethanol by oral gavage. Tracer studies confirmed alcohol aspiration did not occur. Within 30 minutes, alcohol induced degranulation of over 74% of mast cells, and multiple parameters of asthma-like pulmonary inflammation were triggered. Ethanol-gavaged mice had a fivefold increased production of eotaxin-2 (534 pg/mL) and a sevenfold increase in bronchoalveolar eosinophils (70,080 cells). Ethanol induced a 10-fold increase in IL-13, from 84 pg/mL in sensitized mice to 845 pg/mL in ethanol-gavaged sensitized mice. In cockroach allergen-sensitized mice, ethanol triggered asthma-like changes in respiratory physiology and a significant fivefold increase in airway mucin production. Importantly, none of these asthmatic exacerbations were observed in normal mice gavaged with ethanol. Cromolyn sodium effectively stabilized mast cells, yet increased mucin production and bronchoalveolar eosinophil recruitment. Together, these data show a single oral alcohol exposure will trigger asthma-like pulmonary inflammation in allergen-sensitized mice, providing a novel asthma model.

Alcohol impairs the myeloid proliferative response to bacteremia in mice by inhibiting the stem cell antigen-1/ERK pathway

Enhancement of stem cell Ag-1 (Sca-1) expression by myeloid precursors promotes the granulopoietic response to bacterial infection. However, the underlying mechanisms remain unclear. ERK pathway activation strongly enhances proliferation of hematopoietic progenitor cells. In this study, we investigated the role of Sca-1 in promoting ERK-dependent myeloid lineage proliferation and the effects of alcohol on this process. Thirty minutes after i.p. injection of alcohol, mice received i.v. challenge with 5 × 10(7) Escherichia coli for 8 or 24 h. A subset of mice received i.v. BrdU injection 20 h after challenge. Bacteremia increased Sca-1 expression, ERK activation, and proliferation of myeloid and granulopoietic precursors. Alcohol administration suppressed this response and impaired granulocyte production. Sca-1 expression positively correlated with ERK activation and cell cycling, but negatively correlated with myeloperoxidase content in granulopoietic precursors. Alcohol intoxication suppressed ERK activation in granulopoietic precursors and proliferation of these cells during bacteremia. Granulopoietic precursors in Sca-1(-/-) mice failed to activate ERK signaling and could not increase granulomacrophagic CFU activity following bacteremia. These data indicate that Sca-1 expression promotes ERK-dependent myeloid cell proliferation during bacteremia. Suppression of this response could represent an underlying mechanism for developing myelosuppression in alcohol-abusing hosts with severe bacterial infection.

Alcohol abuse and Streptococcus pneumoniae infections: consideration of virulence factors and impaired immune responses

Alcohol is the most frequently abused substance in the world. Both acute and chronic alcohol consumption have diverse and well-documented effects on the human immune system, leading to increased susceptibility to infections like bacterial pneumonia. Streptococcus pneumoniae is the most common bacterial etiology of community-acquired pneumonia worldwide. The frequency and severity of pneumococcal infections in individuals with a history of alcohol abuse is much higher than the general population. Despite this obvious epidemiological relevance, very few experimental studies have focused on the interaction of pneumococci with the immune system of a host acutely or chronically exposed to alcohol. Understanding these host-pathogen interactions is imperative for designing effective prophylactic and therapeutic interventions for such populations. Recent advances in pneumococcal research have greatly improved our understanding of pneumococcal pathogenesis and virulence mechanisms. Additionally, a large body of data is available on the effect of alcohol on the physiology of the lungs and the innate and adaptive immune system of the host. The purpose of this review is to integrate the available knowledge in these diverse areas of for a better understanding of the how the compromised immune system derived from alcohol exposure responds to pneumococcal infections.

Alcohol suppresses the granulopoietic response to pulmonary Streptococcus pneumoniae infection with enhancement of STAT3 signaling

Enhanced granulopoietic activity is crucial for host defense against bacterial pneumonia. Alcohol impairs this response. The underlying mechanisms remain obscure. G-CSF produced by infected lung tissue plays a key role in stimulating bone marrow granulopoiesis. This study investigated the effects of alcohol on G-CSF signaling in the regulation of marrow myeloid progenitor cell proliferation in mice with Streptococcus pneumoniae pneumonia. Chronic alcohol consumption plus acute alcohol intoxication suppressed the increase in blood granulocyte counts following intrapulmonary challenge with S. pneumoniae. This suppression was associated with a significant decrease in bone marrow granulopoietic progenitor cell proliferation. Alcohol treatment significantly enhanced STAT3 phosphorylation in bone marrow cells of animals challenged with S. pneumoniae. In vitro experiments showed that G-CSF-induced activation of STAT3-p27(Kip1) pathway in murine myeloid progenitor cell line 32D-G-CSFR cells was markedly enhanced by alcohol exposure. Alcohol dose dependently inhibited G-CSF-stimulated 32D-G-CSFR cell proliferation. This impairment of myeloid progenitor cell proliferation was not attenuated by inhibition of alcohol metabolism through either the alcohol dehydrogenase pathway or the cytochrome P450 system. These data suggest that alcohol enhances G-CSF-associated STAT3-p27(Kip1) signaling, which impairs granulopoietic progenitor cell proliferation by inducing cell cycling arrest and facilitating their terminal differentiation during the granulopoietic response to pulmonary infection.