Protracted Infections Research Articles

Protective role of antibodies in enteric virus infections: Lessons from primary and secondary immune deficiencies.

Enteric viruses are the main cause of acute gastroenteritis worldwide with a significant morbidity and mortality, especially among children and aged adults. Some enteric viruses also cause disseminated infections and severe neurological manifestations such as poliomyelitis. Protective immunity against these viruses is not well understood in humans, with most knowledge coming from animal models, although the development of poliovirus and rotavirus vaccines has extended our knowledge. In a classical view, innate immunity involves the recognition of foreign DNA or RNA by pathogen recognition receptors leading to the production of interferons and other inflammatory cytokines. Antigen uptake and presentation to T cells and B cells then activate adaptive immunity and, in the case of the mucosal immunity, induce the secretion of dimeric IgA, the more potent immunoglobulins in viral neutralization. The study of Inborn errors of immunity (IEIs) offers a natural opportunity to study nonredundant immunity toward pathogens. In the case of enteric viruses, patients with a defective production of antibodies are at risk of developing neurological complications. Moreover, a recent description of patients with low or absent antibody production with protracted enteric viral infections associated with hepatitis reinforces the prominent role of B cells and immunoglobulins in the control of enteric virus.

Tecovirimat Use under Expanded Access to Treat Mpox in the United States, 2022–2023

BackgroundDuring the ongoing outbreak of clade II monkeypox virus (MPXV), many U.S. patients were prescribed tecovirimat, an antiviral drug that was made available under an expanded access Investigational New Drug (EA-IND) program. We evaluated EA-IND data to summarize characteristics of treated patients, outcomes, and serious adverse events (SAEs).MethodsWe evaluated data from patients prescribed tecovirimat from May 29, 2022, through July 10, 2023. Baseline patient characteristics, clinical courses, and outcomes were evaluated via intake forms, outcome forms, and patient diaries. Data were summarized in aggregate by human immunodeficiency virus (HIV) status and by comorbidities of special interest. Reported SAEs were also compiled.ResultsTecovirimat was prescribed for over 7100 patients in the United States, most often for lesions in sensitive anatomical areas, such as certain anogenital lesions (83.5%; 5135 out of 6148 patients), and pain (52.5%; 3227 out of 6148 patients). The demographic and clinical characteristics mirrored those of patients worldwide. Among the 7181 patients with returned intake forms, 1626 also had returned outcome forms (22.6%). Many patients with severe immunocompromise (e.g., HIV with CD4 counts <200 cells/μl) received multiple courses of tecovirimat (43.1%; 22 out of 51 patients), including intravenously, and often experienced poor outcomes (35.3%; 18 out of 51 patients). Overall, 223 SAEs and 40 deaths were reported. Most SAEs were among patients who were severely immunocompromised, one of whom experienced hallucinations after tecovirimat was administered at twice the standard dose.ConclusionsTecovirimat was used extensively. The returned EA-IND data suggest that life-threatening or protracted infections occurred in persons who were severely immunocompromised. SAEs were not commonly reported. The EA-IND data are not definitive; controlled clinical trial data are essential to elucidating if and how tecovirimat should be used.

Long COVID-19 Infections and Organizing Pneumonia in a Series of Patients with Indolent Lymphoma Treated with Rituximab

Background: Patients with hematologic malignancies have an increased risk of complications and mortality from COVID-19 (SARS-CoV-2). These patients are often more susceptible to protracted COVID-19 infections (e.g., long COVID-19). In addition, patients treated with the CD20-targeted immunotherapy rituximab in B-cell lymphomas are at greater risk for a protracted clinical course with COVID-19, including care in the ICU for respiratory failure. Hypogammaglobulinemia is an independent predictor of increased risk for long-COVID19. Immune depletion both leads to a persistent detection of SARS-CoV-2 and an inability to mount a sustained immune response. Other authors have reported on the appearance of a delayed organizing pneumonia (OP) after acute COVID-19 infection, but these patients were not immunocompromised by rituximab. In this case series, we report on three patients with indolent lymphoma who had the delayed presentation of long COVID-19 after an acute infection. All three were previously treated with rituximab, and each case was notable for prolonged OP that was refractory to steroid therapy. Methods: Summative data for the three patient cases was aggregated from the medical record including available physician notes, diagnostic body imaging, and laboratory data. Results: In total, we found three cases of long COVID-19 in patients with indolent lymphoma from our institution (Table 1). Patient 1 received just two doses of rituximab, Patient 2 received three doses of rituximab, and Patient 3 was treated with rituximab intermittently for nearly three years. All three patients experienced their first COVID-19 infections in August 2022 and had low IgG. This was followed by complications including acute hypoxemic respiratory failure, pulmonary embolism, and organizing pneumonia in these patients two to three months thereafter. These patients continue to have ongoing chronic hypoxemic respiratory failure requiring immune suppression and continuous oxygen support. Conclusions: Immune depletion with rituximab in patients with indolent lymphomas can put them at significant risk of long COVID-19, OP, and chronic hypoxemic respiratory failure after contracting SARS-Cov-2. Such patients may benefit from prolonged immune suppression, but the exact duration remains unclear. The mechanism of long COVID-19 and refractory OP is unclear and complex. Possible mechanisms may include inadequate clearance of virus or a dysfunctional immune response. Table 1: Lymphoma patients who received rituximab and then developed long COVID-19

Protracted viral infections in patients with multiple myeloma receiving bispecific T-cell engager therapy targeting B-cell maturation antigen.

Not available.

Cumulative antimicrobial susceptibilities for respiratory clinical isolates of Mycobacterium avium Complex, Mycobacterium kansasii, and Mycobacterium abscessus from Pakistan 2018 to 2022.

Nontuberculous mycobacteria (NTM) are increasingly identified as causes of protracted pulmonary infections. Antibiotic susceptibility testing requires microdilution methods, which are often unavailable in laboratories in resource-poor settings. We report cumulative antibiograms for the most frequently isolated clinical pulmonary NTM from Pakistan to inform empiric antibiotic management of initial NTM infections. We analyzed data from 2018 to 2022 for the most frequently isolated and clinically relevant NTM isolated from respiratory specimens, i.e., Mycobacterium avium complex (MAC), Mycobacterium abscessus group (MAG), and Mycobacterium kansasii (MK). Antibiograms were developed using the Clinical Laboratory Standards Institute's M39ED5 standard. Percentage susceptibilities and 95% confidence intervals (CI) were calculated. Over 4 years, 529 NTM, comprising 209 MAC, 249 MAG, and 71 MK were analyzed. For MAC and MAG, where clarithromycin (CLR)-based regimens are recommended, CLR was active for 94.8% (95% CI 91.3-96.9), and 77.5% (95% CI 71.4-82.7) isolates, respectively. Combination regimens comprising 3 active drugs CLR + linezolid (LZD) + moxifloxacin for MAC and CLR + LZD + Amikacin for MAG had 98.4% (95% CI 95.9-99.4) and 68.9% (95% CI 62.3-74.8) coverage for pulmonary disease, respectively. For MK, 91.5% (95% CI 82.8-96.1) isolates were susceptible to rifampin (RIF), with a combination of RIF + CLR covering 88.7% (95% CI 79.3-94.2) of MK pulmonary infections, respectively. These data can inform empiric treatment guidance for the most common NTM pulmonary infections, i.e., for MAC, MAG, and MK disease in Pakistan.

044 Metatranscriptomics reveals association of α-, β-, and γ-HPVs with typical epidermodysplasia verruciformis in a large cohort of patients with CIB1, TMC6, or TMC8 mutations

Cutaneous human papillomavirus (HPV) infection typically manifests with isolated warts. However, some patients in familial clustering develop extensive and protracted HPV infections, primarily the β-HPV types 5 and 8, with distinct cutaneous findings. This clinical entity, epidermodysplasia verruciformis (EV), with autosomal recessive inheritance, is characterized by numerous cutaneous flat warts in childhood, which progress into squamous cell carcinomas later in life. The “typical” form of EV, not vulnerable to other infections, is caused by mutations in CIB1, TMC6, or TMC8, which impair keratinocyte-intrinsic immunity to β-HPV infection.

497 Genetic variability of viral and human genomes in a large cohort of patients with typical epidermodysplasia verruciformis

Cutaneous human papillomavirus (HPV) infection typically manifests with isolated warts. However, some patients in familial clustering develop extensive and protracted HPV infections, primarily the β-HPV types 5 and 8, with distinct cutaneous findings. This clinical entity, epidermodysplasia verruciformis (EV), with autosomal recessive inheritance, is characterized by numerous cutaneous flat warts in childhood, which progress into squamous cell carcinomas later in life. The “typical” form of EV, not vulnerable to other infections, is caused by mutations in CIB1, TMC6, or TMC8, which impair keratinocyte-intrinsic immunity to β-HPV infection.

Large Scale SARS-CoV-2 Molecular Testing and Genomic Surveillance Reveal Prolonged Infections, Protracted RNA shedding, and Viral Reinfections.

Large-scale SARS-CoV-2 molecular testing coupled with whole genome sequencing in the diagnostic laboratories is instrumental for real-time genomic surveillance. The extensive genomic, laboratory, and clinical data provide a valuable resource for understanding cases of reinfection versus prolonged RNA shedding and protracted infections. In this study, data from a total of 22,292 clinical specimens, positive by SARS-CoV-2 molecular diagnosis at Johns Hopkins clinical virology laboratory between March 11th 2020 to September 23rd 2021, were used to identify patients with two or more positive results. A total of 3,650 samples collected from 1,529 patients who had between 2 and 20 positive results were identified in a time frame that extended up to 403 days from the first positive. Cycle threshold values (Ct) were available for 1,622 samples, the median of which was over 30 by 11 days after the first positive. Extended recovery of infectious virus on cell culture was notable for up to 70 days after the first positive in immunocompromised patients. Whole genome sequencing data generated as a part of our SARS-CoV-2 genomic surveillance was available for 1,027 samples from patients that had multiple positive tests. Positive samples collected more than 10 days after initial positive with high quality sequences (coverage >90% and mean depth >100), were more likely to be from unvaccinated, or immunosuppressed patients. Reinfections with viral variants of concern were found in 3 patients more than 130 days from prior infections with a different viral clade. In 75 patients that had 2 or more high quality sequences, the acquisition of more substitutions or deletions was associated with lack of vaccination and longer time between the recovered viruses. Our study highlights the value of integrating genomic, laboratory, and clinical data for understanding the biology of SARS-CoV-2 as well as for setting a precedent for future epidemics and pandemics.

Eosinophilic Myenteric Ganglionitis with Degenerative Leiomyopathy

Background: Chronic intestinal pseudo-obstruction (CIPO) is an umbrella term for a range of different conditions characterized by repetitive episodes or continuous symptoms and signs of bowel obstruction, including radiographic evidence of dilated intestines and air-fluid levels, due to impaired propulsion in the absence of an anatomical occluding lesion. It is a diagnostic challenge and can mimic Hirschsprung's disease. Clinical Description: A 10-month-old boy presented with a history of recurrent episodes of constipation since the age of 6.5 months. The first two had resolved with symptomatic treatment. The third had been associated with bilious vomiting and required exploratory laparotomy. He was referred to us when there was no symptomatic improvement. The child underwent extensive workup that included a review of earlier investigations (contrast-enhanced computerized tomography abdomen, barium enema, and sigmoid biopsy) as well as upper gastrointestinal endoscopy, workup for secondary CIPO, esophageal and antroduodenal manometry, genetic studies, for primary CIPO. A laparotomy with concurrent adhesionolysis, appendectomy, gastrostomy, and ileostomy was undertaken, which included full-thickness biopsies at multiple sites. This revealed both degenerative leiomyopathy and eosinophilic myenteric ganglionitis (EMG). Known associations of CIPO, an underactive bladder, and sinus arrhythmias were also detected. Management: The infant was provided with supportive therapy. A trial of steroids was given for the EMG. The child had multiple bad prognostic factors and also protracted multiple nosocomial infections. He succumbed to his illness and complications after 40 days of hospitalization. Conclusion: The combination of EMG and degenerative leiomyopathy has not been reported in CIPO before.

Pseudomonas aeruginosa PAO1 Is Attracted to Bovine Bile in a Novel, Cystic Fibrosis-Derived Bronchial Epithelial Cell Model.

Cystic fibrosis (CF) is a life-threatening, inherited, multi-organ disease that renders patients susceptible throughout their lives to chronic and ultimately deteriorating protracted pulmonary infections. Those infections are dominated in adulthood by the opportunistic pathogen, Pseudomonas aeruginosa (Pa). As with other advancing respiratory illnesses, people with CF (pwCF) also frequently suffer from gastroesophageal reflux disease (GERD), including bile aspiration into the lung. GERD is a major co-morbidity factor in pwCF, with a reported prevalence of 35–81% in affected individuals. Bile is associated with the early acquisition of Pa in CF patients and in vitro studies show that it causes Pa to adopt a chronic lifestyle. We hypothesized that Pa is chemoattracted to bile in the lung environment. To evaluate, we developed a novel chemotaxis experimental system mimicking the lung environment using CF-derived bronchial epithelial (CFBE) cells which allowed for the evaluation of Pa (strain PAO1) chemotaxis in a physiological scenario superior to the standard in vitro systems. We performed qualitative and quantitative chemotaxis tests using this new experimental system, and microcapillary assays to demonstrate that bovine bile is a chemoattractant for Pa and is positively correlated with bile concentration. These results further buttress the hypothesis that bile likely contributes to the colonization and pathogenesis of Pa in the lung, particularly in pwCF.

Changes in the metabolism of innate immune cells of homoithermic animals infected with dormant forms of Yersinia pseudotuberculosis

Under the influence of unfavorable environmental factors, microorganisms pass into a viable, but uncultivated state and form a dormant (dormant) cellular phenotype, characterized by a lack of growth and metabolic activity. Dormant forms of bacteria are not detected by traditional microbiological methods, but they play an important role in the development of protracted and chronic infections in animals and humans. Purpose of the study: to characterize the experimental infectious process in warm-blooded animals, induced by the dormant phenotypes of Y. pseudotuberculosis, and to evaluate changes in the activity of the enzyme systems of inflammatory effector cells. For the study, bacteria were taken from a culture stored under static conditions for 10 years in a test tube under a layer of petroleum jelly at a temperature of 4–6 °C. Ultrastructural features of dormant cell forms were confirmed by transmission electron microscopy. The viability of dormant cells was assessed by the molecular genetic method (PCR). The absence of reproductive activity of the dormant phenotypes of Y. pseudotuberculosis was checked by repeated inoculations in LB broth, Endo and Serov›s media, and incubation at temperatures of 4–6, 22–24 and 37 °C. Further, the activity of the enzyme systems of cells of the inflammatory process effectors in vivo was investigated. During the experimental infection, the animals showed a gradual increase in the number of inflammatory effector cells. The prevailing number of neutrophils (65–70 %) on days 14–21 of infection indicated a developing inflammatory process. Reversion of the dormant form of Y. pseudotuberculosis in vivo and the development of an inflammatory process in the cells of the peritoneal exudate of infected animals inhibits the activity of the oxygen- and nitroxide-dependent bactericidal systems, as evidenced by the low values of lactate dehydrogenase, myeloperoxidase and nitric oxide. Thus, the data obtained indicate the possibility of reversion of the dormant forms of Y. pseudotuberculosis into vegetative forms 21 days after infection. On the part of the cells of innate immunity, modulation of the activity of intracellular enzymes, aimed at the induction of antimicrobial protection, was revealed.

Population Study of Hand and Wrist Manifestations of Congenital Insensitivity to Pain.

Background: Congenital insensitivity to pain is a rare autosomal recessive condition characterized by insensitivity to painful stimuli due to absence of sensory and sympathetic post ganglionic neurons in the skin and skeletal system leading to lack of protective sensation and altered joint propioception. This study was performed to assess hand and wrist manifestations of patients with congenital insensitivity to pain in the Maltese Islands. Methods: Records of public and private hospitals were reviewed to identify patients suffering from this condition. A review of notes, patients, and imaging was performed. A Disabilities of the Arm, Shoulder, and Hand score was obtained to assess level of function. Results: Nine patients were identified. Mean age of diagnosis was 8.9 years. Interphalangeal joints were most commonly affected. Multiple spontaneous or posttraumatic fingertip ulceration occurred in 5 patients. Anhidrosis resulted in more protracted ulcers and infections, requiring amputation of distal and middle phalanges due to osteomyelitis. The wrist joint was less commonly involved and showed more complex joint involvement. Conclusion: The hand and wrist are involved in different ways, with fingertip ulceration leading to potential infection and osteomyelitis in the hand, whereas the wrist joint is involved in cases of increased axial loading and load transfer, such as following prolonged use of walking and mobility aids. The latter should be borne in mind during management of lower limb conditions. Hand care and hygiene is important in all patients, especially in cases of anhidrosis due to the increased rate of ulceration and osteomyelitis requiring surgical intervention. Despite the severity of the condition, patients report good overall function.

Diffuse Lymph-Nodes Microangiopathy as Concurrent Cause of Immunodeficiency in Long-Term Insulin-Dependent Diabetic Patients

Immune abnormalities have been demonstrated in vitro models in genetic (type1) autoimmune (type 2) and metabolic (type 1 and type 2) Insulin-Dependent Diabetes Mellitus (IDDM). However, the precise reason for increased susceptibility to frequent and protracted infections in diabetic patients is still unclear, despite a multitude of in vitro studies which have focused on the metabolic and functional modifications of immune cells Diabetes microangiopathy, which is a peculiar alteration of the disease, has been extensively described in the retina, renal glomeruli, skin, skeletal muscles, peripheral nerves, and other organs but not in lymph nodes. We report our histological and immunohistochemical observations in lymph-nodes removed in multiple sites during autopsy from four patients with long-term IDDM, severe lymphocytpenia and several infectious diseases during their life. The peculiar microangiopathic modifications made by presence of hyaline substance thickening basal membrane of thin vessels and capillaries appear concurrent with lymphodepletion of B and T cells dependent areas of lymph-nodes and with jointed marked reduction of Follicular Dendritic Reticulum Cells (FDRC). Indeed microangiopathy further compromise the traffic and diapedesis of T and B lymphocytes may prevent the transformation of endothelial cells into FDRC with severe immune failure of lymphoid follicles. The histological and immunohistochemical data in this study could provide additional insights into the complex problem of the immunodeficiency in diabetic patients.

Phosphatidylserine-Induced Conformational Modulation of Immune Cell Exhaustion-Associated Receptor TIM3

In the face of chronic cancers and protracted viral infections, human immune cells are known to adopt an exhausted state in which their effector functions are lost. In recent years, a number of inhibitory receptors have been connected to the immune cell exhaustion phenotype; furthermore, ligands capable of activating these receptors have been discovered. The molecular mechanisms by which these ligands affect the exhausted states of immune cells, however, are largely unknown. Here, we present the results of molecular dynamics simulations of one potential exhaustion-associated system: the complex of human inhibitory receptor TIM3 (hTIM3) and its ligand phosphatidylserine (PSF). We find that PSF fundamentally alters the electrostatic environment within hTIM3’s Ca2+ binding site, facilitating the formation of a salt bridge and freeing a tyrosine-containing strand. This liberated tyrosine then collapses into a nearby hydrophobic pocket, anchoring a modified conformational ensemble typified by a β-strand rearrangement. The “electrostatic switching/hydrophobic anchoring” mechanism of conformational modulation reported here suggests a new type of process by which TIM3 activation might be achieved. This work also highlights strategies by which PSF-mediated conformational change could be controlled, either through administration of small molecules, execution of mutations, or modification of receptor phosphorylation states.

Real-time PCR and the ultimate quest for real-time results

It is likely that few readers of this editorial had the experience, in the few years after the principles of the PCR were announced in 1985, of actually performing the method as it was first described [1]. In those days, PCR involved pipetting a new aliquot of Klenow polymerase into the reaction tube after each PCR cycle because the temperatures required for denaturation of the target and amplification products also in activated the enzyme. Most memorably, it required sequential precise pipetting of the reagents into small batches of plastic tubes wedged into styrofoam rafts floating in water baths kept at three different temperatures, with no time for bio-breaks. As graduate students, we were blissfully unaware of the threat of PCR contamination, the management or mismanagement of which ultimately determined the fate of the technology in forensic [2] and medical practice [3,4]. Fortunately, the technology evolved; with the advent of thermostable DNA polymerases, thermal cyclers and real-time PCR; contamination risk was diminished, physical containment requirements were reduced and more laboratories adopted molecular testing [5]. Real-time PCR testing has provided new levels of diagnostic accuracy and medical utility, particularly in the diagnosis of sexually transmitted diseases and protracted viral infections such as HIV and hepatitis C virus. Quantitative molecular methods have become the mainstay of the medical management of chronic viral infections, and will be used increasingly for monitoring treatment responses of a wide variety of infections [6]. Molecular typing methods will be used in real-time to track outbreaks of infections due to healthcare-associated pathogens [7]. Deep sequencing has facilitated metagenomic analysis of multiple prokaryotic pathogens within a biological ecosystem, thus defining diseases associated with shifts in bacterial populations such as inflammatory bowel disease and bacterial vaginosis [8]. Testing in this area may ultimately have bacterial ecology as its focus. From a David H Persing & Ellen Jo Baron* Editorial

High prevalence of IgA class anti-neutrophil cytoplasmic antibodies (ANCA) is associated with increased risk of bacterial infection in patients with cirrhosis

Anti-neutrophil cytoplasmic antibodies (ANCA) are a non-uniform family of antibodies recognizing diverse components of neutrophil granulocytes. ANCA formation might be induced by protracted bacterial infections or probably reflect an abnormal immune response to commensal microorganisms. Bacterial infections are common complications in cirrhosis with high incidence of episodes caused by enteric organisms, therefore, we sought to study the presence and clinical importance of ANCA in cirrhosis. Sera of 385 patients with cirrhosis of different etiologies were assayed for ANCA of IgG, IgA, IgA1, IgA2, and secretory IgA subtypes by indirect immunofluorescence and ELISAs. The control group comprised 202 patients with chronic liver diseases without cirrhosis and 100 healthy subjects. In cirrhosis, a 2-year follow-up, observational study was conducted to assess a possible association between the presence of ANCA and clinically significant bacterial infections. Prevalence of ANCA IgA was significantly higher in cirrhosis (52.2%) compared to chronic liver diseases (18.6%) or healthy controls (0%, p<0.001 for both). ANCA IgA subtyping assays revealed marked increase in the proportion of IgA2 subtype (46% of total ANCA IgA) and presence of the secretory component concurrently. Presence of ANCA IgA was associated with disease-specific clinical characteristics (Child-Pugh stage and presence of ascites, p<0.001). During a 2-year follow-up period, risk of infections was higher among patients with ANCA IgA compared to those without (41.8% vs. 23.4%, p<0.001). ANCA IgA positivity was associated with a shorter time to the first infectious complication (pLogRank <0.001) in Kaplan-Meier analysis and was identified as an independent predictor in multivariate Cox-regression analysis (HR:1.74, 95% CI: 1.18-2.56, p=0.006). Presence of IgA type ANCA is common in cirrhosis. Involvement of gut mucosal immune system is in center of their formation and probably reflects sustained exposure to bacterial constituents.

Rhinovirus Genome Variation during Chronic Upper and Lower Respiratory Tract Infections

Routine screening of lung transplant recipients and hospital patients for respiratory virus infections allowed to identify human rhinovirus (HRV) in the upper and lower respiratory tracts, including immunocompromised hosts chronically infected with the same strain over weeks or months. Phylogenetic analysis of 144 HRV-positive samples showed no apparent correlation between a given viral genotype or species and their ability to invade the lower respiratory tract or lead to protracted infection. By contrast, protracted infections were found almost exclusively in immunocompromised patients, thus suggesting that host factors rather than the virus genotype modulate disease outcome, in particular the immune response. Complete genome sequencing of five chronic cases to study rhinovirus genome adaptation showed that the calculated mutation frequency was in the range observed during acute human infections. Analysis of mutation hot spot regions between specimens collected at different times or in different body sites revealed that non-synonymous changes were mostly concentrated in the viral capsid genes VP1, VP2 and VP3, independent of the HRV type. In an immunosuppressed lung transplant recipient infected with the same HRV strain for more than two years, both classical and ultra-deep sequencing of samples collected at different time points in the upper and lower respiratory tracts showed that these virus populations were phylogenetically indistinguishable over the course of infection, except for the last month. Specific signatures were found in the last two lower respiratory tract populations, including changes in the 5′UTR polypyrimidine tract and the VP2 immunogenic site 2. These results highlight for the first time the ability of a given rhinovirus to evolve in the course of a natural infection in immunocompromised patients and complement data obtained from previous experimental inoculation studies in immunocompetent volunteers.

Functional impairment after treatment with pectoral muscle flaps because of deep sternal wound infection

Objective. Pectoral muscle flaps (PMF) are effective in terminating protracted sternal wound infections (SWI) but long-term outcome remains uncertain. Therefore, the aim of this study was to evaluate long-term outcome in patients treated with PMF. Design. Thirty-four of 263 patients revised because of deep SWI from 1991–2005 were treated with PMF. Of the 21 patients alive, 11 had left-sided, two right-sided and eight bilateral procedures. Sternal debridement without closure of the sternum was done in 17 patients. Nineteen of 21 patients responded to a questionnaire. Results. At follow-up on average 5.9 years (range 1.9–14.8 years) after surgery 63% (12/19) experienced unstable chest. Two thirds (12/18) reported problems carrying a grocery bag and 37% (7/19) had problems putting on a coat. Reduction of power and mobility was more common in the right arm and shoulder even in patients with left-sided PMF. Thirty-two percent (6/19) would have preferred alternative treatment if possible to avoid sternal instability even if healing had been substantially delayed. Conclusions. Surgery with PMF and sternal debridement was associated with long-term disability, which appeared to be significant in one third of the patients. The function of the right arm and shoulder was affected more often despite the majority of procedures being left-sided suggesting that loss of skeletal continuity of the chest wall is more disabling than loss of pectoral muscle function.

Exhausted CD8 T cells become unresponsive to activation by innate cytokines and bystander bacterial infections (45.12)

Abstract During many chronic infections T cell responses initially develop, but succumb to exhaustion, as they lose their ability to produce interferon-γ (IFNγ) in response to antigen. Combinations of interleukins (IL)- 12, 18, and 21 have been shown to induce the antigen-independent production of IFNγ by prototypic memory CD8 T cells; therefore, we evaluated the sensitivity of exhausted lymphocytic choriomeningitis virus (LCMV)-specific CD8 T cells to activation with these cytokines. Our findings show that following acute infection, effector CD8 T cells respond synergistically to stimulation by these cytokines, but this responsiveness is abolished in exhausted T cells. To evaluate mechanisms responsible for this loss of responsiveness, we examined the expression of the cognate cytokine receptors. Whereas effector and memory T cells express the IL-18R, exhausted T cells downregulated the IL-18R but expressed higher levels of the IL-21R. To evaluate the biological consequences of this decreased sensitivity, we challenged cohorts of LCMV infected mice with the intracellular bacterial pathogen Listeria. Although LCMV-specific memory CD8 T cells vigorously respond to the bacterial infection, this responsiveness is severely compromised during protracted or chronic LCMV infections. Collectively, our findings show that exhausted cells downregulate IL-18R and become desensitized to activation by innate cytokines, rendering them unresponsive to secondary bacterial infections.

The roles of eotaxin and the STAT6 signalling pathway in eosinophil recruitment and host resistance to the nematodes Nippostrongylus brasiliensis and Heligmosomoides bakeri

Expulsion of adult Nippostrongylus brasiliensis worms from the small intestine is profoundly impaired in signal transducer and activator of transcription (STAT)6-deficient mice. IL-5 transgenic (Tg) mice with constitutive eosinophilia show profound early resistance in the skin and/or later pre-lung phase of primary infections with N. brasiliensis. This study was designed to assess the importance of the eosinophil chemokine eotaxin and the STAT6/interleukin (IL)-4/IL-13 signalling pathway in early resistance to N. brasiliensis. Eosinophil recruitment into the skin following injection of N. brasiliensis larvae was reduced in STAT6- or eotaxin-deficient/IL-5 Tg double mutant mice. While ablation of eotaxin did not impair resistance in the pre-lung phase of N. brasiliensis infections in IL-5 Tg mice, elimination of STAT6 caused a modest reduction in resistance in both primary and secondary infections on this genetic background. STAT6 −/−-, IL-13 −/−- and IL-4Rα −/−-deficient single mutant and IL-13 −/−/IL-4Rα −/− double mutant mice were more susceptible than WT mice during the pre-lung phase of secondary N. brasiliensis infections. In contrast, primary or secondary resistance were unaffected at either the pre-lung or gut stages of infection in eotaxin −/− single mutant mice. STAT6 −/− and eotaxin −/− mice with or without the IL-5 transgene, were no more susceptible than WT or IL-5 Tg mice to protracted primary infections with Heligmosomoides bakeri, a parasitic nematode that is restricted to the gut. Our data suggest that parasitic nematodes that transit through the skin and lungs en route to the gut may be susceptible to early (pre-lung) innate and adaptive immune mechanisms that are dependent on the STAT6/IL-4/IL-13 signalling pathway, and this may be important for the development of effective therapies and vaccines.