Disseminated Cryptococcosis in Idiopathic CD4+ Lymphocytopenia.

INTRODUCTION: Idiopathic CD4+ Lymphocytopenia (ICL) is a rare entity grouped in non- HIV-related syndromes. ICL is characterized by a marked low CD4 T cell count of <300 cells/mm3 with ambiguous natural history and prognosis. In addition, cryptococcal and nontuberculous mycobacterial infections are reported as known opportunistic infections. Therefore, management turns around vigilant follow-up and treatment of the current clinical scenario of these patients. CASE PRESENTATION: Here, a 55-year-old lady was referred with a history of diffuse headache and intermittent fever for two months, projectile vomiting, and altered mental status for five days. Nonpruritic maculopapular rashes and diffuse desquamation of the skin were noted. She had no significant previous medical history. Based on clinical findings and investigations, she was diagnosed with ICL having disseminated cryptococcosis. Unfortunately, the patient did not undergo specific treatment as she was recognized late, and unfortunately, she died. CONCLUSION: It is of paramount importance to recognize the clinical entity as early as possible to start appropriate treatment, which may positively impact the outcome. Therefore, the clinician must be aware of disseminated cryptococcosis associated with non-HIV states.

Molecular and Cellular Mechanisms of M. tuberculosis and SARS-CoV-2 Infections-Unexpected Similarities of Pathogenesis and What to Expect from Co-Infection.

Tuberculosis is still an important medical and social problem. In recent years, great strides have been made in the fight against M. tuberculosis, especially in the Russian Federation. However, the emergence of a new coronavirus infection (COVID-19) has led to the long-term isolation of the population on the one hand and to the relevance of using personal protective equipment on the other. Our knowledge regarding SARS-CoV-2-induced inflammation and tissue destruction is rapidly expanding, while our understanding of the pathology of human pulmonary tuberculosis gained through more the 100 years of research is still limited. This paper reviews the main molecular and cellular differences and similarities caused by M. tuberculosis and SARS-CoV-2 infections, as well as their critical immunological and pathomorphological features. Immune suppression caused by the SARS-CoV-2 virus may result in certain difficulties in the diagnosis and treatment of tuberculosis. Furthermore, long-term lymphopenia, hyperinflammation, lung tissue injury and imbalance in CD4+ T cell subsets associated with COVID-19 could propagate M. tuberculosis infection and disease progression.

Lymphocyte Immune Response and T Cell Differentiation in Fontan Patients with protein-losing enteropathy.

BACKGROUND: Protein-losing enteropathy (PLE) is a severe complication of the Fontan circulation. There is increasing discussion about whether lymphatic dysregulation is involved as pathomechanism of PLE. This investigation focuses on the interplay between alteration of lymphatic cells and immunologic pathway alterations. METHODS: Micro-ribonucleic acid (miRNA) expression profiling was performed in 49 patients (n = 10 Fontan patients with PLE, n = 30 Fontan patients without PLE, and n = 9 patients with dextro-transposition of the great arteries (dTGA). miRNA pathway analysis was performed to identify significantly enriched pathways. To determine lymphocyte populations and subtypes multiparameter flow cytometry was used. RESULTS: miRNAs pathway analysis of Fontan patients with PLE revealed 20 significantly changed networks of which four of the ten largest were associated with immunologic processes. This finding is supported by significant T cell deficiency with decreased CD4+ count (p = 0.0002), altered CD4 +/CD8+ ratio, and significantly modified CD4+ (p < 0.0001) and CD8+ (p = 0.0002) T cell differentiation toward effector and terminal differentiated T cells in Fontan patients with PLE. Analyses of CD4+ T cell subsets demonstrated significantly increased frequencies of CD4+ CD25+ CD127- regulatory T cells (Treg) in Fontan patients with PLE (p = 0.0011). CONCLUSION: PLE in Fontan patients is associated with severe lymphopenia, T cell deficiency, significant alterations of T cell differentiation, and increased Treg frequency reflecting an immune status of chronic inflammation and shortened protection against pathogens and autoimmunity. These cellular alterations seemed to be dysregulated by several miRNA controlled immunological pathways.

SARS-CoV-2-induced immunodysregulation and the need for higher clinical suspicion for co-infection and secondary infection in COVID-19 patients.

Cases of co-infection and secondary infection emerging during the current Coronavirus Disease-19 (COVID-19) pandemic are a major public health concern. Such cases may result from immunodysregulation induced by the SARS-CoV-2 virus. Pandemic preparedness must include identification of disease natural history and common secondary infections to implement clinical solutions.

The microbial coinfection in COVID-19.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel ß-coronavirus, is the main pathogenic agent of the rapidly spreading pneumonia called coronavirus disease 2019 (COVID-19). SARS-CoV-2 infects much more people, especially the elder population, around the world than other coronavirus, such as SARS-CoV and MERS-CoV, which is challenging current global public health system. Beyond the pathogenesis of SARS-CoV-2, microbial coinfection plays an important role in the occurrence and development of SARS-CoV-2 infection by raising the difficulties of diagnosis, treatment, prognosis of COVID-19, and even increasing the disease symptom and mortality. We summarize the coinfection of virus, bacteria and fungi with SARS-CoV-2, their effects on COVID-19, the reasons of coinfection, and the diagnosis to emphasize the importance of microbial coinfection in COVID-19. KEY POINTS: • Microbial coinfection is a nonnegligible factor in COVID-19. • Microbial coinfection exacerbates the processes of the occurrence, development and prognosis of COVID-19, and the difficulties of clinical diagnosis and treatment. • Different virus, bacteria, and fungi contributed to the coinfection with SARS-CoV-2.

Early Lymphocyte Loss and Increased Granulocyte/Lymphocyte Ratio Predict Systemic Spread of Streptococcus pyogenes in a Mouse Model of Acute Skin Infection.

Background: Group A streptococci may induce lymphopenia, but the value of lymphocyte loss as early biomarkers for systemic spread and severe infection has not been examined systematically. Methods: We evaluated peripheral blood cell indices as biomarkers for severity and spread of infection in a mouse model of Streptococcus pyogenes skin infection, using two isolates of greatly differing virulence. Internal organs were examined histologically. Results: After subcutaneous inoculation, strain AP1 disseminated rapidly to peripheral blood and internal organs, causing frank sepsis. In contrast, seeding of internal organs by 5448 was mild, this strain could not be isolated from blood, and infection remained mostly localized to skin. Histopathologic examination of liver revealed microvesicular fatty change (steatosis) in AP1 infection, and examination of spleen showed elevated apoptosis and blurring of the white pulp/red pulp border late (40 h post infection) in AP1 infection. Both strains caused profound lymphopenia, but lymphocyte loss was more rapid early in AP1 infection, and lymphocyte count at 6 h post infection was the most accurate early marker for AP1 infection (area under the receiver operator curve [AUC] = 0.93), followed by the granulocyte/lymphocyte ratio (AUC = 0.89). Conclusions: The results suggest that virulence of S. pyogenes correlates with the degree of early lymphopenia and underscore the value of peripheral blood indices to predict severity of bacterial infections in mice. Early lymphopenia and elevated granulocyte/lymphocyte ratio merit further investigation as biomarkers for systemic spread of S. pyogenes skin infections in humans and, possibly, related pyogenic streptococci in humans and animals.

Serious Infections in Patients Receiving Ibrutinib for Treatment of Lymphoid Cancer.

Background: Ibrutinib is a Bruton tyrosine kinase inhibitor that is used for the treatment of lymphoid cancers, including chronic lymphocytic leukemia, Waldenström macroglobulinemia, and mantle cell lymphoma. Several case series have described opportunistic infections among ibrutinib recipients, but the full extent of these infections is unknown. We sought to determine the spectrum of serious infections associated with ibrutinib treatment. Methods: We reviewed the electronic medical records of patients with lymphoid cancer at Memorial Sloan Kettering Cancer Center who received ibrutinib during a 5-year period from 1 January 2012 to 31 December 2016. Serious infections were identified by review of the relevant microbiology, clinical laboratory, and radiology data. Risk factors for infection were determined by means of univariate and multivariate analyses. Results: We analyzed findings in 378 patients with lymphoid cancer who received ibrutinib. The most common underlying cancers were chronic lymphocytic leukemia and mantle cell lymphoma. 84% of patients received ibrutinib as monotherapy. Serious infection developed in 43 patients (11.4%), primarily during the first year of ibrutinib treatment. Invasive bacterial infections developed in 23 (53.5%) of these patients, and invasive fungal infections (IFIs) in 16 (37.2%) .The majority of patients with IFIs during ibrutinib therapy (62.5%) lacked classic clinical risk factors for fungal infection (ie, neutropenia, lymphopenia, and receipt of corticosteroids). Infection resulted in death in 6 of the 43 patients (14%). Conclusions: Patients with lymphoid cancer receiving ibrutinib treatment are at risk for serious infections, including IFIs.

Lymphopenia is associated with late onset Pneumocystis jirovecii pneumonia in solid organ transplantation.

BACKGROUND: Pneumocystis jirovecii pneumonia (PJP) affected 5%-15% of solid organ transplant (SOT) recipients prior to universal prophylaxis, classically with trimethoprim-sulfamethoxazole (TMP-SMX). Guidelines generally recommend 6-12 months of prophylaxis post-SOT, yet optimal duration and robust PJP risk stratification have not been established. METHODS: A retrospective, single-center, case-control study of PJP among SOT recipients from January 1998 to December 2013 was conducted. Cases had positive PJ direct fluorescent antibody assay of respiratory specimens. Controls were matched 4:1 by nearest date of SOT. Univariate testing and multivariate logistic regressions were performed. RESULTS: Fifteen cases were identified among 5505 SOT recipients (0.27% rate) and analyzed vs 60 controls. PJP occurred on average 6.1 years (range 0.9-13.8) post-SOT; no case was receiving PJP prophylaxis at diagnosis. Most were treated with reduced immunosuppression and TMP-SMX plus steroids (80%). Six patients (40%) required critical care; 3 (20%) died. There were no significant demographic differences, though cases tended to be older at SOT (54 vs 48 years, P = .1). In univariate analysis, prior viral infection was more common among cases (67% vs 37%, P = .08). Lower absolute lymphocyte count (ALC) at diagnosis date was strongly associated with PJP (400 vs 1230 × 106  cells/µL, P < .001); odds of infection were high with ALC ≤ 500 × 106 cells (OR 18.7, P < .01). CONCLUSION: Pneumocystis jirovecii pneumonia is a rare, late complication of SOT with significant morbidity and mortality. Severe lymphopenia may be useful in identifying SOT recipients who warrant continued or reinstated PJP prophylaxis.

Mycobacterium genavense infections in non-HIV immunocompromised hosts: a systematic review.

BACKGROUND: Mycobacterium genavense is a non-tuberculous mycobacterium which can rarely cause disease in non-HIV immunocompromised hosts. We describe our experience with this unusual infection and perform a systematic review of the literature to describe the features of M. genavense infection in non-HIV immunocompromised hosts. METHODS: All cases of Mycobacterium genavense infection in non-HIV patients at our institution were reviewed. In addition, we conducted a systematic review of the literature to identify previously published cases of M. genavense infections in non-HIV hosts. FINDINGS: Two cases of M. genavense were identified at our center; a 51-year-old renal transplant recipient with a prosthetic knee joint infection and a 66-year-old woman with idiopathic CD4 lymphocytopenia with gastrointestinal tract disease. The systematic review identified 44 cases of M. genavense infection in non-HIV hosts. The most common underlying conditions were solid organ transplantation (40%), sarcoidosis (14%) and hematopoietic stem cell transplantation (7%). Disease most commonly involved the gastrointestinal tract, spleen, liver or bone marrow. Diagnosis was challenging with PCR required for identification in nearly all cases. Over one-third of patients died, which may reflect the combination of infection and underlying comorbidities. Overall cure was achieved in 61% with a mean duration of antimycobacterial therapy of 15.5 months (range 10-24). CONCLUSION: M. genavense infection is a rare mycobacterial infection in non-HIV immunocompromised hosts. It should be suspected in immunocompromised patients presenting with disseminated mycobacterial infection, acid fast bacilli on smear or histopathologic examination, with poor or no growth in mycobacterial cultures.

Intestinal microbiota link lymphopenia to murine autoimmunity via PD-1+CXCR5-/dim B-helper T cell induction.

T cell lymphopenia results in peripheral homeostatic expansion to maintain the T cell immune system, which is termed lymphopenia-induced proliferation (LIP). LIP is a potential risk for expanding autoreactive clones to become pathogenic in human and murine autoimmune diseases. However, the ontogeny of T cells that induce autoantibody production by autoreactive B cells in LIP remains unclear. Transfer of CD4+CD25- conventional T (Tc) cells into T-cell-deficient athymic nude mice has been previously reported as a LIP-induced autoimmune model which develops organ-specific autoimmune diseases and systemic antinuclear antibodies (ANAs). We show here that via LIP in this model, Tc cells proliferated and differentiated into PD-1+CXCR5-/dim B-helper T cells, which promoted splenic germinal center (GC) formation, provided help for autoantibody-producing B cells, and had distinctive features of follicular helper T (Tfh) cells except that they do not express high CXCR5. Intestinal microbiota were essential for their generation, since depletion of them in recipient mice by antibiotics resulted in a reduction of LIP-induced PD-1+CXCR5-/dim B-helper T cells and an amelioration of autoimmune responses. Our findings will contribute to the elucidation of the mechanism of lymphopenia-induced autoimmunity and autoantibody production, and will pave the way for microbiota-targeted novel therapeutic approaches to systemic autoimmune diseases.

Plasma Levels of Neopterin and C-Reactive Protein (CRP) in Tuberculosis (TB) with and without HIV Coinfection in Relation to CD4 Cell Count.

BACKGROUND: While the risk of TB is elevated in HIV-positive subjects with low CD4 cell counts, TB may in itself be associated with CD4 lymphocytopenia. We investigated markers of immune activation (neopterin) and inflammation (CRP) in TB patients with and without HIV coinfection and their association with CD4 cell levels, and determined their predictive capacity as alternative markers of advanced immunosuppression. METHODS: Participants selected from a cohort of adults with TB at Ethiopian health centers (195 HIV+/TB+, 170 HIV-/TB+) and 31 controls were tested for plasma levels of neopterin and CRP. Baseline levels of neopterin and CRP were correlated to CD4 cell count before and after anti-TB treatment (ATT). The performance to predict CD4 cell strata for both markers were investigated using receiver operating curves. RESULTS: Levels of both biomarkers were elevated in TB patients (neopterin: HIV+/TB+ 54 nmol/l, HIV-/TB+ 23 nmol/l, controls 3.8 nmol/l; CRP: HIV+/TB+ 36 µg/ml, HIV-/TB+ 33 µg/ml, controls 0.5 µg/ml). Neopterin levels were inversely correlated (-0.53, p<0.001) to CD4 cell count, whereas this correlation was weaker for CRP (-0.25, p<0.001). Neither of the markers had adequate predictive value for identification of subjects with CD4 cell count <100 cells/mm3 (area under the curve [AUC] 0.64 for neopterin, AUC 0.59 for CRP). CONCLUSION: Neopterin levels were high in adults with TB, both with and without HIV coinfection, with inverse correlation to CD4 cell count. This suggests that immune activation may be involved in TB-related CD4 lymphocytopenia. However, neither neopterin nor CRP showed promise as alternative tests for immunosuppression in patients coinfected with HIV and TB.

Mucormycosis in haematological patients: case report and results of prospective study in Saint Petersburg, Russia.

We prospectively observed 36 haematological patients with mucormycosis from nine hospitals of St. Petersburg during 2004-2013. The most frequent underlying diseases were acute leukaemia (64%), and main risk factors were prolonged neutropenia (92%) and lymphocytopenia (86%). In 50% of the patients, mucormycosis was diagnosed 1-65 days after invasive aspergillosis. Main clinical form of mucormycosis was pulmonary (64%), while two or more organ involvement was noted in 50% of the cases. The most frequent aetiological agents of mucormycosis were Rhizopus spp. (48%). Twelve-week survival rate was 50%. Combination therapy (echinocandins + amphotericin B forms) and recovery from the underlying disease significantly improved the survival rate.

Cryptococcus neoformans meningoencephalitis in a patient with idiopathic CD4+ T lymphocytopenia.

Cryptococcus neoformans is a leading cause of invasive cryptoccocal infections which include meningitis/meningoencephalitis, cerebral cryptococcoma, invasive pulmonary and mediastinal infection. Invasive infection is mainly diagnosed in immunocompromised patients, especially in HIV-infected individuals. There is a rising number of patients with invasive cryptococcal infections in immunocompromised patients who are HIV-negative. Among several primary immunodeficiency syndromes, considered as possible reasons for these invasive infections, idiopathic CD4+ T lymphocytopenia (ICL) is most frequently diagnosed. The pathogenesis of this rare syndrome is still unknown, while its clinical spectrum ranges from an asymptomatic laboratory abnormality to life-threatening opportunistic infections. Here we present an HIV-negative young man suffering from cryptococcal meningoencephalitis in whom ICL was diagnosed.

Nonalloreactive T cells prevent donor lymphocyte infusion-induced graft-versus-host disease by controlling microbial stimuli.

In mice, graft-versus-host reactions, associated with powerful graft-versus-tumor effects, can be achieved without graft-versus-host disease (GVHD) by delayed administration of donor lymphocyte infusions (DLI) to established mixed chimeras. However, GVHD sometimes occurs after DLI in established mixed chimeric patients. In contrast to mice, in which T cell recovery from the thymus occurs prior to DLI administration, human T cell reconstitution following T cell-depleted hematopoietic cell transplantation is slow, resulting in lymphopenia at the time of DLI. We demonstrate in this study that T cell lymphopenia is an independent risk factor for GVHD following DLI in the absence of known inflammatory stimuli. DLI-induced GVHD was prevented in lymphopenic recipients by prior administration of a small number of nonalloreactive polyclonal T cells, insufficient to prevent lymphopenia-associated expansion of subsequently administered T cells, through a regulatory T cell-independent mechanism. GVHD was not inhibited by T cells with irrelevant specificity. Moreover, administration of antibiotics reduced the severity of GVHD in lymphopenic hosts. Accumulation of DLI-derived effector T cells and host hematopoietic cell elimination were markedly diminished by regulatory T cell-depleted, nonalloreactive T cells. Finally, thymectomized mixed chimeras showed increased GVHD following delayed DLI. Collectively, our data demonstrate that in the absence of known conditioning-induced inflammatory stimuli, T cell lymphopenia is a risk factor for GVHD in mixed chimeras receiving delayed DLI. Our data suggest that the predisposition to GVHD can at least in part be explained by the presence of occult inflammatory stimuli due to the absence of T cells to control microbial infections.

Pneumonic tularemia in rabbits resembles the human disease as illustrated by radiographic and hematological changes after infection.

BACKGROUND: Pneumonic tularemia is caused by inhalation of the gram negative bacterium, Francisella tularensis. Because of concerns that tularemia could be used as a bioterrorism agent, vaccines and therapeutics are urgently needed. Animal models of pneumonic tularemia with a pathophysiology similar to the human disease are needed to evaluate the efficacy of these potential medical countermeasures. PRINCIPAL FINDINGS: Rabbits exposed to aerosols containing Francisella tularensis strain SCHU S4 developed a rapidly progressive fatal pneumonic disease. Clinical signs became evident on the third day after exposure with development of a fever (>40.5°C) and a sharp decline in both food and water intake. Blood samples collected on day 4 found lymphopenia and a decrease in platelet counts coupled with elevations in erythrocyte sedimentation rate, alanine aminotransferase, cholesterol, granulocytes and monocytes. Radiographs demonstrated the development of pneumonia and abnormalities of intestinal gas consistent with ileus. On average, rabbits were moribund 5.1 days after exposure; no rabbits survived exposure at any dose (190-54,000 cfu). Gross evaluation of tissues taken at necropsy showed evidence of pathology in the lungs, spleen, liver, kidney and intestines. Bacterial counts confirmed bacterial dissemination from the lungs to the liver and spleen. CONCLUSIONS/SIGNIFICANCE: The pathophysiology of pneumonic tularemia in rabbits resembles what has been reported for humans. Rabbits therefore are a relevant model of the human disease caused by type A strains of F. tularensis.

Evidence for polymicrobic flora translocating in peripheral blood of HIV-infected patients with poor immune response to antiretroviral therapy.

In advanced HIV infection, the homeostatic balance between gastrointestinal indigenous bacteria and gut immunity fails and microbes are able to overcome the intestinal barrier and gain the systemic circulation. Because microbial translocation is not fully controlled by antiviral therapy and is associated with inefficient CD4+ reconstitution, we investigated the profile of translocating bacteria in peripheral blood of 44 HIV-infected patients starting therapy with advanced CD4+ T-lymphopenia and displaying poor CD4+ recovery on virologically suppressive HAART. According to CD4+ reconstitution at 12-months HAART, patients were considered Partial Immunological Responders, PIRs (CD4+≥250/µl, n = 29) and Immunological non Responders, INRs (CD4+<200/µl, n = 15)). We show that PIRs and INRs present similarly elevated plasma levels of lipopolysaccharide (LPS) and its ligand sCD14 that were not lowered by virologically suppressive therapy. Bacterial 16S rRNA gene amplification and sequencing resulted in a highly polymicrobic peripheral blood microbiota both prior and after 12-month HAART. Several differences in bacterial composition were shown between patients' groups, mainly the lack of probiotic Lactobacillaceae both prior and after therapy in INRs. Failure to control microbial translocation on HAART is associated with a polymicrobic flora circulating in peripheral blood that is not substantially modified by therapy.

TCR revision generates functional CD4+ T cells.

CD4(+)Vß5(+) peripheral T cells in C57BL/6 mice respond to encounter with a peripherally expressed endogenous superantigen by undergoing either deletion or TCR revision. In this latter process, cells lose surface Vß5 expression and undergo RAG-dependent rearrangement of endogenous TCRß genes, driving surface expression of novel TCRs. Although postrevision CD4(+)Vß5(-)TCRß(+) T cells accumulate with age in Vß5 transgenic mice and bear a diverse TCR Vß repertoire, it is unknown whether they respond to homeostatic and antigenic stimuli and thus may benefit the host. We demonstrate in this study that postrevision cells are functional. These cells have a high rate of steady-state homeostatic proliferation in situ, and they undergo extensive MHC class II-dependent lymphopenia-induced proliferation. Importantly, postrevision cells do not proliferate in response to the tolerizing superantigen, implicating TCR revision as a mechanism of tolerance induction and demonstrating that TCR-dependent activation of postrevision cells is not driven by the transgene-encoded receptor. Postrevision cells proliferate extensively to commensal bacterial Ags and can generate I-A(b)-restricted responses to Ag by producing IFN-γ following Listeria monocytogenes challenge. These data show that rescued postrevision T cells are responsive to homeostatic signals and recognize self- and foreign peptides in the context of self-MHC and are thus useful to the host.

[Analysis of patients with positive acid-fast bacilli culture and negative T-SPOT.TB results].

BACKGROUND: T-SPOT.TB is a sensitive test that detects interferon-gamma producing T-cells in tuberculosis patients following stimulation with tuberculosis-specific antigens. Our study was aimed to investigate the possible causes of false negative results of the test by analyzing the patients with positive acid-fast bacilli (AFB) culture and negative T-SPOT.TB results. METHODS: We investigated 138 patients with positive AFB culture results reported between January 2009 and April 2010. Medical records of these patients were reviewed for the results of T-SPOT.TB test, AFB culture, PCR for Mycobacterium tuberculosis (TB-PCR), chest X-ray, drug treatment, etc. Diagnosis of tuberculosis was confirmed by positive TB-PCR or identification of Mycobacterium tuberculosis (MTB). Sensitivity of T-SPOT.TB test was calculated and the possible causes of AFB culture positive and T-SPOT.TB negative results were analyzed. RESULTS: T-SPOT.TB test was performed in 63 of the 138 patients with AFB culture positive results. Fifty-six (88.9%) were positive and 7 patients (11.1%) were negative on T-SPOT.TB test. Of these 7 negative cases, 4 were confirmed as nontuberculous mycobacteria (NTM), 2 were suspected as NTM and diagnosis could not be confirmed in 1. Six of these 7 patients were over 70 yr old and 6 patients had lymphocytopenia. T-SPOT.TB negative results were not observed in any of the 44 patients confirmed to have active tuberculosis (sensitivity 100%). CONCLUSIONS: Our results suggest that T-SPOT.TB test is very sensitive for diagnosing active tuberculosis. NTM may be the main cause of AFB culture positive and T-SPOT.TB negative results, but MTB infection in immunocompromised patients also has to be considered.