Follicular CD8 T cells accumulate in HIV infection and can kill infected cells in vitro via bispecific antibodies

Cytolytic CD8 T cells play a crucial role in the control and elimination of virus-infected cells and are a major focus of HIV cure efforts. However, it has been shown that HIV-specific CD8 T cells are infrequently found within germinal centers (GCs), a predominant site of active and latent HIV infection. We demonstrate that HIV infection induces marked changes in the phenotype, frequency, and localization of CD8 T cells within the lymph node (LN). Significantly increased frequencies of CD8 T cells in the B cell follicles and GCs were found in LNs from treated and untreated HIV-infected individuals. This profile was associated with persistent local immune activation but did not appear to be directly related to local viral replication. Follicular CD8 (fCD8) T cells, despite compromised cytokine polyfunctionality, showed good cytolytic potential characterized by high ex vivo expression of granzyme B and perforin. We used an anti-HIV/anti-CD3 bispecific antibody in a redirected killing assay and found that fCD8 T cells had better killing activity than did non-fCD8 T cells. Our results indicate that CD8 T cells with potent cytolytic activity are recruited to GCs during HIV infection and, if appropriately redirected to kill HIV-infected cells, could be an effective component of an HIV cure strategy.

Targeting tyrosine kinase receptors in hepatocellular carcinoma

The recent discoveries of genomic and molecular markers in hepatocellular carcinoma (HCC) have improved the understanding about the complexity of the signal transduction pathways as well as their relevance in normal and liver cancer cells. The identification of the functional repercussions of punctual mutations and crosstalk among cell signaling will promote the identification of specific combinatorial targeted molecular therapies to specific subsets of patients which will allow the development of personalized-based therapy and increase the survival of patients. Numerous molecular targets are in the cross-road between oncogenic and anti-apoptotic programs, genetic or epigenetic alterations, which overall may have a similar cellular phenotype. The standard antineoplastic chemotherapeutic regimes based on cytotoxic agents leads to significant side effect and modest response rates, marginal changes in natural history, and toxicities that may impact the quality of life of patients. Different strategies involving gene therapy, targeted antibodies or small molecules have been used to regulate cell death/proliferation signals, as well as angiogenesis in liver tumors. In this sense, Sorafenib recently approved for renal cell carcinoma, represents the first tyrosine kinase inhibitor (TKI) licensed for the treatment of patients with advanced HCC. This review summarizes the current status of molecular receptor TKI-based targeted therapy in HCC driving different pathways involved in cell survival, proliferation, migration, angiogenesis and metastasis, which include the regulation of Raf/MEK/ERK, PI3K/Akt/mTOR, and Jak/STAT cell signaling. The study also provides information about cell signaling crosstalk relevant in tyrosine kinase receptors (TKR)-based systemic therapy in HCC.

Comparative assessment of inoculum effects on the antimicrobial activity of amoxycillin-clavulanate and piperacillin-tazobactam with extended-spectrum beta-lactamase-producing and extended-spectrum beta-lactamase-non-producing Escherichia coli isolates

A significant inoculum-size effect has been observed with piperacillin-tazobactam, and has been associated with beta-lactamase production in extended-spectrum beta-lactamase (ESBL) producers. This association has not been previously studied in the case of amoxycillin-clavulanate. Piperacillin-tazobactam and amoxycillin-clavulanate were compared, using high inocula of susceptible strains either harbouring ESBLs or not. Two non-ESBL-producing and 15 amoxycillin-clavulanate-susceptible and piperacillin-tazobactam-susceptible ESBL-producing Escherichia coli isolates, and their respective transconjugants, were tested in dilution susceptibility tests using standard and 100-fold higher inocula. Three ESBL-producing strains and E. coli ATCC 25922 were selected for time-kill studies using standard and high initial inocula. At high inocula, MICs of piperacillin increased >eight-fold for non-ESBL-producing strains, and MICs of piperacillin-tazobactam (8:1 ratio or with tazobactam fixed at 4 mg/L) increased>eight-fold for all ESBL-producing strains. However, amoxycillin MICs were not affected by a high inoculum with non-ESBL-producing strains, whereas the MICs of amoxycillin-clavulanate (2:1 and 4:1) increased <or=four-fold for ESBL producers, using the broth and agar dilution methods. In kinetic studies at a high inoculum, amoxycillin and amoxycillin-clavulanate were bactericidal against E. coli ATCC 25922, whereas piperacillin and piperacillin-tazobactam yielded decreases of <1 log(10) CFU/mL. Similarly, at a high inoculum, only amoxycillin-clavulanate was able to maintain bactericidal rates of killing over 24 h against the ESBL-positive E. coli isolates. The stability of amoxycillin-clavulanate and the contrasting results obtained with piperacillin-tazobactam against high inocula of ESBL-non-producing and ESBL-producing E. coli strains appear to be related to aspects other than the amount of beta-lactamase production.

Genotypic diversity of imipenem resistant isolates of Acinetobacter baumannii in Spain

OBJECTIVES

To investigate relevant clinical and microbiological features of Acinetobacter baumannii in Spanish hospitals and to establish the genotypic diversity of imipenem resistant isolates.

MATERIAL AND METHODS

Seven Spanish hospitals collected 354 consecutive isolates that were subjected to antimicrobial susceptibility testing by standard methods. Further genetic analysis was determined by PFGE in a subset of 135 isolates from three hospitals selected because each of them presented high-, medium-, and low imipenem resistance rates.

RESULTS

Most isolates were from males (61.9%), age >65 years (52.3%), admitted to ICU (35.6%), and isolated from the respiratory tract (31.1%). Rates of carbapenem- and sulbactam resistance were 44.9% and 39.9%, respectively. Colistin was active against multiresistant isolates. Rates of imipenem resistance varied according to individual hospital (average: 43.8%; range: 13.5%-85.0%), medical department (more prevalent in ICU), and clinical sample (higher in isolates from the respiratory tract). Of the 135 isolates studied by PFGE (64 of them imipenem-resistant), 115 (85.1%) were distributed among 14 clusters and 20 were unrelated. Of the imipenem-resistant isolates, 45 (70.3%) belonged to six clusters that also had imipenem- susceptible isolates; 14 constituted four exclusive clusters, and five were unrelated.

CONCLUSIONS

Acquisition of imipenem resistance in A. baumannii is likely due to both clonal and non-clonal dissemination; resistance rates strongly vary between different hospitals and even between different hospital departments.

[Etiology and diagnosis of severe retroperitoneal hematoma: therapeutic options and surgical indication]

Retroperitoneal hematoma is a rare entity with clinical consequences that vary according to the speed and amount of bleeding. Thus, it may be asymptomatic, in which case it is usually diagnosed incidentally through imaging tests, or severe, in which case the most common symptoms are pain and hypovolemic shock. We report three cases of severe retroperitoneal hematoma. Although the literature on the subject describes a wide variety of causes, in all three patients the etiology was tumoral, consisting of one suprarenal myelolipoma, one renal adenocarcinoma and one suprarenal metastasis from bronchogenic adenocarcinoma. Computed tomography was the imaging test employed not only to determine the nature of the process (hematoma, abscess, tumor) but also to assess compression of adjacent structures and the occurrence of active bleeding. Conservative treatment consisting of volemic replacement and correction of coagulation was initially attempted. However, all three patients required emergency surgery due to hemodynamic instability in two patients and compression of the vena cava in the other.