Biomarkers of Immunotherapy Response in Patients with Non-Small-Cell Lung Cancer: Microbiota Composition, Short-Chain Fatty Acids, and Intestinal Permeability.

Immune checkpoint inhibitors have been proposed as the standard treatment for different stages of non-small-cell lung cancer in multiple indications. Not all patients benefit from these treatments, however, and certain patients develop immune-related adverse events. Although the search for predictors of response to these drugs is a major field of research, these issues have yet to be resolved. It has been postulated that microbiota could play a relevant role in conditioning the response to cancer treatments; however, the human factor of intestinal permeability also needs to be considered as it is closely related to the regulation of host-microbiota interaction. In this article, we analyzed the possible relationship between the response to immune checkpoint inhibitors and the onset of immune-related adverse events, gut microbiota status, and intestinal membrane permeability. In a pioneering step, we also measured short-chain fatty acid content in feces. Although the correlation analyses failed to identify predictive biomarkers, even when all variables were integrated, our patients' microbial gut ecosystems were rich and diverse, and the intestinal barrier's integrity was preserved. These results add new knowledge on the composition of microbiota and its correlation with barrier permeability and short-chain fatty acids and suggest that more studies are required before these potential biomarkers can be incorporated into the clinical management of patients via immune checkpoint inhibitor treatment.

The importance of prevalence and pre-test probability on the microbiological diagnosis of SARS-CoV-2: the case of Spain in 2020 / La importancia de la prevalencia y de la probabilidad pre-test en el diagnóstico microbiológico de SARS-CoV-2: el caso de España en 2020

Objectives. The aim of this work was to estimate the con ditioned probability for the diagnosis of SARS-CoV-2 infection with reverse transcription polymerase chain reaction (RT-PCR), viral antigen rapid diagnostic tests (Ag-RDT), and antibody detection tests depending on the prevalence in the specific healthcare settings in Spain in 2020, and on the pre-test prob ability (PTP) according to the clinical situation, age and un known or close contacts of the patient. Material and methods. Performance parameters of tests were obtained from literature. Prevalence data and PTP were obtained from Spanish sources and a survey, respectively. The post-test probability is the positive predictive value (PPV) when test is positive. For negative result, we also calculated the probability of having the infection (false negatives). Results. For both RT-PCR and viral Ag-RDT, the lowest PPV values were for the population screenings. This strategy proved to be useful in ruling out infection but generates a high number of false positives. At individual level, both tools provided high PPV (≥ 97%) when the PTP values are over 35%. In seroprevalence studies, though the specificity of IgG alone tests is high, under low seroprevalence, false positives cannot be avoided. Total antibodies tests are useful for diagnosis of COVID-19 in those doubtful cases with RT-PCR or Ag-RDT tests being repeatedly negative. Conclusions. The interpretating of results depends not only on the accuracy of the test, but also on the prevalence of the infection in different settings, and the PTP associated to the patient before performing the test (AU)

bjetivos. En este trabajo estimamos la probabilidad con dicionada del diagnóstico de infección por SARS-CoV-2 con RT PCR, pruebas de antígenos virales (Ag-RDT) y pruebas de detec ción de anticuerpos, en función de la prevalencia en España en diferentes ámbitos durante 2020, y de la probabilidad pre-test (PPT) según la situación clínica, edad y contactos del paciente. Material y métodos. Los parámetros de rendimiento de las pruebas se obtuvieron de bibliografía. Los datos de preva lencia y PPT se obtuvieron de fuentes españolas y de una en cuesta, respectivamente. La probabilidad post-test es el valor predictivo positivo (VPP) cuando la prueba es positiva. Para el resultado negativo, también calculamos la probabilidad de te ner la infección (falsos negativos). Resultados. Tanto con RT-PCR como con Ag-RDT, los va lores más bajos de VPP se detectaron en los cribados poblacio nales, que demostraron ser útiles para descartar la infección, pero generan muchos falsos positivos. A nivel individual, am bas pruebas proporcionaron un VPP ≥ 97% cuando los valores de PPT son superiores al 35%. En estudios de seroprevalencia, aunque la especificidad de las pruebas de IgG sola es alta, si la seroprevalencia es baja, no se pueden evitar falsos positivos. Además, las pruebas de anticuerpos totales pueden ayudar al diagnóstico de COVID-19 en aquellos casos dudosos con prue bas de RT-PCR o Ag-RDT repetidamente negativas. Conclusiones. La interpretación de los resultados depen de no sólo del rendimiento de las pruebas, sino también de la prevalencia de la infección en diferentes ámbitos, y de la PPT asociada al paciente antes de realizar la prueba (AU)

The Impact of Colistin Resistance on the Activation of Innate Immunity by Lipopolysaccharide Modification.

Colistin resistance is acquired by different lipopolysaccharide (LPS) modifications. We proposed to evaluate the of effect in vivo colistin resistance acquisition on the innate immune response. We used a pair of ST11 clone Klebsiella pneumoniae strains: an OXA-48, CTX-M-15 K. pneumoniae strain susceptible to colistin (CS-Kp) isolated from a urinary infection and its colistin-resistant variant (CR-Kp) from the same patient after prolonged treatment with colistin. No mutation of previously described genes for colistin resistance (pmrA, pmrB, mgrB, phoP/Q, arnA, arnC, arnT, ugdH, and crrAB) was found in the CR-Kp genome; however, LPS modifications were characterized by negative-ion matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. The strains were cocultured with human monocytes to determine their survival after phagocytosis and induction to apoptosis. Also, monocytes were stimulated with bacterial LPS to study cytokine and immune checkpoint production. The addition of 4-amino-4-deoxy-l-arabinose (Ara4N) to lipid A of CR-Kp accounted for the colistin resistance. CR-Kp survived significantly longer inside human monocytes after being phagocytosed than did the CS-Kp strain. In addition, LPS from CR-Kp induced both higher apoptosis in monocytes and higher levels of cytokine and immune checkpoint production than LPS from CS-Kp. Our data reveal a variable impact of colistin resistance on the innate immune system, depending on the responsible mechanism. Adding Ara4N to LPS in K. pneumoniae increases bacterial survival after phagocytosis and elicits a higher inflammatory response than its colistin-susceptible counterpart.